I am a guitar player AND do my own electrical repair and modifications....thank you Steve so much for all of this new found knowledge you graciously impart in all of your teaching videos!!! I put it to very good use, for I play in a rock band. People will always love rock!! Rock and blues will NEVER die!!! ( dream come true video with Marshall Superlead, 6CA7 tubes, and everything variac!!! I love my early 70's Superleads!! ) PS...Hamer's have killer necks, wood, and tone! Damn this current inflation crisis...I want a Powerstation attenuator!!!
This is a master class in how the power to/from an amp interacts with the output of the sound. I want to play with a variac on an older amp that i way too clean and loud. He brought up all the issues I never considered, so now I can approach my tone quest more succinctly. Also, his playing is sick!
This is one of the coolest videos about how biasing and input voltage affects an amplifier and the different ways to achieve it, basically showing us Steve Fryette’s 50+ years of experience in a Cliff’s Notes version. Bottom line seems to me that the Power Station is THE answer for optimizing the tone of probably all tube amps. Thanks for making this video and especially thanks to Steve Fryette for being so generous with sharing his knowledge.👍🏻🤘🏻
Great, thorough video by Steve. Thanks for putting this together and as always....it depends on what they end use wants. Both tones...EL34 and standard volume and bias is different than 6CA7 variaced. Tone is in the ear of the person playing, neither right nor wrong, but definitely different!
WOW what an eye opener for the electronics ignorant musician! I just bought a Bugera Ps1 and was about to buy a Variac, but it seems like the Power Soak will do a better job of getting me what I want anyhow. Thanks Mr. Fryette! That's why you're a legend in the game!
Awesome breakdown of variac and attenuation methods. One other super valuable feature of the Power Station is that once you "lock in" your amps sweet spot, you can then dial your output volume to match your speakers sweet spot for break up or clean up. Now your amp and speakers are dialed for optimum touch responsiveness and pick attack articulation. My PS is EASILY one of the best purchases I've made in years.
I have an old variac just like the one that you have pictured in the shot for the video and it actually reads really really close to what it says on the actual scale which is pretty cool but yeah if you're going to do work on amplifiers you got to have a variac. Great video guys!
Wow, that was amazing. I’m sold, I’ve gotta have a power station. The amp with Electro Harmonix tubes sounded much better than the 2 tube NOS variac solution. The tone with NOS into the Power Station must be heavenly. I’ve been adding effects loops and master volumes to amps that weren’t originally designed with them (Marshall Plexi, Fender Bassman, Fender Deluxe), and not getting the results I liked. Now I know how to achieve what I was intending.
In the early 60's my parents upgraded from a Crosley TV (B&W) to a DeForest Console TV/Stereo to play LPs. A TV repairman recommended a Variac to operate the unit at optimum voltage, being 100% Vacuum Tube. And boy, did it sound sweet. I just ordered a Brown Box to run my vintage amps, hoping for better tone.
i have a 1959 HW circuit, ~68 type circuit. i love the 90V sound, at times. i love van halen and his early sound. however, of all the amps i have had, the sound of the 100 watt plexi head really going hard cant be replaced. the variac tone doesnt smack you in the ears and say listen to me near like the full unhinged amp. when you roll the guitar back the 100w also is super touch sensitive. you hear everything that comes near the strings. the 100 w plexi is just such a badass amp in original form. so i built a bucking transformer/box to give me wall current or 90V and made my bias circuit switch able. so when i switch wall voltage i switch bias as well. now as mood changes i can change the amp in seconds. why bucking transformer, one it was cheaper than a quality variac, two it doesnt drift, three it made it easier to switch voltages in my opinion and a little more idiot proof. four its more robust.
I'm getting a 100watt marshall clone made with a 90v switch. The amp also has individual bias adjustment pots for the four tubes. I'm going to drop and rebias as you have. Does your amp run hot doing this?
