This isn't any Marshall or SVT or boutique amp, it's a cheapo. Seeking an affordable really good-sounding practice (& occasional recording) bluesy amp, I picked up a beat-up Peavey Classic 50 head with 4 EL84 outputs and two 4X10 bottoms with stock Peavey blue-marvel 10" speakers. I pretty much know what these amps are like, they get a decent clean sound, and break up pretty early, not really very powerful... but playing across the line between clean and dirty makes these amps very "emotive" IMHO for a bluesy style. Their distortion is OK but a bit treble and brittle rather than "creamy" (partly due to the 10" guitar speakers but I like the sound of 10's, even knowing how one 15 would make a nice delta-blues style sound even for guitar). I'm sealing the cabinets so they will even work for bass guitar practice as long as I don't try to get loud...after all that really is 8 10's much like an SVT for lead-style bass though of course it's not going to go very low or loud or clean and sealing the cabinets pushes resonance even higher. I don't have any delusions that this is much of an amp, but could be fun; it's probably going to end up in my bedroom. It's so beat up that I'm rebuilding it before I even turn it on. I'm replacing all the pots, changing the input network between the input jack and the grid of the first tube to my personal favorite design, adding a traditional Fender-style "bright" switch across the first volume pot, adding small modern fender-style "DEEP" switches to double the coupling capacitors between stages for a little more bass when I practice bass, upgrading the small-size Accutronics reverb tank to their larger long-decay 3-spring unit with the same input & output impedances, doubling up all the power supply electroytics, putting in a half-power switch that disconnects the cathodes on two output tubes, and building a larger cabinet for the head, and covering it with new fake-tweed patterned Tolex to match the bottoms. So far, it's been REALLY cheap for what I'm ending up with, as it's been recently re-tubed with Mesa EL84 tubes (I didn't check the 12AX7 tubes). I might add a potentiometer to the feedback circuit. And a back-panel potentiometer in series with the zener limiter on the reverb drive (reverb send & return are IC op-amps so they didn't need a trasnaformer). Maybe even install bias adjustment pots and a built-in meter.
What I'd really like to do is upgrade the cheap output transformer to the Mercury Magnetics upgrade items made for this amp. But they're overpriced IMHO. Even with a typical 10% discount below list they're still so exepnsive they cost more than the entire amp. But I'm still considering it, and lusting for their upgrade power transformer too.
I don't see a model-specific upgrade output transformer from other manufacturers. Anybody got a good recommendation for a cheaper upgrade output transformer for 4 EL84's?
Pretty amazing they can squeeze 50 (admittedly dirty) watts out of this thing with only 4 EL84's, when the Peavey Classic 30 also has 4 EL84's and only makes 30 watts.
But I really don't know if I could squeeze much more out of it. I look at it this way: the Classic 50 is a Classic 30 without the cheap transformers; but I don't know how much better it might be with even better transformers.
Since this doesn't have 5150-type gain, I would also like to get rid of ALL hum and hiss. Sealing the cabinets makes them a bit less efficient, but it also reduces the amount of audible noise.
Of course, like I said, this is all conjecture since I haven't even heard it yet. But looking at the little output tubes, little trannys, little reverb tank, little potentiometers, I sure wasn't impressed.
What I'd really like to do is upgrade the cheap output transformer to the Mercury Magnetics upgrade items made for this amp. But they're overpriced IMHO. Even with a typical 10% discount below list they're still so exepnsive they cost more than the entire amp. But I'm still considering it, and lusting for their upgrade power transformer too.
I don't see a model-specific upgrade output transformer from other manufacturers. Anybody got a good recommendation for a cheaper upgrade output transformer for 4 EL84's?
Pretty amazing they can squeeze 50 (admittedly dirty) watts out of this thing with only 4 EL84's, when the Peavey Classic 30 also has 4 EL84's and only makes 30 watts.
But I really don't know if I could squeeze much more out of it. I look at it this way: the Classic 50 is a Classic 30 without the cheap transformers; but I don't know how much better it might be with even better transformers.
Since this doesn't have 5150-type gain, I would also like to get rid of ALL hum and hiss. Sealing the cabinets makes them a bit less efficient, but it also reduces the amount of audible noise.
Of course, like I said, this is all conjecture since I haven't even heard it yet. But looking at the little output tubes, little trannys, little reverb tank, little potentiometers, I sure wasn't impressed.
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What about adding chokes to the power supply in a guitar amp? This seemed to be a common practice in the days of tube rectifiers when caps were large; especially adding inductors between the various power supply sections, instead of just the series resistors between parallel caps?
Besides the advantages of a higher-order filter, how does the charge density of inductors compare to capacitors; I imagine caps are lighter but which stores more energy for a given physical dimensional size?
These bluesy amps are sometimes intentionally built to have some power supply sag, but I prefer a more punchy clean and some dynamics to my dirt.
Besides the advantages of a higher-order filter, how does the charge density of inductors compare to capacitors; I imagine caps are lighter but which stores more energy for a given physical dimensional size?
