Great Video. Was trained in the Navy on vacuum tube technology, in 1974 but your way of explaining these concepts is very clear. Thanks. Keep up the good work.
Aside from all I have learned from you after already working on tube amps for years, I love how there will be a random hot rod (or sand rail) sometimes just in frame lol. I know you build cars too, it's just a great addition to your uploads.
Fabulous videos, thank you and Rusty for all the hard work! Towards the end of the video you declined to go down the rabbit hole of the full purpose of the resistors and interaction between the capacitors and resistors as beyond the scope of the video - please consider doing another video on that subject, it was the part I was particularly hoping to learn more about! Thanks again : )
Uncle Doug, unknown to you, I've under your apprenticeship for a while now. Your training videos are very helpful to a wanna be tube amp tech, thank you! I want to understand the why, not just change parts and you provide simple, straight forward explanations that are easy to understand. Hopefully I'll be able to graduate someday..... :) The tone stack video is perfect timing for me, since I've been working on repairing, now converting a Bogen M330A PA amp for guitar (2x7868s). I replaced the Bogen tone stack (treble and bass) with a tweed version, but it ended up too dirty (I might need to move the tone stack location?). My next attempt is the fender TMB tone stack. Your Part 1 is helping me understand and I can't waiting for Part 2 so I can try it out on the Bogen.
These are FANTASTIC! Everyone should watch these, and Rusty is just the icing on the cake. Dogs just move anything onto the next level. Thanks for making these, you are providing a valuable public service.
Uncle Doug I see people are smartening up and subscribing. If you want to really learn, it's all you, but if all you want is to see someone shotgun parts to make an amp work well just about any RUclipsr can do this, you are a great teacher. You troubleshoot and hit the spot and offer modding to make it more beefy or less, kinda like electrical porn. I'm 58, Brad the Guitologist could be my son and he knows more than I do, I was late in this game, but worked many of others, but lately I'm figuring out more and more on his site and stop the video and make a comment. More and more I'm getting it right and have to go back to delete my comment or reply saying what I did thanks to you. Thank you...
Hi Uncle Doug, So many light bulbs went off in my head watrching this video. I've been tinkering with tube amps for a while but there where areas that I did not really understand that well. The way you explain things is brilliant....for the first time I really get it.WOW! Thank you very kindly sir! Subscribed.
Even though I know the operation of capacitors in passing frequency but had never though about it being in terms wavelength.. The low pass filter is why we see orange-red sunsets, or a full moon eclipse is often a ruddy red. :-) Our atmosphere is a low pass filter. Lucky for us, or we probably wouldn't be here...(at least in this form) Great job with these instructional videos, thanks much!!
@@UncleDoug Thanks, same reason we hear the hip-hop bass from two miles away yet nothing else of the recording, the longer the wavelength the further it travels in our atmosphere. :-)
I'm sure the cat has a high pass brain-capacitor in her head, that filters out all non-food-related sound frequencies from your voice! I could see it working in her eyes!
Thanks very much for the time and effort that you devote to passing on your vast knowledge. You have been such a huge help to me in my journey of learning this difficult skill and I want you to know that I appreciate your generosity very much. Cheers from Pat down under.
Interesting stuff Doug, I am about to attempt my first tube amp experience with converting a PA system, it basically just has one tone knob, this is helping to give me a clearer direction on what needs to happen. Thank you Doug.
The amount of pleasure when you type "passive tone control uncledoug" into that tube search box and find out there's not only one, but two (at least) videos covering the subject. Ahhh.....
I hope you put the soldering pen down so you could turn up the volume and take notes, MM.....not to do a quick RUclips search for "Russian Pole Dancer" :)
UD & R... I have my first question... If I am going to design a prototype amplifier, would it be smart to use a variable resistor in all the locations where tone can be affected so I can "tune" the circuit to the sweet spots? Then when the desired value is discovered, change out the variable resistor with a fixed value resistor for subsequent non-prototype builds? Thanks.
What you're describing is an excellent way to optimize any audio circuit.....clip in a pot, dial in the tone you seek, and then hardwire that chosen resistance value into the circuit. Same with capacitors.....wire in a low value cap and then bridge it (touch the leads of another cap to its leads.....in parallel) with other value caps to find the perfect capacitance for your circuit. All the calculations in the world can't match a hand-tuned audio circuit.
Oh man. That's a great tip on the caps. I'm guessing I'll use some kind of proto board to swap certain pieces in and out of the circuits. For me it's all about the experimentation and hooking up the caps in parallel will let me do just that!
Glad to see ya. Your knowledge is priceless. Great video. No russian pole dancers for me. Lol. ( pretty much wanna know your half hour lesson on that resistor. );) cool tube frame
Just wanted to add another thanks. Was working on an amp that made no sense to me after 2nd valve. Your cathode follower explanation was spot on and explained why I was so confused.
Another great video... I was fiddling around with my amp in my garage looking at the tone stack of my Fender Blues Deluxe amp and my phone alerts me you uploaded a new video about tone stacks! Unreal. Also your cat looks exactly like my cat only mine is a boy and boy is he finicky. I love your videos so keep 'em coming! I'm learning a lot!
First off, thank you so much for all of your videos, they are incredibly informative, cover the material in an easy to understand language, and are entertaining as well - you have a wonderfully understated sense of humour!! On the topic of tone stacks, at the point where you introduce the more standard appearance of a high and low pass filter in a circuit, I'm not grasping the effect of the resistor in its two positions. My level of understanding only goes so far as to know that this combination results in a certain output frequency response based on the values of each, but how the resistor affects the outcome is unclear. Is there a way to look at what the resistor does that is visually similar to understand as your explanation of the capacitor in the circuit? The information allows me to look at more parts of a preamp or amplifier circuit and understand the affects of all of the components, such a great thing to understand when wanting to modify a circuit!! Cheers and stay well!!
Well, ain't that quick!!! I was just a couple of minutes into the section when I typed the question above, am finding my answer at around the 22 minute mark!! As was the statement in a popular skit on SNL, "never mind" ;-)
I'm really enjoying you videos, Uncle Doug. I first watched them just to see a little amp repair and learn a bit but these are so much more educational than I expected. You manage to turn every repair into an educational opportunity yet I never feel overwhelmed.
I love the way you explain things. I'm sure you are really PROFESSOR Uncle Doug! If not, then please start up U.D. Tone University...you'll have a ton of students...me included. Thanks for these vids...the best on RUclips.
PeterPug007 You're welcome, Peter, and thanks for the very nice comments. Rusty and I are real happy you're enjoying our videos. Thanks for watching :)
You obviously never been to college because if he was a professor it would take about six years to understand what he made perfectly clear in about 30 minutes.
I just recently stumbled across your videos and instantly subscribed! Your videos really help me grasp what's going on the amp. Now while I wait for part 2, off to watching pole dancing. ;-)
Thanks so much, Daniel. Rusty and I kid around a little sometimes, but we really try to make the videos clear, concise, and informative. It's good to know that viewers (like you) are enjoying them.
Uncle Doug Viewers like me are enjoying them too! I didn't really UNDERSTAND just how similar (equal and opposite) a low-pass filter was to a high-pass filter until I saw you drawing it out and narrating in plain English. THANK YOU!
You're quite welcome, Adam. Yes, the two filters are really quite similar in design but opposite in function......which is an unusual combination. It's always good to hear from you. Please stay tuned for part 2, I think you will like it :)
Uncle Doug I will be anxiously awaiting part 2. I need to understand the theory of the cathode-follower better, because I know I can do a much more effective tone control if most of the preamp stages are left alone to drive each other into clipping, then a late-stage cathode-follower takes the ALREADY DISTORTED signal and sculpts it into a mor mixable tone. This is why so many people prefer to have an eq pedal in the effects loop of a relatively high-gain amp, rather than just try to shape the tone early in the signal path, but I don't want to have to complicate a build with adding a separate path for an effects loop. Can't wait to see you and Rusty for round 2!