@@Bairov not any hotter than usual. I ended up putting a pair of small rack fans in the back of my amp. They push air into the head and out the top vent. The hot smell went away when I did this. This means I leave the back off the head. I leave my amp on 8 for volume. Then just attenuate it down as best I can. So it’s always running hard. It’s blown a couple cheap cap cans because of this. Replaced them all with f &t and they’ve been good since. My amp runs 505 volts on the plates with 125 wall voltage. Then pile drives into a rock crusher attenuator. Lowest db I can get is 93. Any lower and the attenuator hats way too hot. It’s a killer amp. I liked the low voltage sound but it took away the amp that I liked playing on. The feel was gone. The concusive sound was way less. So I put it back. Thought about putting in a switch and doing as yours is being done but decided I wouldn’t play like that very often since I like the way the amp is stock Btw. For what it’s work I put nos mustard caps all through the amp. Shipped from Scotland I think. Small difference but I thought what the hell
@@Bairov good call on rebias it’s a must. Your plates will be around 330-350 volts so the bias has to be fixed. Also a proper hand wired amp is really nice since it’s far easier to work on. So you should be good to go there too Be prepared. If you’ve never played on a a plexi it really exposes your playing. It made me play different. I was used to more gain and endless sustain. Now this amp exposes my short comings. Kind of like switching from hummocks to singles.
I have 6l6's in one of my heads and I actually like the gain. They don't breakup as soon but when they give it up it's a solid gain structure that's fun to play over. Maybe a little less sustain, unless that's the circuit.
IIUC power scaling uses a FET of some sort which allows the voltage through it to be adjusted. Steve said it acts as a regulator, I'm not clear why - I mean the FET is not really the same as a beefed up 7812 for example, what am I missing?
Hey Steve! Can you speak on why you cant use a Variac with Brownface amps that have the bias tremolo? Smoked one of mine trying to drop the voltage and the bias went crazy on a 6G2 Princeton. Cheers!
Well designed Power Scaling circuits do sag and certainly don't sound sterile. They're also very quiet at all power levels. Best built into an amp specifically designed around that rather than as an add on I would say however.
what they say in the video is that sag is more stable set on a precise level on solid state rectifiers and mostly on amps with regulators than on tube rectified amps. They don't say the variac is useless without a tube rectifier they just say you'll have less range of changing the sag depending on the amp. great information
@Music_is_fun I was referring to "Power Scaling" which is very different to a simple variac. It's another attempt to get cranked amp sounds at low volumes: you could say a "rival" to Fryette products and I felt the dismissive comments directed at it in the video were basically not true: ask Suhr, Stephenson etc who know how to use the technology: it's far from sterile and sag is completely achievable in power scaling systems. Every solution to the tube amp volume problem has pros and cons
Not so much interested in using one for performance but rather for repairs and building. In the case of building a new amp or kit, or for bringing an amp that’s been sitting for a while up slowly for maintenance and/or repair, how long of a process is it to bring an amp from 0V to full input voltage? I’ve never been able to find any kind of real reference (though I’m sure I just haven’t looked long enough) as to how slowly an amp (especially one that’s never been powered up) should be brought up to full input voltage. This is just the kind of info people like me need to keep from frying something in the design and creation process. Thanks for sharing your knowledge!!
Depends on your level of confidence and shelf age of parts. New parts don't need this and production amps are usually consistent enough that they don't need it either. We power up units off the production line with the power switch. They get an initial power up check to make sure all of the basics are good. We just keep a thumb on the switch in case there's an issue.
It may sound crazy but, at home or in the studio I love running a '67 Fender Deluxe Reverb through a Variac at around 40V and max volume. It's got an amazing overdrive sound that's not flubby. Almost as if I was using a buffered pedal. So, on a separate note, I'm assuming you're using 18V because that is the available tap from your chosen transformer and say you want to go lower than 90V with the Variac and still keep the preamp filaments regulated, why not run the filaments in parallel at 6.3V instead of in series at 12.6V giving you a lot more room to work with?
hello, when lowering the voltage using the variac, what happens to the heater voltage? will having voltages below 6 volts in the heater section cause something to the tubes? thank you.................................
Am I understanding correctly, variac'ing the 100 watt plexi down to 90 volts makes the amp output 18watts? If so that's great news for my new project. 100 watt amp with two power tubes pulled that is. So with all 4, is that doubled?
I am building a 100 watt plexi and plan to run it into my Torpedo CaptorX for recording and just playing. The Captor only takes a 100 watt load and I'm worried about overloading it as I plan on cranking the amp. Would using one of these reduce the output to a safe wattage and is there a way to monitor it accurately?
Here is what is Bad Ass about this video folks... He Is Hot Switching The Speaker Output Between His Speaker and Load! And No Smoke Was Released In This Video...Damn Those Circuit Boards Are Sexy!
