The most important tube in your amp

[Rockin_Ron]

Have you all read this? Seems pretty interesting and I did not know this. I'm new to this tube stuff and I'm been concentrating on the signal gain chain specifically V1; which everyone says is the most important in developing your tone.

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


Let discuss. Is anyone using these 12AT7s like he suggests for greater touch sensitivity?

 

[212Mavguy]

Great read there...Myles rose has a great rep for his work with guitar amps. However, he is incorrect as far as the amount of gain in a 12at7. it is in the 40's, not the 60's as he has said. Nitpicking aside, I agree with his words about the importance of the phase inverter, and yes, it is the hardest working tube in a push pull amp design. Another thing he mentioned that I disagree with is about his assertion that 12at7 tubes are not all that suitable for a V! position. That depends on the amp circuit. Personally, I have had great results using a 12at7 in a V1 position, with great touch sensitivity to boot. This is in more than one amp design, too.

For the amount of time it takes to swap out a tube in a particular position, turn the amp back on, letting it warm up, and playing through it, seems kinda foolish to just accept some one's words (mine too!) without taking the time to do for one's self and listen to see what one's fingers and ears think. :shock:

I'm not a touring musician, but if I were, there would still not be anything but vintage tubes in my amps, and there is no problem with finding a replacement because I have stocked up enough preamp tubes to last several human lifetimes for several players. It's not that hard to patiently stock up on what you like over a period of time...

 

[crane]

it is in the 40's, not the 60's as he has said

Gain factor of a 12AT7 is 60 no ?
5751 is 70, 12AY7 is 44 and 12AU7 is 17.
That's what you can read everywhere.

 

[212Mavguy]

Crane is right, I stand corrected.

 

[Old BF Shred]

Interesting info!
I will be experimenting with the PI, for sure. The good news is that the stock Mesa 12ax7 "russian" is essentially an "ax7lps". They seem to work well, that's for sure. I also have an 'at7' or two laying around and I'll see how those do in the Ace. I'll let you all know how this works out......

I had the privilege of talking to Myles a couple years back.....he recommended replacement tubes for my Triaxis. He told me he was (still is?) the man responsible for taking care of Al DiMeola's Triaxis rig....so he has some real world experience in these preamps. His selections did sound very good (GT's, as is no surprise) although I've swapped things around since.....
Take care!

 

[Timbre Wolf]

The phase-inverter (PI) can be a very influential tube, depending on amp, and depending on how you're using the amp, and how you make changes to the PI. Changing from 12AX7 to 12AT7 can mean you've got a cleaner-behaving power section; I've taken to using an E180CC (European Philips 7062), to bring the PI breakup down even more, in my tweed Bandmaster-inspired Richter 5E7+ (E180CC is to 12AT7 as 5751 is to 12AX7, for you SAT-takers). And different tonal characters can be had by swapping brands.

That said, I have disagreed strongly with some of Myles' more rigid statements (such as the one Mavguy mentioned, about not using 12AT7 as V1), based upon my own experience. I also urge readers to not adopt his biased opinions as your own preconceived notions:

For the amount of time it takes to swap out a tube in a particular position, turn the amp back on, letting it warm up, and playing through it, seems kinda foolish to just accept some one's words (mine too!) without taking the time to do for one's self and listen to see what one's fingers and ears think. :shock:

That statement should be posted as a banner on the Tubes page.

- T

 

[crane]

For the amount of time it takes to swap out a tube in a particular position, turn the amp back on, letting it warm up, and playing through it, seems kinda foolish to just accept some one's words (mine too!) without taking the time to do for one's self and listen to see what one's fingers and ears think. :shock:

That statement should be posted as a banner on the Tubes page.

+1000

 

[Don]

If you want to learn more about how tubes effect the sound of an amp, experiment with a simple amp like a tweed Deluxe. When I received my tweed Deluxe (5E3) clone it had all NOS tubes in it except for the phase inverter. The guy who built the amp figured that tube that effected the amp's tone the least so he put a cheap 12AX7 there.

Even though my local amp tech agreed with the builder, out of curiosity, I tried different old 12AX7s there (I have a bunch of pulls from old organs and HI-FIs). We were both surprised that the amp's tone was improved pretty dramatically. I ended up settling with an RCA 7025 in the position.