An interesting concept, Adam. Please let me know how it turns out. If you are still uncertain about cathode follower theory, then do some Internet searches on the topic and (my favorite) download a schematic that features a CF and study each of its inputs, outputs, voltages, etc. Using this, you can then create a CF within another non-CF circuit. Best of luck !!
Another excellent video. I'm glad you mentioned the question of the role of a resistor in RC filters. I've always wondered the same thing. I look forward to part 2. One small request-Would it be possible to shoot/upload 720p videos? The highest res that I can chose in the player is 360p, and at that resolution the schematics are kind of blurry. Thank you for taking the time to make these clear and concise videos.
Greetings, CNS. Yes, the mysterious resistor has always been a sticking point for me too. Re the improved resolution, I thought I was uploading in high resolution (since the video is shot that way) but apparently not. I apologize if the image is a little blurry, and will look into improving the uploading process I have been using. Thanks !!!
Think of a resistive potential divider where the output at the junction of the resistors depends on the resistors' relative values. An RC filter is a potential divider where one of the resistors has been replaced with a capacitor whose reactance (resistance to AC) depends on the frequency of the signal voltage applied to it. As the frequency of the input signal changes, the capacitor's reactance changes and therefore so does the proportion of the input signal which appears at the output.
Thanks for this well-researched and well presented lecture. However, I have a few minor things regarding the topic on transformer and rectification of a-c to d-c from other lectures. 1. Maybe you should mention the difference between RMS and peak valves. 2. When people say 520V CT, don't they mean 260V, not 1040V as implied. 3. Ripple current. After the a-c is rectified, the voltage presented to the smoothing capacitor is the peak value. In this case, it is 260V d-c x 1.414. Not 260V d-c. This is very important as the valves will fail later because the B+ is well outside of their operating limits. 4. The ripple voltage is quite small, not as shown in the diagram. otherwise, you'll have massive distortion when you crank the volume up! These are only very minor details, however, it makes the difference between live and death of the output tubes! Thank you very much for your attention. Baulau Cheung.
I understand, Leo.....and I apologize for not saying it more often, but Vox amps are rare as hen's teeth in my area. I never get a chance to work on any of them.
The resistor makes it a frequency dependant voltage divider. Both the resistance and capacitance determine the cut off frequency of the filter with the equation f=1/(2*pi*R*C) where f is frequency in Herz (cycles per second) R is resistance in Ohms and C is capacitance in Fahrad. Of course the output impedance of the previous stage must be low enough and the imput impedance of the next stage must be high enough to be of negligible influence on the filter or then you calculate those in.
Doug, I love your videos. Do you plan to discuss designing B+ power rails, bias circuits, the inverter bridge or why the 5f6a (and plexi style amps) choose 2 different plate bias resistor values to drive the power tubes? I hope you and Rusty keep this up!! Thank you!
+AviEdelson You're welcome, Avi. I'm glad you enjoy the videos. I have already posted videos covering the Power Supply, Biasing of SE and DE circuits, changing from Fixed to Variable Bias, etc. I have no experience with inverters......perhaps you mean full wave bridge rectifier, which I rarely encounter in vintage tube amps, but are well covered in numerous Internet sites. Also, I am not familiar with plate bias resistors.....perhaps you mean plate resistors. If so, then altering the value of the plate resistor between stages alters the gain. Higher value PR yields greater gain, and vice versa. If you mean bias resistors, then altering them will change the tube bias and affect the volume level at which breakup occurs (i.e. headroom). Cool bias yields more headroom, and vice versa. Thanks for watching.
I’m just getting into modding and this video is GREAT for the beginner. I just have some incomplete understanding about the resister and capacitor placement in tone filters. Why a resistor before a cap in low pass and why bother with the resistor to ground at all in high pass? As mentioned I’m just starting. Thanx! (Ha! Never mind I didn’t watch the whole video before asking 😁)
Im a mechanical engineer. I took E-science in college,.. I got a B in the class, but it was just an endurance test, and I kind of put all of the math in a compressed ball of knowledge that I would discard as soon as the situation allowed... Fast forward 25 years... My hobbies have once again drug me into deep waters.... I dont know why, but I have to understand how all of this works,... Needless to say, but this explanation is so practical and consumable that I just can't stop watching these videos.... I wish there was a way to assign a value to people that were willing and able to spend the effort to present an otherwise difficult to understand topic in practical terms. Its as if someone handed me an exaplaination free of charge, and thanked me for accepting,,, Im very greatfull....
REALLY liking your new videos U.D. Have a question about your formula for the Peak to RMS to power calculation at the end of the video. You say to multiply the the end result (Times) .707. Shouldn't you convert the the peak voltage first? Like (6 X .707) squared over the Resistance? Also, the scope reading is Peak to Peak, is that different than "Peak" value. I mean is a voltmeter reading the RMS value of "Peak" or "Peak to Peak" voltage?
Thanks for your input, Dean. Yes, the formula correction was already addressed in a statement I pinned to the top of the Comments section yesterday. Peak value for the formula is the amplitude of the AC wave from 0 to peak voltage. If it were peak-to-peak, it would be zero. An AC voltmeter reads it the same way and then converts it to RMS.
Thank you for all of your dedicated work. I'm a visual learner so reading is very difficult, which makes vacuum tubes a very difficult hobby to understand. Capacitors have *always* been difficult for me to understand for some reason (for the past four years I've been in the EE hobby) and you have been able to explain it to me perfectly. You explain *why* exactly how I need it.
Hey Uncle Doug, Thanks for the great theorizing of the circuits components and their basic variables. I saw alot of what the great designers like Leo Fender,JimMarshall, Tom Jennings,Dallas Reeves, to name a few including the bolstering of the latter Randall Smith of Mesa to the Soldanos had in mind and the overall designs of passive to active. I use a downloaeded Tonestack Calculator and it makes it easier using your input to achieve a great deal of information I either didn't have or didn't understand.!! I've seen you explain many of their concepts in depth! It's more than just adding or changing a resistor, or capacitor here and there, but I didn't lose interest and best I could at least rewind and start again!!! I have an incredible amount(s) of bookmarks and have applied alot to my own works,..I noticed this last forum also relates to the basic use of the .001uf for the ''Treble Bleed'' on my guitar's Volume pot and Tone control. After awhile it all seems to make sense, please keep up the great works!!
You're welcome, Nelson. It's always good to hear from you. Rusty and I will do our best to keep up the video production.....as long as you promise to keep watching :)
Uncle Doug I just have to say, I truly appreciate your explanations. You lay out the information so well. I refer to your tutorials all the time. I noticed the new tutorial, so I figured it was time to check in at Ampaholics Unanimous and let you know how grateful I am for your help. I look forward to seeing the next one. Thanks Again.
Thanks, OOS. Rusty is a method actor, much like Brando, Hoffman, and De Niro, and tends to "live the part". Since the script calls for him to appear to be lazy and disinterested, he has simply assumed these qualities. In real life, however, he is a bundle of energy and enthusiasm. In fact, he would tell you all this himself.....but he is currently taking his fourth nap of the day :)
I got a question for you. I have an old Fender Deluxe D-3 Tweed I'v tinkered with, with limited knowledge, by putting a 30w output transformer, 6L6s instead of 6V6s and replaced the rectifier with Diodes. I have been using it for a power amp and it sounds awesome, tapped the phase inverter and eliminated the preamp section. I want to put the front end back but wondered if anyone ever wired the first valve in parallel since it is designated for two independent inputs and use both sides for a single input. Have you ever a 12AX7 in parallel? I talked to some kid back in the early 80s that said he did it with his rig for more headroom and a Fat, Bell like tone. Will it blow it up, ha!? I love your vids. Makes me wish I would have gone into building as well as performing. You'r an inspiration. Thanks
It wouldn't "blow up", but as you said, it is not a common way to wire a 12AX7. In my experience, too much gain in the pre-amp does not produce good tone or more headroom.....but the only way to know for sure is to try it and see. Meanwhile, I'm wondering how your power transformer is coping with all the excess current demands of the 6L6's.