A well designed, constructed, laid out, etc hi gain amplifier can be very quiet with AC filaments on all preamp stages. DC heaters are somewhat of a myth.
I would like to ask you one question. I use a new Chinese variac on my Marshall JTM45 and my Ceriatone HRM 50 watt amps. I have heard that you cannot run a guitar amp for a long time on one of these Chinese variacs. Is this true that these variacs maybe too risky to use. So far I have only run the variac for usually an hour with amps rebiased at 115 volts or 118. Just wondering. I see you use the Chinese made variacs. I assume they're safe on your amp.
Ideally, the variac you use should be rated at twice the power useage of the amp measured from the wall outlet. That info is usually listed on the back of the amp. You'll normally see something like "117V, 300W" on the back near the outlet. But since that rating is the absolute maximum the amp will draw, and that will be a lot less in actual practice when you use a variac, it is safe to use something like a 500W - sometimes stated 500VA - variac. Where it was made is these days pretty irrelevant. A variac rated at 1000VA will simply run a little cooler.
The pair of 6CA7s at 120v gave you 32 watts huh? A pair of EL34s would have given you closer to 50 watts? If I understood correctly, then that explains why my Sylvannia 6CA7 pair just gave me just 32 Watts in a JCM 800 1987. That means 6CA7s would help tame a non master volume Marshall a wee bit. I do not want to put lots of miles on those 6CA7s and just kind of curate them (I have a few old tubes I use to compare modern ones with -- Chinese ECC83s seem to compare best to my old Mullard and Brimar ones). P.S. Now I have a PS-2A I do not need to tame the amps like I needed to do for my previous reactive load. I do get a bit nervous cranking amps into reactive loads though. I blew up my brand new 1959RR so bad using a 1960a cab and also a Palmer Speaker Sim that they gave me a refund (something in the amp was not right and the voltage went really high the tech said). I find myself using Softube plugin amps more often at home, because I can't blow up a plugin and it does not seem worth the tube wear doing hours running scales and stuff to a metronome -- or aimlessly noodling lol :P
The difference between 6CA7 and EL34 isn't really that "deep". True pentode outout tubes have a suppressor grid, which was invented and patented by Phillips. None of the American manufacturers wanted to pay Phillips for the patent rights to manufacture their own pentodes, so the American engineers developed plate structures that were designed to form and shape the electron beam and in some manner imitate the effect of a suppressor grid. The 6L6, 6V6, 6BQ5, and 6CA7 are all "beam power tubes", not pentodes. The 6BQ5 was an American attempt at imitating an EL84 as closely as possible without running afoul of the patents, and the 6CA7 was designed to get as close as possible to the performance of an EL34 without running afoul of the patent. The pinouts are usually the same and you can generally interchange EL34 with 6CA7 in most circuits (and interchange 6BQ5 with EL84 in most circuits) but they might require rebiasing for best possible performance, lowest or highest distortion, and highest power output, and they might not sound quite the same. By the way it isn't uncommon to see vintage European made EL84 tubes that were imported and rebranded "6BQ5" by RCA, GE or Sylvania (despite the American branding, the tubes often say "made in Gt Britain); but for some reason its less common to see American-branded "6CA7" tubes that are actually a European import. The majority of vintage or NOS American- made/branded 6CA7 tubes will be in a fat glass bottle, similar to what you see on a 6L6GC. If they're skinny, straight sided glass bottles, they're almost certainly European imports from Mullard, Amperex or Telefunken, and typically marked with the country of origin. Amperex was originally a Long Island-based NY company making industrial tubes, and apparently they entered into a licensing and import deal or merger with Phillips; and at some point Sylvania had manufacturing deals with GE and also had an import deal going with Philips (probably explains why we see lots of NOS military JAN-spec Phillips tubes ---- the US military would not have wanted to be directly dependent on a European manufacturer for tubes).
As we said in this video, we'll get into more detail on the related Malcontents episode, which we did. We also discussed manufacturers cross-marketing in the Mals tube episode. Not to this particular extent though because, you know, margaritas...
@@FryetteAmpsthanks for the heads up, I'll check out the other episides. There's so much history lost around the development, manufacture, patents, licensing, rebranding and distribution of tubes, and the inevitable mergers and corporate takeovers. Things got really weird in the late 70's and 80's with companies like National and IEC Servicemaster importing and rebranding tubes. They could be Mullard or Tele and they could be absolute crap from anywhere that was rebranded to look like good European imports (ServiceMaster was notorious for junk).
