you mean you wish your physics teacher taught you about tube amps?? yeah, me too 😆 for real though, Uncle Doug is an excellent teacher and that's a skill in and of itself, on top of his skill with tube amps. i bet he would make an excellent lesson on literally anything on which he is well informed.
@@mrman3565 The first recorded use of 'kid' as a colloquial term for 'human child' was in the 16th century. By the time Charles Dickens used it in 'Oliver Twist' it had been in use for over two centuries, so yeah, I agree that it's a bit early to accept it into the language just yet. Let's give it another 400 years or so and see if it sticks.
I have learned more from @Uncle Doug about vacuum tube/valve electronics than I ever did working on my ee major. I can't thank you enough for all the work you do, sharing your invaluable knowledge.
Exactly, again the old saying, They don't teach you this in school. I have learned more in one month of Doug videos about tube amps, than I can imagine. Very well presented with everyday English language.
Amen. I was a technician in the Air Force. I was trained in Electronic Principles twice, with years of other formal training for electronic and electrical; yet, I emerged from all that training without being able to explain how to bias something. I often marvel at my notes that I took - I recognize the hand writing, but I suppose I held that information long enough to pass a test then dumped it. And in a nuclear weapon system, the troubleshooting is very narrow and clearly defined. One must have certain certifications to troubleshoot beyond what the book says for obvious reasons. But - watching Uncle (Professor) Doug has blown the door open for me and I'm recalling things I learned ins 1984. And the best part of all: I'm having FUN! I retired a few months ago for medical reasons and dreaded it. Now, holy cow - I'm digging into this and having a blast! I should've retired sooner to do this!
1.) My use of the phrase "plate resistor" to describe the 4.7/3.3 Meg wet or dry reverb resistor is meant figuratively (i.e. to describe its function), not literally. 2.) My definition of "Clipping" was inadvertently "clipped" from the video. Here is a proper definition: Clipping is waveform distortion that occurs when amplifier output tube(s) are overdriven and forced to deliver an output voltage or current beyond their maximum capability. Clipping is highly undesirable in both SS and HiFi circuits, while it is often utilized in tube amplification to enhance guitar tone. Crossover distortion, however, sounds awful and is never desirable. 3.) Clean "headroom" is the term used to describe the maximum amount of amplifier output possible before clipping begins. Maximum RMS output power is routinely measured pre-clipping, i.e. clean headroom only. 4.) I inadvertently expressed the decibel scale as being linear instead of logarithmic, during my explanation of gain vs volume. I should have stuck with "volts" instead ;) 5.) A few viewers have commented on the audio quality during the bias comparison. Recall that this is a "recording of a recording" so any artifacts are essentially doubled.
Excellent video Uncle Douglas. It appears from oscilloscope outputs that the crossover distortion shoulders are present at low and high amplifier output/gain. Whereas clipping type distortion occurs when the amplifier volume is cranked past a specific level. Can our ears pick up crossover distortion? Cheers from down under.
Imagine the confusion at the electronic stores with lines of people asking for wet resistors. Demanding to get them, small riots breaking out. Anarchy. Society breaks down and cats take over the world
Bless you Uncle Doug for sharing your wisdom with us. I have always wondered how changing component values in the Tone Circuit effects the Tone and Frequency Response:) You are an amazing Educator and Instructor. I am a visual learner and you have always exceeded all my expectations. Your educational videos will be used as a historical reference archive for this generation and generations to come. Your an honorable and humble man spreading love to all your viewers. Great Karma in your community!!!
best electronic teacher/engineer I've heard explanations spot on. I have qualification in industrial electronics all for solid state micro processors and digital I always wanted to learn about vacuum tube technology and now I have learned from the master. I am now servicing my own valve amps and building valve equaliser preamps. You do have the best voice, very therapeutic.
A great presentation as always. Hypothesis, experimentation, validation and calibration very clearly and concisely presented. Also room for the subjectivity that is real, meaningful, and at the heart of all music. Bravo!
I love your technical videos. I am almost confident enough to tackle an amp build myself because of how well you explain things. I’ve gone back and watched all of your old tutorial videos multiple times.
I love when you go through schematics and explain in detail what is going on, etc. This is what makes your channel so so so special, your ability to teach in a very direct and understandable way, show us what is happening in the amps physically and then show us again on paper. Very comprehensive. I LOVE YOUR TECHNICAL VIDEOS TO DEATH.
both parts were great. i'm so impressed that you not only show that there are bias differences but that you are also open to change your mind based upon your testing. and, the differences in the circuits was very educational. thank you! i'm lucky i have a 66 deluxe reverb that everyone who plays it won't play any of my other amps!
Thx uncle Doug . Your videos bring happiness and a light of hope lately. 2020 is the worse year so far in my life. Thank you so much. Hope you have a great day.
Thank you Uncle Doug. You made sense out of the hours of videos with conflicting information and over or under technical detail and just plain nonsense that i have endured trying to learn the skill of tube amp biasing. This is the last video i need to watch on the subject, i wish it had been the first. Thank you Sir.
Bless you Uncle Doug for another amazing educational video. We are all locked down, so we turn off the TV and turn on Uncle Doug's inspirational videos. We want more:)
Uncle Doug can you get me some schematics on your volt and amp meter that you put your tubes in to measure the amps and volts on the match tube.s@@UncleDoug
Uncle doug your channel is just so awesome. Whenever I have a question about tube amps, you always have a video for it. And yours always has the best explanation!
This channel is keeping me awake all night. I wish all this info was out many years ago when I wanted to do this kind of work a lot more. I work on my own amps well enough but not to this depth. I can't seen to stop watching video after video. Nothing better to do anyway lol.
Unless your dream amp (circuit) already exists, or you’ve already built it, I’d like to see you build one. All the bells and whistles. I’ve seen about 90% of your videos now. Going into reruns to reinforce what I’ve learned. I bought a late 50’s Stromberg Carlson AU57 PA amp and had the schematic blown up to blueprint size. It has 4 inputs, 5 12AX7’s, 2 6L6G’s, 2 12AU7’s, a 5U4GB, and a 6X4. I’m not sure if I’m going to restore it or turn it into something else at this point. Should be an interesting winter project.
Hi from England...heard about Uncle Doug's" valve channel" only this evening from a friend.We both have a collection of valve "babies",Fender blues juniors,Vox AC15's,Peavey delta Blues,and right back to a 1958 Watkins dominator...I am amazed at the wealth of information that is available here...an absolute gold mine for us" tone hounds"....and delivered with an authority and conviction that is easily absorbed,even if you don't have a major in electronics ..thanks Uncle Doug,keep them coming....and Stay Safe.......Dave ..midnight and still watching!