I also experimented with several of tubes in V1. The amp came with a Delco labeled 12AY7 in V1 (tweed Deluxes originally used a 12AY7 in V1). I tried RCA, GE, Amperex Bugle Boy, Telefunken, Mullard, etc. 12AX7s there, all with varying tone. In the end I preferred the 12AY7 that was in it for it's lower gain. I haven't had any other 12AY7s to try.

Later, I had an NOS Sylvania 6V6 power tube suffer a mechanical failure and was able to experiment with a bunch of old 6V6s at a local amp tech's shop. That was a lot of fun. In the end we found a great sounding set of GE 6V6s that I traded some other tubes to him for.

I have not tried 6L6 power tubes in the amp though the amp's PT and filter caps can handle them.

I have also tried different rectifiers in this amp (5R4 and 5U4) and like the NOS 5Y3 that I bought it with the best. These didn't change tone as much as feel and "texture".

The tube in this amp that affected the tone the most (when the same type of tube was used) was the power tubes followed by V1, V2 and finally, the rectifier. Keep in mind that this is a low powered non-master volume amp that gets it's tone from being cranked up almost as high as it will go.

I see companies selling tube sets for a variety of Mesa/Boogie amps and they often specify the same tubes for V1, V2, V3, etc... regardless of the amplifier model. That doesn't always make sense, for instance, V2 is the first gain stage on an Express!

As 212Mavguy said,

For the amount of time it takes to swap out a tube in a particular position, turn the amp back on, letting it warm up, and playing through it, seems kinda foolish to just accept some one's words (mine too!) without taking the time to do for one's self and listen to see what one's fingers and ears think.

 

[Rockin_Ron]

Interesting discussion and opinions guys! Is anybody currently running a 12AT7 in the PI location on a LSS? Did you notice any difference? I'm running a RCA 7025 there now after pulling all the MESA tubes. Can't say that I'm noticing any tone difference or any more touch sensitivity. Maybe I don't know what to listen for.

Anyhow since I do like the 1958 long plate Mullards I'm running in V1 & V2 so much (best so far from all the tubes I've tried); I figure I'd buy some 12AT7 Mullards. I just bought some off of ebay will this description:

Mullard Made in Great Britain ECC81/12AT7 Tubes. Tested at 89 and 94 on Sencore TC130 Tube Checker where 70 is Minimum. No Shorts or Grid Leakage. Both have code Tk1...R9A Grey plates. Will these sound any good??

I guess I'm going with Mavguy's statement and listening myself. Although if one is not careful this can get addictive and very expensive.

Kind of like these guys:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=220425564942
So far I've just bought used stuff. The NOS or supposed NOS is even more insanely expensive and I wonder if you can really hear the difference??

 

[Timbre Wolf]

Interesting discussion and opinions guys! Is anybody currently running a 12AT7 in the PI location on a LSS? Did you notice any difference? I'm running a RCA 7025 there now after pulling all the MESA tubes. Can't say that I'm noticing any tone difference or any more touch sensitivity. Maybe I don't know what to listen for.

You definitely won't hear any difference in the single-ended mode; there is no PI used in that setting. The medium and high power modes are where you'd possibly hear/feel changes to the PI, and the closer to full power you are playing, the more you'll probably notice differences.

- T

 

[Goran]

Hi everyone,
a question, as I am on the way to retube my Stiletto Ace Combo.
Would a Jan Philips 5751 be a good choice in the V5 poition of my amp? I have read that a Sovtek LPS 12ax7 is often recommended in this position, so are there any arguments that a JanP. 5751 would be perhaps even a better choice or is simply this Sovtek LPS the best choice for V%?

regards,
Goran

 

[MrMarkIII]

My experience has been the simpler the amp (tweed Fenders), the more dramatic the effect.
More un-simple amps (Mesa), not so much.
This is still like asking which is better, Nestle's or Hershey's? YMMV.

 

[Goran]

I would say get both, try them out, and listen for yourself. I personally like the LPS and in my old DR I would use it over a 5751. I wasn't too fond of the gain drop of a 5751. But both should make good effects loop or reverb drivers. So whichever one you decide not to use can always at the very least be used there.

