# Advice on tubes



## guitarman2 (Aug 25, 2006)

As I'm trying to determine what I need in NOS preamp tubes I'd like to break it down to each position as I'm coming to understand that not all positions would benefit or necessarily require an NOS tube in each position.
From V1 to V4 is my preamps and I'm not sure I understand the function of each. All explanations of the positions came from David Allen but some I still don't understand. I wouldn't want to change how he designed this unless someone has a a good argument and some experience as to why say for example a 12AT7 would work nicely as they'd be a cheaper NOS opton. For clean headroom in this amp I have plenty so don't need lower gain tubes for V1.
The amp is an Allen Old Flame.

V1 - This is the first gain stage and I think its fairly plain that this can benefit from a good NOS tube If anyone has any input here I'd gladly listen

V2 - According to David Allen this drives the tank. I'm not sure what that means. The reverb tank? If so how would changing from 12AX7 to 12AT7 affect this?

V3 - reverb recovery + gain stage. Not sure what this means with "+ gain stage" NOS or current production for this?

V4 - Phase inverter. According to Myles Rose this is the most important tube in the amp. As well its the tube that he advises to change with every output tube change or at least every other. So an NOS might not be practical here. He says he likes the Sovtek 12AX7LPS.http://www.guitaramplifierblueprinting.com/files/Phaseinverter.pdf
So should I maybe skip putting NOS here? Would it benefit from being balanced?

So basically looking for recommendations of whether all positions really need NOS and a better understanding of what, exactly V2 and V3 here are. Would any of the pre tubes benefit from being balanced?


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## Kerry Brown (Mar 31, 2014)

What tone are you looking for? NOS doesn't necessarily mean better. I'm no expert on tubes but I have tried a few quite expensive NOS tubes and really couldn't hear a lot of difference over good quality new tubes. I've had very good results with these in a Mesa TA-30 and an AC15.

www.thetubestore.com - Preferred Series 7025 Audio Tubes


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## guitarman2 (Aug 25, 2006)

Kerry Brown said:


> What tone are you looking for? NOS doesn't necessarily mean better. I'm no expert on tubes but I have tried a few quite expensive NOS tubes and really couldn't hear a lot of difference over good quality new tubes. I've had very good results with these in a Mesa TA-30 and an AC15.
> 
> www.thetubestore.com - Preferred Series 7025 Audio Tubes


Not really looking to change the tone, necessarily. My original intention was to replace all 4 12AX7 tubes with NOS for longevity. Reading an article by Myles Rose (expert in the field) seems that may not be a good idea. For example the Phase invertor is the hardest hit tube and he recommends it be changed every output tube change or at least every other. That may be expensive to use NOS in that position. As far as tone improvement goes its commonly understood that v1 has the most impact. So maybe NOS there for sure. For my amp that leaves V2 and V3. The reverb driver and the recovery + gain stage. Not sure what that means "+ gain stage" but in these 2 positions I'm wondering if NOS is also a waste as they aren't ridden hard.
As for the other tubes, rectifier and power tubes, I've decided I will buy an NOS rectifier as it meets my requirement for longevity or at least they're supposed to last longer than current production. And the output tubes as they are changed more frequently I'll stick to current production unless I can come across a great deal on NOS. Great deals are unlikely anymore on good NOS.
As well Myles Rose seems to think that Output tubes have much less influence on the tone as some think.

http://www.guitaramplifierblueprinting.com/files/Phaseinverter.pdf


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## Kerry Brown (Mar 31, 2014)

Again, my experience is fairly limited but I've never had a pre-amp tube wear out or go bad. I'm sure it happens but I've never seen it. I sometimes change pre-amp tubes looking for a different tone but I've never had to change one. Not sure about phase inverters but I've never changed one because I had to.


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## guitarman2 (Aug 25, 2006)

Kerry Brown said:


> Again, my experience is fairly limited but I've never had a pre-amp tube wear out or go bad. I'm sure it happens but I've never seen it. I sometimes change pre-amp tubes looking for a different tone but I've never had to change one. Not sure about phase inverters but I've never changed one because I had to.


