For those wondering, his post-change tone sounds to my ears not at all different from my stock GA-15. Totally random anecdote on my part but fwiw, I will make these mods. Thank you, sir! This little amp does EVERYTHING. Yes, glaring defects - the input jack is crap (replace it), dusty bottom/back mount (worst place possible), it's a 10in, also I've heard the tube mounts are flammable (change them), etc. but for my money there is no amp more responsive to your guitar controls than this one, takes pedals extremely well, and is absolutely portable. Who needs mediocrity?!
I worked at a store that was a Trace Elliot dealer when the Velocette was introduced. Plugged into a 4x12 cabinet was pretty great and it was too soon to realize their problems. I didn’t work on amps back then. Great video.
fwiw, we use those screw terminals on ship's generator panels, locally on the engines. they're not expected to run problem free for 10yrs, but they're also subject to EXTREME vibration and lots of heat, often 24/7 for weeks on end. so they do work, but i'd think that in an amp, everything would work better if soldered, especially since it's dealing with audio signals, rather than industrial signals. anyway, just a thought.
My goodness the amount of ground you are covering in all of these short and to the point features are one day going to be a textbook of amptech commonsense that virtually could save every namebrand amp out there! Thank you.
Psionic and D-Lab are kings of UA-cam. A good tech is a good tech but it takes someone special to be able want to share their knowledge with everyone. I just work on my own amps but I went from knowing nothing to biasing and then to minor troubleshooting and repair. Buying a scope and signal generator will be my next thing, I just have to know what to looking for when purchasing them.
Thanks for pointing out these flaws. Although I'm now really disillusioned about this amp... I own one and like the sound quite a lot. I think I will invest in these changes. I don't understand amp technology very well, but just one question: You were talking about maybe also replacing the grid stoppers. Is this a necessary step or will it also be OK to just replace 1.) the screen grid resistors and 2.) change the resistor to cool of the bias? Hope ou can answer that! thanks
Really interesting discussion of EL-84 circuits. I bought a Blues Jr. in 2001 that ate power tubes until I added adjustable bias; however, it still ran hot in temperature and is buggy beyond belief at this point. It’s surprising that Bill Machrone was the guru for Blues Junior mods for a very long time yet never mentioned the screen grid resistors. Yes - they are 100 ohms. (No disrespect for Bill - he passed on a few years ago)
If you don't have an air compressor with which to blow out the dust from the amp cabinet, a leaf-blower will work ---- preferably battery-powered, on the lowest setting (probably a good idea to put something over the back of the speaker to protect it from the air pressure). I've found numerous uses for mine, such as blowing the clothes-dryer lint out of the exhaust duct to the outside; and blowing the water out of the outside garden-hose pipe back to the drain plug in the basement, in preparation for winter.
I love mine..I bought mine after the tube sockets were replaced with better ones and had a new transformer. So the previous owner dealt with all the headaches. That being said,I love mine and so do my band mates. I do run mine into a bigger 112 cab with a Blue Alnico Speaker. But that being said, its my fave amp out of over a dozen tube amps. I have Fenders, Vox's, Carvin's, but this one to me has one cuts through in a band mix better than all my other amps. My drummer loves it and says it's his fave amp I use because the strings ring more clearly than with my other amps. I do find that these amps have a love hate thing going on. I was a luthier when they came out and remember how many of these amps needed work. I remember dealers blowing them out cheaply after the sockets started melting. However you get a good one with no issues and its a great pedal Platform for blues lovers. . Paul Jackson Jr. Used one live at a show. He sounded great. What made me want one was the now late Sean Costello used one live one night with his goldtop Les Paul (53 I think) and his guitar never sounded better imo. I guess its all in the eye of the beholder. I've gigged with mine for a few years with no issues and tons of compliments on my sound. Now I have a Trace Elliot Velocette too. It sounds like ass honestly. They must have worked something out between those two tonally. Idk.
That amp sounds great. May be a bad design but that amp is one of my best sounding amps. Also, never burned a tube. Been using it for years. You maybe had some other problems. I have the GA-15RV. The GA-15RV came with a vintage 30
" Uh-oh, the infamous Trace Elliott bass amp has f****d up again". David Lindley, at an ElRayoX gig, around 1988. It seems that this has been a continual problem, not only for the original company but also their "heirs and assigns". That metal rear-grille looks like it would rattle if the amp was played loud ---- or if the stock speaker was replaced with something that had more bass output.
