Archon preamp tube layout chart?

I would put a 12AT7 in the PI spot (V5?), that will help keep it cleaner. Also, try a 5751 in V1 and V4 for starters, and maybe even try 5751s in V2 and V3. For even less gain, a 12AY7 in V1 and/or V4. Same for the loop, start with a 5751 in the loop (V6?).
 
V 1 or V4... check and see what they are, and if not JJ, replace one or both with JJ (assuming we're talking only new tubes). JJ will tame the top end.

That was the answer to your question. Perhaps a better solution though is somewhere else in the chain... reduce presence or treble, make sure speakers are broken in, use good guitar cables...remove any pedals with bad buffers from in front of the amp, etc.

Cool I’ll check V1 and V4 and see what’s in it. I bought my Archon 100 new so what is the factory preamp tube brand? I know the power tubes are Ruby’s and I thought the preamp tubes were listed as JJ online but they might be something else but I haven’t checked yet to see.

Would you recommend something else besides a 12ax7 for V1 or is an12ax7 best? I know this is all personal choice or taste but just wondering.

And any recommendations for the FX Loop tube?
 
I would put a 12AT7 in the PI spot (V5?), that will help keep it cleaner. Also, try a 5751 in V1 and V4 for starters, and maybe even try 5751s in V2 and V3. For even less gain, a 12AY7 in V1 and/or V4. Same for the loop, start with a 5751 in the loop (V6?).

I would suggest not putting any lower gain tubes in the PI slot, since he said he wants to retain headroom. Same for V1 and V4. If you want to smooth out the top end of the clean channel only and with pre-amp tubes, and if there are JJs in there now, then NOS may be your only option.

And, with all due respect, I don't recommend replacing PI or Loop with lower gain tubes if you want to retain clean headroom. I am one of those who subscribe to the believe that lower gain tubes almost never give more headroom, they simply allow you to turn the dial further before something distorts, but in MOST circuits, it will still distort at the same level of gain. So maybe your clean channel finally starts clipping at 8 on the knob but you drop a 5751 in one of the stages and now it stays clean all the way to 10... yeah, but it's still not as loud as it was at 8 with the AX7 in there.

In fact... Every time I read that putting a 12AY7 here or a 5751 there gives an amp "more clean headroom," I cringe... It might give you more range of control over a gain channel. It might make your amp stay clean up higher on the dials, etc. But reducing gain of pre-amp stages, PI, Loops, etc almost never gives you more clean headroom. It only gives you more clean range on the dials but only because there's less output at any given dial number. Feel free to disagree. I know there are very few circumstances were one tube early in the circuit just might push the next stage into breakup very quickly so that a lower gain tube lets you stop just before that spot more easily, etc. But I've tried it with numerous amps and read/studied about it for years, and I believe that it almost never gives more clean headroom.
 
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I actually used both volume and tone controls constantly on my first "good" guitar, my Ibanez Artist. But it had the LP style layout of dual volume/dual tone. But how I used them was different than most. I put the neck volume on 1 and bridge volume on 10. My rhythm tone was the middle position, with the volume reduced just enough by the neck pickup volume knob. Lead was just flip it to the bridge, and clean was neck. It stayed that way most of the time, but when I wanted a neck lead tone, I just rolled the neck volume up to 10.

Then I had blues rock stuff where I'd do the opposite. Bridge volume at 1, neck at 10, etc. That was before I had pedals so I couldn't stomp on a boost or OD for solos and I didn't like (still don't... much) actively rolling knobs around while I play, so that provided 3 tones I needed with just the pickup selector switch.

The tone knobs were then used for effect... rolling them down for a wah-ish fat tone, etc. I did the same with my Les Paul. Got all messed up when I got my first Kramer VH guitar and my Pacer and my Strat. Had to improvise. Then get a pedal. Or 3.
 
I would suggest not putting any lower gain tubes in the PI slot, since he said he wants to retain headroom. Same for V1 and V4. If you want to smooth out the top end of the clean channel only and with pre-amp tubes, and if there are JJs in there now, then NOS may be your only option.

And, with all due respect, I don't recommend replacing PI or Loop with lower gain tubes if you want to retain clean headroom. I am one of those who subscribe to the believe that lower gain tubes almost never give more headroom, they simply allow you to turn the dial further before something distorts, but in MOST circuits, it will still distort at the same level of gain. So maybe your clean channel finally starts clipping at 8 on the knob but you drop a 5751 in one of the stages and now it stays clean all the way to 10... yeah, but it's still not as loud as it was at 8 with the AX7 in there.