Years ago I remember reading some article that stated you should change all preamp tubes at least every other power tube change.
And now in the article I posted above by Myles Rose he states that only the phase invertor needs to be changed at least every other power tube change. The article states that the phase invertor is the most important tube in the amp.
I really don't think I need to change any tubes in my Old Flame head right now it sounds great. But the reason I'm going to change it is to provide my self with back up tubes, which currently I have none. I bought the amp back at the beginning of the year, its a 2011 and I'm pretty sure the tubes are original. However the original owner used it only at home and died about 2 years ago, where the amp sat at his brothers house until I bought it.
So I'll change the tubes out and use the existing tubes as backups cause I know they work. So now I have to determine what the best retube would be and unfortunately I'm an obsessive sort, about the small things that may or may not matter.


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## nonreverb (Sep 19, 2006)

Don't get too caught up with the idea that the PI MUST be changed when you replace the power tubes. That is simply not the case. A good quality preamp tube in the PI can last for years. If there's any preamp tube that would need attention, it's the driver in the Fender reverb circuit. That 12AT7 is used as a 1/2 to 1 watt amplifier (you can actually hook a speaker up to it and it will work) and is worked harder than all the other preamp tubes in the amp.
The issue to be addressed is noisy or microphonic preamp tubes. They're by far the most problematic.....and for the record, I see plenty of microphonic, noisy NOS tubes as new ones.


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## WCGill (Mar 27, 2009)

Myles Rose was just a shill for Groove Tubes and the old "PI must be replaced when changing the power tubes" comes from Aspen Pittman, Mr. Groove Tubes himself so he could sell more tubes. Fake news!


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## guitarman2 (Aug 25, 2006)

WCGill said:


> Myles Rose was just a shill for Groove Tubes and the old "PI must be replaced when changing the power tubes" comes from Aspen Pittman, Mr. Groove Tubes himself so he could sell more tubes. Fake news!


Myles Rose seems to be a universally accepted expert in the field of tubes used in guitar amps. But I wouldn't put it past anyone in the field to influence based on improving sales. However, why wouldn't he just say you should change all your tubes every power tube change? Surely that would go even farther for improving sales.


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## DaddyDog (Apr 21, 2017)

Kerry Brown said:


> NOS doesn't necessarily mean better. I'm no expert on tubes but I have tried a few quite expensive NOS tubes and really couldn't hear a lot of difference over good quality new tubes.


 Ditto. Same experience here. Went on a tear recently to acquire old Brimar tubes.


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## guitarman2 (Aug 25, 2006)

DaddyDog said:


> Ditto. Same experience here. Went on a tear recently to acquire old Brimar tubes.


My main goal more so than tone is longevity. Which NOS tubes are supposed to give. I guess there are no guarantees though.


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## guitarman2 (Aug 25, 2006)

This is what I have figured out so far. The following is what I think I'll try for now.

*V1* NOS JAN GE 12AX7WA. this will be the most expensive tube I use at $90US

*V2 *Reverb Driver Mullard 12AT7WA This is a fairly expensive tube at $49.95 US. I debated whether to use the JAN Phillips 12AT7WC as its only $15.95 US but the Mullard seems to get reviewed better.

*V3 *Reverb recovery + gain stage. Still not sure what to do here. I don't understand what type of 12AX7 works best here. Does it greatly affect the tone? Is a very low microphonic tube best here? Is NOS a waste here?

*V4 *Phase Inverter. I'm gonna give the Sovtek 12AX7LPS a go here as it seems popular for this position and its a low risk financial experiment at $15.95 US

So does anyone have any recommendations for *V3*? I did ask David Allen if a 12AT7 was a wise idea for the Phase inverter so depending on what he says may influence what I do.


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## Granny Gremlin (Jun 3, 2016)

guitarman2 said:


> V3 - reverb recovery + gain stage. Not sure what this means with "+ gain stage" NOS or current production for this?