The designers rigged this thing to be a hand grenade. But once you fix it, they’re awesome. The trick is run the both knobs on 12 o’clock. And ride guitar volume and tone.
Rewire the sockets and try using Electro Harmonix 6973s. New EL84s kind of suck. 7189A was a super EL84/6BQ5, but good luck finding them! UK Mullard Brimar EL84s were so tough that USA tube manufacturers like GE, RCA, Sylvania, Tung Sol, Westinghouse, or CBS Hytron just re-stamped the Mullard EL84s as 7189As all the time. ;-) No MOSFET B+ & screens regulation? My old Maggies run 7189As up at around 450 Volts plate.
No, I'm not rewiring the sockets (cutting and redoing traces on the PCB) of this cheap amp. It would exceed the value. The Tube Store sells 7189s. I use them in Voxes.
The sentence fragment, "Right before it caught on fire,....", should be in the introduction of any repair video. Is that a rebadged Trace Elliot Vellocette?
or... leave it alone & change tubes more often. similar values as Matchless Lightning. They run Hot NBD, its part of the sound. and YES you can definitely hear the difference when using larger bias & screen resistors. I'd much rather kill tubes than tone, any day, any way.
My Carvin Belair has 350 ohm screen resistors on top of 400+ volts on the plates and a 2.5k output transformer or you could think in terms of 5k for just a pair of el84 tubes. I was thinking of intentionally mismatch the impedance to get up to 5k transformer impedance for the 4 tubes, (ie. 10k for a pair of el84 tubes). Maybe I will look into upping the screen resistance as well? The Carvin is a fixed biased amp vs. cathode bias. So I don’t know if that makes things cooler in general? Or is irrelevant? Anyone here have experience with these el84 based Carvin amps want to chime in? Am I missing something? They seem like a recipe to eat tubes and spark forest fires?
Up those screen grids and set the fixed bias to about 55% idle. 5K primary impedance would be better. Add flyback diodes from plates to ground. tubedepot.com/products/r3000-25a-3000v-high-voltage-protection-diode
@@PsionicAudio cool, thanks. Brimar data sheet says 2 watt maximum screen grid dissipation of 2 watts at zero signal & 4 watts at maximum signal. So I was thinking of putting in an ammeter in line to see what the current is? Thing is, those are Brimar 1960s el84 ratings. So I imagine the the 4 watts dissipation at max signal has been downgraded for modern production tubes. And I never exactly know what “max. Signal” means? Maximum clean signal before clipping, (basically whatever the amplitude of the fundamental tone is even if in distortion). Or do you consider max signal when you’re in full tilt distortion? Because harmonics add power to the power made from the fundamental.
Welcome to the dark side. In general, data sheets refer to the max clean signal. At the end of the day, in the real world, it's the screen voltage that needs more focus than the screen current. The datasheet G2 max is 300VDC. Take that pretty seriously. You can exceed that, but you don't want to go more than 50V over that. And when you limit screen voltage you end up limiting screen current, so by focusing on the voltage the current usually comes along for the ride. You can decouple screens from the existing screen supply, or use zeners at the screens, but first try just increasing the screen grid resistors. You can go up to 2.2K if needed.
@@PsionicAudio I think my screen grids are at 385 volts, I don’t what Carvin was thinking? Or maybe they figured we should think of el84 tubes as cheap things you should be ready to toss every 3-4 months?
If it was my amp I'd shotgun the guts and wire it all up on terminal strips. Edit: For guys that own this amp it might not be a bad idea to source some NOS 7189 or 7320 tubes for the output.
Thanks! Just examined the El-84 power section in my amp and found all 1Kohm screen grid resistors - very very helpful
For those wondering, his post-change tone sounds to my ears not at all different from my stock GA-15. Totally random anecdote on my part but fwiw, I will make these mods. Thank you, sir! This little amp does EVERYTHING. Yes, glaring defects - the input jack is crap (replace it), dusty bottom/back mount (worst place possible), it's a 10in, also I've heard the tube mounts are flammable (change them), etc. but for my money there is no amp more responsive to your guitar controls than this one, takes pedals extremely well, and is absolutely portable. Who needs mediocrity?!