@@FryetteAmps , that was a good discussion. I would have liked ro see some discussion around heater-current draw and whether any of the re-labeled and "re-imagined" Russian (or Chinese) tubes exceed the original heater-draw specs sufficiently to cause overheated or blown power trannies; like those "weak" 6L6 types being relabeled as high-voltage 6V6's ---- do they draw .45 A per tube, or .9A per tube? And do "modern 6550's draw 1.5A, with modern 6550A drawing 1.8A, per the 1960's tube specs? Because I have a "DOUBT" rule pertaining to tube "substitution" and "upgrade" with modern production tubes: DOn't Unintentionally Blow Transformers! By the way I have never read anything scholarly about migration of air molecules, O2 or Nitrogen, into a tube over time unless the seal is bad around one of the pins or lead out wires, in which case usually it's quite obvious because the getter will turn snow white. The only info I ever read that possibly related to permeability or susceptibility of glass envelopes to air infiltration is that certain tubes were designed to withstand *low* air pressure in high-flying military planes (like the Chatham 5R4GY potato masher rectifier); and some transmitting tubes used special high temperature glass or quartz. Pertaining to contamination of the vacuum as tubes age, whether in use or stored away as NOS, water vapor was a particularly troublesome contaminant, and some tube types had their plates and other parts *baked in hydrogen* to drive out contaminants (according to the reference book "Tube Lore" by Lidwell Sibley). Hmm, would you want a high-temperature hydrogen furnace operating iin the neighboring industrial park? The quality and insulating qualities of the mica insulators is gonna be important as well (Russia supposedly has excellent quality mica) and the wafers are presumably baked to drive out moisture and then sometimes coated with compounds to increase their insulating factor. Having encountered tubes with interelement leakage, I have to wonder if some of the metallic materials in the getter got splattered on the insulators when the tube was flashed with the spot RF beam, or if the cathodes sputtered away some emissive material onto the micas or (worse) onto the grids, screens or plates, causing gassy behavior and thermal runaway. I also read somewhere that the KT series of kinkless tetrodes were purportedly originally built with gold plated or perhaps carbonized grids to minimize grid emission, but I don't know if such manufacturing techniques were ever applied to more modern Russian or Chinese tube manufacturing. 99.9% of my tube experience has been with vintage American and European tubes, and as you've pointed out, the original design, engineering specs and manufacturing processes used for our favorite vintage tubes is often merely a suggestion at best to the modern tube manufacturers.
@@FryetteAmps , ps, A discussion of the 6BQ5 beam power tube versus true pentode EL84, as well as their tougher semi-equivalent the 7189 and 7189A, seems in order. Especially germane to the discussion is whether there are any additional pinouts being used for heat dissipation of the grid and screen, or cases like the 7189A where the pin out is changed so that only the 7189A will work in certain amplifiers (like some older Magnatones) that run at voltages and dissipation well above what a 6BQ5, EL84 or regular 7189 can handle. And, does anybody make a usable "6973" these days?
I am a guitar player AND do my own electrical repair and modifications....thank you Steve so much for all of this new found knowledge you graciously impart in all of your teaching videos!!! I put it to very good use, for I play in a rock band. People will always love rock!! Rock and blues will NEVER die!!! ( dream come true video with Marshall Superlead, 6CA7 tubes, and everything variac!!! I love my early 70's Superleads!! ) PS...Hamer's have killer necks, wood, and tone! Damn this current inflation crisis...I want a Powerstation attenuator!!!
Me too!! The PS 2 is a "Bucket List" piece of gear for me!!
Thanks for taking the time to share these insights Steve. Fantastic overview and demonstration, really enjoyed it !
Man this is the best tech vid i have seen yet, i need to pick up some more test gear, and get into this myself
This is a master class in how the power to/from an amp interacts with the output of the sound. I want to play with a variac on an older amp that i way too clean and loud. He brought up all the issues I never considered, so now I can approach my tone quest more succinctly.
Also, his playing is sick!
This is one of the coolest videos about how biasing and input voltage affects an amplifier and the different ways to achieve it, basically showing us Steve Fryette’s 50+ years of experience in a Cliff’s Notes version.