Each 12A_7 tube is a dual triode - 2 tubes in one bottle. So half of V3 is the reverb recovery and the other half is some other gain stage (the power section driver maybe.... or maybe something earlier in the preamp circuit). Why the hell they didn't just make one tube do both reverb tank driver and recovery boggles the mind though (possibly uses both halves for the driver- seen that before).



guitarman2 said:


> V4 - Phase inverter. According to Myles Rose this is the most important tube in the amp. As well its the tube that he advises to change with every output tube change or at least every other. So an NOS might not be practical here. He says he likes the Sovtek 12AX7LPS.http://www.guitaramplifierblueprinting.com/files/Phaseinverter.pdf
> So should I maybe skip putting NOS here? Would it benefit from being balanced?


Utter voodoo. Change it when it gets weak; has nothing to do with when you change the power tubes. The reason I suspect he would say this is because it can be one of the hardest working tubes in the amp, depending, but still.

It can be a significant element in the tone. If you're gonna put NOS anywhere this would be a candidate (longevity and robustness - no new prod tubes come close ; tone is a matter of taste and varries). Balanced halves can be good here depending on the type of PI circuit they are using, but not essential.



guitarman2 said:


> V2 - According to David Allen this drives the tank. I'm not sure what that means. The reverb tank? If so how would changing from 12AX7 to 12AT7 affect this?


Yes reverb driver. Do not deviate from the manufacturer recommended tube here unless you have a very good reason. Now IF the reverb driver does in fact use both triodes, and the reverb is crashing out/too hot, then sure, try replacing the X with a T, otherwise leave well enough alone. That may be too weak though (especially if the drive circuit uses both halves).




guitarman2 said:


> So basically looking for recommendations of whether all positions really need NOS and a better understanding of what, exactly V2 and V3 here are. Would any of the pre tubes benefit from being balanced?


There is no reason to use a balanced tube (both halves gain matched) except in the case of some PI types; and even then it is not absolutely necessary, but more so the only place where any sort of reasonable case can be made. Balanced dual triodes are mostly needed for stereo applications (each half of the 12A_7 is separate channel - usually seen in hifi or pro rec gear) or maybe if you use a dual triode in push-pull for a balanced differential amp which is rare but I have seen (in mic preamps).


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## guitarman2 (Aug 25, 2006)

Granny Gremlin said:


> Utter voodoo. Change it when it gets weak; has nothing to do with when you change the power tubes. The reason I suspect he would say this is because it can be one of the hardest working tubes in the amp, depending, but still.
> 
> It can be a significant element in the tone. If you're gonna put NOS anywhere this would be a candidate (longevity and robustness - no new prod tubes come close ; tone is a matter of taste and varries). Balanced halves can be good here depending on the type of PI circuit they are using, but not essential.


The Sovtek 12AX7LPS seems to get a lot of praise in the PI and I think I'll give it a try as its a low risk financial experiment. I don't mind if I have to change that one out a little more frequently. I can always substitute an NOS tube later on.




Granny Gremlin said:


> Yes reverb driver. Do not deviate from the manufacturer recommended tube here unless you have a very good reason. Now IF the reverb driver does in fact use both triodes, and the reverb is crashing out/too hot, then sure, try replacing the X with a T, otherwise leave well enough alone. That may be too weak though (especially if the drive circuit uses both halves).


I emailed David Allen and asked if it would be all right to use a 12AT7 in place of the 12AX7 that was in there. He said it would be fine and that he sometimes uses the 12AT7. I found an archived thread on another forum where someone asked him about this and he replied that he uses what ever is convenient on supply. I find my reverb weaker than I would have thought not as nice as some other fender reverbs that I've had. As well it sometimes starts to howl microphincally a bit suggesting maybe the tube is going bad. I also read that even though the 12AT7 is lower gain that some players have noticed more reverb when replacing a 12AX7 with a 12AT7. Something to do with the voltages. So I'll experiment with an NOS 12AT7 and see how it goes.

For V3 I've decided to use a JAN GE 12AX7WA as I've read that the gain stage in this tube is fairly important to the signal chain. Could be a bit of an unnecessary expensive venture. Not sure.