I worked at a store that was a Trace Elliot dealer when the Velocette was introduced. Plugged into a 4x12 cabinet was pretty great and it was too soon to realize their problems. I didn’t work on amps back then. Great video.
fwiw, we use those screw terminals on ship's generator panels, locally on the engines. they're not expected to run problem free for 10yrs, but they're also subject to EXTREME vibration and lots of heat, often 24/7 for weeks on end. so they do work, but i'd think that in an amp, everything would work better if soldered, especially since it's dealing with audio signals, rather than industrial signals.
anyway, just a thought.
My goodness the amount of ground you are covering in all of these short and to the point features are one day going to be a textbook of amptech commonsense that virtually could save every namebrand amp out there! Thank you.
Psionic and D-Lab are kings of UA-cam. A good tech is a good tech but it takes someone special to be able want to share their knowledge with everyone. I just work on my own amps but I went from knowing nothing to biasing and then to minor troubleshooting and repair. Buying a scope and signal generator will be my next thing, I just have to know what to looking for when purchasing them.
Thanks for pointing out these flaws. Although I'm now really disillusioned about this amp... I own one and like the sound quite a lot. I think I will invest in these changes. I don't understand amp technology very well, but just one question: You were talking about maybe also replacing the grid stoppers. Is this a necessary step or will it also be OK to just replace 1.) the screen grid resistors and 2.) change the resistor to cool of the bias? Hope ou can answer that! thanks
Really interesting discussion of EL-84 circuits. I bought a Blues Jr. in 2001 that ate power tubes until I added adjustable bias; however, it still ran hot in temperature and is buggy beyond belief at this point. It’s surprising that Bill Machrone was the guru for Blues Junior mods for a very long time yet never mentioned the screen grid resistors. Yes - they are 100 ohms. (No disrespect for Bill - he passed on a few years ago)
If you don't have an air compressor with which to blow out the dust from the amp cabinet, a leaf-blower will work ---- preferably battery-powered, on the lowest setting (probably a good idea to put something over the back of the speaker to protect it from the air pressure). I've found numerous uses for mine, such as blowing the clothes-dryer lint out of the exhaust duct to the outside; and blowing the water out of the outside garden-hose pipe back to the drain plug in the basement, in preparation for winter.
excellent, thanks!
I love mine..I bought mine after the tube sockets were replaced with better ones and had a new transformer. So the previous owner dealt with all the headaches.
That being said,I love mine and so do my band mates.
I do run mine into a bigger 112 cab with a Blue Alnico Speaker.
But that being said, its my fave amp out of over a dozen tube amps.
I have Fenders, Vox's, Carvin's, but this one to me has one cuts through in a band mix better than all my other amps.
My drummer loves it and says it's his fave amp I use because the strings ring more clearly than with my other amps.
I do find that these amps have a love hate thing going on. I was a luthier when they came out and remember how many of these amps needed work. I remember dealers blowing them out cheaply after the sockets started melting.
However you get a good one with no issues and its a great pedal Platform for blues lovers. .
Paul Jackson Jr. Used one live at a show. He sounded great. What made me want one was the now late Sean Costello used one live one night with his goldtop Les Paul (53 I think) and his guitar never sounded better imo.
I guess its all in the eye of the beholder. I've gigged with mine for a few years with no issues and tons of compliments on my sound.
Now I have a Trace Elliot Velocette too. It sounds like ass honestly. They must have worked something out between those two tonally. Idk.
That amp sounds great. May be a bad design but that amp is one of my best sounding amps. Also, never burned a tube. Been using it for years. You maybe had some other problems. I have the GA-15RV. The GA-15RV came with a vintage 30
I'm glad your running-with-scissors experience has been good. Your sample size is smaller than mine.
" Uh-oh, the infamous Trace Elliott bass amp has f****d up again". David Lindley, at an ElRayoX gig, around 1988. It seems that this has been a continual problem, not only for the original company but also their "heirs and assigns".
That metal rear-grille looks like it would rattle if the amp was played loud ---- or if the stock speaker was replaced with something that had more bass output.
The designers rigged this thing to be a hand grenade. But once you fix it, they’re awesome. The trick is run the both knobs on 12 o’clock. And ride guitar volume and tone.