At one point I had all LPS in my DR and it was good enough for gigging. My favorite of the modern tubes. I'm not sure about the whole "LPSs fail in the cathode follower position" thing or whether it's still a problem or not. I didn't have any problems with them in my DR or Fender HRDV. But maybe something to check into before attempting something like that. Maybe someone here can chime in on that.

For the record, I do like my GE 5751 in my Fender and my Marshall, but never liked the way it affected my Mesa.

Ok, will try. I have orderd some preamp tubes and wanted to try them out to see if there are changes in the sound of my amp (Stiletto Ace). But after I started reading about all the problems like Cathode Follower positions and so on, I get the feeling that this all is a little bit too much for me, as I have never changed a single tube. At this point I am thinking probably the best thing would have been "stick to the Mesa tubes before you blow up your amp".

This is a little off topic now: I will get also a matched pair of NOS Siemens RFT EL 34. I was looking for Mesa EL34 STR-450, but since I am in Europe there was no store which had those tubes, so I ordered a pair of NOS Siemens EL34 as it said on the Mesa site that this is the same tube. Could a problem occur if I put them into the poweramp, as I don't know if it is enough that the pair is matched or should the tubes in the poweramp also be biased (I really have no clue)?

Regards
Goran

 

[Goran]

Naw.. It ain't too much for you. That's what we're here for. If you can change a light-bulb, you can change your tubes. To my knowledge the LPS is the only tube I heard about having problems with the Cathode follower thing. As long as you're using 12ax7, 12at7, 5751 tubes, you won't hurt your preamp.

Here's some vids for you just to give a basic run-down on how to change them.

http://www.youtube.com/watch?v=ww8rOXnYHsE&feature=channel_page

http://www.youtube.com/watch?v=eoeXHIEbyx0&feature=related

http://www.youtube.com/watch?v=oq8ITOSb990&feature=related

http://www.youtube.com/watch?v=UqPvQFQ69ak&feature=related

http://www.youtube.com/watch?v=X-QePIj5MSw&feature=related

You seem kind of lost here.. Are you looking for a particular sound, or just looking to re-tube. Modern preamp tubes will work, but NOS tubes will sound better. They cost more, but they're worth the extra money spent in my opinion.

So let's just start with what kind of sound you're looking for.

It would be nice if someone like Stokes, Mav or Thom could chime in on your power tube question. I only used GT, Mesa, and =C= 6l6's in my Mesa.

Shredd6, thanks for your reply and you're right, lost is the right word, mate!

Well, regarding the sound, I'm quite happy with the clean channel and figuered out through using the 2nd channel that the Stiletto Ace is a bright amp and that this also was the intention. Also this brightness and harshness comes to a great part from the V30 speaker. (and I might say don't forget your pickups people, when dealing with the Stiletto Aces' brightness!)
The intention for the retubing is actually, if it is possible, to tame a little bit the brightness with some higher quality tubes like the NOS Siemens RFT EL 34 in the poweramp and if this should not work, then simply to have quality tubes that should last longer than Mesa stock tubes. Somebody in another forum told me, that even if this Siemens EL34 are matched, problems could occur and I should bias (?) them before installing, but he strongly recommended not to install them at all and to stick to Mesa tubes.
So, are they "safe" to install them?
Hopefully in the end I won't have a pair of tubes lying around my house, but what the heck, I am learining! I made an order on thetubestore.com if someone should ask.

So I kept on reading this forum, and people had actually success with taming the Stiletto a bit, so here is the part when I became interested, as the tubes in my Stiletto are now over one and a half years in use, and I simply wanted to see what difference would a retubing make. And actually, I should learn it finally, as I am planning to buy my 2nd Mesa!
I ordered, besides the NOS EL34, also some Tung-sol 12ax7, JAN Philips 5751, Svetlana 12ax7, because those tubes can't be found here where I live (Croatia/Europe). In stores here, we have mostly JJ, EH, Mesa stock tubes and sometimes even GT, that's why I didn't order one of those manufacturers.