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## nonreverb (Sep 19, 2006)

You can use a 12AX7 in the reverb drive of a Fender....but it won't like it for long. The reason being the 12AX7 has more gain but does not have the current rating that a 12AT7 has. In the reverb drive circuit, a 12AX7 is being worked hard and will wear out faster. Reverb problems can be cause by a number of things. If the tank is not the correct one or if a spring has come loose. Also the recovery circuit can sometimes be the problem as well.


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## Tone Chaser (Mar 2, 2014)

You are overthinking all of this.

This is a “durable” JAN 5Y3 WGTA that was new in the box. I put it in my 1974 Fender Bronco amp that was fully gone through by a very good tech. The third time I went to use the amp, there was silence.


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## Frenchy99 (Oct 15, 2016)

I wonder if guy s like Eddie Van Halen bothers with NOS tubes ?!?!


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## Tone Chaser (Mar 2, 2014)

Frenchy99 said:


> I wonder if guy s like Eddie Van Halen bothers with NOS tubes ?!?!


Performing live, at volume, with multiple amps, I really doubt it. It would be financially foolish as well.

Anything goes in a studio, so maybe there, but most likely in a few prized amps in his collection.


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## guitarman2 (Aug 25, 2006)

Frenchy99 said:


> I wonder if guy s like Eddie Van Halen bothers with NOS tubes ?!?!


I hear a lot about some of these famous guitarists who's techs change out tubes quite frequently. Like every show or maybe once a month. So its unlikely that they're buying NOS. 
As I said previously my main goal isn't to necessarily gain some magical tone through NOS tubes. I'm primarily looking at trying to achieve longevity. Putting in more ruggedly spec'd tubes that will last a long time. I'm mainly concerned with the preamp tubes because good NOS tubes can last a very long time and the rectifier as a good one can last as long as I'll be playing. The power tubes I'm not as concerned with although I might try to find a couple of good ones but once they're worn I'll probably look at current production.

I put some new tubes in this afternoon.

V1 JAN GE 12AX7WA
v2 Reverb driver Mullard 12AT7WA CV4024
V3 Reverb recovery + gain stage Preferred series 12AX7
V4 Phase Invertor Sovtek 12AX7LPS

I really haven't noticed a dramatic change in tone. Some things have improved. It was already an amazing sounding amp. The preamp tubes have been in there along with the other tubes for 7 years. Now maybe one reason there isn't a lot of difference is I haven't yet changed the output tubes or the rectifier. But those tubes do have less influence on tone.
I switched the reverb driver from a 12AX7 to a 12AT7 after confirming with David Allen that he him self uses one or the other based on convenience. After putting in the Mullard 12AT7, which is fairly pricey for a 12AT7 I noticed no difference in the reverb. The reverb for a 3 knob is not one of the shining features of my Allen Old Flame. Not real splashy like a nice Fender 3 knob but for my uses its more than adequate. The 12AT7 did nothing to improve it nor did it make it sound any less. I am happy because the fact that I can use a 12AT7 and its a really good NOS means it should last a very long time.
V3, I wasn't sure what to do there. Was almost going to spring for another JAN GE but at the last minute decided to go with what is reported to be a good current production with the tubestores preferred seried. I'll have to give that position more thought.
For V4 for now I went with what seems to be a popular choice for the phase inverter. It seems that tube is reviewed well for tone as it affects the power tubes. I'll probably not notice much difference there until I change the power tubes, if my understanding of how it works is correct. I'm debating whether I should try a 12AT7 in that position. I'm waiting on confirmation from the amp builder as to whether thats advisable. 
The biggest change in this preamp tube change is in the operation of the "RAW" knob. The RAW knob when dimed all the way completely lifts the tone stack adding more gain. Before I changed the tubes I kept the RAW knob between noon and 1 oclock. This fattened the tone up somewhat. With the master at about noon and the gain about 1 there was a slight bit of hair on the notes if I dug in. Now with those settings theres full on nice Blackface breakup. It sounds heavenly sweet but I don't like the lack of clean headroom. So I bump the master to about 3 oclock and the RAW knob all the way back to between 9 and 10 and its back to more clean headroom with just slight hair if I dig in. If I'm able to put a 12AT7 in the phase inverter I'm going to give that a try and see if it increases headroom.