These bluesy amps are sometimes intentionally built to have some power supply sag, but I prefer a more punchy clean and some dynamics to my dirt.
No offense, but I see a lot of "this oughta be..." thinking.
Closed back cabs just don;t sound like open back cabs, you prefer whichever one you like. As to reducing noise, I think that is more a matter of the closed cab being more of a beamer, and you aren;t standing in the beam. The open back spreads the sound around more.
Hiss is an artifact of gain and noisy parts. You MIGHT reduce hiss some with different resistors, or might not. Less noisy tubes maybe, but you'd have to try all different types in each socket to see how to manage that. But between a scope, knowledge of circuits, and even trial and error, you should be able to localize sources of hiss.
Hum is not generic, ther are a hundred sources of hum and a hundred ways to cure it - one per cause. Point being that if you have grounding issues in the preamp, no amount of larger filter caps will have any effect on it. And likewise, if you have a little ripple hum coming from the filter cap grounding, no amount of shielding in the preamp will have any effect on it. You propose adding chokes, OK fine. The choke then is a power supply filter, specifically B+. The question must be asked, DOES your hum come from power supply ripple? Not only that, even if your hum is 120Hz (meaning it comes from ripple), it MAY need larger filter caps, or it MAY be a matter of an improperly shared bit of copper trace on the pc board. I sure wouldn't just throw chokes at the amp without a reason up front.
" It's so beat up that I'm rebuilding it before I even turn it on."
This scares me. The C50 is a great little amp, and tearing into it and throwing a bunch of parts at it without even knowing how it sounds or plays, just seems counterproductive. In my humble opinion, you should assess the needs of the amp and then address them.
The Classic 50 drags 50 watts out of four EL84 while the Classic 30 draws only 30 watts. Tubes don;t make the watts, they only control the power from the power supply going to the speaker. They are called "valves" in much of the world for a good reason - they act as valves for current. SO the fact the C50 and C30 has the same number of power tubes is like a car engine having the same number of cylinders. How can my kid's hot car drag 350 horsepower from 8 cylinders when my wifes car also has 8 cylinders but only makes 150 horsepower?
My old buzz-kill thinking is that you ought to get the thing and play through it to finmd out what good qualities it has and what you hate about it, then go about addressing THOSE things.
And I;d also recommend going to a web site like Blue Guitar and reading up on the various modifications people have done to the Classic 50 (and the Classic 30 for that matter, I even got in on that one), you may find some of them are exactly what you are looking for.
The Blue Guitar
Closed back cabs just don;t sound like open back cabs, you prefer whichever one you like. As to reducing noise, I think that is more a matter of the closed cab being more of a beamer, and you aren;t standing in the beam. The open back spreads the sound around more.
Hiss is an artifact of gain and noisy parts. You MIGHT reduce hiss some with different resistors, or might not. Less noisy tubes maybe, but you'd have to try all different types in each socket to see how to manage that. But between a scope, knowledge of circuits, and even trial and error, you should be able to localize sources of hiss.
Hum is not generic, ther are a hundred sources of hum and a hundred ways to cure it - one per cause. Point being that if you have grounding issues in the preamp, no amount of larger filter caps will have any effect on it. And likewise, if you have a little ripple hum coming from the filter cap grounding, no amount of shielding in the preamp will have any effect on it. You propose adding chokes, OK fine. The choke then is a power supply filter, specifically B+. The question must be asked, DOES your hum come from power supply ripple? Not only that, even if your hum is 120Hz (meaning it comes from ripple), it MAY need larger filter caps, or it MAY be a matter of an improperly shared bit of copper trace on the pc board. I sure wouldn't just throw chokes at the amp without a reason up front.
" It's so beat up that I'm rebuilding it before I even turn it on."
This scares me. The C50 is a great little amp, and tearing into it and throwing a bunch of parts at it without even knowing how it sounds or plays, just seems counterproductive. In my humble opinion, you should assess the needs of the amp and then address them.
The Classic 50 drags 50 watts out of four EL84 while the Classic 30 draws only 30 watts. Tubes don;t make the watts, they only control the power from the power supply going to the speaker. They are called "valves" in much of the world for a good reason - they act as valves for current. SO the fact the C50 and C30 has the same number of power tubes is like a car engine having the same number of cylinders. How can my kid's hot car drag 350 horsepower from 8 cylinders when my wifes car also has 8 cylinders but only makes 150 horsepower?
My old buzz-kill thinking is that you ought to get the thing and play through it to finmd out what good qualities it has and what you hate about it, then go about addressing THOSE things.
And I;d also recommend going to a web site like Blue Guitar and reading up on the various modifications people have done to the Classic 50 (and the Classic 30 for that matter, I even got in on that one), you may find some of them are exactly what you are looking for.
The Blue Guitar
It's a Peavey.
Don't fiddle with it.
Most importantly, don't **** with the transformers, you'll ruin it.
Read the Hartley Peavey whitepapers, with the emphasis on #3.