Is that a dune buggy in your garage? What the hell, how many cars do you have? Its just not fair. Great video i had no idea caps are used to absorb frequencies. Amazing little devils aren't they? Enjoy, Dennis Do you have the link to the Russian Pole dancer? Kidding!
My dog, Ranger, lays under my bench and locates dropped screws and components for me. He keeps me from spending all my time searching for dropped parts. Gotta love dogs! I like how you include Rusty in your videos. :-)
Hi uncle Doug! Love your videos. I have a question about the output for the midrange frequencies. Towards the end of the video, you changed the potentiometer for the midrange filter on the Marshall to a lower value. This put a greater dip and less gain in the midrange frequencies. Why did that work? Is it because the output resistance from the midrange was lessened, resulting in less gain? Thank you for your videos!
Nick Zeak Tone stack interactions are quite complex, Nick.....alteration of any single pot setting will also affect the other two......but, as with all passive tone controls, reducing the resistance of the mid-range pot simply allowed more of that portion (mid-range frequencies) of the signal to go to ground. This resulted in a decrease of mid-range frequencies being sent to the output tubes and speaker, and a resulting dip in the middle portion of the frequency spectrum.
Doug: "Kitty? 'r you ready to take over the camera work on this video?" Cat: "I'd be ready to take over the world, if I only knew how this strange thing worked..." I love cats :) I hope she's nice to rusty!
I'm not sure if you've filmed part 2 yet, and this may be a tall order here due to time constraints, but if possible, I would appreciate you exploring one additional tone stack: The Baxandall tone stack made famous by Ampeg.
Alva, the original Baxandall stack was an active tone circuit, used primarily in solid-state HiFi and Stereo amps. It's passive form was developed by a man named James. As we will see in Part 2, the majority of tone stacks used in tube amps have a pronounced mid-range "scoop" to compensate for the mid-range intense output of the guitar pickup. The James circuit (at neutral settings) has a "flat" output with no MR scoop. I will add the James audio spectrum to Part 2 to address this difference. Thanks for the input :)
Uncle Doug Bandaxall or shelving filters, in german "kuhschwanz" (=cowtale) because of the frequency response curves;) (i do like that point of view) is derived from the telephone filter designs in the early 30th of the 19th century and then later on used in the recording industry followed by high class audio (Fisher, Marantz, McIntosh,Braun -- to name a few) You can build it active or passive, the main advantage is that they do *not* interact with eachother. The topology is the Sallen/Key filter design. To me this is *by far* more easier to understand than the "wired" tone stacks ;)
Very nice video, the tale of the judgemental capacitor is just sweet :) You wrote somewhere, that Rusty does all the script writing, so no wonder he's not interested in mere camera work, having written such a masterpiece ;)
Thanks so much, Stan. Yes, Rusty vacillates between cinematography, script writing (and editing), and mastering the Lydian Scale on his '59 Les Paul.....he's a very talented and versatile hound :) ^. .^
Thanks Doug for all of your efforts, you are like the teacher I always wanted. I love your videos. So informative and easy to understand. I could make valve amps all day long.
Wait…there’s a “Russian pole dancing video”?! Thank you so much for videos like this one! I have referenced your videos so many times. They really have enhanced my love of tube amplifiers.
22:35 could you please make that 30 minute video explaining the interaction between the capacitor and the resistor? We really don't like Russian pole dancer videos as much as you think. Thanks! ... (I'm trying so hard to understand the mids knobs, I don't get it. All the other controls I understand)
I am deeply move by your dedication and focus. Capacitors require time to charge and discharge. This is what determines their ability to pass or block different frequencies. The resistor interacts with the capacitor to enhance this capability by altering and fine tuning the charge/discharge rate.
I'll try to get part 2 out in the next few days, Charles. Every time I think it's ready, I remember some additional points that need to be included. Also, I will introduce you to a program that will make your project much easier. See you soon :) ^. .^
Might make a video on the time constant of caps in R/C networks as it relates to surface area of the plates and the dielectric material and thickness etc. The larger a plate the greater the microfarad value ( other factors being the same.) thus the relatively longer charge time. The cap doesn't really sense dc but rather stops charging when the plates become saturated thus impeding frequencies below its cutoff frequency. The smaller the cap the shorter the charge time, thus the higher the frequencies it passes (or attenuates if shunted to ground}
First: Thank you Uncle Doug for sharing . I would love to k now "what the hack does the resistor do?" Every time I see a drawing of a HPF this question pops in my mind. I know how to make it work, but I don`t know How it works. (I know how to calculate the cutoff frequency, but when I do it, I don`t know what I am really doing, the physics background.) And I am not in peace with it. .. So in this case I would prefer to watch 30min of a video explaining this, than the pole dancer :)
Greetings, Martin. The frequency response of a capacitor is based mainly on the speed at which it can charge and discharge. Low-value (i.e. pf) caps "pass" high frequencies because they can charge and discharge very rapidly.....the opposite is true with high-value (i.e uf). caps. The resistor alters and "fine tunes" the charge/discharge rate of the cap.
Just a quick revelation, that helped me to understand this. Here you say, "the lower the value of the capacitor, the higher the frequency it passes" (Here in this video: ruclips.net/video/BatwDYFJ9ug/видео.html ) This wording is confusing, and If I may I would suggest the following instead: "The smaller a capacitor's value, the higher the cut off frequency range will be shifted. Below that the capacitor will cut every frequency, above that it will pass all." Reasons: The word "smaller" represents the less capacitance value better then "lower". "the higher the frequency it passes" wording is just too loose, and does not make much sense. It passes frequencies above a certain "cut off point", not one frequency. "Cut off frequency point" is also a confusing term. We have a narrow cut off frequency range, in which the cutting is gradually done. There is no point of such frequency. Wording means a lot when learning new things.
no active circuits such as baxendale CAN CUT as well as boost bass and treble etc. the maun advantge of active tone controls is that you can get a greater db of gain/cut then passive circuit
I need to go back over these wonderful videos. Trying to understand what's going on in some of the classic Fender amps (e.g., Bandmaster, Vibroverb et al) where they use a given pot value in the tone controls, but with a 50 or 70k "tap" - not sure how that works or how it's accomplished. But pretty sure it contributes to the uniqueness of their sound. OK self, back to school. This great library is perma-linked in my browser. Thanks again so much Uncle Doug. Surf on!
Why is it that when you turn the treble middle and bass off on a Boogie F50/5.50 it's like turning the volume off? I cut the mid down for Blackface sound, the bass is about 9 o clock. Treble at 11 oclock or noon. Basically. More amp hiss than guitar volume. All the volume is in the tone knobs! How come?
Passive tone stacks, as used in virtually all guitar amps (including yours, most likely), function by reducing portions of the signal.....the undesired frequencies are sent to ground. Apparently, in your tone circuit, which may or may not be functioning properly, when Treble is at 1/2 and Bass is at 1/4, too much signal goes to ground. Full volume can probably only be attained by having both tone settings at 100%. You might contact Mesa to see if this is the way they designed it, or if your amp tone circuit is malfunctioning.