The amp sounded at it's best at the highest bias level tested. The bass tightened up, and the highs and mids sounded more defined. I guess I'm not too surprised by the results. The tubes were designed and engineered to run optimally around 70% plate dissipation. Anything below that did not sound great at all. I would say that 60% is even too low. I would be curious to hear what 65% sounds like. I'm also curious how it would sound at above 70% up to the point of redplating. Perhaps that test would be better done with a fresh set of tubes.
Thanks so much, Jason. I agree that the 60% to 70% range was the sweet spot. I doubt that going beyond 70% would yield any significant improvement in tone.
I couldn’t agree more with all of the comments made about you Uncle Doug! Your channel is the best I’ve seen for really learning and understanding how tube amplifiers function. I wanted to learn how to maintain and repair my own tube amplifiers. You do a great job teaching electronic theory, tube/transistor theory, electrical and electronic circuitry. Best yet you teach how it all works together to make that Magic happen in tube amps that gives a guitar it’s voice that makes it cry and sing!!! I don’t care what the voice modeling amps salesman say. NOTHING BEATS the sound of a tube amp. They can say their modeling amps can copy the sound of all the greatest tube amps all in one amplifier until the cows come home. We all know what comes out of a cow too! B….S…. But at the end of the day it’s still just a second rate copy at best of the original genuine article. When I first started watching your channel I didn’t know jack squat about tube amps and now I am learning one video at a time. Thank you so much for making these videos!!!!! Your furry four legged friends are very cool too. One last thing, your tone generator is pretty wild. It puts out some of the best gasoline powered leaf blower simulations I’ve ever heard. LOL
Dear U.D : The quality of this channel is unmatched! Thank you so much for your generosity and willingness to share your knowledge with us. As usual : you the man! 🤘🏼
Always good to see someone dispel amplifier myths and half-truths through the application of science. Maybe next you could convince guitarists that measuring DC resistance of pickups in isolation doesn't tell them anything about the output voltage!
The dear old uncle from the heaven of tube knowledge and pedagogy did it again. thank you so much for making these wonderful videos. So much knowledge put in to a beautiful package of clear and precise language and no nonsence methodes. Easy to skip x-mas shopping :-)
Thanks, John. That's beyond my ability at the moment. I would have to get my hands on a proper Dumble amp in order to make any legitimate observations.
I thoroughly enjoy your "Technical Second Features" as you described at the tail end of the video. I actually enjoy watching all of your videos, you speak my language. Thank You for your work!!
Everyone out there in you tube land needs to see this.. absolutely broken down to the ground and built back up with full explanation for what you did. Then break down the differences between a 900 to 4+k fender amp . With fantastic guests commentary towards the clipping. Uncle doug busting there butts . Thank you . We all love you and wish you well . Cheers ! .
Howdy there Uncle D.! I Have not chimed in for quite some time so I'm seizing the opportunity now. I hope you are doing well out there...you sound healthy and strong, as usual! I just wanted to thank you once again for your continual, generous sharing of your wealth of knowledge and good humor! It was apparently Destiny or Fate that I was born and/or became alcoholic...just as it was, by Design that I continue my SUPER DUPER GRATEFUL recovery from alcoholism. I am so happy to have turned into a Fully Blown Ampaholic, due in no small part to you! Thanks for helping me in my transformation in BOTH departments!!! Life has been a wonderfully wild ride for me since I found myself alive in this world and I'm so glad you have been a part of it! Three Cheers for you Uncle Doug! Long may you run! Much Love~Whiskey Tango Delta
Wow, thanks so much for your very nice comments, WTD. It's good to hear that you have moved away from a dangerous obsession and toward a creative one. Best of luck with your continued transformation.
Mr Doug, I'd really like to call you a master of knowledge transfer and I really think you have a gift! Your videos are great in so many aspects and they are a jewel for anybody that knows how to recognize it. Best regards and please do keep up the excellent job. With great respect, Kreso
Mi estimado Uncle Doug, it is amazing the teaching skills you have, you was, if not in this life in some past, the best "Maestro" I've ever known or existed. Me quito el sombrero para saludarlo! Un fuerte abrazo desde Mexico.
This type of video is the best educational and informative that I can remember. Your knowledge and also the level of documentation take the "class" to a level of comprehension that even a non-technical skilled person can understand. Great Job Uncle Doug!
I ve been watching your videos and find them extremely informative and useful. I would really be happy to watch you talking some day about the , not so clear , subject of Grounds and proper grounding techniques in tube amplifiers.:-)
i can definitely hear the goodness at 60% and 70%. Good looking DR you have there Doug! I have a Blackface DR myself and it's biased around 68% because that's what sounds good to my ears. Another excellent video sir! Many Thanks!
If your looking for how to videos on building any kind of amplifier THIS is the right place. Congratulations on a wonderful explanation on this particular part of practical amp design Uncle Doug. You and Mr. Paul Carlson are the best teachers when it comes to electronics design on RUclips in my honest humble opinion!
It's all been said, but I hit a hurdle 50 years ago, "Temperature coefficient of resistance". I baulked and never got over it. Math meeting science, loved the science... If Uncle Doug was my teacher! So I compulsively listen and learn, even though most of the content will never be used. Thanks Doug ;)
School is in session! Great way to start the day. In the hi-fi world, when designing an amplifier, a lot of work goes into deciding where you want to 'specify' the bias point, as it sets how much Class A region ( lowest distortion) you have and how much power you can deliver, and how the idle current will effect the tube life. Take note youtube viewers, this IS meat and potatoes tech, teaching the REAL facts and how engineering choices alter the sound of an amplifier. In the hi-fi world we not only listen, we use test signals and distortion analyzers. Right now I am designing a push-pull 6BQ5 amplifier output stage. It is going to be switchable between triode and ultra linear pentode modes, and have a 2 position bias switch, allowing choice of shorter tube life lowest distortion larger Class A region, or for less Class A overlap giving longer tube life and a few more watts, at the sacrifice of slightly higher coloration.
Bravo Uncle Doug! Once again you have added an insightful, technically important bit of content that should help everyone with their understanding of the best use of their amplifiers. You should continue with the technical series as it does give so much necessary information about various types of issues. Thanks again for all your efforts on our behalf about these interesting and important topics.
Well, that was delightfully nerdy. I liked it. Before everybody runs off and rebiases their amps to 70%, it bears repeating that 70% isn't a magical target, it's the maximum safe bias for most unmodified commercial amps. It's frighteningly easy to cook your tubes even at colder bias if the primary impedance is too low or the plate voltage is too high.
I was wondering if anyone would bring this up. I have a bassman with 460 to 470 plate volts and a 2k primary impedance. It's biased very cool with the factory balance setup but after doing some reading I decided not to heat things up. Sounds fine as is.. I read about more than a few marshall owners cooking valves when their primary impedance was less than 2k
I nominate uncle dough for coolest person on RUclips, And the information provided is a lif4esaver as well as a true helping hand. Please continue making these videos. thanks from Portland Oregon
Thank you for yet another great video. I feel inspired to go through my amp collection and do a similar analysis. With my ears getting older, a scope analysis may yield new results. I would however inject the input signal (possibly pre-amplified by an external transistor-based booster) directly into the phase inverter to make sure that any distortion resulting from overdriven preamp-tubes is eliminated.