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## DavidP (Mar 7, 2006)

Welcome to the NOS rabbit hole... Yes NOS tubes are preferable to most current production BUT, you're taking a gamble on longevity depending on your supplier... Even reputable folk like Mike Kropotkin (KCA NOS Tubes) will warranty NOS only for 30 days, TubeStore gives 3 months on current production. As the NOS supply dwindles, the $$ go up, as well as the possibility that what looks like NOS in original box was a pull for a new replacement 50 years ago. I have a 'vault' of NOS acquired over a couple of decades, and given what some fetch (like Blackburn Mullards) I'm very selective as to what goes in my amps and for what purpose. I'm tempted to sell some off as they are doing better than the stock market! Frankly, I really don't hear a significant difference when playing out, while it can make an impact in a studio. I'd pay good $$ for a Mullard rectifier (if you need 5AR4/GZ34) as it will likely outlive you; for other rectifiers I'd seek out JAN (Joint Army Navy) Philips tubes that are still out there for a decent price. I'd also spring for a RCA/GE 21AX7 or a 5751(my preference) in V1, maybe a Mullard 12AT7 for the reverb driver in a Fender, but I use current production for the other preamp tubes. The Sovtek 12AX7LPS is a great phase inverter tube, and anything microphonic goes into the tremolo socket. Power tubes are a whole other story, but not now...


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## guitarman2 (Aug 25, 2006)

Well the more I play this amp the more I feel I underestimated the tone improvements. But I think the tubes that were in there were past their best before so that could have a lot to do with it.


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## Brett Pearson (Apr 26, 2016)

In my experience, the biggest tonal variation comes from the power tubes. I have rolled lots of preamp tubes and while they do provide different tones, the differences are subtle. Power tubes on the other hand can really open up the sound or compress it in a way that is immediately noticeable. Compare an old Marconi 6v6 to an RCA 6v6 and you will hear the difference right away. A lot of the newer tubes sound great and do a good job and as many forum members have said, NOS does not always mean better and if you have a lot of tubes in your amp, it can get very expensive. There is a LOT of marketing BS in the tube and guitar amp industry and if you aren't careful you can spend a small fortune on tubes and at the end of it all, wind up having to tell yourself the amp sounds better whether it does or not just to justify your investment. You really have to run a tube hard to wear it out. Some amp designs will, but most don't. I have had old 60's amps with the original branded tubes still in them that test 100% or close to it after 40+ years! And as Tone Chaser pointed out, I have put in a cherished NOS tube only to have it fail after a few hours of running. From what I have read on their website, you can run the old flame with 6v6 or 6l6 power tubes. If you run 6v6, I would try a set of old RCA's in the power section and see what you think. The RCA 6v6 is very transparent and articulate sounding tube as is the RCA 6L6 blackplate although these are getting expensive. It is a rabbit hole for sure, but it sure is fun. If you are ever out my way, bring your amp and we can roll some tubes.


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## BSTheTech (Sep 30, 2015)

You are WAY overthinking this. If you want more headroom throw a 12AT7 in V1. Otherwise get a "nice " set of newer quality tubes and be done. I've had great luck with the gold pinned Gold Lions. They are a little more though than the JJ's/GT's etc.


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## blue_dog (Feb 7, 2013)

BSTheTech said:


> You are WAY overthinking this. If you want more headroom throw a 12AT7 in V1. Otherwise get a "nice " set of newer quality tubes and be done. I've had great luck with the gold pinned Gold Lions. They are a little more though than the JJ's/GT's etc.


+1. 12ATY in V1 or run the power tubes at a lower bias. Save yourself the money, the Allen should sound good sound good regardless of the NOS tubes


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## Budda (May 29, 2007)

BSTheTech said:


> You are WAY overthinking this. If you want more headroom throw a 12AT7 in V1. Otherwise get a "nice " set of newer quality tubes and be done. I've had great luck with the gold pinned Gold Lions. They are a little more though than the JJ's/GT's etc.