In fact... Every time I read that putting a 12AY7 here or a 5751 there gives an amp "more clean headroom," I cringe... It might give you more range of control over a gain channel. It might make your amp stay clean up higher on the dials, etc. But reducing gain of pre-amp stages, PI, Loops, etc almost never gives you more clean headroom. It only gives you more clean range on the dials but only because there's less output at any given dial number. Feel free to disagree. I know there are very few circumstances were one tube early in the circuit just might push the next stage into breakup very quickly so that a lower gain tube lets you stop just before that spot more easily, etc. But I've tried it with numerous amps and read/studied about it for years, and I believe that it almost never gives more clean headroom.

If I hadn’t done it a hundred times, I might agree with you, but the fact remains that more gain leads to earlier breakup. I’ve had great success using a 5751 in V1 and a 12AT7 in the PI, not only for keeping the cleans, but also smoothing the gain side. I realize it’s all personal preference, but I get paid very well to do things like this, and have been doing it for many years.

Here is a good demo of using lower gain tubes, and you can even see the clipping (more square wave) shown on the scope with the higher gain tubes, and the clipping drops off with the lower gain tubes.
https://www.thetubestore.com/gain-factor

Remember that it takes 10 times the wattage to be twice as loud, and the opposite is true also. If you reduce gain by 30%, the volume won’t be reduced very much, but the clipping will be reduced.

BTW, I agree with you about Dream Theater, Petrucci rocks! :cool:
 
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While I realize things are complicated with multiple gain stages, please tell me what part of this is wrong. If Gain stage B overdrives at a made up number of 100, and gain stage A when wide open can push it to 130, then pretending the pot sweep was simple 1-10, then gain stage A would overdrive gain stage be somewhere around 7 on the knob. Reducing the gain of stage A to 100 would then allow you to turn it to 10 without overdriving stage B. But, it is the same drive thru the circuit at 10 as the original was at 7. You have lowered gain, but haven't increased headroom.

That is very oversimplified on purpose. Please explain to me where it is not applicable. You reduce the P/I you're simply not hitting the power stage as hard. Maybe it doesn't overdrive like it did before, but only because you aren't pushing it as far. I'm not disputing a reduction of clipping. I get that. But there is no increase in clean headroom, which is what is claimed.

I'm no amp designer and I don't claim I'm right and everyone else is wrong. But so far, nobody has ever been able to explain to me how reducing gain through any gain stage INCREASES clean headroom. It simply reduces gain and lowers the output of the next stage... and I'm saying that turning the knob down on the higher gain tube will yield a spot where it doesn't break up and that will be at the same actual output as it happened with a lower gain tube, but with the lower gain tube the knobs will be turned higher to get to that point.

Do you disagree with this?

I could go on and this is interesting. But time consuming. LOL If you have a multiple gain stage preamp section for example, there is NO question you can reduce gain by dropping a lower gain tube in there. But that doesn't make the amps clean tones louder/increase clean headroom, it just reduces the level of gain in that stage. See again, I don't dispute that it makes the amp cleaner. That's a given. But it doesn't make it cleaner-louder.

IMHO And I do not get paid anything for these opinions. :) But I have tried for years to find a way that this couldn't be true, and I haven't found one yet that I could understand. I'm not saying it's not possible with multiple gain stages intentionally designed to distort, that you couldn't lower them all to just the right amount that none overdrives the other and the end result is you maybe get more true output... headroom, without overdriving any of the stages. But I don't see that being a norm in any of the amps I've ever analyzed.
 
Cool I’ll check V1 and V4 and see what’s in it. I bought my Archon 100 new so what is the factory preamp tube brand? I know the power tubes are Ruby’s and I thought the preamp tubes were listed as JJ online but they might be something else but I haven’t checked yet to see.

Would you recommend something else besides a 12ax7 for V1 or is an12ax7 best? I know this is all personal choice or taste but just wondering.

And any recommendations for the FX Loop tube?
I found current production tung sol 12ax7 in v1,4,5 smooth things out compared to the stock JJ preamp tubes. I play with both master volumes between 9-10:00. It’s not massive difference, but noticeable.
 
I would put a 12AT7 in the PI spot (V5?), that will help keep it cleaner. Also, try a 5751 in V1 and V4 for starters, and maybe even try 5751s in V2 and V3. For even less gain, a 12AY7 in V1 and/or V4. Same for the loop, start with a 5751 in the loop (V6?).

I will pick some of these tubes up as well along with some Tung Sol 12ax7’s for testing around with.

If I hadn’t done it a hundred times, I might agree with you, but the fact remains that more gain leads to earlier breakup. I’ve had great success using a 5751 in V1 and a 12AT7 in the PI, not only for keeping the cleans, but also smoothing the gain side. I realize it’s all personal preference, but I get paid very well to do things like this, and have been doing it for many years.