Dear Uncle Doug, I think you have an error in the bottom half of the page at approximately 38:45. 2x gain would actually be a 6.02 dB increase, not a 50 dB increase as you’ve shown in the first line of the example, etc.. Change the dBs to VRMS or Vpp and you’re golden. Armed by all the great knowledge I’ve picked up from you, I’m going to attempt a from-scratch amp build this winter - thank you!! Maybe something inspired by a 50W Hiwatt. As I tell everyone I know, Uncle Doug is the best on the Internet! All the best, John.
Great video Uncle Doug! Finally some truth in tone/break-up in tube bias.. I’m a big fan of NOS tubes too. Even the metal ones. They seem to match up better.. Be well, Tom
I love it when Doug refers to frequency as "cycles" and not "hertz". I hated it when they (whoever they are) changed the terminology. And it happened while I was in Tech school in the Air Force. Keep it up Doug. Old guys rule!
A big thumbs up for the first section, as well as the "PART 2" addendum. My ears heard and the compared scope traces seem to confirm a slight increase in clarity from 60% to 70%, though there seems to be a slight bit more dynamic range at 60%. This would lead me to believe that is why many folks end up "splitting the difference" in the 65% range. And to some comments regarding EL34s, they should probably never be used in a truly "stock" Deluxe Reverb, due to the higher heater current they demand! If you have a home built and/or hot rodded Deluxe, with a more robust heater winding in your transformer, then all is good! And again, Thank You to Uncle Doug!
Thank you for the second 1/2 of the video. I could never figure out why one was different from the other and why one resistor would be in place of another.
I can both hear and see that as the Bias was increased the frequency curve was altered. The bottom got tighter (less sloppy distortion), the low-mids were accentuated, and the upper-mids were smoothed out. Obviously, invreasing bias increases compression. As a rock guitarist, I am always looking at/for the differences between 6L6 and EL34 where compression is concerned. I'd love to see you get your hands on both the EVH 5150III and EVH 5150IIIS (6L6 vs EL34 respectively) just to graph comparatively. Also, Mesa Boogie has an amplifier called the "Triple Crown" which has the ability to switch between the two valve and bias choices (Mesa/Boogie Triple Crown TC-100 - 100-watt Rackmount Tube Head | Sweetwater). I'd love to see a Hiwatt 100 watt amp with the features that these previously mentioned amps have. The best of all possible worlds!
Now repeat everything using a compressor/limiter at various points in the signal chain and factor in tube degradation and capacitor drift and compensate for variations in wall voltage and temperature...and by the time you are done you will have PSH (permanent shift of hearing) caused rapid onset aging...Outstanding work
Thank you Uncle Doug. I have a twin 65 reissue that I will be checking for these changes as well. I already found it had the wrong Reverb transformer with 1/4 of the proper ohmic value (per comparison). That was a mind bender but obvious when checking part numbers from schematic. Big difference!
Very nice. It would be interesting to see the same experiment with 80% to 100% and then look at the whole 40% to 100% spectrum just for grins. I imagine that there is a point of diminishing returns somewhere in there, tube/transformer lifespan notwithstanding. The blackface/silverface comparisons were also fascinating. I wonder what the price difference between the GZ34 and and the 5U4GB would have been when one could buy tubes by the handful just about anywhere in any town. Cheers, Uncle Doug! Merry Christmas!
No one seems to recommend the higher wattage biasing, Michael. My guess is that improvement in tone is negligible and tube/component lifespan is reduced. I would guess that GZ34's have always been more expensive.
Wish you lived in Vancouver Canada Doug. Really interesting stuff. I'm learning so much about vintage Deluxe Reverbs. I recently bought a used 1981 DR (European Export model). I was told it had the AB schematic, but not 100% sure. It was unused by the owner who stored it shortly after inheriting it from a relative. I gave it to my amp tech who has told me that there is no need to make any modifications. I just popped some Dual Matched JJ 6V6's in the amp as the originals were not well matched. He advised me not to change any of the original caps as they seemed fine. I have yet to give it a good workout and use it gigging so I won't make any mods unless I hear something untoward. However, from this video, I don't really think modding it to blackface specs would make that much difference to the sound. Upgrading the tubes may have a more significant impact as well as swapping out the speaker. Luckily I have a friend with a 79 Silverface which has had the 'blackface' mod. I'm interested to see if there is a difference in sound. Great stuff.
Thanks for another great vid and a tremendous effort Doug. I dare say that theirs a huge difference when bedroom playing and a live performance. At low bias on stage (below 70%) the amp gets scratchy and weird shit starts happening. Basically, low bias simply doesn't cut it live. When I play at home I have some amps (60+ amps) that I bias cool
Wow Wow Wow Wow. I'm SPEECHLESS. Your knowledge and your ability to teach is just mind boggling. I've been an advanced class amateur radio operator (Canada)) since 1982 and I thought that I understood tube amps. Au contraire as they say en Francais , LOL. I have learned SO MUCH from your channel!! I'm a Patreon contributor and with good reason. Thank you SO much for these videos. There is so much info in this video... I will be watching again and again and again. One cannot glean all this info in one viewing. I do have a question about the AB763 reservoir caps shown in the schematic being in parallel, when, on my 68 silver face Super Reverb, as well as every amp I've seen, they are in series. Whats going on with that??. Thanks again, for sharing your wealth of knowledge, Uncle Doug. Give the kitties a good ear scratching from me.
Thanks so much for your very kind words, Bob. Fender tried different circuit features in their amps, retaining those that worked well and eliminating those that did not. Apparently, the series configuration was superior with its much higher voltage tolerance.
I'm behind on my videos. Happy New Years Doug. Great video as always. Cool second part if you ask me. Learned some timeline history in the second half. Of course the big question is what about 80% to 90% hot? Of course you used to be able to walk into 7-11 and check and get tubes then. I know you remember lol.
@@UncleDoug Well, of course you are correct in what you do, Doug, and I did enjoy it. But I would need a more private conversation to better qualify my response, and that's probably surplus to your requirements. Cheers. Keep up the good work.