I bought a 12AT7 for my 2203 a few years ago, never did get around to putting it in. Maybe I'll finally try that after this tour.


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## BSTheTech (Sep 30, 2015)

Budda said:


> I bought a 12AT7 for my 2203 a few years ago, never did get around to putting it in. Maybe I'll finally try that after this tour.


Never heard of anyone needing more cleans in a fire breathing dragon, but check it out...Who knows HNG^%$


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## Budda (May 29, 2007)

BSTheTech said:


> Never heard of anyone needing more cleans in a fire breathing dragon, but check it out...Who knows HNG^%$


Outside of the studio mine stays clean. And loud


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## guitarman2 (Aug 25, 2006)

DavidP said:


> Welcome to the NOS rabbit hole... Yes NOS tubes are preferable to most current production BUT, you're taking a gamble on longevity depending on your supplier... Even reputable folk like Mike Kropotkin (KCA NOS Tubes) will warranty NOS only for 30 days, TubeStore gives 3 months on current production. As the NOS supply dwindles, the $$ go up, as well as the possibility that what looks like NOS in original box was a pull for a new replacement 50 years ago. I have a 'vault' of NOS acquired over a couple of decades, and given what some fetch (like Blackburn Mullards) I'm very selective as to what goes in my amps and for what purpose. I'm tempted to sell some off as they are doing better than the stock market! Frankly, I really don't hear a significant difference when playing out, while it can make an impact in a studio. I'd pay good $$ for a Mullard rectifier (if you need 5AR4/GZ34) as it will likely outlive you; for other rectifiers I'd seek out JAN (Joint Army Navy) Philips tubes that are still out there for a decent price. I'd also spring for a RCA/GE 21AX7 or a 5751(my preference) in V1, maybe a Mullard 12AT7 for the reverb driver in a Fender, but I use current production for the other preamp tubes. The Sovtek 12AX7LPS is a great phase inverter tube, and anything microphonic goes into the tremolo socket. Power tubes are a whole other story, but not now...


Its not the tone I'm after so much as the longevity. I just bought an used Mullard 5AR4 online that will be here next week. Just hoping it lasts forever. I'll keep a spare new production around for back up and eventually buy another old one for backup. For power tubes, in my old flame I use 6L6. I'll be changing the sovteks that are in there probably for new production unless I find a decent deal on NOS. What you say about power tubes making the most dramatic difference in tone is opposite of just about everything else I read. Most say its the preamp tubes, specifically V1.


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## WCGill (Mar 27, 2009)

BSTheTech said:


> You are WAY overthinking this. If you want more headroom throw a 12AT7 in V1. Otherwise get a "nice " set of newer quality tubes and be done. I've had great luck with the gold pinned Gold Lions. They are a little more though than the JJ's/GT's etc.


12AY7 and 5751 are better choices for V1 gain reduction. They're direct subs for a 12AX7, 12AT7 is not.


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## guitarman2 (Aug 25, 2006)

WCGill said:


> 12AY7 and 5751 are better choices for V1 gain reduction. They're direct subs for a 12AX7, *12AT7 is
> not*.


I'm using a 12AT7 in v2 (reverb driver) in place of a 12AX7 that David Allen had in there. Direct replacement. I had confirmed with David Allen (the amp builder) that this was ok.


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## WCGill (Mar 27, 2009)

12AT7 would be my first choice for reverb driver, depending on the circuit as it's able to handle more current than a 12AX7. And to reiterate, 12AT7 is *not* a direct replacement for a 12AX7 but if you like it, do it, it probably won't hurt anything.


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## Budda (May 29, 2007)

WCGill said:


> 12AY7 and 5751 are better choices for V1 gain reduction. They're direct subs for a 12AX7, 12AT7 is not.


What are the differences?


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## cboutilier (Jan 12, 2016)

Budda said:


> What are the differences?


IIRC the AT is not intended to be an audio tube like the AY, 5751, and AX. 

