Modern Day 12AX7s

[ItsaBass]

Re: Modern Day 12AX7s

i dunno....ive been using an aT7 as the first tube in my twin for about a week now. It sounds pretty good and makes the volume knob a lot more manageable.

Anyway back to ax7s:
tung sols if you want clarity
jjs for fat bottom and smooth top
EH are good all rounders with a nice mid chunk.

Or possibly some combo? E.g. a JJ in the first slot and an EHX in the second to give combined characteristics?

What effect does a 12AT7 in the phase inverter slot have vs. 12AX7?

 

[Jolly_Rancher]

Re: Modern Day 12AX7s

Myles Rose posted some data on a batch of new Tung Sol X7's and they seem to be the most consistent new production X7's.

 

[IanBallard]

Re: Modern Day 12AX7s

I like Tung-Sols as a tone-generator, but they are kind of wimpy for PI usage. I use JJ's for V2, V3 or PI... it fills out the tone nicely but can be a little dark in the main driver stage. They are VERY reliable though. I also like Electro-Harmonix tubes a lot. Currently, I have an Tung-Sol in V1, an EH in V2 and JJ's in the last two slots. I also like Groove Tube Chinese AX7's. The GT Russians are a bit harsh, imho.

Honestly, I've had bad luck with old, vintage ECC83/AX7's... microphonic problems. Maybe they just weren't stored well.

 

[That90'sGuy]

Re: Modern Day 12AX7s

Over the years, I've come to rely on EH 12ax7s. They've sounded better than JJ's in every single amp I've used them in, but I am a fan of mids, so the darker and smoother sound of JJs just aren't my personal thing. Bogner designed most of his amps around chinese tubes and I do like the Shuguang stuff in my Shiva, but in my Vox the EH stuff just sounds right. I can't say I've ever tried the Tung Sol, but it sounds like it's a fine tube.

 

[the guy who invented fire]

Re: Modern Day 12AX7s

If memory is right?

12AX7 Gain factor of 100
12AT7 Gain Factor of 70

Yep.

 

[Jolly_Rancher]

Re: Modern Day 12AX7s

BUT, the trans-conductance and current draw are WAY different between the X7 and T7. So, they are not exactly interchangeable.

 

[STRATDELUXER97]

Re: Modern Day 12AX7s

Yep.

More useless knowledge right? ;o)

 

[jeremy]

Re: Modern Day 12AX7s

the 12at7 is different than a 12ax7 in a bunch of ways besides agin. im too deep in 17 year old scotch to out it together right now but if you want he same agin as a 12at7 but with the right 12ax7 stuff get a 5751. very similar to a 12ax7 but with less gain

 

[STRATDELUXER97]

Re: Modern Day 12AX7s

the 12at7 is different than a 12ax7 in a bunch of ways besides agin. im too deep in 17 year old scotch to out it together right now but if you want he same agin as a 12at7 but with the right 12ax7 stuff get a 5751. very similar to a 12ax7 but with less gain

Yes the 5751 SRV tube....Forgot about that one..

 

[Rick330man]

Re: Modern Day 12AX7s

Tonally, I like the Sovtek 12AX7LPS quite a bit. However, I just had one die on me: gas leak/white frosting.

The new TS 12AX7 sounds decent, but doesn't blow me away.

The best current production tubes to my ears are still the Shuguang manufactured 12AX7s. They sound pretty close to NOS and reliability has been very good. I've had several come stock in amps and I ordered a batch of 25 from Doug's tubes. Very happy with them.

EH 12AX7 - reliable but too thin and shrill. Great PI tube.

JJ - tames the highs in a trebly or shrill amp, but lacking in detail. Terrible phase inverter, where it does something that ends up dulling the sound. Myles Rose had written about this. I know exactly what he is talking about because I have heard it in my own amps.