I planned the tung-sol for V1, on V2 perhaps JJ or EH(?).
I wanted to leave on V3 and V4 the stock tubes and don't want to touch them, as they work for almost 16 months, but only for now, until I aquire some more information about this Cathode Follower thing, or perhaps is there a good alternative for Shuguangs in these places? Could a JAN-Philips 5751 work here? As I remember tung sol is a BIG NO for V3 and V4 (apparently Sovtek LPS too).
And then finally there is the V5. Someone recommended a Sovtek LPS in this position, my question: what about a JJ 12ax7 or a EH12ax7 in this poition? Any good?
This position is crucial, as explained already in this topic. So what would be the best solution beside a Sovtek LPS for V5?

So, hopefully you didn't all fall asleep because of my long description and perhaps someone can point me into the right direction from here!

Regards,
Goran

 

[Goran]

shredd6 thanks man, you helped me a lot!
Looks like I will make some more tube ordering but thats ok.

 

[212Mavguy]

On those Siemens el34's...if you wish to try them, do so in a dark room. With a bit of luck they will work fine. If the bias setting in your amp is too cold for those, they will sound thin and nasty, if that Mesa bias setting is too hot, the plates will begin to glow reddish from heat in a few minutes, that is a sign that you need to not run those in your amp. Siemens el34's are wonderful tubes, they will last much longer than any new production tube as long as the bias is not excessively hot. However, if your amp is under warranty, Mesa will not cover damage caused by running non mesa tubes in your amp, in fact, if they find out you have run non mesa tubes during warranty period your warranty will be void...

 

[Rockin_Ron]

Anyhow since I do like the 1958 long plate Mullards I'm running in V1 & V2 so much (best so far from all the tubes I've tried); I figure I'd buy some 12AT7 Mullards. I just bought some off of ebay will this description:

Mullard Made in Great Britain ECC81/12AT7 Tubes. Tested at 89 and 94 on Sencore TC130 Tube Checker where 70 is Minimum. No Shorts or Grid Leakage. Both have code Tk1...R9A Grey plates.

I running the above tubes, just the the AT7s in the mail today. I've swapped these AT7s out of both V4 & V5 and checked against the RCA 12AX7s I had in those spots. Playing at 15 watts with the master at 9 and then 12 o'clock..... tell me what I should be listening for as I really can't tell any difference.

 

[Goran]

On those Siemens el34's...if you wish to try them, do so in a dark room. With a bit of luck they will work fine. If the bias setting in your amp is too cold for those, they will sound thin and nasty, if that Mesa bias setting is too hot, the plates will begin to glow reddish from heat in a few minutes, that is a sign that you need to not run those in your amp. Siemens el34's are wonderful tubes, they will last much longer than any new production tube as long as the bias is not excessively hot. However, if your amp is under warranty, Mesa will not cover damage caused by running non mesa tubes in your amp, in fact, if they find out you have run non mesa tubes during warranty period your warranty will be void...

I don't think I will try them out for now. The amp is still under warranty, but even if it wouldn't be, I am far too unexperienced to put put them in and try them out. I will "play" a little bit with the preamp tubes for starters, probably next week they will arrive, but regarding the powertubes, I will order some EL 34 from Mesa and replace then my current EL34. But am going to keep those Siemens, as I have read a lot of positive things about them, and who knows, perhaps in the near future I will switch them in this amp, or eventually in another one. So, my first steps will be trying out the preamp positions and work myself from there. Thanks for your comments on my "tube problem"!

Kind regards
Goran

 

[Koreth]

While I will agree that Myles Rose knows quite a bit about tubes and tube amps and has plenty of wisdom and experience to share, I disagree with his opinion that a balanced phase inverter tube is the most important. Taken by itself, his argument makes sense. However, when you then take a look at circuit diagrams of many amps and see the different value components on each half of the phase inverter circuit (82k plate resistor on one side, 100k on the other), his argument stops making as much sense. Why put a tube with a perfect balance in transconductance, voltage gain and output current into a circuit that's just going to unbalance it again? There must be something else going on here. Then after reading this article, which explains the how and why of a phase inverter circuit, Myles Rose's argument falls apart, IMO.

Now, I don't think that balance in a phase inverter circuit is a bad thing, far from it. However, I don't think it's something to fret over to the point of paying premium for those rare perfectly balanced tubes. If the PI tube has one side nearly dead that isn't driving the tubes and the other side is near full power, than yeah, you'll have problems. If both sections are relatively close to another, then I don't think one needs to worry.