Bottom line seems to me that the Power Station is THE answer for optimizing the tone of probably all tube amps.
Thanks for making this video and especially thanks to Steve Fryette for being so generous with sharing his knowledge.👍🏻🤘🏻
Appreciate the knowledge. Wish this would have came out back when everyone was raving about power scaling 10ish years ago.
Great, thorough video by Steve. Thanks for putting this together and as always....it depends on what they end use wants. Both tones...EL34 and standard volume and bias is different than 6CA7 variaced. Tone is in the ear of the person playing, neither right nor wrong, but definitely different!
So much knowledge shared on this channel. Thanks so much!
The most important question is, where do you get one of those Sound City shirts?
Thanks for taking the time to film and share this. Absolutely fascinating.
Fantastic Video, I learned a lot. Thank you for an hour of your time making this.
Thank you so much for your time and knowledge…🙏
WOW what an eye opener for the electronics ignorant musician! I just bought a Bugera Ps1 and was about to buy a Variac, but it seems like the Power Soak will do a better job of getting me what I want anyhow. Thanks Mr. Fryette! That's why you're a legend in the game!
What a great explanation. Thank you for the time.
Awesome breakdown of variac and attenuation methods. One other super valuable feature of the Power Station is that once you "lock in" your amps sweet spot, you can then dial your output volume to match your speakers sweet spot for break up or clean up. Now your amp and speakers are dialed for optimum touch responsiveness and pick attack articulation. My PS is EASILY one of the best purchases I've made in years.
Mr. Fryette, you have a nice touch. 👍🎸
Damn that's a great sounding amp.
So much knowledge shared. Thank you Steve.
I have an old variac just like the one that you have pictured in the shot for the video and it actually reads really really close to what it says on the actual scale which is pretty cool but yeah if you're going to do work on amplifiers you got to have a variac. Great video guys!
I liked the tone at the end the best.
Very useful, thanks for putting this together.
Awessome Video !! Killer Hamer too!!!!
Wow ive learned so much from your videos, I'd like to come work there for you as an intern just so I could learn.
very interesting video
Great video! Thanks for sharing.
Wow, that was amazing. I’m sold, I’ve gotta have a power station. The amp with Electro Harmonix tubes sounded much better than the 2 tube NOS variac solution. The tone with NOS into the Power Station must be heavenly. I’ve been adding effects loops and master volumes to amps that weren’t originally designed with them (Marshall Plexi, Fender Bassman, Fender Deluxe), and not getting the results I liked. Now I know how to achieve what I was intending.
awesome info!!!
1971 seems to be a magic year!
In the early 60's my parents upgraded from a Crosley TV (B&W) to a DeForest Console TV/Stereo to play LPs.
A TV repairman recommended a Variac to operate the unit at optimum voltage, being 100% Vacuum Tube.
And boy, did it sound sweet.
I just ordered a Brown Box to run my vintage amps, hoping for better tone.
Your fingers are dripping with tone!!!
i have a 1959 HW circuit, ~68 type circuit. i love the 90V sound, at times. i love van halen and his early sound. however, of all the amps i have had, the sound of the 100 watt plexi head really going hard cant be replaced. the variac tone doesnt smack you in the ears and say listen to me near like the full unhinged amp. when you roll the guitar back the 100w also is super touch sensitive. you hear everything that comes near the strings. the 100 w plexi is just such a badass amp in original form.
so i built a bucking transformer/box to give me wall current or 90V and made my bias circuit switch able. so when i switch wall voltage i switch bias as well. now as mood changes i can change the amp in seconds.
why bucking transformer, one it was cheaper than a quality variac, two it doesnt drift, three it made it easier to switch voltages in my opinion and a little more idiot proof. four its more robust.
I'm getting a 100watt marshall clone made with a 90v switch. The amp also has individual bias adjustment pots for the four tubes. I'm going to drop and rebias as you have. Does your amp run hot doing this?
@@Bairov not any hotter than usual. I ended up putting a pair of small rack fans in the back of my amp. They push air into the head and out the top vent. The hot smell went away when I did this. This means I leave the back off the head. I leave my amp on 8 for volume. Then just attenuate it down as best I can. So it’s always running hard. It’s blown a couple cheap cap cans because of this. Replaced them all with f &t and they’ve been good since.