I like both 60% & 70%. 60% 7.17 W. would make your tubes last longer right? I noticed each time you go up the Bass body sound goes up. I prefer 60%. Full dynamic range and easy on the amp. Maybe split the difference 65% 👍
It's my understanding that Fender biased those output tubes to get close to 10.5-11 watts out of each 6V6, so they could make good on their 22 watt amp claim. Am I wrong? You would be the one to know. I thought the best overall sound, through my headphones was at the 70% bias. I must say this video was my most favorite of all of the technical videos. You not only gave us an audio demo, you showed them on the oscilloscope and the analysis program! Seeing is believing! You could have made the later part of this video a separate video comparing the Blackface to the Silverface amps, so thank you for including it. I was able to enjoy 2 cups of dark roast while viewing! Gerald Weber did some videos on this subject but you really made it clear of the differences and how to do any changes, if you want to. This video should be viewed by anyone who desires to build a DR. Many options could be experimented with to hone in on ones perfect tone! I plan a single channel AB763 and found the differences valuable. Love from NW Colorado. Thanxz
Thanks for all your very nice comments, ATL. Yes, I feel that Fender over-biased their smaller amps to achieve somewhat inflated output wattage values.
Maybe it's a bit pretentious or opinionated to say, but I think that this just shows how it was designed to be played like how the tubes were supposed to be used technically. My favourite part is always the schematic studies. Thanks for another educational and entertaining episode, Doug.
The last year I have begun biasing my vintage Fenders by ear, rather than following an amp tech’s assessment and, of course, they sound much better to me.
Love the circuit analysis part 2 video. Would love a similar video for the push-pull princetons. Also, would be great if these were distinct videos on RUclips for easy searching and access. Thanks for the amazing RUclips content. Long time viewer.
@@UncleDoug thank you Soo much for doing this...as always. Great feedback and at one point, you wondered if maybe it was biased beyond 70%. I know some amp designers and people do intentionally bias above 70, and have confirmed 100 and about 110%!...but the open question is...what does that do? Thanks again for you time Uncle! 😀
all i can say is: i wish i had teacher of physics like Uncle Doug when i was young
Thanks, G58 :)
Me two.
Me too!
you mean you wish your physics teacher taught you about tube amps?? yeah, me too 😆 for real though, Uncle Doug is an excellent teacher and that's a skill in and of itself, on top of his skill with tube amps. i bet he would make an excellent lesson on literally anything on which he is well informed.
A grammar teacher would have helped more. 😂
Kids should listen to your channel just to learn how to speak English.
Thanks, Eric :)
Yes Doug, you need far more LIKES, you knows, init's then children will also understand you!!
@@mrman3565 The first recorded use of 'kid' as a colloquial term for 'human child' was in the 16th century. By the time Charles Dickens used it in 'Oliver Twist' it had been in use for over two centuries, so yeah, I agree that it's a bit early to accept it into the language just yet. Let's give it another 400 years or so and see if it sticks.
@@circusbrains Yes, indeed, CB. I was a classroom Math & Science teacher for many years.
@@frmcf Well said, McF :)
I have learned more from @Uncle Doug about vacuum tube/valve electronics than I ever did working on my ee major. I can't thank you enough for all the work you do, sharing your invaluable knowledge.
He is a great teacher.
Thanks so much, Luke. It's really rewarding to hear that our videos are helpful.
Thanks, Jennifer. From you, it means a lot.
Exactly, again the old saying, They don't teach you this in school. I have learned more in one month of Doug videos about tube amps, than I can imagine. Very well presented with everyday English language.
Amen. I was a technician in the Air Force. I was trained in Electronic Principles twice, with years of other formal training for electronic and electrical; yet, I emerged from all that training without being able to explain how to bias something. I often marvel at my notes that I took - I recognize the hand writing, but I suppose I held that information long enough to pass a test then dumped it. And in a nuclear weapon system, the troubleshooting is very narrow and clearly defined. One must have certain certifications to troubleshoot beyond what the book says for obvious reasons. But - watching Uncle (Professor) Doug has blown the door open for me and I'm recalling things I learned ins 1984. And the best part of all: I'm having FUN! I retired a few months ago for medical reasons and dreaded it. Now, holy cow - I'm digging into this and having a blast! I should've retired sooner to do this!
Doug; you have the best radio voice ever-------and your dominion of the English language is astounding. I type this before I watch the whole video.
You are so kind to say so, JG. Thanks !!!
@@UncleDoug You are right up there with the guy from Distinguished Spirits.
I hear a Gene Shepherd clone in U.D.’s voice.
ADDENDA:
1.) My use of the phrase "plate resistor" to describe the 4.7/3.3 Meg wet or dry reverb resistor is meant figuratively (i.e. to describe its function), not literally.
2.) My definition of "Clipping" was inadvertently "clipped" from the video. Here is a proper definition: Clipping is waveform distortion that occurs when amplifier output tube(s) are overdriven and forced to deliver an output voltage or current beyond their maximum capability. Clipping is highly undesirable in both SS and HiFi circuits, while it is often utilized in tube amplification to enhance guitar tone. Crossover distortion, however, sounds awful and is never desirable.
3.) Clean "headroom" is the term used to describe the maximum amount of amplifier output possible before clipping begins. Maximum RMS output power is routinely measured pre-clipping, i.e. clean headroom only.
4.) I inadvertently expressed the decibel scale as being linear instead of logarithmic, during my explanation of gain vs volume. I should have stuck with "volts" instead ;)
5.) A few viewers have commented on the audio quality during the bias comparison. Recall that this is a "recording of a recording" so any artifacts are essentially doubled.
Excellent video Uncle Douglas.
It appears from oscilloscope outputs that the crossover distortion shoulders are present at low and high amplifier output/gain.
Whereas clipping type distortion occurs when the amplifier volume is cranked past a specific level.
Can our ears pick up crossover distortion?
Cheers from down under.
Imagine the confusion at the electronic stores with lines of people asking for wet resistors. Demanding to get them, small riots breaking out. Anarchy. Society breaks down and cats take over the world
@@PetraKann Yes, indeed, Petra. Crossover distortion is quite noticeable and unpleasant.....as you can hear in the 40% audio clip.
@@rjprivate We might be better off in the long run, RJ, considering the current state of affairs.
@@PetraKann - I am pretty sure, your ears can pick up Crossover Distortion... It does not sound very pleasing - hence all the efforts to avoid it...
Bless you Uncle Doug for sharing your wisdom with us.
I have always wondered how changing component values in the Tone Circuit effects the Tone and Frequency Response:)
You are an amazing Educator and Instructor. I am a visual learner and you have always exceeded all my expectations.
Your educational videos will be used as a historical reference archive for this generation and generations to come.
Your an honorable and humble man spreading love to all your viewers.
Great Karma in your community!!!
Wow, thanks so much, F1. We truly appreciate your very nice comments.
OK, who's the yutz that gave this a thumbs down. There's one in every crowd I guess.
Perhaps it was a leper whose nose detached from his face while coincidentally over the thumbs down key ;)
3 now , it’s a beak fest of epic proportions:(
@@v12dot maybe they're just biased against this video for some reason
They saw "Headroom" and thought it was porn.