Peavey.com
Don't fiddle with it.
Most importantly, don't **** with the transformers, you'll ruin it.
Read the Hartley Peavey whitepapers, with the emphasis on #3.
Peavey.com
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SO nobody's tried the Mercury Magnetics transformers for the C50; no genuine first-hand knowledge at all... I can't find anybody who's tried it. Like I said, it's mostly the transformers that make the c50 a 50 and not a 30; they're obviously not too shabby. I have liked the Mercury Magnetics output trannys for some Fenders, those suit my tastes with nice clean highs and tight bass, and smooth gentle transition into subtle creamy harmonics from the tubes. But each model and application is different... Just too darn expensive to try on a lark.
Anyway, of course you're all correct that I should try it first. But "if it ain't broke don't fix it" is not my motto; "nothing ventured nothing learned". I got it running last night. No surprises, except that it's in better electrical condition than mechanical.
What it really really needs first is a quieter fan, this one's shot and really noisy. Fan in series with a resistor runs off of 120AC according to the schematic. I expected a computer fan driven off filament supply. Might just get a new one from Peavey. When I build the new case I'll build in two opposed-flow air paths to muffle, like the new IBM mainframes use. The small pots, true to their nature, are predictably noisy to operate but sound OK when not being touched, so I was able to evaluate what I had.
Oh yes, I read the 'blue guitar' mods before I even bid on this amp on eBay. Not much there, but he's absolutely correct about the dirty "channel" C18 and C1 inter-stage coupling caps values being very small. I suspect Peavey wanted to limit bandwidth in dirty mode so that low bass in pick attack didn't make the tubes really compress the output way too much and then have the note volume bloom louder in sustain. I don't want more than just a little compression, not much power supply sag either. I know that's bluesy stuff that customers for these amps want, but not quite what I'm after. But I want the bass back, even in dirty mode.
I'm definitely going to make the circuit from the input jack to the first grid just like I did on my Alembic FB2, cause it's what I like. But I might consider making it somewhat adjustable to accomodate guitars with a lot more output than what I usually play.
There was some site where they converted the phase splitter to a long-tailed pair (might have been blue guitar again in the advanced mods?), but that might be more than I'm willing to pursue.
The dirty channel needs some voicing, but this amp has potential. I like the way it relay-switches out the 'clean' volume control and switches in two more gain stages with different volume controls before & after the additional stages (rather than actually switching between entire channels). Very economical use of resources. Now if only the relay also switched between alternate master volume controls so you had two complete alternate settings. I used to run my favorite Alembic FB2 preamp (which I've owned a few of, and modded subtly) similarly, either using one channel (2 stages) or relay-switching its two channels in series (4 stages). I'd like to replace R8 with a 1M audio taper volume pot, giving the dirty mode a volume before, between, and after the 2 stages that get insterted by the relay. I will install a Fender-style " Bright" switch across the hot to wiper of the "clean" volume pot and the dirty "pre" volume also.
I'll probably add a small switch to add a second cap to the presence control.
One thing I liked about the two Alembic Fender-ish preamp channels in series was the two sets of tone controls; I could change the 'tone' of the distortion independently from the 'tone' of the guitar. For intance, I would usually boost the treble in a very early stage, then generate some distortion in the middle stages, then cut the treble in a later stage. The real guitar's treble was boosted & cut, but the distortion generated between the tone controls only had its treble cut. This made for a really great creamy distortion that wasn't irritating, but chords had wonderful complexity and beats.
This preamp does (predictably) have more noise than I can tolerate considering it doesn't have a ton of gain, and despite a decent grounding scheme and intelligent layout that keeps the power tranny etc. over a foot and a half away from the high-gain sections. Of course, the Alembic benchmark had a dedicated power supply for the preamp, and a LOT more big filter caps for the preamp B+. Filament transformer is center-tapped but there's no hum balance pot, might be worth installing one.
The first stage in clean mode (first two stages in dirty mode) are driven from their own resistor-isolated B+ supply caps. The B++ supply for the other preamp stages, driver, and splitter also has its own resistor-isolated caps. No voltages indicated on the schematic though. I'll probably do a bit of measurement and simulation and get some cheap chokes to replace the resistors and double up the caps in the power supply. But for the outrageous price Mercury Magnetics charges for their upgrade power tranny for this amp I could build multipple completely isolated dedicated power supplies using multiple stock power trannys LOL.
The reverb needs some work to approach Fender standards. I don't think the op-amps and transistor driver and recovery amp are a problem at all. Decent current drive (as opposed to voltage). But there's a pair of zeners which limit the input level. I'll experiment there just a little bit and a little at the recovery amp too, and replace the mini-size medium-decay tank with a full-size long-decay Accutronics with the same input and output impedances.
The good news is that it's going to work OK for me for practicing bass too.
A lot of high-fi tube fanatics use DC for the filament heaters. But NOBODY I know of does this with guitar preamps. My dad says he suspects the tube life suffers when the filaments run on DC. Anybody got any real knowledge to share about using DC for the preamp filaments? How much hum originates with the heaters compared to the B supply anyway?