 

[Soulcrusher_X]

Re: Modern Day 12AX7s

I always use a tung sol in v 1. They have a nice crunch and sparkle, but I usually use JJs or Penta C9s in the rest of the gain spots to fatten the tone. Too many TS can be shrill. The Penta Shuguangs are real nice too. Warmer than regular chinese tubes but still have all the grind. I usually use long plate tubes in the PI, the JJ ecc803 being my favorite and the Mullard RI being a close second.

 

[STRATDELUXER97]

Re: Modern Day 12AX7s

Great info from you all...

 

[Chickenwings]

Re: Modern Day 12AX7s

Or possibly some combo? E.g. a JJ in the first slot and an EHX in the second to give combined characteristics?

What effect does a 12AT7 in the phase inverter slot have vs. 12AX7?

aHA! I can actually answer this one!
12aT7s can handle roughly 10 times the plate voltage of an ax7. The PI is actually the hardest working tube in your amp. Often, when people think they are hearing power tube saturation, it is very often the PI on the redline.
You can swap out your PI in a lot of fender amps for an ax7 for a little more of that warm compressed feeling, but they dont last too long! Its a pretty godawful noise when things go pear shaped too! ....at least thats what ive found! lol. Some amps (musicmans in particular) can totally drop their bundle if the PI tube fails, so if you are gonna go swapping things, make sure you know the risks.
here's a cool link to read:
http://www.guitaramplifierblueprinting.com/files/Phaseinverter.pdf

As far as swapping brands goes (like jjs in v1 then ehs later) yeh its all good. Ive been doing it for years. I like EHs because they are low noise and reliable, but i like the tone of jjs so actually i usually have a jj in v1 or 2 then eh in the rest of the slots. I generally have jjs in the power section in all my amps whether it be 6L6, 6v6 or EL34 or 84. Tung sols are great in a dark amp and jjs are great for more bottom.
V1 is usually the biggest determinant of your basic tone shaping as far as preamp tubes go, the rest often do other jobs like amplifying the reverb or doing PI duties etc.

 

[USAPatriot]

Re: Modern Day 12AX7s

Okay if a 12AU7 is acting as a phase inverter - I had to look all of this up and yes, my amp is a push-pull - does it in effect halve the wattage assuming I balance the difference out in biasing the power stage? I ask because we got burned out of our house in August and are temporarily in an apartment where even 40 watts is too much. It'd be desirable to be able to max my master volume, keep my tone and hopefully have managable overall volume.

(been trying to trade a Line 6 Spider IV 150w for an HT-5 stack on craigslist but so far no takers.) Thanks. -Rod-

 

[TwilightOdyssey]

Re: Modern Day 12AX7s

Some interesting stuff in this thread.

I have a mess of OS 12AX7s and 5751s --

My go-to for modern 12AX7s is the JJ ECC803S; it is slightly less gainy than the 83S and modeled after the Telefunken valve of the same name.

If you have a single channel amp and are pushing it into power-valve distortion, a 5751 in the V1 slot will help keep things from getting totally out of control, gain-wise, especially if you are using pedals in front of your amp. Otherwise, I find that some circuits get waaay too bright/brittle/hard when using a 5751 in V1.

For old stock 12AX7s, I like black-label Mullards, Toshiba, and Siemens ...

 

[the guy who invented fire]

Re: Modern Day 12AX7s

The 5751 is a GREAT tube if you want to keep it cleaner...same basic tone as a 12AX7 (which is 12AT7 isn't!) and a gain factor of 80 so still more than a T7 but still way less than an X7

 

[glassman]

Re: Modern Day 12AX7s

Hey John! Good thread topic! I can't really give an opinion based on tone as much as I can on reliability though...almost all of my clients are gigging players so my opinion is based on what lives and what dies unexpectedly.

I don't sell a lot of tubes; I do replace a lot of failed tubes though. Most guys buy their stuff on the internet anymore. I stock the Chinese 5th generation and 7th generation 12AX7s and the JJ 12AX7s...and that's it. I have too many instances of EH, TungSol reissue and Sovtek LPS failures to really recommend them IN A PERFORMANCE SITUATION. That goes for all of their 12**7 type tubes. They are great sounding tubes though.