I don't know who thumbs down any uncle doug videos but there are some real spiteful people in the guitar/amp tech world
best electronic teacher/engineer I've heard explanations spot on. I have qualification in industrial electronics all for solid state micro processors and digital I always wanted to learn about vacuum tube technology and now I have learned from the master. I am now servicing my own valve amps and building valve equaliser preamps. You do have the best voice, very therapeutic.
Thanks so much for your very nice comments, Clyde.
A great presentation as always. Hypothesis, experimentation, validation and calibration very clearly and concisely presented. Also room for the subjectivity that is real, meaningful, and at the heart of all music. Bravo!
Thanks for a very kind appraisal. Our goal was each of the criteria you mentioned.
I love your technical videos. I am almost confident enough to tackle an amp build myself because of how well you explain things. I’ve gone back and watched all of your old tutorial videos multiple times.
That's great to hear, Michael. It makes it all worthwhile for us.
Love me some Uncle Doug in the morning. It’s 20 degrees here in Spokane and this upload warmed me right up.
Bask in the warmth of our output tubes, Vaden :)
@@UncleDoug} g 00 gold 9
I love when you go through schematics and explain in detail what is going on, etc. This is what makes your channel so so so special, your ability to teach in a very direct and understandable way, show us what is happening in the amps physically and then show us again on paper. Very comprehensive. I LOVE YOUR TECHNICAL VIDEOS TO DEATH.
Wow.....thanks so much, Sean. I'm glad the videos are clear and enjoyable.
I definitely think the 40% sounded clippy but above 50% it started to clean up. IMO 70% sounds best, maybe that's why that's they suggested 70%.
Agreed, Tim. The 70% recommendation does seem to be the best. Now we can actually understand why.
Cross over distortion is very audible
have I missed the link to the actual recording used for the test? :-/
both parts were great. i'm so impressed that you not only show that there are bias differences but that you are also open to change your mind based upon your testing. and, the differences in the circuits was very educational. thank you!
i'm lucky i have a 66 deluxe reverb that everyone who plays it won't play any of my other amps!
Thanks so much, Michael. I appreciate your kind and accurate comments. You are a lucky guy to have such a great amp.
Thx uncle Doug . Your videos bring happiness and a light of hope lately. 2020 is the worse year so far in my life. Thank you so much. Hope you have a great day.
You're quite welcome, Ken. I don't think any of us would choose to relive this year, but hopefully 2021 will be a better one.
@@UncleDoug 👍 🎄 🍻 😎
Nothing like a Practical mind for solving problems and teaching others, and Uncle Doug, you have a great practical Mind, thanks!
Thanks so much, Rene :)
This video is a classic already.
Thanks, H :)
Thank you Uncle Doug. You made sense out of the hours of videos with conflicting information and over or under technical detail and just plain nonsense that i have endured trying to learn the skill of tube amp biasing. This is the last video i need to watch on the subject, i wish it had been the first. Thank you Sir.
You're welcome, DS. We're glad you enjoyed it.
Bless you Uncle Doug for another amazing educational video. We are all locked down, so we turn off the TV and turn on Uncle Doug's inspirational videos. We want more:)
Thanks so much, F1. We are working furiously on future videos for you :)
Uncle Doug can you get me some schematics on your volt and amp meter that you put your tubes in to measure the amps and volts on the match tube.s@@UncleDoug
Like others have said, I learn more here than all the study materials available period. Thanks Doug for your detailed information and resources.
You're welcome, Larry. I'm glad the videos are helpful.
Also, yes, please continue the tech talk! I'm loving it.
Will do, GL.
Uncle doug your channel is just so awesome. Whenever I have a question about tube amps, you always have a video for it. And yours always has the best explanation!
Thanks, Daniel. We're glad you enjoy our vids :)
Doug, this is one of your best presentations yet. I learned a lot from this one, thank you!
Thanks so much. I really tried to make this a good one, and I appreciate your kind words.
This channel is keeping me awake all night.
I wish all this info was out many years ago when I wanted to do this kind of work a lot more.
I work on my own amps well enough but not to this depth.
I can't seen to stop watching video after video.
Nothing better to do anyway lol.
We're glad you find the videos addictive and helpful, Jerry :)
Unless your dream amp (circuit) already exists, or you’ve already built it, I’d like to see you build one. All the bells and whistles.
I’ve seen about 90% of your videos now. Going into reruns to reinforce what I’ve learned. I bought a late 50’s Stromberg Carlson AU57 PA amp and had the schematic blown up to blueprint size. It has 4 inputs, 5 12AX7’s, 2 6L6G’s, 2 12AU7’s, a 5U4GB, and a 6X4. I’m not sure if I’m going to restore it or turn it into something else at this point. Should be an interesting winter project.
Thanks, FT. I think a Princeton Reverb is pretty close to my ideal circuit.....great tone and effects but not too bulky. Good luck with your project.
Hi from England...heard about Uncle Doug's" valve channel" only this evening from a friend.We both have a collection of valve "babies",Fender blues juniors,Vox AC15's,Peavey delta Blues,and right back to a 1958 Watkins dominator...I am amazed at the wealth of information that is available here...an absolute gold mine for us" tone hounds"....and delivered with an authority and conviction that is easily absorbed,even if you don't have a major in electronics ..thanks Uncle Doug,keep them coming....and Stay Safe.......Dave ..midnight and still watching!
Welcome to our channel, Dave. All "Tone Hounds" are welcome :) Have a great holiday season.
I'd like to add my extra upvote for the part2 of the video. I really enjoy this kind of content.
Thanks, O. Your vote is noted.....and appreciated.
Wonderful experiment, Uncle Doug. Just the facts. You’re a treasure.
Thanks, Ryan :)
I always click the thumbs up on all your videos before watching them. I have learned so much from watching these.
The amp sounded at it's best at the highest bias level tested. The bass tightened up, and the highs and mids sounded more defined. I guess I'm not too surprised by the results. The tubes were designed and engineered to run optimally around 70% plate dissipation. Anything below that did not sound great at all. I would say that 60% is even too low. I would be curious to hear what 65% sounds like. I'm also curious how it would sound at above 70% up to the point of redplating. Perhaps that test would be better done with a fresh set of tubes.
Thanks so much, Jason. I agree that the 60% to 70% range was the sweet spot. I doubt that going beyond 70% would yield any significant improvement in tone.
I couldn’t agree more with all of the comments made about you Uncle Doug! Your channel is the best I’ve seen for really learning and understanding how tube amplifiers function.
I wanted to learn how to maintain and repair my own tube amplifiers. You do a great job teaching electronic theory, tube/transistor theory, electrical and electronic circuitry. Best yet you teach how it all works together to make that Magic happen in tube amps that gives a guitar it’s voice that makes it cry and sing!!!
I don’t care what the voice modeling amps salesman say. NOTHING BEATS the sound of a tube amp. They can say their modeling amps can copy the sound of all the greatest tube amps all in one amplifier until the cows come home. We all know what comes out of a cow too! B….S…. But at the end of the day it’s still just a second rate copy at best of the original genuine article.