Anyway, of course you're all correct that I should try it first. But "if it ain't broke don't fix it" is not my motto; "nothing ventured nothing learned". I got it running last night. No surprises, except that it's in better electrical condition than mechanical.
What it really really needs first is a quieter fan, this one's shot and really noisy. Fan in series with a resistor runs off of 120AC according to the schematic. I expected a computer fan driven off filament supply. Might just get a new one from Peavey. When I build the new case I'll build in two opposed-flow air paths to muffle, like the new IBM mainframes use. The small pots, true to their nature, are predictably noisy to operate but sound OK when not being touched, so I was able to evaluate what I had.
Oh yes, I read the 'blue guitar' mods before I even bid on this amp on eBay. Not much there, but he's absolutely correct about the dirty "channel" C18 and C1 inter-stage coupling caps values being very small. I suspect Peavey wanted to limit bandwidth in dirty mode so that low bass in pick attack didn't make the tubes really compress the output way too much and then have the note volume bloom louder in sustain. I don't want more than just a little compression, not much power supply sag either. I know that's bluesy stuff that customers for these amps want, but not quite what I'm after. But I want the bass back, even in dirty mode.
I'm definitely going to make the circuit from the input jack to the first grid just like I did on my Alembic FB2, cause it's what I like. But I might consider making it somewhat adjustable to accomodate guitars with a lot more output than what I usually play.
There was some site where they converted the phase splitter to a long-tailed pair (might have been blue guitar again in the advanced mods?), but that might be more than I'm willing to pursue.
The dirty channel needs some voicing, but this amp has potential. I like the way it relay-switches out the 'clean' volume control and switches in two more gain stages with different volume controls before & after the additional stages (rather than actually switching between entire channels). Very economical use of resources. Now if only the relay also switched between alternate master volume controls so you had two complete alternate settings. I used to run my favorite Alembic FB2 preamp (which I've owned a few of, and modded subtly) similarly, either using one channel (2 stages) or relay-switching its two channels in series (4 stages). I'd like to replace R8 with a 1M audio taper volume pot, giving the dirty mode a volume before, between, and after the 2 stages that get insterted by the relay. I will install a Fender-style " Bright" switch across the hot to wiper of the "clean" volume pot and the dirty "pre" volume also.
I'll probably add a small switch to add a second cap to the presence control.
One thing I liked about the two Alembic Fender-ish preamp channels in series was the two sets of tone controls; I could change the 'tone' of the distortion independently from the 'tone' of the guitar. For intance, I would usually boost the treble in a very early stage, then generate some distortion in the middle stages, then cut the treble in a later stage. The real guitar's treble was boosted & cut, but the distortion generated between the tone controls only had its treble cut. This made for a really great creamy distortion that wasn't irritating, but chords had wonderful complexity and beats.
This preamp does (predictably) have more noise than I can tolerate considering it doesn't have a ton of gain, and despite a decent grounding scheme and intelligent layout that keeps the power tranny etc. over a foot and a half away from the high-gain sections. Of course, the Alembic benchmark had a dedicated power supply for the preamp, and a LOT more big filter caps for the preamp B+. Filament transformer is center-tapped but there's no hum balance pot, might be worth installing one.
The first stage in clean mode (first two stages in dirty mode) are driven from their own resistor-isolated B+ supply caps. The B++ supply for the other preamp stages, driver, and splitter also has its own resistor-isolated caps. No voltages indicated on the schematic though. I'll probably do a bit of measurement and simulation and get some cheap chokes to replace the resistors and double up the caps in the power supply. But for the outrageous price Mercury Magnetics charges for their upgrade power tranny for this amp I could build multipple completely isolated dedicated power supplies using multiple stock power trannys LOL.
The reverb needs some work to approach Fender standards. I don't think the op-amps and transistor driver and recovery amp are a problem at all. Decent current drive (as opposed to voltage). But there's a pair of zeners which limit the input level. I'll experiment there just a little bit and a little at the recovery amp too, and replace the mini-size medium-decay tank with a full-size long-decay Accutronics with the same input and output impedances.
The good news is that it's going to work OK for me for practicing bass too.
A lot of high-fi tube fanatics use DC for the filament heaters. But NOBODY I know of does this with guitar preamps. My dad says he suspects the tube life suffers when the filaments run on DC. Anybody got any real knowledge to share about using DC for the preamp filaments? How much hum originates with the heaters compared to the B supply anyway?
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Stop and think about those zeners on the reverb input. The tube circuits can handle tons of signal level, and if you add even more all they do is clip. The reverb is driven by an op amp running between -27v and ground, the input is referenced to -14v. You can;t feed the op amp more than 14v peak of signal or the inoput will exceed the rails on the IC. That will damage the IC. That is why the zeners are there, they prevent any signal excursion past the rails.
I'd wager a squirt of Deoxit into each control will cure just about all their noise.