As an example, on of my regulars brought in his SVT a month or so ago. He had bought a sextet of 6550s and two EH 12AU7s on line...he wanted me to check the amp out and put the tubes in and bias them. They were the opening band for Five Finger Death Punch and want to be certain his stuff was solid. I voiced concerns about the EH 12AU7s but he was assured from the place he bought them that they were solid (reputable online seller). Fast forward to last week...he calls me from ??? and tells me his SVT died. Three of the 6550s redplated and ran away on him. He replaced them with his spare set and they did the same thing. I reminded him of my concerns about the EH 12AU7s...in an SVT, the bias adjustment controls the 12AU7 which sets the bias. If a 12AU7 dies, the amp fries. Luckily he had the old ones (which were still good and road tested) with him. He put them in (old Chinese 12AU7s) and it biased up good. That's just a worst case scenario.

Preamp and PI tube failures typically are an inconvenience at most but nobody wants to break down in the middle of a set. That's why I put in what I put in...I don't need bad press because a tube failed unexpectedly.

Sorry about the rant and my comments should only be taken in context and not as a condemnation of any particular tube.

 

[STRATDELUXER97]

Re: Modern Day 12AX7s

Hey John! Good thread topic! I can't really give an opinion based on tone as much as I can on reliability though...almost all of my clients are gigging players so my opinion is based on what lives and what dies unexpectedly.

I don't sell a lot of tubes; I do replace a lot of failed tubes though. Most guys buy their stuff on the internet anymore. I stock the Chinese 5th generation and 7th generation 12AX7s and the JJ 12AX7s...and that's it. I have too many instances of EH, TungSol reissue and Sovtek LPS failures to really recommend them IN A PERFORMANCE SITUATION. That goes for all of their 12**7 type tubes. They are great sounding tubes though.

As an example, on of my regulars brought in his SVT a month or so ago. He had bought a sextet of 6550s and two EH 12AU7s on line...he wanted me to check the amp out and put the tubes in and bias them. They were the opening band for Five Finger Death Punch and want to be certain his stuff was solid. I voiced concerns about the EH 12AU7s but he was assured from the place he bought them that they were solid (reputable online seller). Fast forward to last week...he calls me from ??? and tells me his SVT died. Three of the 6550s redplated and ran away on him. He replaced them with his spare set and they did the same thing. I reminded him of my concerns about the EH 12AU7s...in an SVT, the bias adjustment controls the 12AU7 which sets the bias. If a 12AU7 dies, the amp fries. Luckily he had the old ones (which were still good and road tested) with him. He put them in (old Chinese 12AU7s) and it biased up good. That's just a worst case scenario.

Preamp and PI tube failures typically are an inconvenience at most but nobody wants to break down in the middle of a set. That's why I put in what I put in...I don't need bad press because a tube failed unexpectedly.

Sorry about the rant and my comments should only be taken in context and not as a condemnation of any particular tube.

And an excellent reply from you also buddy! I still have quite a few really good RCA and other 12AX7s but they aren't going to last me forever...Thought I'd try some newer tubes...Memory tells me I tryed the new Tung sols in my Pro Reverb amp..I Liked it but gave the tube to my buddy and he stuck it into his amp...In an early Fender the RCAs are pretty hard to beat...In my Marshall I have an original Mullard in V1 and I think a GT 12AX7M in V2? For the PI I just use a strong and reliable x7 there..Not sure whats in there right now(Maybe a 12AXLPS)?

 

[PRSfan nym 1985]

Re: Modern Day 12AX7s

Okay if a 12AU7 is acting as a phase inverter - I had to look all of this up and yes, my amp is a push-pull - does it in effect halve the wattage assuming I balance the difference out in biasing the power stage? I ask because we got burned out of our house in August and are temporarily in an apartment where even 40 watts is too much. It'd be desirable to be able to max my master volume, keep my tone and hopefully have managable overall volume.