Another most excellent video Uncle Doug. I've watched it a couple times and enjoyed the Pt.2 amp comparison between the Fender Marshall and Vox amps. Now I know why the Beatles with their Voxs sounded so much brighter than other Brit groups using Marshalls. I was poking around at digikey's site afterward and found their online schematic tool. I know you like to draw your own, but this might come in handy for more complicated circuits. www.digikey.com/schemeit Thanks again for clear coverage of another dense topic.
You're welcome, Andrew. No video posting is complete and official until I hear from you:) Maybe I can get Anastasia to join forces and assist Rusty in video production. During breaks, she could do also do some pole dancing in my workshop......Rusty and I would certainly enjoy the comradery (no pun intended).
Capacitors: you can yhj k of them as, a goalie in a hockey game. He can block a puck shot towards the net. He can probably block a few pucks a minute. Start throwing 100-1000 pucks a minute at him more hes going to miss blocking many of those pucks and they will make it to the goal= the other side of the capacitor. In review: The more pucks per minute( higher frequency), more get past the goalie (through the capacitor).
I'm betting the 'hi--pass' version is what is used in the tone stack of a Rickenbacker GUITAR, where the bridge P/U signal passes from the switch, thru a .0047µ cap, on to the volume pot.
I personally would've enjoyed the decision towards the end, when you chose not to break down all the various 'hows' and 'whys' regarding a resistor's innate functionality within RC networks, if you could've simply briefly supplemented a couple small examples generalizing the relationship between the size of a resistor and the capacitor's overall selectivity in frequency bands. LOL but acknowledging the borderline nit-picky nature of this request isn't lost on me whatsoever haha! I supremely dig all of your channel's content and the overall manner in how you layout all the various concepts and processes pertaining to the respective subject matter in a slightly compartmentalized, albeit, streamlined fashion! This level of commitment, discipline, and plumb dedication to provide a means of formidable education to the public deserves any/all the acknowledgment and success in this lifetime!
Thanks for your very nice comments, H. There are always ways that a video could have been better, but we simply try to do the best we can in a reasonable time frame.
So far so good uncle Doug. We’re gettin it. At least most of it. I’m a mechanical wizard and pretty good with electricity but when it comes to radio and amplifier type circuitry that’s where I start slamming into the wall. I’m good with regular resistance, good with transformers and some inductance but capacitors were the cliff to drive over. They’re coming around more and more. That last part of this one with the ‘ why is there a resistor in the circuit ?’ even made sense to me before you even asked that. I just knew they probably worked together somehow, couldn’t explain it, just knew they balance out together somehow
well, I was really enjoying learning tons about amp circuitry. Then I am now forced to stop this video learning session to go watch a Russian pole dancer. You shouldn't say such things around suggestive people. All kidding aside, I love your style of teaching.
In your calculations for Xc are you assuming any capacitance impedance less than 600 ohms is passing all of the signal. 1/(2*pi*0.1uf*3khz) = 500 Ohm. Good lesson.
Again,Thank you for all of your videos. Very educational. I'm try to learn and understand as much as possible. May I ask, if the tone stack is at the beginning, does the input signal go through the tone stack then to Volume one? Am I on the right track ? Thanks. I keep going over your videos for refreshes.
I have to say, out of all the RUclips videos I've ever watched, you are the absolute best teacher I've ever seen
Wow, thanks so much :)
I really like these videos too. It’s wonderful to finally understand how these things work-and my dad used to build ham radios from scratch..
Your the best thanks so much for your time to teach us
Bob Barcus Thanks so much, Bob :)
10 thumbs down? Must be from amp techs and builders... Sharing and demystifying the sacred arcane knowledge of tone. Best channel on RUclips!!!
Thanks, TJ. I like to think that all ten disapprovals come from one slobbering idiot with 10 different accounts :)
Building and repairing tube amps seems to be a lost art ... Thanks for promoting and teaching us this craft!
You're welcome, Sammy :)
Great Video. Was trained in the Navy on vacuum tube technology, in 1974 but your way of explaining these concepts is very clear. Thanks. Keep up the good work.
Thanks, Mike. Will do :)
Aside from all I have learned from you after already working on tube amps for years, I love how there will be a random hot rod (or sand rail) sometimes just in frame lol. I know you build cars too, it's just a great addition to your uploads.
Thanks, Mark. We try to add some variety to our videos to maintain your interest.
Really awesome explanation of high and low pass filters. Thank you.
Glad it was helpful, Leo.
Fabulous videos, thank you and Rusty for all the hard work! Towards the end of the video you declined to go down the rabbit hole of the full purpose of the resistors and interaction between the capacitors and resistors as beyond the scope of the video - please consider doing another video on that subject, it was the part I was particularly hoping to learn more about! Thanks again : )
Thanks so much, Justin. Please look at the Valve Wizard site to see his explanation of the LTP phase inversion circuit.
I so enjoy all your tube videos. I’ve wanted these for so long! Thank you!!👍🏻
Thanks, R7 :)
Uncle Doug, unknown to you, I've under your apprenticeship for a while now. Your training videos are very helpful to a wanna be tube amp tech, thank you! I want to understand the why, not just change parts and you provide simple, straight forward explanations that are easy to understand. Hopefully I'll be able to graduate someday..... :)
The tone stack video is perfect timing for me, since I've been working on repairing, now converting a Bogen M330A PA amp for guitar (2x7868s). I replaced the Bogen tone stack (treble and bass) with a tweed version, but it ended up too dirty (I might need to move the tone stack location?). My next attempt is the fender TMB tone stack. Your Part 1 is helping me understand and I can't waiting for Part 2 so I can try it out on the Bogen.
all makes sense-thankyou for keeping it at the level to comprehend without going into nuances-perfect teaching method
Thanks so much, Vincent. I'm glad the video was helpful :)
These are FANTASTIC! Everyone should watch these, and Rusty is just the icing on the cake. Dogs just move anything onto the next level. Thanks for making these, you are providing a valuable public service.
+johndogwater You're welcome, John.....glad you enjoy the videos :)
Thanks for a wonderful explanation of the circuit involved.
You're welcome, Larry. Glad it was helpful!
Uncle Doug I see people are smartening up and subscribing. If you want to really learn, it's all you, but if all you want is to see someone shotgun parts to make an amp work well just about any RUclipsr can do this, you are a great teacher. You troubleshoot and hit the spot and offer modding to make it more beefy or less, kinda like electrical porn. I'm 58, Brad the Guitologist could be my son and he knows more than I do, I was late in this game, but worked many of others, but lately I'm figuring out more and more on his site and stop the video and make a comment. More and more I'm getting it right and have to go back to delete my comment or reply saying what I did thanks to you. Thank you...
You are quite welcome, Mr. B. We're glad that our channel has been helpful to you and wish you the very best.
Hi Uncle Doug,
So many light bulbs went off in my head watrching this video. I've been tinkering with tube amps for a while but there where areas that I did not really understand that well. The way you explain things is brilliant....for the first time I really get it.WOW!
Thank you very kindly sir! Subscribed.
FreddysFrets You're quite welcome, Fred, and welcome aboard the UD & Rusty Channel. Thanks for watching and subscribing :)
thank you, Uncle. I wish I had this kind of teacher in the university 10 yrs ago.
Epic Crapton You're welcome, Epic (Rusty loves your screen name). We're glad the video was helpful :)
Great name Epic!
I had a big OH moment went you were explaining frequencies lol "How frequently the signal alternates." XD
Even though I know the operation of capacitors in passing frequency but had never though about it being in terms wavelength.. The low pass filter is why we see orange-red sunsets, or a full moon eclipse is often a ruddy red. :-) Our atmosphere is a low pass filter. Lucky for us, or we probably wouldn't be here...(at least in this form)
Great job with these instructional videos, thanks much!!