What do you mean NOBODY runs preamp tubes on DC heaters in guitar amps? This very amp has the two first preamp tube heaters wired in series across -27vDC. They have been making this amp that way for 20 years. The 5150 is still in production - now named 6505 - and has been also for 20 years, there are four preamp tubes with heaters wired in series between +24vDC and -24vDC. The 1991 Rockmaster preamp has all its tubes running on DC heaters, it is a preamp unit. The 1988 Peavey Triumph ran V1,2,3 on DC heaters. In looking, I see even AC heaters are often lifted by DC voltage, like the 1983 Rock Master Head or Encore 65 from the same year. SO peavey themselves have been running DC preamp heaters now for decades.
Peavey is not alone, Marshall runs the first couple preamp tubes on DC heaters in many amps. A quick look and I see it in the TSL/DSL series, and others.
Tube life suffer? Nah. I run a pro audio repair shop, I can count on my fingers the number of tubes with failed heaters I have replaced in the last 10-15 years. Tube heater failure is just not an issue. The tubes will go microphonic or noisy or quit working, long before the heater dies.
Hum through the heaters is POTENTIAL hum, you don;t always see it. Heaters have more than one way to let hum into a circuit. B+ ripple will certainly cause hum as will lack of good filtration on the bias supply. But also QUITE common is grounding issue causing hum. If a preamp ground shares copper with the ground return of a B+ filter cap, you will get ripple in that preamp. That is a separate issue from lack of enough filter cap. There is radiated hum from any AC carrying wires into sensitive circuits, ther is poor grounding, especially around jacks. There is a huge list of potential hum sources, and each has its own cure.
I'd wager a squirt of Deoxit into each control will cure just about all their noise.
What do you mean NOBODY runs preamp tubes on DC heaters in guitar amps? This very amp has the two first preamp tube heaters wired in series across -27vDC. They have been making this amp that way for 20 years. The 5150 is still in production - now named 6505 - and has been also for 20 years, there are four preamp tubes with heaters wired in series between +24vDC and -24vDC. The 1991 Rockmaster preamp has all its tubes running on DC heaters, it is a preamp unit. The 1988 Peavey Triumph ran V1,2,3 on DC heaters. In looking, I see even AC heaters are often lifted by DC voltage, like the 1983 Rock Master Head or Encore 65 from the same year. SO peavey themselves have been running DC preamp heaters now for decades.
Peavey is not alone, Marshall runs the first couple preamp tubes on DC heaters in many amps. A quick look and I see it in the TSL/DSL series, and others.
Tube life suffer? Nah. I run a pro audio repair shop, I can count on my fingers the number of tubes with failed heaters I have replaced in the last 10-15 years. Tube heater failure is just not an issue. The tubes will go microphonic or noisy or quit working, long before the heater dies.
Hum through the heaters is POTENTIAL hum, you don;t always see it. Heaters have more than one way to let hum into a circuit. B+ ripple will certainly cause hum as will lack of good filtration on the bias supply. But also QUITE common is grounding issue causing hum. If a preamp ground shares copper with the ground return of a B+ filter cap, you will get ripple in that preamp. That is a separate issue from lack of enough filter cap. There is radiated hum from any AC carrying wires into sensitive circuits, ther is poor grounding, especially around jacks. There is a huge list of potential hum sources, and each has its own cure.
LOL in my enthusiasm I must come off as a dumb kid about to rip into it. Don't worry, I'm being careful and moving slowly, looking twice and asking first. Bought a good fan today, same kind of shaded-pole 120vAC motor, about the same but a better ( rated quieter, sufficient output) brand. A lot of quiet fans use shorter-life bearings and insist on vertical mounting, and the very quietest are low-voltage DC computer fans sometimes run from pulses. For now I'll leave the same type fan, same series resistor, might add some speed control later.
Enzo, thanks! I had no clue they already used DC heaters!!!! I must be blind, V1A pin 4 to ground, 9 the common for two heaters in V1 not connected, V1B pin 5 to V2A pin 4, 9 common in V2 not connected, V2B pin 5 to 27V- thank you for making me look again! I'm impressed, by Peavey & you! Well, that's one thing less to think about doing.
I still think Peavey's white papers are self-serving doc of a misguided mission, at least so far. Nice to see what he's thinking though, and sharing his extensive experience. But IMHO he's promoting urban legend about transformer saturation being part of tube amp charm. I've been hearing that claim for years, but I've never liked the sound. Then again, I never liked my Marshall.