(been trying to trade a Line 6 Spider IV 150w for an HT-5 stack on craigslist but so far no takers.) Thanks. -Rod-

imho no tube swap is going to make that amp more desireable for apartment playing. Swapping the PI isn't going to change the ouput level of your power tubes. I use a Vox AC4tv mini and that amp can be too much in an apartment. I've also tried Epi Valve Jr, Blackstar HT5, Blackstar HT1, Fender Champion 600, Fender Pro Jr, etc.

Problem is any tube amp (or even SS amp) will be loud it really doesn't take much to penetrate paper thin walls with hardly any insulation maybe YMMV but I doubt it.

A lot of those low watt amps I pointed out can actually handle gigging with bass, drums, etc. The only thing you won't get out of a 5 watt or less amp is clean headroom (ie a good clean tone that will cut over the drummer). The difference between a cranked 5 watt and a 40 watt amp really isn't as pronounced as one would think a lot of it is just giving you more clean headroom.

I would say your best bet for an apartment would be trying an attenuator, but I don't get the same sound out of those again YMMV. To be honest with you my favorite apartment amps to date are probably my Fender Mustang I and my Vox Pathfinder 15, both are excellent sounding SS amps.

For an apartment you really just want to make sure you get the smallest speaker possible (6-8" is ideal) and a master volume. 10's and 12's seem to project too much of everything and they usually run more efficiently which makes them seem louder.

 

[Soulcrusher_X]

Re: Modern Day 12AX7s

Hey John! Good thread topic! I can't really give an opinion based on tone as much as I can on reliability though...almost all of my clients are gigging players so my opinion is based on what lives and what dies unexpectedly.

I don't sell a lot of tubes; I do replace a lot of failed tubes though. Most guys buy their stuff on the internet anymore. I stock the Chinese 5th generation and 7th generation 12AX7s and the JJ 12AX7s...and that's it. I have too many instances of EH, TungSol reissue and Sovtek LPS failures to really recommend them IN A PERFORMANCE SITUATION. That goes for all of their 12**7 type tubes. They are great sounding tubes though.

As an example, on of my regulars brought in his SVT a month or so ago. He had bought a sextet of 6550s and two EH 12AU7s on line...he wanted me to check the amp out and put the tubes in and bias them. They were the opening band for Five Finger Death Punch and want to be certain his stuff was solid. I voiced concerns about the EH 12AU7s but he was assured from the place he bought them that they were solid (reputable online seller). Fast forward to last week...he calls me from ??? and tells me his SVT died. Three of the 6550s redplated and ran away on him. He replaced them with his spare set and they did the same thing. I reminded him of my concerns about the EH 12AU7s...in an SVT, the bias adjustment controls the 12AU7 which sets the bias. If a 12AU7 dies, the amp fries. Luckily he had the old ones (which were still good and road tested) with him. He put them in (old Chinese 12AU7s) and it biased up good. That's just a worst case scenario.

Preamp and PI tube failures typically are an inconvenience at most but nobody wants to break down in the middle of a set. That's why I put in what I put in...I don't need bad press because a tube failed unexpectedly.

Sorry about the rant and my comments should only be taken in context and not as a condemnation of any particular tube.

I havent had any TungSol tubes fail, but a good deal of them have become very noisy. I usually take them out soon after they do so. Maybe Ive avoided failures that way. I HAVE had a few EHX failures and an LPS go south. The JJs and Chinese tubes have always lasted. I dont think Ive ever changed one out due to failure.

I personally think that the ehx and ts tubes are great for high gain rhythms, but the JJs are better for creamy leads. The chinese tubes arevthe best combination of grind and leads. I just wish the chinese power tubes last longer. I really like the Ruby 6L6MSTR Chinese tube, but they dont seem to last as long as most other tubes.