When I first started watching your channel I didn’t know jack squat about tube amps and now I am learning one video at a time. Thank you so much for making these videos!!!!! Your furry four legged friends are very cool too. One last thing, your tone generator is pretty wild. It puts out some of the best gasoline powered leaf blower simulations I’ve ever heard. LOL
Thanks for all the great comments, Jeff :)
@@UncleDoug You’re welcome and thank you!
Dear U.D : The quality of this channel is unmatched!
Thank you so much for your generosity and willingness to share your knowledge with us.
As usual : you the man! 🤘🏼
Wow....thanks so much, Adrien. Hearing from great viewers like you makes it all worthwhile :)
Thanks for another great vid uncle doug! Youve been teaching me about amp science since i was an 8th grader and im 20 now!
You're welcome, LF. You're making me feel old ;)
Always good to see someone dispel amplifier myths and half-truths through the application of science. Maybe next you could convince guitarists that measuring DC resistance of pickups in isolation doesn't tell them anything about the output voltage!
Thanks, Frank. I'll keep your suggestion in mind :)
The dear old uncle from the heaven of tube knowledge and pedagogy did it again. thank you so much for making these wonderful videos. So much knowledge put in to a beautiful package of clear and precise language and no nonsence methodes. Easy to skip x-mas shopping :-)
Thanks so much for your very kind words, Jan. We really appreciate them :)
Excellent presentation as usual Uncle Doug, could you expose the Dumble myth as a fact or fiction?!
Thanks, John. That's beyond my ability at the moment. I would have to get my hands on a proper Dumble amp in order to make any legitimate observations.
I thoroughly enjoy your "Technical Second Features" as you described at the tail end of the video. I actually enjoy watching all of your videos, you speak my language. Thank You for your work!!
You're welcome, Steve.
Everyone out there in you tube land needs to see this.. absolutely broken down to the ground and built back up with full explanation for what you did. Then break down the differences between a 900 to 4+k fender amp . With fantastic guests commentary towards the clipping. Uncle doug busting there butts . Thank you . We all love you and wish you well . Cheers ! .
Wow.....Thanks so much, W4. So glad you liked the video :) Likewise on the good wishes.
Howdy there Uncle D.! I Have not chimed in for quite some time so I'm seizing the opportunity now. I hope you are doing well out there...you sound healthy and strong, as usual! I just wanted to thank you once again for your continual, generous sharing of your wealth of knowledge and good humor! It was apparently Destiny or Fate that I was born and/or became alcoholic...just as it was, by Design that I continue my SUPER DUPER GRATEFUL recovery from alcoholism. I am so happy to have turned into a Fully Blown Ampaholic, due in no small part to you! Thanks for helping me in my transformation in BOTH departments!!! Life has been a wonderfully wild ride for me since I found myself alive in this world and I'm so glad you have been a part of it! Three Cheers for you Uncle Doug! Long may you run! Much Love~Whiskey Tango Delta
Wow, thanks so much for your very nice comments, WTD. It's good to hear that you have moved away from a dangerous obsession and toward a creative one. Best of luck with your continued transformation.
Every Video from Uncle Doug is "Classroom in Session"
Thanks, Shyam. I hope the "classes" are enjoyable :)
Mr Doug, I'd really like to call you a master of knowledge transfer and I really think you have a gift!
Your videos are great in so many aspects and they are a jewel for anybody that knows how to recognize it.
Best regards and please do keep up the excellent job.
With great respect,
Kreso
Wow, thanks so much, Kreso. We will :)
Mi estimado Uncle Doug, it is amazing the teaching skills you have, you was, if not in this life in some past, the best "Maestro" I've ever known or existed. Me quito el sombrero para saludarlo! Un fuerte abrazo desde Mexico.
Wow, thanks so much, Juan. We really appreciate your very kind words and wish you the very best :)
This type of video is the best educational and informative that I can remember. Your knowledge and also the level of documentation take the "class" to a level of comprehension that even a non-technical skilled person can understand. Great Job Uncle Doug!
Thanks so much, Juan. I sincerely appreciate your kind words and am glad you enjoyed the video.
That was excellent Uncle Doug! Thank You 👌
Glad you enjoyed it, CS :)
Thanks so much. Finally data driven results showing what cold vs. hot biasing does. 👍
You're welcome, JM :)
little hair on the peach at higher volumes~
I ve been watching your videos and find them extremely informative and useful. I would really be happy to watch you talking some day about the , not so clear , subject of Grounds and proper grounding techniques in tube amplifiers.:-)
Thanks, Mark. I'll keep your suggestion in mind for the future.
i can definitely hear the goodness at 60% and 70%. Good looking DR you have there Doug! I have a Blackface DR myself and it's biased around 68% because that's what sounds good to my ears. Another excellent video sir! Many Thanks!
Agreed, Cary. The sweet spot varies but somewhere between 60% and 70% seems to give the best bang for the buck. Thanks !!!
Very interesting and informative video. Great job Uncle Doug, Thank you for going the extra mile.
You're welcome, Jeff.
If your looking for how to videos on building any kind of amplifier THIS is the right place. Congratulations on a wonderful explanation on this particular part of
practical amp design Uncle Doug. You and Mr. Paul Carlson are the best teachers when it comes to electronics design on RUclips in my honest humble opinion!
Wow....thanks so much, HM. We really appreciate it :)
Another excellent tutorial on Bias and circuit changes from Blackface to Silverface! Thanks, Uncle Doug.
You're welcome, T. Glad you liked it :)
hearing trouble with the spectrum, as if pieces of the sound get eaten~
The interface and the daw may be clocked differently.
Yes, that happens a lot ;)
I'm thinking 65% dissipation may sound best. Might EL34s be different than 6V6s when it comes to optimal tone?
It's a personal preference, John, and yes, I think different tubes respond differently to bias levels.
It's all been said, but I hit a hurdle 50 years ago, "Temperature coefficient of resistance". I baulked and never got over it. Math meeting science, loved the science... If Uncle Doug was my teacher! So I compulsively listen and learn, even though most of the content will never be used. Thanks Doug ;)
You're welcome, Garry. Thanks for watching :)
School is in session! Great way to start the day. In the hi-fi world, when designing an amplifier, a lot of work goes into deciding where you want to 'specify' the bias point, as it sets how much Class A region ( lowest distortion) you have and how much power you can deliver, and how the idle current will effect the tube life. Take note youtube viewers, this IS meat and potatoes tech, teaching the REAL facts and how engineering choices alter the sound of an amplifier. In the hi-fi world we not only listen, we use test signals and distortion analyzers. Right now I am designing a push-pull 6BQ5 amplifier output stage. It is going to be switchable between triode and ultra linear pentode modes, and have a 2 position bias switch, allowing choice of shorter tube life lowest distortion larger Class A region, or for less Class A overlap giving longer tube life and a few more watts, at the sacrifice of slightly higher coloration.