As such, it has different current requirements, and different sonic characteristics.


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## DavidP (Mar 7, 2006)

guitarman2 said:


> What you say about power tubes making the most dramatic difference in tone is opposite of just about everything else I read. Most say its the preamp tubes, specifically V1.


Hmm, what I said is power tubes are "another story" (well, another rabbit hole IMHO and a discussion that could go on for pages!) not "...the most dramatic difference." 
Agree 100% with playing around with V1 and that can make a dramatic difference. Without jumping into the power tube rabbit hole, I have an old amp tech friend who swears by the older wafer base Russian 6P3S-E (6P3C-E) over other 6L6GCs in his Fender blackface/silverface rebuilds, and buys them by the case! As he does a lot of work for pro players, reliability is a key concern for him. Remember, you gotta crank that amp to really get those power tubes to show their stuff.

Tube rolling is interesting, but can become a costly addiction!


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## Budda (May 29, 2007)

cboutilier said:


> IIRC the AT is not intended to be an audio tube like the AY, 5751, and AX.
> 
> As such, it has different current requirements, and different sonic characteristics.


So whats the tonal difference haha


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## cboutilier (Jan 12, 2016)

Budda said:


> So whats the tonal difference haha


They are generally considered to give a thinner tone, and less bass response, in addition to the increased headroom.


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## Budda (May 29, 2007)

cboutilier said:


> They are generally considered to give a thinner tone, and less bass response, in addition to the increased headroom.


The 12AT7 or the 12AY7?


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## cboutilier (Jan 12, 2016)

Budda said:


> The 12AT7 or the 12AY7?


The AT. The AY, in my experience sounds about the same as an AX turned down 2-3 "volumes".


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## High/Deaf (Aug 19, 2009)

DavidP said:


> Hmm, what I said is power tubes are "another story" (well, another rabbit hole IMHO and a discussion that could go on for pages!) not "...the most dramatic difference."
> Agree 100% with playing around with V1 and that can make a dramatic difference. Without jumping into the power tube rabbit hole, I have an old amp tech friend who swears by the older wafer base Russian 6P3S-E (6P3C-E) over other 6L6GCs in his Fender blackface/silverface rebuilds, and buys them by the case! As he does a lot of work for pro players, reliability is a key concern for him. Remember, you gotta crank that amp to really get those power tubes to show their stuff.
> 
> Tube rolling is interesting, but can become a costly addiction!


IMO, V1 (and possibly V2 depending on amp topology) probably makes the most difference no matter how you run the amp. It is always in circuit and tiny differences will reflect through the amp, clean or dirty. 

Power tubes sound the same if they are run linear (clean). I believe you mostly hear the design of the circuit and not specifically the tubes. If you run the power section non-linear (into power tube distortion), that's when the different power tubes have different sonic characteristics. And, IMO, those differences are more apparent than the differences in pre-amp tube variations. They just aren't consistently there, for every player all the time, like the V1 / V2 variation is. 


I find it varies from amp to amp as well. I don't hear much change when I roll tubes in my DRRI. But I had a drastic change in my Sunn T50C distortion channel when I tried 5751's and AY7's. It was harsh with nothing but AX7's in the path and I think reducing the gain at certain stages made the distortion characteristics more pleasing to my ear. I'm not a high-gain kinda guy and that might be part of the reason why.


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## cboutilier (Jan 12, 2016)

High/Deaf said:


> IMO, V1 (and possibly V2 depending on amp topology) probably makes the most difference no matter how you run the amp. It is always in circuit and tiny differences will reflect through the amp, clean or dirty.
> 
> Power tubes sound the same if they are run linear (clean). I believe you mostly hear the design of the circuit and not specifically the tubes. If you run the power section non-linear (into power tube distortion), that's when the different power tubes have different sonic characteristics. And, IMO, those differences are more apparent than the differences in pre-amp tube variations. They just aren't consistently there, for every player all the time, like the V1 / V2 variation is.
> 
> ...


I agree. I had an amp that was very 59 Bassman like in design, but with a quad of EL84s. It still sounded like a tweed Fender.


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