From Leo: I like the sound of EL84's pushed a little hard, but not to Kamikaze levels. Good modification.
I hate those Trace push on terminal connectors for the filaments. If it hasn't burnt up yet, it will.
Great video Lyle, thank you. I always learn a lot here. Is it my eye or is the upright black electrolytic cap on the right bulged on the top ?
Thanks! Plastic is, the metal beneath isn't.
Not a great place to have the controls either. Sounds good. Love EL84 amps. Great work!
Great advice and presentation!
Rewire the sockets and try using Electro Harmonix 6973s. New EL84s kind of suck. 7189A was a super EL84/6BQ5, but good luck finding them! UK Mullard Brimar EL84s were so tough that USA tube manufacturers like GE, RCA, Sylvania, Tung Sol, Westinghouse, or CBS Hytron just re-stamped the Mullard EL84s as 7189As all the time. ;-) No MOSFET B+ & screens regulation? My old Maggies run 7189As up at around 450 Volts plate.
No, I'm not rewiring the sockets (cutting and redoing traces on the PCB) of this cheap amp. It would exceed the value.
The Tube Store sells 7189s. I use them in Voxes.
What about the ga30??
Ah once again gibsons reputation precedes itself .
The sentence fragment, "Right before it caught on fire,....", should be in the introduction of any repair video. Is that a rebadged Trace Elliot Vellocette?
Yup. I even say so in the video.
or... leave it alone & change tubes more often. similar values as Matchless Lightning. They run Hot NBD, its part of the sound. and YES you can definitely hear the difference when using larger bias & screen resistors. I'd much rather kill tubes than tone, any day, any way.
How many Voxes have you worked on?
My Carvin Belair has 350 ohm screen resistors on top of 400+ volts on the plates and a 2.5k output transformer or you could think in terms of 5k for just a pair of el84 tubes. I was thinking of intentionally mismatch the impedance to get up to 5k transformer impedance for the 4 tubes, (ie. 10k for a pair of el84 tubes). Maybe I will look into upping the screen resistance as well? The Carvin is a fixed biased amp vs. cathode bias. So I don’t know if that makes things cooler in general? Or is irrelevant? Anyone here have experience with these el84 based Carvin amps want to chime in? Am I missing something? They seem like a recipe to eat tubes and spark forest fires?
Up those screen grids and set the fixed bias to about 55% idle. 5K primary impedance would be better. Add flyback diodes from plates to ground.
tubedepot.com/products/r3000-25a-3000v-high-voltage-protection-diode
@@PsionicAudio cool, thanks. Brimar data sheet says 2 watt maximum screen grid dissipation of 2 watts at zero signal & 4 watts at maximum signal. So I was thinking of putting in an ammeter in line to see what the current is? Thing is, those are Brimar 1960s el84 ratings. So I imagine the the 4 watts dissipation at max signal has been downgraded for modern production tubes. And I never exactly know what “max. Signal” means? Maximum clean signal before clipping, (basically whatever the amplitude of the fundamental tone is even if in distortion). Or do you consider max signal when you’re in full tilt distortion? Because harmonics add power to the power made from the fundamental.
Welcome to the dark side.
In general, data sheets refer to the max clean signal.
At the end of the day, in the real world, it's the screen voltage that needs more focus than the screen current. The datasheet G2 max is 300VDC. Take that pretty seriously. You can exceed that, but you don't want to go more than 50V over that. And when you limit screen voltage you end up limiting screen current, so by focusing on the voltage the current usually comes along for the ride.
You can decouple screens from the existing screen supply, or use zeners at the screens, but first try just increasing the screen grid resistors. You can go up to 2.2K if needed.
@@PsionicAudio I think my screen grids are at 385 volts, I don’t what Carvin was thinking? Or maybe they figured we should think of el84 tubes as cheap things you should be ready to toss every 3-4 months?
There's a reason Carvins aren't vintage - they're just old.
If it was my amp I'd shotgun the guts and wire it all up on terminal strips.
Edit: For guys that own this amp it might not be a bad idea to source some NOS 7189 or 7320 tubes for the output.
it just looks so odd to see volume and tone knobs "on the floor", so to speak ... stupid is as stupid did!