Here is a good demo of using lower gain tubes, and you can even see the clipping (more square wave) shown on the scope with the higher gain tubes, and the clipping drops off with the lower gain tubes.
https://www.thetubestore.com/gain-factor

Remember that it takes 10 times the wattage to be twice as loud, and the opposite is true also. If you reduce gain by 30%, the volume won’t be reduced very much, but the clipping will be reduced.

BTW, I agree with you about Dream Theater, Petrucci rocks! :cool:

Been watching many of videos and been reading lots and I totally agree with what your saying about 12ax7 vs 5751 and more - it makes sense and totally understand and agree. I’ll order some of these tubes as well and see what magic will happen :)


I would suggest not putting any lower gain tubes in the PI slot, since he said he wants to retain headroom. Same for V1 and V4. If you want to smooth out the top end of the clean channel only and with pre-amp tubes, and if there are JJs in there now, then NOS may be your only option.

And, with all due respect, I don't recommend replacing PI or Loop with lower gain tubes if you want to retain clean headroom. I am one of those who subscribe to the believe that lower gain tubes almost never give more headroom, they simply allow you to turn the dial further before something distorts, but in MOST circuits, it will still distort at the same level of gain. So maybe your clean channel finally starts clipping at 8 on the knob but you drop a 5751 in one of the stages and now it stays clean all the way to 10... yeah, but it's still not as loud as it was at 8 with the AX7 in there.

In fact... Every time I read that putting a 12AY7 here or a 5751 there gives an amp "more clean headroom," I cringe... It might give you more range of control over a gain channel. It might make your amp stay clean up higher on the dials, etc. But reducing gain of pre-amp stages, PI, Loops, etc almost never gives you more clean headroom. It only gives you more clean range on the dials but only because there's less output at any given dial number. Feel free to disagree. I know there are very few circumstances were one tube early in the circuit just might push the next stage into breakup very quickly so that a lower gain tube lets you stop just before that spot more easily, etc. But I've tried it with numerous amps and read/studied about it for years, and I believe that it almost never gives more clean headroom.

Looked at preamp tubes when I got home and they are JJ ECC83S and reminder I bought/purchased the amp brand new so these are what PRS shipped with from the factory. After researching these tubes I get a lot of people describing these as harsh, extremely bright and aggressive - which is what I’ve been trying to describe here. Below vchizzle recommended the Tung Sol 12ax7 and when I searched and compared the JJ ECC83S to the Tung Sol 12ax7 most if not all recommended the Tung Sol 12ax7 because it’s very smooth and musical while the JJ ECC83C was described as being very harsh, overly bright and aggressive. So there are JJ ECC803S’s which are not to be compared to JJ ECC83S.

I think what I’m experiencing is exactly how the JJ ECC83S’s are described as by many. Decent tube but harsh, overly bright and aggressive.


I found current production tung sol 12ax7 in v1,4,5 smooth things out compared to the stock JJ preamp tubes. I play with both master volumes between 9-10:00. It’s not massive difference, but noticeable.


Researched these Tung Sol 12ax7 and seen lots of great things. I also researched Tung Sol 12ax7 compared to the stock JJ ECC83S tubes and almost all described the JJ ECC83S as exactly what I am experiencing which is harsh, overly bright and aggressive and the Tung Sol in comparison was described as very smooth and musical. I’m gonna order some of these Tung Sol 12ax7’s and see what I get, hopefully something great :)
 
While I realize things are complicated with multiple gain stages, please tell me what part of this is wrong. If Gain stage B overdrives at a made up number of 100, and gain stage A when wide open can push it to 130, then pretending the pot sweep was simple 1-10, then gain stage A would overdrive gain stage be somewhere around 7 on the knob. Reducing the gain of stage A to 100 would then allow you to turn it to 10 without overdriving stage B. But, it is the same drive thru the circuit at 10 as the original was at 7. You have lowered gain, but haven't increased headroom.

That is very oversimplified on purpose. Please explain to me where it is not applicable. You reduce the P/I you're simply not hitting the power stage as hard. Maybe it doesn't overdrive like it did before, but only because you aren't pushing it as far. I'm not disputing a reduction of clipping. I get that. But there is no increase in clean headroom, which is what is claimed.

I'm no amp designer and I don't claim I'm right and everyone else is wrong. But so far, nobody has ever been able to explain to me how reducing gain through any gain stage INCREASES clean headroom. It simply reduces gain and lowers the output of the next stage... and I'm saying that turning the knob down on the higher gain tube will yield a spot where it doesn't break up and that will be at the same actual output as it happened with a lower gain tube, but with the lower gain tube the knobs will be turned higher to get to that point.