You're welcome, Clarence. I like your analogies and observations.
@@UncleDoug Thanks, same reason we hear the hip-hop bass from two miles away yet nothing else of the recording, the longer the wavelength the further it travels in our atmosphere. :-)
Excellent observation, Clarence. The power contained in bass frequencies is much greater.....which is why sub-woofers have their own power supply.
I'm sure the cat has a high pass brain-capacitor in her head, that filters out all non-food-related sound frequencies from your voice! I could see it working in her eyes!
That, and back-scratching frequencies ;)
That beautiful grey cat at 11:33! I had a medium grey like her. Bella was a spicy but wonderful member of our family from 2018 to 2024!
She was a feral kitten that showed up in our front yard, pregnant and starving. She has become one of the most treasured members of our family.
Wonderful video, it's simply amazing how well taught this is and easy to understand. Thank you for all the time you put into this.
You're welcome, Brian. Glad you liked it.
Great Video Uncle Doug !! Rusty did a great job keeping the camera steady !! I am looking forward to Part 2 !!
Thanks so much, Donald. Rusty is nervous that he may lose his job to the cat. A little workplace competition is always good for productivity :)
Just decided to start learning about how tube amps work and can't believe how amazing these videos are.
Also, Rusty rules.
Thanks, Logan. We're glad you enjoy them.
Very useful stuff here, very clear explanation and your funny too with your dog, thumbs up.
Thanks very much for the time and effort that you devote to passing on your vast knowledge. You have been such a huge help to me in my journey of learning this difficult skill and I want you to know that I appreciate your generosity very much. Cheers from Pat down under.
You're quite welcome, Pat. Thanks so much for the very nice comments.
Interesting stuff Doug, I am about to attempt my first tube amp experience with converting a PA system, it basically just has one tone knob, this is helping to give me a clearer direction on what needs to happen. Thank you Doug.
You're welcome, Pat. Good luck with your project.
The amount of pleasure when you type "passive tone control uncledoug" into that tube search box and find out there's not only one, but two (at least) videos covering the subject. Ahhh.....
Thanks, ML. We try to cover all the bases :)
You are an amazing teacher thank you for sharing your time and knowledge.
You're welcome, Josh :)
I was listening to this as a podcast right up until we got to Russian dancer and thats when I put down the soldering pen.
I hope you put the soldering pen down so you could turn up the volume and take notes, MM.....not to do a quick RUclips search for "Russian Pole Dancer" :)
I've always preferred the plate driven tone stacks. I tend to like a lot of sculpting capabilities
UD & R... I have my first question... If I am going to design a prototype amplifier, would it be smart to use a variable resistor in all the locations where tone can be affected so I can "tune" the circuit to the sweet spots? Then when the desired value is discovered, change out the variable resistor with a fixed value resistor for subsequent non-prototype builds? Thanks.
What you're describing is an excellent way to optimize any audio circuit.....clip in a pot, dial in the tone you seek, and then hardwire that chosen resistance value into the circuit. Same with capacitors.....wire in a low value cap and then bridge it (touch the leads of another cap to its leads.....in parallel) with other value caps to find the perfect capacitance for your circuit. All the calculations in the world can't match a hand-tuned audio circuit.
Oh man. That's a great tip on the caps. I'm guessing I'll use some kind of proto board to swap certain pieces in and out of the circuits. For me it's all about the experimentation and hooking up the caps in parallel will let me do just that!
Glad to see ya. Your knowledge is priceless. Great video. No russian pole dancers for me. Lol. ( pretty much wanna know your half hour lesson on that resistor. );) cool tube frame
Glad you liked it, RH. Stay away from those Russian Pole Dancers.....they'll elevate your plate dissipation to dangerous levels :)
Very nicely done.
Just wanted to add another thanks. Was working on an amp that made no sense to me after 2nd valve. Your cathode follower explanation was spot on and explained why I was so confused.
Another great video... I was fiddling around with my amp in my garage looking at the tone stack of my Fender Blues Deluxe amp and my phone alerts me you uploaded a new video about tone stacks! Unreal. Also your cat looks exactly like my cat only mine is a boy and boy is he finicky. I love your videos so keep 'em coming! I'm learning a lot!
Thanks for the great comments, Tony. I'm glad you enjoyed the video, and relieved to know that I'm not the only owner of a finicky, spoiled kitty :)
Uncle Doug, I knew you were cool, but I didn't know you were cool enough to park your dune buggy in the living room.
+Nick paflas Yes, the wife resisted at first, but finally gave in when I showed her how the exhausts could be used as a barbecue grill :)
Your videos are gold. Thank you!
I'm glad you enjoy them, MM.
First off, thank you so much for all of your videos, they are incredibly informative, cover the material in an easy to understand language, and are entertaining as well - you have a wonderfully understated sense of humour!!
On the topic of tone stacks, at the point where you introduce the more standard appearance of a high and low pass filter in a circuit, I'm not grasping the effect of the resistor in its two positions. My level of understanding only goes so far as to know that this combination results in a certain output frequency response based on the values of each, but how the resistor affects the outcome is unclear. Is there a way to look at what the resistor does that is visually similar to understand as your explanation of the capacitor in the circuit?
The information allows me to look at more parts of a preamp or amplifier circuit and understand the affects of all of the components, such a great thing to understand when wanting to modify a circuit!! Cheers and stay well!!
Well, ain't that quick!!! I was just a couple of minutes into the section when I typed the question above, am finding my answer at around the 22 minute mark!!
As was the statement in a popular skit on SNL, "never mind" ;-)
I'm glad the answer was provided in the video, TW. Thanks for watching and subscribing.
thanks for the awesome explanation rusty
Woof :)
I'm really enjoying you videos, Uncle Doug. I first watched them just to see a little amp repair and learn a bit but these are so much more educational than I expected. You manage to turn every repair into an educational opportunity yet I never feel overwhelmed.
That's great to hear, RB. We try to make our videos as entertaining and informative as possible.
I love the way you explain things. I'm sure you are really PROFESSOR Uncle Doug! If not, then please start up U.D. Tone University...you'll have a ton of students...me included.
Thanks for these vids...the best on RUclips.
PeterPug007 You're welcome, Peter, and thanks for the very nice comments. Rusty and I are real happy you're enjoying our videos. Thanks for watching :)
You obviously never been to college because if he was a professor it would take about six years to understand what he made perfectly clear in about 30 minutes.
I just recently stumbled across your videos and instantly subscribed! Your videos really help me grasp what's going on the amp. Now while I wait for part 2, off to watching pole dancing. ;-)
Thanks for subscribing, Gman. I'm glad to hear that the videos are helpful.....and please give Anastasia my regards ;))
Thanks Doug, you are invaluable.
You're welcome, Blair. It is kind of you to say so :)
I very much enjoy how very well made these videos are. A real air of professionalism.
Thanks so much, Daniel. Rusty and I kid around a little sometimes, but we really try to make the videos clear, concise, and informative. It's good to know that viewers (like you) are enjoying them.
Uncle Doug Viewers like me are enjoying them too! I didn't really UNDERSTAND just how similar (equal and opposite) a low-pass filter was to a high-pass filter until I saw you drawing it out and narrating in plain English. THANK YOU!
You're quite welcome, Adam. Yes, the two filters are really quite similar in design but opposite in function......which is an unusual combination. It's always good to hear from you. Please stay tuned for part 2, I think you will like it :)
Uncle Doug I will be anxiously awaiting part 2. I need to understand the theory of the cathode-follower better, because I know I can do a much more effective tone control if most of the preamp stages are left alone to drive each other into clipping, then a late-stage cathode-follower takes the ALREADY DISTORTED signal and sculpts it into a mor mixable tone. This is why so many people prefer to have an eq pedal in the effects loop of a relatively high-gain amp, rather than just try to shape the tone early in the signal path, but I don't want to have to complicate a build with adding a separate path for an effects loop. Can't wait to see you and Rusty for round 2!