I understand what the zeners are there for, and if I was selling these to rockers I'd put them in too. I might be grateful it I ever do something stupid. I see other tube preamp / opamp reverb combinations without them or with a resistor to soften the knee, but I doubt the zeners ever even come into play in my use, so they probably do no harm if they do nothing in my use. Peavey makes these amps to withstand 1000 times the level I drive into it with no pedals and no powered pickups. I've got a lot of reasearch and measurement before I do anything to the reverb circuit. Right now I know it's never over-driven or I would hear the spring, but I doubt the zeners are limiting yet. But I don't even know whether I want to increase the drive or increase the sensitivity of the recovery amp section. I never hear the sound of springs over-driven. I suspect that what I will try first is just adding a 'reverb drive' knob so I can adjust a good signal level to the spring despite the wide variation of the level from the first tube stages. Like when I use my Peavey valverb, I can adjust the input and output levels; my favorite Fenders didn't have it but seperate controls for reverb drive and post-reverb mix are really practical and useful if you play a wide range of input levels and volumes, especially when I'm going for clean/quiet/dynamic-range. But just changing to a long-decay model tank, whether short or long delay or short or long physically, might help make the reverb sound more prominent just by the persistence of the reverberation effect. Then again, I have an all-tube Peavey Valverb in the garage, and it sounds a hell of a lot better, and I love the tone control on the reverberation sound. But even my old all-transistor Tapco reverb could sound OK when I upgraded the reverb tank, and the EQ controls for the reverberation again made a big difference. So I don't see any reason I can't get the classic 50 reverb to work a lot better with a drive level control and maybe adding a primitive tone-control high-cut pot too. In an ideal world I'd have some control of compression/expansion before the reverb drive.
There seems to be stong consensus that the "dirty" mode has too much treble and too little bass, and that the reberb sounds "weak". If that's the worst problems, that should be easy to address. I think those are both side-effects of the amp being designed to handle being over-driven with much stronger inputs.
This weekend I'll try it with 2 el-84's to get an idea what the half-power switch will sound like.
BTW this amp's volume is fine. I want it to handle an exceptionally wide range of volumes and clean/dirty sounds, and I still might add some kind of power-soak.
I would like to work on getting the background noise level quieter. I haven't really tested with a shorted input, to hear just the amp. I would be interested in just trying an alternate new set of tubes for comparison.
Yes, I could glue a knob onto the broken shaft, I could spray out the pots; but IMHO good pots are really important to the whole feel of an amp, and I am really spoiled from the quality of the controls in the Alembic. Good sliders on a quality board and the Alembic preamp have made me pretty intolerant of teensie pots with their scratchy noises during adjustment.
It makes some random relativley quiet popping and fizzy noises. There's quite a power turn-off "POP" even if it's already in standby.
Enzo, thanks! I had no clue they already used DC heaters!!!! I must be blind, V1A pin 4 to ground, 9 the common for two heaters in V1 not connected, V1B pin 5 to V2A pin 4, 9 common in V2 not connected, V2B pin 5 to 27V- thank you for making me look again! I'm impressed, by Peavey & you! Well, that's one thing less to think about doing.
I still think Peavey's white papers are self-serving doc of a misguided mission, at least so far. Nice to see what he's thinking though, and sharing his extensive experience. But IMHO he's promoting urban legend about transformer saturation being part of tube amp charm. I've been hearing that claim for years, but I've never liked the sound. Then again, I never liked my Marshall.
I understand what the zeners are there for, and if I was selling these to rockers I'd put them in too. I might be grateful it I ever do something stupid. I see other tube preamp / opamp reverb combinations without them or with a resistor to soften the knee, but I doubt the zeners ever even come into play in my use, so they probably do no harm if they do nothing in my use. Peavey makes these amps to withstand 1000 times the level I drive into it with no pedals and no powered pickups. I've got a lot of reasearch and measurement before I do anything to the reverb circuit. Right now I know it's never over-driven or I would hear the spring, but I doubt the zeners are limiting yet. But I don't even know whether I want to increase the drive or increase the sensitivity of the recovery amp section. I never hear the sound of springs over-driven. I suspect that what I will try first is just adding a 'reverb drive' knob so I can adjust a good signal level to the spring despite the wide variation of the level from the first tube stages. Like when I use my Peavey valverb, I can adjust the input and output levels; my favorite Fenders didn't have it but seperate controls for reverb drive and post-reverb mix are really practical and useful if you play a wide range of input levels and volumes, especially when I'm going for clean/quiet/dynamic-range. But just changing to a long-decay model tank, whether short or long delay or short or long physically, might help make the reverb sound more prominent just by the persistence of the reverberation effect. Then again, I have an all-tube Peavey Valverb in the garage, and it sounds a hell of a lot better, and I love the tone control on the reverberation sound. But even my old all-transistor Tapco reverb could sound OK when I upgraded the reverb tank, and the EQ controls for the reverberation again made a big difference. So I don't see any reason I can't get the classic 50 reverb to work a lot better with a drive level control and maybe adding a primitive tone-control high-cut pot too. In an ideal world I'd have some control of compression/expansion before the reverb drive.
There seems to be stong consensus that the "dirty" mode has too much treble and too little bass, and that the reberb sounds "weak". If that's the worst problems, that should be easy to address. I think those are both side-effects of the amp being designed to handle being over-driven with much stronger inputs.
This weekend I'll try it with 2 el-84's to get an idea what the half-power switch will sound like.
BTW this amp's volume is fine. I want it to handle an exceptionally wide range of volumes and clean/dirty sounds, and I still might add some kind of power-soak.