My amp runs 505 volts on the plates with 125 wall voltage. Then pile drives into a rock crusher attenuator. Lowest db I can get is 93. Any lower and the attenuator hats way too hot. It’s a killer amp. I liked the low voltage sound but it took away the amp that I liked playing on. The feel was gone. The concusive sound was way less. So I put it back.
Thought about putting in a switch and doing as yours is being done but decided I wouldn’t play like that very often since I like the way the amp is stock
Btw. For what it’s work I put nos mustard caps all through the amp. Shipped from Scotland I think. Small difference but I thought what the hell
@@Bairov good call on rebias it’s a must. Your plates will be around 330-350 volts so the bias has to be fixed.
Also a proper hand wired amp is really nice since it’s far easier to work on. So you should be good to go there too
Be prepared. If you’ve never played on a a plexi it really exposes your playing. It made me play different. I was used to more gain and endless sustain. Now this amp exposes my short comings. Kind of like switching from hummocks to singles.
I have 6l6's in one of my heads and I actually like the gain. They don't breakup as soon but when they give it up it's a solid gain structure that's fun to play over. Maybe a little less sustain, unless that's the circuit.
Sounds awesome.
I have a pitbull VHT amp. Could you mod it to sound more like that Marshall?
Much obliged
That store in Seattle is REPC.
IIUC power scaling uses a FET of some sort which allows the voltage through it to be adjusted. Steve said it acts as a regulator, I'm not clear why - I mean the FET is not really the same as a beefed up 7812 for example, what am I missing?
Hey Steve! Can you speak on why you cant use a Variac with Brownface amps that have the bias tremolo? Smoked one of mine trying to drop the voltage and the bias went crazy on a 6G2 Princeton. Cheers!
Well designed Power Scaling circuits do sag and certainly don't sound sterile. They're also very quiet at all power levels. Best built into an amp specifically designed around that rather than as an add on I would say however.
Link to a schematic of aforementioned well designed power scaling circuit. please.
@@FryetteAmps talk to Mark Stephenson
what they say in the video is that sag is more stable set on a precise level on solid state rectifiers and mostly on amps with regulators than on tube rectified amps. They don't say the variac is useless without a tube rectifier they just say you'll have less range of changing the sag depending on the amp. great information
@Music_is_fun I was referring to "Power Scaling" which is very different to a simple variac. It's another attempt to get cranked amp sounds at low volumes: you could say a "rival" to Fryette products and I felt the dismissive comments directed at it in the video were basically not true: ask Suhr, Stephenson etc who know how to use the technology: it's far from sterile and sag is completely achievable in power scaling systems. Every solution to the tube amp volume problem has pros and cons
Not so much interested in using one for performance but rather for repairs and building. In the case of building a new amp or kit, or for bringing an amp that’s been sitting for a while up slowly for maintenance and/or repair, how long of a process is it to bring an amp from 0V to full input voltage? I’ve never been able to find any kind of real reference (though I’m sure I just haven’t looked long enough) as to how slowly an amp (especially one that’s never been powered up) should be brought up to full input voltage. This is just the kind of info people like me need to keep from frying something in the design and creation process. Thanks for sharing your knowledge!!
Depends on your level of confidence and shelf age of parts. New parts don't need this and production amps are usually consistent enough that they don't need it either. We power up units off the production line with the power switch. They get an initial power up check to make sure all of the basics are good. We just keep a thumb on the switch in case there's an issue.
I variac'd my katana ...but all it did was make it smell funny
My 5150 iconic did the same 🤣💀
It may sound crazy but, at home or in the studio I love running a '67 Fender Deluxe Reverb through a Variac at around 40V and max volume. It's got an amazing overdrive sound that's not flubby. Almost as if I was using a buffered pedal. So, on a separate note, I'm assuming you're using 18V because that is the available tap from your chosen transformer and say you want to go lower than 90V with the Variac and still keep the preamp filaments regulated, why not run the filaments in parallel at 6.3V instead of in series at 12.6V giving you a lot more room to work with?
hello, when lowering the voltage using the variac, what happens to the heater voltage? will having voltages below 6 volts in the heater section cause something to the tubes? thank you.................................
No. Tube nerds may disagree on esoteric technical grounds that typically do not apply here.
Am I understanding correctly, variac'ing the 100 watt plexi down to 90 volts makes the amp output 18watts? If so that's great news for my new project. 100 watt amp with two power tubes pulled that is. So with all 4, is that doubled?