Thanks so much for your very knowledgeable and informative input, Jennifer.
We appreciate everything you do.long live uncle doug and dlab.
Thanks, Eric :)
Fully agree! I would like to add El Paso tube amps to the list as well.
Bravo Uncle Doug!
Once again you have added an insightful, technically important bit of content that should help everyone with their understanding of the best use of their amplifiers. You should continue with the technical series as it does give so much necessary information about various types of issues. Thanks again for all your efforts on our behalf about these interesting and important topics.
You're quite welcome, Robert. We will definitely keep producing technical videos.
Well, that was delightfully nerdy. I liked it. Before everybody runs off and rebiases their amps to 70%, it bears repeating that 70% isn't a magical target, it's the maximum safe bias for most unmodified commercial amps. It's frighteningly easy to cook your tubes even at colder bias if the primary impedance is too low or the plate voltage is too high.
I was wondering if anyone would bring this up. I have a bassman with 460 to 470 plate volts and a 2k primary impedance. It's biased very cool with the factory balance setup but after doing some reading I decided not to heat things up. Sounds fine as is.. I read about more than a few marshall owners cooking valves when their primary impedance was less than 2k
Thanks for your helpful input, David.
Uncle Doug, I like your expertise and enjoy your humour...keep on Sir
Thanks, Nino. Will do :)
Excellent lesson in scientific methodology applied to tube amplified audio! Yes, please, MORE of these technical "second feature" videos. JP
Thanks, C. Will do :)
analysis can never be a weakness, authenticity may mean whether or not the b'gosh's straps are connected~
Excellent topic with a peerless presentation. Thanks again Uncle Dave and et. al.
Thanks so much, Frank. Glad you enjoyed it.
As always, EXCELLENT VIDEO. Tons of valuable information that applies to any tube amp. Great Reverb information as well.
Thanks so much, Gonzo. Glad you enjoyed it :)
I nominate uncle dough for coolest person on RUclips, And the information provided is a lif4esaver as well as a true helping hand.
Please continue making these videos.
thanks from Portland Oregon
You are more than kind, Joseph. Thanks !! Will do.
To me 60% biasing sounded more free of distortion !🥰!
Thanks for your input, Ana.
Thank you for yet another great video. I feel inspired to go through my amp collection and do a similar analysis. With my ears getting older, a scope analysis may yield new results. I would however inject the input signal (possibly pre-amplified by an external transistor-based booster) directly into the phase inverter to make sure that any distortion resulting from overdriven preamp-tubes is eliminated.
Sounds like a worthy experiment, TSX. Good luck with it.
wow, such subtleties~ thanks for taking the time to figure all this out for us~
our pleasure, Jay. Glad you liked it!
who hits the dislike on an uncle doug video?! some peoples kids.....jeez. great video!
Thanks, Will. I suspect they are cave-dwelling Neanderthals poking at the keyboard with their prehensile tails.
Another terrific learning experience. Thank you Uncle Doug.
You're welcome, ReF. Glad you enjoyed it
Dear Uncle Doug, I think you have an error in the bottom half of the page at approximately 38:45. 2x gain would actually be a 6.02 dB increase, not a 50 dB increase as you’ve shown in the first line of the example, etc.. Change the dBs to VRMS or Vpp and you’re golden. Armed by all the great knowledge I’ve picked up from you, I’m going to attempt a from-scratch amp build this winter - thank you!! Maybe something inspired by a 50W Hiwatt. As I tell everyone I know, Uncle Doug is the best on the Internet! All the best, John.
Greetings, John. The decibel error was addressed in the 1st (pinned) comment. Thanks for your input and best of luck with your amp-building project.
Great video Uncle Doug! Finally some truth in tone/break-up in tube bias.. I’m a big fan of NOS tubes too. Even the metal ones. They seem to match up better.. Be well, Tom
Thanks, Tom. Will do.....you, too, I hope :)
Yet another gem from Uncle Doug.
Thanks, John.
I love it when Doug refers to frequency as "cycles" and not "hertz". I hated it when they (whoever they are) changed the terminology. And it happened while I was in Tech school in the Air Force. Keep it up Doug. Old guys rule!
My guitar amp is loud. How loud is it? It hertz my ears.
Heck yes, Phil. We old timers need to stick together :)
A big thumbs up for the first section, as well as the "PART 2" addendum. My ears heard and the compared scope traces seem to confirm a slight increase in clarity from 60% to 70%, though there seems to be a slight bit more dynamic range at 60%. This would lead me to believe that is why many folks end up "splitting the difference" in the 65% range. And to some comments regarding EL34s, they should probably never be used in a truly "stock" Deluxe Reverb, due to the higher heater current they demand! If you have a home built and/or hot rodded Deluxe, with a more robust heater winding in your transformer, then all is good! And again, Thank You to Uncle Doug!
Thanks so much for your nice comments and helpful input, Gene.
Thank you for the second 1/2 of the video. I could never figure out why one was different from the other and why one resistor would be in place of another.
You're welcome, Marcus. Glad it helped :)
Thanks for your hard work, most appreciated.
You're quite welcome, Martin :)
I can both hear and see that as the Bias was increased the frequency curve was altered. The bottom got tighter (less sloppy distortion), the low-mids were accentuated, and the upper-mids were smoothed out. Obviously, invreasing bias increases compression. As a rock guitarist, I am always looking at/for the differences between 6L6 and EL34 where compression is concerned. I'd love to see you get your hands on both the EVH 5150III and EVH 5150IIIS (6L6 vs EL34 respectively) just to graph comparatively. Also, Mesa Boogie has an amplifier called the "Triple Crown" which has the ability to switch between the two valve and bias choices (Mesa/Boogie Triple Crown TC-100 - 100-watt Rackmount Tube Head | Sweetwater). I'd love to see a Hiwatt 100 watt amp with the features that these previously mentioned amps have. The best of all possible worlds!
Hopefully, some day we will be able to provide the comparisons you described, Kieron.
Now repeat everything using a compressor/limiter at various points in the signal chain and factor in tube degradation and capacitor drift and compensate for variations in wall voltage and temperature...and by the time you are done you will have PSH (permanent shift of hearing) caused rapid onset aging...Outstanding work
Thanks, Paul :)
Thank you Uncle Doug. I have a twin 65 reissue that I will be checking for these changes as well. I already found it had the wrong Reverb transformer with 1/4 of the proper ohmic value (per comparison). That was a mind bender but obvious when checking part numbers from schematic. Big difference!
You're welcome, Randolph. I'm glad the videos are helpful.
I really loved the comparison with the schematics unbelievable video I loved it Thank you !
Glad you enjoyed it, Lee.
Great video Doug! Yes to more of everything!
You got it, Alan. Thanks !!