I would like to work on getting the background noise level quieter. I haven't really tested with a shorted input, to hear just the amp. I would be interested in just trying an alternate new set of tubes for comparison.
Yes, I could glue a knob onto the broken shaft, I could spray out the pots; but IMHO good pots are really important to the whole feel of an amp, and I am really spoiled from the quality of the controls in the Alembic. Good sliders on a quality board and the Alembic preamp have made me pretty intolerant of teensie pots with their scratchy noises during adjustment.
It makes some random relativley quiet popping and fizzy noises. There's quite a power turn-off "POP" even if it's already in standby.
Of course it is your project. There is an old trick on Fender amps. Most old Fenders had a Normal channel - plain - and a Vibrato channel with reverb. The reverb return cable plugged into the reverb recovery jack on the rear. You could Plug the reverb return cable into the unused Normal input on the front, and now that channel's controls act as reverb controls. SOunds versatile. But mostly we wind up just setting it and leaving it alone. Same in my experience with adding "Dwell" controls to reverb drive. It seems like it would be oh so useful, and then a month later we realize we just turn it all the way up and leave it.
Pots are pots, and if you like different ones, go for it. I will say that when these little pots are scratchy, it is not from size, it is from dirt, or the occasional loose DC voltage. And if you are used to sliders, well good luck putting sliders into this Peavey. I have always found that sliders are far more likely to go noisy from contaminants than are rotary pots. As to broken ones, Peavey has all of them in stock, not expensive at all, and the parts department at Peavey will gladly sell them to anyone. Parts orders must be CALLED in, no email orders.
Pots are pots, and if you like different ones, go for it. I will say that when these little pots are scratchy, it is not from size, it is from dirt, or the occasional loose DC voltage. And if you are used to sliders, well good luck putting sliders into this Peavey. I have always found that sliders are far more likely to go noisy from contaminants than are rotary pots. As to broken ones, Peavey has all of them in stock, not expensive at all, and the parts department at Peavey will gladly sell them to anyone. Parts orders must be CALLED in, no email orders.
I've been biting my tongue, as your enthusiasm is obvious. But when you say, "I never liked my Marshall"....
Despite the tweed covering, the Classic series do sound like Marshalls. And to make things worse, they were voiced when EVH was hanging around. The more you say about what you want, the more I think the Peavey will be fighting you every step of the way.
Look, for the price of the transformers, you could buy a slightly broken Fender and have a much better platform to modify.
Despite the tweed covering, the Classic series do sound like Marshalls. And to make things worse, they were voiced when EVH was hanging around. The more you say about what you want, the more I think the Peavey will be fighting you every step of the way.
Look, for the price of the transformers, you could buy a slightly broken Fender and have a much better platform to modify.
Indeed, if I stop contracting and get a "regular" permanent job with some security I'll probably start looking at old Fenders with 2 JBL 12's and a nice reverb, or possibly building one. Unless I need a bass amp by then. Meanwhile, this might grow on me. There was more about the Marshall I didn't like; for instance those Greenback speakers and the huge cabinets were SO efficient but rearely pleasant, kind of honking sound. Then again, when I was a teen I never really liked my strat; I didn't like the pickup positioning and how their magnetic fields affected the strings, the bolt-on neck, the cheap way everything mounted on the pickguard, the crummy screws the vibrato mounted on. Yet plenty of great music came from the same honking guitar, often with the same honking amp, which never sounded good with me playing them. I really like an SVT for guitar or bass, though I'd like to add reverb; I'd love to just pick up a VR some day.
Anyway, I finally got a guitar today, so I don't have to use just a bass. I had to sell all my Travis Bean guitars and basses when money got tight between contracts; that money allowed me to keep the house. But I bought a MusicYo-era Kramer with an OK flame top and floyd-rose for really cheap from the Goodwill auction site for really cheap. 'course these offshore ones were pretty cheap to start with, long after the US shutown and before Gibson picked 'em up, I think list was about $260 when new. UPS left if on somebodys lawn 10 blocks away, at 2111 instead of 2911. UPS knew where it was, but hadn't picked it up, so when they told me I ran over & got it. Anyway, this little Peavey is a lot easier to live with than the big Marshall. And it CAN sound similar to how I wanted the Marshall to sound.
Anyway, I finally got a guitar today, so I don't have to use just a bass. I had to sell all my Travis Bean guitars and basses when money got tight between contracts; that money allowed me to keep the house. But I bought a MusicYo-era Kramer with an OK flame top and floyd-rose for really cheap from the Goodwill auction site for really cheap. 'course these offshore ones were pretty cheap to start with, long after the US shutown and before Gibson picked 'em up, I think list was about $260 when new. UPS left if on somebodys lawn 10 blocks away, at 2111 instead of 2911. UPS knew where it was, but hadn't picked it up, so when they told me I ran over & got it. Anyway, this little Peavey is a lot easier to live with than the big Marshall. And it CAN sound similar to how I wanted the Marshall to sound.