An interesting concept, Adam. Please let me know how it turns out. If you are still uncertain about cathode follower theory, then do some Internet searches on the topic and (my favorite) download a schematic that features a CF and study each of its inputs, outputs, voltages, etc. Using this, you can then create a CF within another non-CF circuit. Best of luck !!
Another excellent video. I'm glad you mentioned the question of the role of a resistor in RC filters. I've always wondered the same thing. I look forward to part 2. One small request-Would it be possible to shoot/upload 720p videos? The highest res that I can chose in the player is 360p, and at that resolution the schematics are kind of blurry. Thank you for taking the time to make these clear and concise videos.
Greetings, CNS. Yes, the mysterious resistor has always been a sticking point for me too. Re the improved resolution, I thought I was uploading in high resolution (since the video is shot that way) but apparently not. I apologize if the image is a little blurry, and will look into improving the uploading process I have been using. Thanks !!!
Uncle Doug Great, thanks!
Think of a resistive potential divider where the output at the junction of the resistors depends on the resistors' relative values. An RC filter is a potential divider where one of the resistors has been replaced with a capacitor whose reactance (resistance to AC) depends on the frequency of the signal voltage applied to it. As the frequency of the input signal changes, the capacitor's reactance changes and therefore so does the proportion of the input signal which appears at the output.
Thanks Uncle Doug, another excellent lesson. I've learnt so much from your videos, can't wait for part two.
You're welcome, Ian. Positive feedback from viewers (like you) makes it all worthwhile. Part 2 should be posted in the next few days, so stay tuned :)
Thanks for this well-researched and well presented lecture. However, I have a few minor things regarding the topic on transformer and rectification of a-c to d-c from other lectures.
1. Maybe you should mention the difference between RMS and peak valves.
2. When people say 520V CT, don't they mean 260V, not 1040V as implied.
3. Ripple current. After the a-c is rectified, the voltage presented to the smoothing capacitor is the peak value. In this case, it is 260V d-c x 1.414. Not 260V d-c. This is very important as the valves will fail later because the B+ is well outside of their operating limits.
4. The ripple voltage is quite small, not as shown in the diagram. otherwise, you'll have massive distortion when you crank the volume up!
These are only very minor details, however, it makes the difference between live and death of the output tubes! Thank you very much for your attention.
Baulau Cheung.
You're welcome, BC. Thanks for your very nice comments and input. Please see my other videos that address most of your concerns.
My heart leaped when you said Vox. :D
I understand, Leo.....and I apologize for not saying it more often, but Vox amps are rare as hen's teeth in my area. I never get a chance to work on any of them.
A very informative video! I'm trying to build my own guitar amp and this video helped me a lot! subed :)
smehtarocks Welcome aboard. Glad you enjoyed the video......thanks for subscribing :)
The resistor makes it a frequency dependant voltage divider. Both the resistance and capacitance determine the cut off frequency of the filter with the equation f=1/(2*pi*R*C) where f is frequency in Herz (cycles per second) R is resistance in Ohms and C is capacitance in Fahrad.
Of course the output impedance of the previous stage must be low enough and the imput impedance of the next stage must be high enough to be of negligible influence on the filter or then you calculate those in.
Yes, since both resistance and capacitance are included in the cut-off frequency formula, both factors influence the resulting value.
Doug, I love your videos. Do you plan to discuss designing B+ power rails, bias circuits, the inverter bridge or why the 5f6a (and plexi style amps) choose 2 different plate bias resistor values to drive the power tubes? I hope you and Rusty keep this up!! Thank you!
+AviEdelson You're welcome, Avi. I'm glad you enjoy the videos. I have already posted videos covering the Power Supply, Biasing of SE and DE circuits, changing from Fixed to Variable Bias, etc. I have no experience with inverters......perhaps you mean full wave bridge rectifier, which I rarely encounter in vintage tube amps, but are well covered in numerous Internet sites. Also, I am not familiar with plate bias resistors.....perhaps you mean plate resistors. If so, then altering the value of the plate resistor between stages alters the gain. Higher value PR yields greater gain, and vice versa. If you mean bias resistors, then altering them will change the tube bias and affect the volume level at which breakup occurs (i.e. headroom). Cool bias yields more headroom, and vice versa. Thanks for watching.
I’m just getting into modding and this video is GREAT for the beginner. I just have some incomplete understanding about the resister and capacitor placement in tone filters. Why a resistor before a cap in low pass and why bother with the resistor to ground at all in high pass? As mentioned I’m just starting. Thanx! (Ha! Never mind I didn’t watch the whole video before asking 😁)
Thanks !!! Hopefully the video answered your questions, William.
Great video! Many thanks.
+SiliconSet You're welcome, SS :)
Im a mechanical engineer. I took E-science in college,.. I got a B in the class, but it was just an endurance test, and I kind of put all of the math in a compressed ball of knowledge that I would discard as soon as the situation allowed... Fast forward 25 years... My hobbies have once again drug me into deep waters.... I dont know why, but I have to understand how all of this works,... Needless to say, but this explanation is so practical and consumable that I just can't stop watching these videos.... I wish there was a way to assign a value to people that were willing and able to spend the effort to present an otherwise difficult to understand topic in practical terms. Its as if someone handed me an exaplaination free of charge, and thanked me for accepting,,, Im very greatfull....
We appreciate your very kind comments, Jeremiah, and are glad that our videos have been helpful :)
REALLY liking your new videos U.D. Have a question about your formula for the Peak to RMS to power calculation at the end of the video. You say to multiply the the end result (Times) .707. Shouldn't you convert the the peak voltage first? Like (6 X .707) squared over the Resistance? Also, the scope reading is Peak to Peak, is that different than "Peak" value. I mean is a voltmeter reading the RMS value of "Peak" or "Peak to Peak" voltage?
Thanks for your input, Dean. Yes, the formula correction was already addressed in a statement I pinned to the top of the Comments section yesterday. Peak value for the formula is the amplitude of the AC wave from 0 to peak voltage. If it were peak-to-peak, it would be zero. An AC voltmeter reads it the same way and then converts it to RMS.
Another great video, my learning curve keeps climbing lol cheers!!
Greetings, Mudy. May your learning curve be as vertical as Anastasia's pole ;)
Thank you for all of your dedicated work. I'm a visual learner so reading is very difficult, which makes vacuum tubes a very difficult hobby to understand. Capacitors have *always* been difficult for me to understand for some reason (for the past four years I've been in the EE hobby) and you have been able to explain it to me perfectly. You explain *why* exactly how I need it.
You're welcome, Bob. Rusty and I are really glad that our videos are helpful to you. Thanks for watching :)
I am 72 and it has been a long time since I was in electronics so this is back to school for me.
Awesome video!
+Ogre Badogre Thanks, OB :)
Hey Uncle Doug, Thanks for the great theorizing of the circuits components and their basic variables. I saw alot of what the great designers like Leo Fender,JimMarshall, Tom Jennings,Dallas Reeves, to name a few including the bolstering of the latter Randall Smith of Mesa to the Soldanos had in mind and the overall designs of passive to active. I use a downloaeded Tonestack Calculator and it makes it easier using your input to achieve a great deal of information I either didn't have or didn't understand.!!
I've seen you explain many of their concepts in depth! It's more than just adding or changing a resistor, or capacitor here and there, but I didn't lose interest and best I could at least rewind and start again!!! I have an incredible amount(s) of bookmarks and have applied alot to my own works,..I noticed this last forum also relates to the basic use of the .001uf for the ''Treble Bleed'' on my guitar's Volume pot and Tone control. After awhile it all seems to make sense, please keep up the great works!!