Very nice. It would be interesting to see the same experiment with 80% to 100% and then look at the whole 40% to 100% spectrum just for grins. I imagine that there is a point of diminishing returns somewhere in there, tube/transformer lifespan notwithstanding. The blackface/silverface comparisons were also fascinating. I wonder what the price difference between the GZ34 and and the 5U4GB would have been when one could buy tubes by the handful just about anywhere in any town. Cheers, Uncle Doug! Merry Christmas!
No one seems to recommend the higher wattage biasing, Michael. My guess is that improvement in tone is negligible and tube/component lifespan is reduced. I would guess that GZ34's have always been more expensive.
Wish you lived in Vancouver Canada Doug. Really interesting stuff. I'm learning so much about vintage Deluxe Reverbs. I recently bought a used 1981 DR (European Export model). I was told it had the AB schematic, but not 100% sure. It was unused by the owner who stored it shortly after inheriting it from a relative. I gave it to my amp tech who has told me that there is no need to make any modifications. I just popped some Dual Matched JJ 6V6's in the amp as the originals were not well matched. He advised me not to change any of the original caps as they seemed fine. I have yet to give it a good workout and use it gigging so I won't make any mods unless I hear something untoward. However, from this video, I don't really think modding it to blackface specs would make that much difference to the sound. Upgrading the tubes may have a more significant impact as well as swapping out the speaker. Luckily I have a friend with a 79 Silverface which has had the 'blackface' mod. I'm interested to see if there is a difference in sound. Great stuff.
Thanks for sharing, Peter. Best of luck with your Deluxe Reverb.
Great knowledge packed video! Thank you Uncle Doug!
You're welcome, Carlos :)
I agree, the tone was better to me as it increased and 70% was the best. Thanks for this public service.
You're welcome, Will. Glad you enjoyed the video.
Thanks for another great vid and a tremendous effort Doug. I dare say that theirs a huge difference when bedroom playing and a live performance. At low bias on stage (below 70%) the amp gets scratchy and weird shit starts happening. Basically, low bias simply doesn't cut it live. When I play at home I have some amps (60+ amps) that I
bias cool
Thanks for the helpful input, Jimi.
I really enjoyed the second feature and learned some good tips. Thank you.
Glad it was helpful, Rex. More similar features will follow.
Wow Wow Wow Wow. I'm SPEECHLESS. Your knowledge and your ability to teach is just mind boggling. I've been an advanced class amateur radio operator (Canada)) since 1982 and I thought that I understood tube amps. Au contraire as they say en Francais , LOL. I have learned SO MUCH from your channel!! I'm a Patreon contributor and with good reason. Thank you SO much for these videos. There is so much info in this video... I will be watching again and again and again. One cannot glean all this info in one viewing.
I do have a question about the AB763 reservoir caps shown in the schematic being in parallel, when, on my 68 silver face Super Reverb, as well as every amp I've seen, they are in series. Whats going on with that??.
Thanks again, for sharing your wealth of knowledge, Uncle Doug.
Give the kitties a good ear scratching from me.
Thanks so much for your very kind words, Bob. Fender tried different circuit features in their amps, retaining those that worked well and eliminating those that did not. Apparently, the series configuration was superior with its much higher voltage tolerance.
I'm behind on my videos. Happy New Years Doug. Great video as always. Cool second part if you ask me. Learned some timeline history in the second half. Of course the big question is what about 80% to 90% hot? Of course you used to be able to walk into 7-11 and check and get tubes then. I know you remember lol.
Thanks, Bert. You're welcome to experiment on your own amp ;) Yes, I do remember the tube testers at Radio Shack and the drug store.
I haven't heard it yet. I can't wait any more, Uncle Doug.
I hope you enjoy it, Tony.
@@UncleDoug Well, of course you are correct in what you do, Doug, and I did enjoy it. But I would need a more private conversation to better qualify my response, and that's probably surplus to your requirements. Cheers. Keep up the good work.
I like both 60% & 70%.
60% 7.17 W. would make your tubes last longer right?
I noticed each time you go up the Bass body sound goes up.
I prefer 60%. Full dynamic range and easy on the amp. Maybe split the difference 65% 👍
That makes good sense, Ronnie. Agreed.
It's my understanding that Fender biased those output tubes to get close to 10.5-11 watts out of each 6V6, so they could make good on their 22 watt amp claim. Am I wrong? You would be the one to know. I thought the best overall sound, through my headphones was at the 70% bias. I must say this video was my most favorite of all of the technical videos. You not only gave us an audio demo, you showed them on the oscilloscope and the analysis program! Seeing is believing! You could have made the later part of this video a separate video comparing the Blackface to the Silverface amps, so thank you for including it. I was able to enjoy 2 cups of dark roast while viewing! Gerald Weber did some videos on this subject but you really made it clear of the differences and how to do any changes, if you want to. This video should be viewed by anyone who desires to build a DR. Many options could be experimented with to hone in on ones perfect tone! I plan a single channel AB763 and found the differences valuable. Love from NW Colorado. Thanxz
Thanks for all your very nice comments, ATL. Yes, I feel that Fender over-biased their smaller amps to achieve somewhat inflated output wattage values.
Well done. Very educational.
Thanks, Max :)
Maybe it's a bit pretentious or opinionated to say, but I think that this just shows how it was designed to be played like how the tubes were supposed to be used technically.
My favourite part is always the schematic studies. Thanks for another educational and entertaining episode, Doug.
Thanks for your input, Yuppi.
The last year I have begun biasing my vintage Fenders by ear, rather than following an amp tech’s assessment and, of course, they sound much better to me.
I recall a mechanic who would set ignition timing in race cars by ear. Most of the time, the engines survived :)
Love the circuit analysis part 2 video. Would love a similar video for the push-pull princetons. Also, would be great if these were distinct videos on RUclips for easy searching and access. Thanks for the amazing RUclips content. Long time viewer.
I'm glad you liked it, Thomas. I do intend to post the part 2 portion as a stand-alone video to facilitate searches.
Great video, but I would also investigate over-driving the tubes and also do 80, 90, and 100%!
Hopefully someone will repeat the experiment at 88%, 90%, and 100% and let us know what happens.
@@UncleDoug thank you Soo much for doing this...as always. Great feedback and at one point, you wondered if maybe it was biased beyond 70%. I know some amp designers and people do intentionally bias above 70, and have confirmed 100 and about 110%!...but the open question is...what does that do? Thanks again for you time Uncle! 😀
Hi Uncle Doug!! Merry Christmas and Happy New Year!!
Thanks so much !! Same to you, JL :)
Thanks for this! Very interesting indeed!
Glad you enjoyed it, Shred.
Well done Uncle Doug, well done.
Thanks twice, Mark :)
Thanks for posting this video- very informative - I honestly cant tell the difference due to the distorted sound. I sounds like the mic is clipping.
I'm sorry the audio was suboptimal, Peter.