Do you disagree with this?

I could go on and this is interesting. But time consuming. LOL If you have a multiple gain stage preamp section for example, there is NO question you can reduce gain by dropping a lower gain tube in there. But that doesn't make the amps clean tones louder/increase clean headroom, it just reduces the level of gain in that stage. See again, I don't dispute that it makes the amp cleaner. That's a given. But it doesn't make it cleaner-louder.

IMHO And I do not get paid anything for these opinions. :) But I have tried for years to find a way that this couldn't be true, and I haven't found one yet that I could understand. I'm not saying it's not possible with multiple gain stages intentionally designed to distort, that you couldn't lower them all to just the right amount that none overdrives the other and the end result is you maybe get more true output... headroom, without overdriving any of the stages. But I don't see that being a norm in any of the amps I've ever analyzed.

It is really just a matter of clipping (distortion), you can’t get more volume, just more distortion. You can reduce the clipping, and keep the signal voltage level very close to what it was, by using a slightly lower gain tube. More distortion does not equal much more volume out, considering the volume/wattage curve (10 times the wattage to double the volume). Once you have a square wave output (much distortion), increasing the gain only increases the distortion, not much more volume.

I see what you are saying, and you are correct, the headroom isn’t really increased with lower gain tubes, the distortion is decreased, so you can get more clean volume by turning the amp up without increasing the distortion. This is perceived by the human ear as “more” clean headroom.

Does that make sense? :)
 
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It absolutely does. But, turning the knob further for the same volume, does not equal “more clean headroom” which is what so many people say. It’s a misnomer. You can’t get more clean headroom, which is SOLELY a result of power without overdrive (which simply means in most cases MORE WATTS), by reducing preamp gain, P/I gain, etc.

If each stage drives the next stage fully to the point of overdrive but not beyond, you will achieve maximum clean output, or maximum headroom. The second one stage overdrives the next, you have “overdrive/distortion/compression” etc. But reducing that actual gain in any one stage can’t make “more headroom”... more clean volume level. And that is my issue with the commonly head notion that “lower gain this or that increases clean headroom.”

I’m a hack. (No secret there). But I have a friend who is an E/E who walked me through some exercises with real circuits (all analog, all SS by the way) to teach me how gain staging worked. I was doing breadboard circuits and running each stage through a scope to see if/when it was clipping and what that did to the next stage. Then plugging that in as a guitar overdrive/boost type pedal. We did one stage, two, three, even four, with no EQ, then started dropping fixed tone stacks in to test their varying results. This guy insists that there is no way less gain equals more headroom and he showed me in multiple circuits how that worked.

So again I say, I’m not saying it doesn’t have effects of making an amp cleaner or whatever. I know that it does. It might even be preferable with certain desired results. Like I said, I have a buddy who put a 5751 in his P/I and insists the amp is better than ever for him. It is! He can drive the preamp further and the output stage easier which results in his desired tone at a lower volume. I understand how we can manipulate the gain stages. I just think this is something that is widely “believed” and it’s technically.... incorrect. But I’m apparently flawed like that. I thank a waiter and when they say “no problem” my immediate thought is “I thanked YOU and I’m tipping YOU. I’m glad I wasn’t a problem for you!”
 
You should have your buddy show you the same thing with tube gain stages. Totally different animal, as clipping is not the same with SS vs tube. ;)
 
You should have your buddy show you the same thing with tube gain stages. Totally different animal, as clipping is not the same with SS vs tube. ;)

We did and I get that. Just didn't breadboard them like we were the SS versions. Something about 450V and bare wires that we were a bit skeptical about. :)
He had some SPICE model program we were using. We did an analysis of several Mesa amps vs. the classic Marshall JCM800 vs. a Fender Deluxe. The Mark IV took me weeks to go through.
 
You're both arguing the same point, but coming to slightly different conclusions.

Preamp Valves are class A amplifiers, no feedback at frequencies above the cathode cap pole. Each stage pretty much slams the next stage. But many amp makers follow a gain stage with a resistor divider so that each stage pushes less on the following stage, and therefore each stage clips a little, rather than flat out.

High gain amps are often an exception, in that one stage is saturated all to heck. In this case, changing to a lower gain tube at the front has less effect.

For amps that have a bit of saturation in each stage, changing the tube gain in one or two stages can change the character of the clipping. In this case, cleaning up a stage or two limits the clipping to the remaining stages. Turning up the volume /gain gives more clip, but in fewer stages, more like a high gain amp.

Headroom vs. Volume is strictly a power amp effect. More watts gives more clean headroom assuming the preamp is minimally clipped.
 
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