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I still keep looking at those Mercury magnetics transformers. Am I just mesmerized BECAUSE they're so expensive? I can't possibly justify the price of the upgrade power transformer. But as a joke I'd mentioned that a second Peavey power transformer would cost one heck of a lot less and do just as much to stiffen the supply and much more to isolate the power amp section from the preamp section. I know this is not a hi-fi, but this isn't a totally crazy idea. I'm going to price one.
I've got nothing for you but more generic warnings about messing with one of James Brown's designs. There's only one way to find out, and it's really about what you like.
I love the Classic 50. I heard Seymour Duncan play through one, and he totally nailed those "Blow by Blow" tones with his TeleGib. I'd own one, but they're big and heavy, and I'm at that age where I'm getting smaller every year, so I got the Classic 30, instead.
I love the Classic 50. I heard Seymour Duncan play through one, and he totally nailed those "Blow by Blow" tones with his TeleGib. I'd own one, but they're big and heavy, and I'm at that age where I'm getting smaller every year, so I got the Classic 30, instead.
I ordered the missing chicken-head knobs (but in various '50's colors). It's really difficult to read the labels on the chrome background; it works worse than it looks. At the very least it needs a panel light, like a shaded LED at each knob label. Making groups different colors should help (maybe dark red for the 'hot-dirty' channel, off-white for the clean, '50's turquoise pastel for the 3 tone controls, bright white for the master, black for the presence).
I also ordered a handful of Solen .047 coupling capacitors.
I still need to put together the order for Peavey. Pots and tweed twill-patterned Tolex. I actually considered going with various non-tweed/twill patterened vinyls, but the speaker cabinet looks good and the head will look best if it matches.
A friend gave me a free Acutronics long-decay full-size tank. Actually I think it might have come out of the old Tapco reverb when I upgraded the tanks. But I think the input impedance is twice the stock value, like stock is and "E" 800 ohm but this is an "F" 1925 ohm.
I also ordered a handful of Solen .047 coupling capacitors.
I still need to put together the order for Peavey. Pots and tweed twill-patterned Tolex. I actually considered going with various non-tweed/twill patterened vinyls, but the speaker cabinet looks good and the head will look best if it matches.
A friend gave me a free Acutronics long-decay full-size tank. Actually I think it might have come out of the old Tapco reverb when I upgraded the tanks. But I think the input impedance is twice the stock value, like stock is and "E" 800 ohm but this is an "F" 1925 ohm.
The reverb tanks are surprisingly cheap, so I'll probably just order the right one.
BTW I have seen some threads where people blew the op-amp and had to replace it. So indeed those zeners get called to action at least sometimes (though they obviously don't always do their job either). I've gotten a lot of advice suggesting favorite op-amp upgrades, but quite honestly at the low stock levels of reverb the signal to noise seems OK because when the signal mixed in is this low any noise is inaudible or masked.
As I play with this more, the reverb isn't really all that weak unless you have "Pipeline" and "Wipeout" in your set list. It's more the operational procedure I'm used to; turning the knob way up to hear the reberb, then setting the actual level to use. Kind of like "what's that soudn like when I'm this dirty" "oh yeah" "OK I'll take about this much of that". Especially using reverbs with their own tone control, I want to be able to hear it all-wet. But the range of the mix pot is really a pretty usable range. Same with the tone controls; the controls are really somewhat more subtle than I'm used to, but their range is very usable. But again, in practical operation in a noisy environment I turn up & down to hear the extremes and listen to the band and how it affects a strum and pick before I make my selection. For the reverb, if I had a little "solo pre-fader listen' button to hear just the reverb full-wet I probably wouldn't need more range on the knob.
BTW I have seen some threads where people blew the op-amp and had to replace it. So indeed those zeners get called to action at least sometimes (though they obviously don't always do their job either). I've gotten a lot of advice suggesting favorite op-amp upgrades, but quite honestly at the low stock levels of reverb the signal to noise seems OK because when the signal mixed in is this low any noise is inaudible or masked.
As I play with this more, the reverb isn't really all that weak unless you have "Pipeline" and "Wipeout" in your set list. It's more the operational procedure I'm used to; turning the knob way up to hear the reberb, then setting the actual level to use. Kind of like "what's that soudn like when I'm this dirty" "oh yeah" "OK I'll take about this much of that". Especially using reverbs with their own tone control, I want to be able to hear it all-wet. But the range of the mix pot is really a pretty usable range. Same with the tone controls; the controls are really somewhat more subtle than I'm used to, but their range is very usable. But again, in practical operation in a noisy environment I turn up & down to hear the extremes and listen to the band and how it affects a strum and pick before I make my selection. For the reverb, if I had a little "solo pre-fader listen' button to hear just the reverb full-wet I probably wouldn't need more range on the knob.
There's that Marshall influence I mentioned.
I think Jim was going for the then-current high-end hifi look, like H.H. Scott.
Chickenheads are a lot more practical for guitar players. Or fluted "RCA" knobs with the big white line.
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