You're welcome, Nelson. It's always good to hear from you. Rusty and I will do our best to keep up the video production.....as long as you promise to keep watching :)
Uncle Doug I just have to say, I truly appreciate your explanations. You lay out the information so well. I refer to your tutorials all the time. I noticed the new tutorial, so I figured it was time to check in at Ampaholics Unanimous and let you know how grateful I am for your help. I look forward to seeing the next one. Thanks Again.
You're quite welcome, P. It's great to hear that the videos are understandable and helpful. Welcome back to Ampaholics Unanimous :)))
Iove your dogs
Another informative video Uncle Doug, but I think you need to give poor Rusty his walking papers, he does too much loafing on the job!!!
Thanks, OOS. Rusty is a method actor, much like Brando, Hoffman, and De Niro, and tends to "live the part". Since the script calls for him to appear to be lazy and disinterested, he has simply assumed these qualities. In real life, however, he is a bundle of energy and enthusiasm. In fact, he would tell you all this himself.....but he is currently taking his fourth nap of the day :)
I got a question for you. I have an old Fender Deluxe D-3 Tweed I'v tinkered with, with limited knowledge, by putting a 30w output transformer, 6L6s instead of 6V6s and replaced the rectifier with Diodes. I have been using it for a power amp and it sounds awesome, tapped the phase inverter and eliminated the preamp section. I want to put the front end back but wondered if anyone ever wired the first valve in parallel since it is designated for two independent inputs and use both sides for a single input. Have you ever a 12AX7 in parallel? I talked to some kid back in the early 80s that said he did it with his rig for more headroom and a Fat, Bell like tone. Will it blow it up, ha!? I love your vids. Makes me wish I would have gone into building as well as performing. You'r an inspiration. Thanks
It wouldn't "blow up", but as you said, it is not a common way to wire a 12AX7. In my experience, too much gain in the pre-amp does not produce good tone or more headroom.....but the only way to know for sure is to try it and see. Meanwhile, I'm wondering how your power transformer is coping with all the excess current demands of the 6L6's.
Is that a dune buggy in your garage? What the hell, how many cars do you have? Its just not fair. Great video i had no idea caps are used to absorb frequencies. Amazing little devils aren't they? Enjoy, Dennis Do you have the link to the Russian Pole dancer? Kidding!
These videos have been made over several years, Dennis, and cars come and go. I never own many at one time. Be sure to watch our video on capacitors.
Wonderful video and great instructional design. I loved it!
Thanks so much, Justin. Rusty and I are glad you enjoyed the video :)
Rusty cracks me up!
He is a droll little fellow......and a great workshop companion.
My dog, Ranger, lays under my bench and locates dropped screws and components for me. He keeps me from spending all my time searching for dropped parts. Gotta love dogs! I like how you include Rusty in your videos. :-)
Hi uncle Doug! Love your videos. I have a question about the output for the midrange frequencies. Towards the end of the video, you changed the potentiometer for the midrange filter on the Marshall to a lower value. This put a greater dip and less gain in the midrange frequencies. Why did that work? Is it because the output resistance from the midrange was lessened, resulting in less gain? Thank you for your videos!
Nick Zeak Tone stack interactions are quite complex, Nick.....alteration of any single pot setting will also affect the other two......but, as with all passive tone controls, reducing the resistance of the mid-range pot simply allowed more of that portion (mid-range frequencies) of the signal to go to ground. This resulted in a decrease of mid-range frequencies being sent to the output tubes and speaker, and a resulting dip in the middle portion of the frequency spectrum.
Doug: "Kitty? 'r you ready to take over the camera work on this video?"
Cat: "I'd be ready to take over the world, if I only knew how this strange thing worked..."
I love cats :) I hope she's nice to rusty!
Greetings, JF. They have a mutual non-aggression pact. Rusty sneaks in an occasional sniff, but otherwise they try to ignore each other.
I'm not sure if you've filmed part 2 yet, and this may be a tall order here due to time constraints, but if possible, I would appreciate you exploring one additional tone stack: The Baxandall tone stack made famous by Ampeg.
Alva, the original Baxandall stack was an active tone circuit, used primarily in solid-state HiFi and Stereo amps. It's passive form was developed by a man named James. As we will see in Part 2, the majority of tone stacks used in tube amps have a pronounced mid-range "scoop" to compensate for the mid-range intense output of the guitar pickup. The James circuit (at neutral settings) has a "flat" output with no MR scoop. I will add the James audio spectrum to Part 2 to address this difference. Thanks for the input :)
Uncle Doug
Bandaxall or shelving filters, in german "kuhschwanz" (=cowtale) because of the frequency response curves;) (i do like that point of view) is derived from the telephone filter designs in the early 30th of the 19th century and then later on used in the recording industry followed by high class audio (Fisher, Marantz, McIntosh,Braun -- to name a few)
You can build it active or passive, the main advantage is that they do *not* interact with eachother. The topology is the Sallen/Key filter design. To me this is *by far* more easier to understand than the "wired" tone stacks ;)
I can see where the Baxandall's lack of interaction would make them a whole lot easier to understand. Tone stack interactions are very complex.
Very nice video, the tale of the judgemental capacitor is just sweet :)
You wrote somewhere, that Rusty does all the script writing, so no wonder he's not interested in mere camera work, having written such a masterpiece ;)
Thanks so much, Stan. Yes, Rusty vacillates between cinematography, script writing (and editing), and mastering the Lydian Scale on his '59 Les Paul.....he's a very talented and versatile hound :) ^. .^
Rusty, at about the 1:30 mark: "Yeah, no... not feelin' it today, Doug!"
That pretty well described Rusty at any and all times ;)
Thanks Doug for all of your efforts, you are like the teacher I always wanted. I love your videos. So informative and easy to understand. I could make valve amps all day long.
Wow, thanks so much, Davey. We really appreciate it :)
Great stuff. Thanks for what you do!
You're welcome, Howard :)
This is a remarkable presentation and truly gives practical information we can all use! Thank you! Stuart
You're welcome, Stuart. We sincerely appreciate your very nice comments :)
Wait…there’s a “Russian pole dancing video”?! Thank you so much for videos like this one! I have referenced your videos so many times. They really have enhanced my love of tube amplifiers.
Yes, indeed, Roly.......and they are a sight to behold. We're glad you enjoy our videos :)
22:35 could you please make that 30 minute video explaining the interaction between the capacitor and the resistor? We really don't like Russian pole dancer videos as much as you think. Thanks!
... (I'm trying so hard to understand the mids knobs, I don't get it. All the other controls I understand)
I am deeply move by your dedication and focus. Capacitors require time to charge and discharge. This is what determines their ability to pass or block different frequencies. The resistor interacts with the capacitor to enhance this capability by altering and fine tuning the charge/discharge rate.
@@UncleDoug okay, I think that's all I need. The rate of charge and discharge, that's the piece I was missing. Thanks so much!
Can hardly wait for part 2! I'm working on a tone stack project right now, so this is timely and appreciated info.
I'll try to get part 2 out in the next few days, Charles. Every time I think it's ready, I remember some additional points that need to be included. Also, I will introduce you to a program that will make your project much easier. See you soon :) ^. .^
Might make a video on the time constant of caps in R/C networks as it relates to surface area of the plates and the dielectric material and thickness etc. The larger a plate the greater the microfarad value ( other factors being the same.) thus the relatively longer charge time. The cap doesn't really sense dc but rather stops charging when the plates become saturated thus impeding frequencies below its cutoff frequency. The smaller the cap the shorter the charge time, thus the higher the frequencies it passes (or attenuates if shunted to ground}
Excellent explanation, Jerry. Thanks !!