The 28 volts (that works out to 100!watts RMS) on the yellow multimeter….where is the 28 volt signal feeding that multimeter coming from?
The speaker out from the amp into an 8 ohm load.
I am building a 100 watt plexi and plan to run it into my Torpedo CaptorX for recording and just playing. The Captor only takes a 100 watt load and I'm worried about overloading it as I plan on cranking the amp. Would using one of these reduce the output to a safe wattage and is there a way to monitor it accurately?
Here is what is Bad Ass about this video folks... He Is Hot Switching The Speaker Output Between His Speaker and Load! And No Smoke Was Released In This Video...Damn Those Circuit Boards Are Sexy!
I thought Eddie used a light bulb current limiter?
A well designed, constructed, laid out, etc hi gain amplifier can be very quiet with AC filaments on all preamp stages. DC heaters are somewhat of a myth.
I would like to ask you one question. I use a new Chinese variac on my Marshall JTM45 and my Ceriatone HRM 50 watt amps. I have heard that you cannot run a guitar amp for a long time on one of these Chinese variacs. Is this true that these variacs maybe too risky to use. So far I have only run the variac for usually an hour with amps rebiased at 115 volts or 118. Just wondering. I see you use the Chinese made variacs. I assume they're safe on your amp.
Ideally, the variac you use should be rated at twice the power useage of the amp measured from the wall outlet. That info is usually listed on the back of the amp. You'll normally see something like "117V, 300W" on the back near the outlet. But since that rating is the absolute maximum the amp will draw, and that will be a lot less in actual practice when you use a variac, it is safe to use something like a 500W - sometimes stated 500VA - variac. Where it was made is these days pretty irrelevant. A variac rated at 1000VA will simply run a little cooler.
@@FryetteAmps thank you so much for answering my question. Love your videos. Michel from Niagara Falls, Ontario, Canada
I need a PS 100 wow
120v 2 tubes 6CA7 standard bias 36w 47:23
90v 2 tubes 6CA7 max bias -30v 18w(= -45v with 4 tubes @120 v AC) 49:50
120v 4 tubes EL 34 standard bias 130w? Powerstation 54:01
The pair of 6CA7s at 120v gave you 32 watts huh? A pair of EL34s would have given you closer to 50 watts? If I understood correctly, then that explains why my Sylvannia 6CA7 pair just gave me just 32 Watts in a JCM 800 1987. That means 6CA7s would help tame a non master volume Marshall a wee bit.
I do not want to put lots of miles on those 6CA7s and just kind of curate them (I have a few old tubes I use to compare modern ones with -- Chinese ECC83s seem to compare best to my old Mullard and Brimar ones).
P.S. Now I have a PS-2A I do not need to tame the amps like I needed to do for my previous reactive load. I do get a bit nervous cranking amps into reactive loads though. I blew up my brand new 1959RR so bad using a 1960a cab and also a Palmer Speaker Sim that they gave me a refund (something in the amp was not right and the voltage went really high the tech said). I find myself using Softube plugin amps more often at home, because I can't blow up a plugin and it does not seem worth the tube wear doing hours running scales and stuff to a metronome -- or aimlessly noodling lol :P
The difference between 6CA7 and EL34 isn't really that "deep". True pentode outout tubes have a suppressor grid, which was invented and patented by Phillips. None of the American manufacturers wanted to pay Phillips for the patent rights to manufacture their own pentodes, so the American engineers developed plate structures that were designed to form and shape the electron beam and in some manner imitate the effect of a suppressor grid. The 6L6, 6V6, 6BQ5, and 6CA7 are all "beam power tubes", not pentodes. The 6BQ5 was an American attempt at imitating an EL84 as closely as possible without running afoul of the patents, and the 6CA7 was designed to get as close as possible to the performance of an EL34 without running afoul of the patent. The pinouts are usually the same and you can generally interchange EL34 with 6CA7 in most circuits (and interchange 6BQ5 with EL84 in most circuits) but they might require rebiasing for best possible performance, lowest or highest distortion, and highest power output, and they might not sound quite the same.