Very easy to learn video. Thak you very much for sharing your knowledge in such a way.
Regards from Argentina.
flaconsius You're welcome.....glad you liked it :) Best wishes from Rusty and UD.
Thank you so much!! You're this moms' favorite professor. I subscribed and shared
+Kim Orellana You're welcome, Kim. We really appreciate it :)
That capacitor is a frequencist
I never looked at it that way, Bob ;)
First: Thank you Uncle Doug for sharing .
I would love to k now "what the hack does the resistor do?"
Every time I see a drawing of a HPF this question pops in my mind.
I know how to make it work, but I don`t know How it works.
(I know how to calculate the cutoff frequency, but when I do it, I don`t know what I am really doing, the physics background.)
And I am not in peace with it.
.. So in this case I would prefer to watch 30min of a video explaining this, than the pole dancer :)
Greetings, Martin. The frequency response of a capacitor is based mainly on the speed at which it can charge and discharge. Low-value (i.e. pf) caps "pass" high frequencies because they can charge and discharge very rapidly.....the opposite is true with high-value (i.e uf). caps. The resistor alters and "fine tunes" the charge/discharge rate of the cap.
Just a quick revelation, that helped me to understand this.
Here you say, "the lower the value of the capacitor, the higher the frequency it passes"
(Here in this video: ruclips.net/video/BatwDYFJ9ug/видео.html )
This wording is confusing, and If I may I would suggest the following instead:
"The smaller a capacitor's value, the higher the cut off frequency range will be shifted. Below that the capacitor will cut every frequency, above that it will pass all."
Reasons:
The word "smaller" represents the less capacitance value better then "lower".
"the higher the frequency it passes" wording is just too loose, and does not make much sense. It passes frequencies above a certain "cut off point", not one frequency.
"Cut off frequency point" is also a confusing term. We have a narrow cut off frequency range, in which the cutting is gradually done. There is no point of such frequency.
Wording means a lot when learning new things.
Thanks for your input, Greg, but I'm sticking with my original statement. To me it's much clearer and more concise.
no active circuits such as baxendale CAN CUT as well as boost bass and treble etc. the maun advantge of active tone controls is that you can get a greater db of gain/cut then passive circuit
I need to go back over these wonderful videos. Trying to understand what's going on in some of the classic Fender amps (e.g., Bandmaster, Vibroverb et al) where they use a given pot value in the tone controls, but with a 50 or 70k "tap" - not sure how that works or how it's accomplished. But pretty sure it contributes to the uniqueness of their sound. OK self, back to school. This great library is perma-linked in my browser. Thanks again so much Uncle Doug. Surf on!
+Wes Howard You're welcome, Wes. It's great to hear that the videos are helpful. Best of luck with your self-education and your projects :)
I love Rusty's enthusiasm! I just found your channel. Love the content!
Yes, he did tend to be hyperactive at times ;) Welcome :)
Why is it that when you turn the treble middle and bass off on a Boogie F50/5.50 it's like turning the volume off?
I cut the mid down for Blackface sound, the bass is about 9 o clock. Treble at 11 oclock or noon.
Basically. More amp hiss than guitar volume. All the volume is in the tone knobs! How come?
Passive tone stacks, as used in virtually all guitar amps (including yours, most likely), function by reducing portions of the signal.....the undesired frequencies are sent to ground. Apparently, in your tone circuit, which may or may not be functioning properly, when Treble is at 1/2 and Bass is at 1/4, too much signal goes to ground. Full volume can probably only be attained by having both tone settings at 100%. You might contact Mesa to see if this is the way they designed it, or if your amp tone circuit is malfunctioning.
Another most excellent video Uncle Doug. I've watched it a couple times and enjoyed the Pt.2 amp comparison between the Fender Marshall and Vox amps. Now I know why the Beatles with their Voxs sounded so much brighter than other Brit groups using Marshalls. I was poking around at digikey's site afterward and found their online schematic tool. I know you like to draw your own, but this might come in handy for more complicated circuits. www.digikey.com/schemeit Thanks again for clear coverage of another dense topic.
You're quite welcome, Carl. Rusty and I sincerely appreciate your input. I will check out the digikey site....thanks for sending the link.
Another excellent treatise. Thank you. Now to find that Russian pole dancer video. :))
You're welcome, Andrew. No video posting is complete and official until I hear from you:) Maybe I can get Anastasia to join forces and assist Rusty in video production. During breaks, she could do also do some pole dancing in my workshop......Rusty and I would certainly enjoy the comradery (no pun intended).
Capacitors: you can yhj k of them as, a goalie in a hockey game. He can block a puck shot towards the net. He can probably block a few pucks a minute. Start throwing 100-1000 pucks a minute at him more hes going to miss blocking many of those pucks and they will make it to the goal= the other side of the capacitor. In review: The more pucks per minute( higher frequency), more get past the goalie (through the capacitor).
Thanks for this interesting analogy, Bryan.
I'm betting the 'hi--pass' version is what is used in the tone stack of a Rickenbacker GUITAR, where the bridge P/U signal passes from the switch, thru a .0047µ cap, on to the volume pot.
You may be right, RA.
I personally would've enjoyed the decision towards the end, when you chose not to break down all the various 'hows' and 'whys' regarding a resistor's innate functionality within RC networks, if you could've simply briefly supplemented a couple small examples generalizing the relationship between the size of a resistor and the capacitor's overall selectivity in frequency bands. LOL but acknowledging the borderline nit-picky nature of this request isn't lost on me whatsoever haha! I supremely dig all of your channel's content and the overall manner in how you layout all the various concepts and processes pertaining to the respective subject matter in a slightly compartmentalized, albeit, streamlined fashion! This level of commitment, discipline, and plumb dedication to provide a means of formidable education to the public deserves any/all the acknowledgment and success in this lifetime!
Thanks for your very nice comments, H. There are always ways that a video could have been better, but we simply try to do the best we can in a reasonable time frame.
So far so good uncle Doug. We’re gettin it. At least most of it. I’m a mechanical wizard and pretty good with electricity but when it comes to radio and amplifier type circuitry that’s where I start slamming into the wall.
I’m good with regular resistance, good with transformers and some inductance but capacitors were the cliff to drive over. They’re coming around more and more.
That last part of this one with the ‘ why is there a resistor in the circuit ?’ even made sense to me before you even asked that. I just knew they probably worked together somehow, couldn’t explain it, just knew they balance out together somehow
It sounds like you're making progress, Michael. Keep up the good work.
Uncle Doug - Thanks again for the superior instruction!!!
You're quite welcome, Kevin, and thanks for the kind appraisal :)
well, I was really enjoying learning tons about amp circuitry. Then I am now forced to stop this video learning session to go watch a Russian pole dancer. You shouldn't say such things around suggestive people. All kidding aside, I love your style of teaching.
That's great to hear, William. I'm glad the videos are (almost) as enjoyable as watching Anastasia in action ;) Thanks so much :)
Love watching your vids…………always interesting 👍
We're glad you do, Snip :)
In your calculations for Xc are you assuming any capacitance impedance less than 600 ohms is passing all of the signal. 1/(2*pi*0.1uf*3khz) = 500 Ohm. Good lesson.
Thanks, AC.
Again,Thank you for all of your videos. Very educational. I'm try to learn and understand as much as possible. May I ask, if the tone stack is at the beginning, does the input signal go through the tone stack then to Volume one? Am I on the right track ? Thanks. I keep going over your videos for refreshes.
The video was from quite a few years ago, JH. I honestly don't recall the exact circuit.
Loving the channel, Uncle Doug. It's a pleasure to watch.
Thanks so much, PD....glad you like it :)