By the way it isn't uncommon to see vintage European made EL84 tubes that were imported and rebranded "6BQ5" by RCA, GE or Sylvania (despite the American branding, the tubes often say "made in Gt Britain); but for some reason its less common to see American-branded "6CA7" tubes that are actually a European import. The majority of vintage or NOS American- made/branded 6CA7 tubes will be in a fat glass bottle, similar to what you see on a 6L6GC. If they're skinny, straight sided glass bottles, they're almost certainly European imports from Mullard, Amperex or Telefunken, and typically marked with the country of origin. Amperex was originally a Long Island-based NY company making industrial tubes, and apparently they entered into a licensing and import deal or merger with Phillips; and at some point Sylvania had manufacturing deals with GE and also had an import deal going with Philips (probably explains why we see lots of NOS military JAN-spec Phillips tubes ---- the US military would not have wanted to be directly dependent on a European manufacturer for tubes).
As we said in this video, we'll get into more detail on the related Malcontents episode, which we did. We also discussed manufacturers cross-marketing in the Mals tube episode. Not to this particular extent though because, you know, margaritas...
@@FryetteAmpsthanks for the heads up, I'll check out the other episides. There's so much history lost around the development, manufacture, patents, licensing, rebranding and distribution of tubes, and the inevitable mergers and corporate takeovers. Things got really weird in the late 70's and 80's with companies like National and IEC Servicemaster importing and rebranding tubes. They could be Mullard or Tele and they could be absolute crap from anywhere that was rebranded to look like good European imports (ServiceMaster was notorious for junk).
@@goodun2974 ruclips.net/video/syjtzkwlUjg/видео.html
@@FryetteAmps , that was a good discussion. I would have liked ro see some discussion around heater-current draw and whether any of the re-labeled and "re-imagined" Russian (or Chinese) tubes exceed the original heater-draw specs sufficiently to cause overheated or blown power trannies; like those "weak" 6L6 types being relabeled as high-voltage 6V6's ---- do they draw .45 A per tube, or .9A per tube? And do "modern 6550's draw 1.5A, with modern 6550A drawing 1.8A, per the 1960's tube specs? Because I have a "DOUBT" rule pertaining to tube "substitution" and "upgrade" with modern production tubes: DOn't Unintentionally Blow Transformers!
By the way I have never read anything scholarly about migration of air molecules, O2 or Nitrogen, into a tube over time unless the seal is bad around one of the pins or lead out wires, in which case usually it's quite obvious because the getter will turn snow white. The only info I ever
read that possibly related to permeability or susceptibility of glass envelopes to air infiltration is that certain tubes were designed to withstand *low* air pressure in high-flying military planes (like the Chatham 5R4GY potato masher rectifier); and some transmitting tubes used special high temperature glass or quartz. Pertaining to contamination of the vacuum as tubes age, whether in use or stored away as NOS, water vapor was a particularly troublesome contaminant, and some tube types had their plates and other parts *baked in hydrogen* to drive out contaminants (according to the reference book "Tube Lore" by Lidwell Sibley). Hmm, would you want a high-temperature hydrogen furnace operating iin the neighboring industrial park?
The quality and insulating qualities of the mica insulators is gonna be important as well (Russia supposedly has excellent quality mica) and the wafers are presumably baked to drive out moisture and then sometimes coated with compounds to increase their insulating factor. Having encountered tubes with interelement leakage, I have to wonder if some of the metallic materials in the getter got splattered on the insulators when the tube was flashed with the spot RF beam, or if the cathodes sputtered away some emissive material onto the micas or (worse) onto the grids, screens or plates, causing gassy behavior and thermal runaway.
I also read somewhere that the KT series of kinkless tetrodes were purportedly originally built with gold plated or perhaps carbonized grids to minimize grid emission, but I don't know if such manufacturing techniques were ever applied to more modern Russian or Chinese tube manufacturing. 99.9% of my tube experience has been with vintage American and European tubes, and as you've pointed out, the original design, engineering specs and manufacturing processes used for our favorite vintage tubes is often merely a suggestion at best to the modern tube manufacturers.
@@FryetteAmps , ps, A discussion of the 6BQ5 beam power tube versus true pentode EL84, as well as their tougher semi-equivalent the 7189 and 7189A, seems in order. Especially germane to the discussion is whether there are any additional pinouts being used for heat dissipation of the grid and screen, or cases like the 7189A where the pin out is changed so that only the 7189A will work in certain amplifiers (like some older Magnatones) that run at voltages and dissipation well above what a 6BQ5, EL84 or regular 7189 can handle. And, does anybody make a usable "6973" these days?