# The difference tubes make is HUGE! - NOS 12AX7 reviews contained



## Beano Addict (Jun 26, 2013)

Brought my 1964 Marshall JTM45 replica I posted about in the following thread to one of my friend's house. NAD : 1964 Marshall JTM45 replica! Best one you've ever seen! (pic-heavy)

The amp started with a couple of Shuguangs in the power section with a current production Tungsol in V2 and a TheTubeStore 7025 in V3.

My friend has in his possession a few boxes of NOS and ANOS preamp tubes which we experimented quite a bit with. The power amp tubes were easy. He had 2 pairs of GEC KT66s ; one with the grey glass (50s) and another with clear glass which the date codes indicated they were from 1963. Unfortunately, the latter pair tested way too far from each other ; 11mA, to be exact. So I passed on those and got the grey glass ones which seem to be more sought after and tested with 3 to 4mA so much more acceptable. Biased at 36mA. Honestly, after hearing those, the Shuguangs won't ever be in my amp! GEC or bust! I've read dozens of time about the figurative wet blanket being lifted from the amp and although it's cliché to say this, nothing could be a better analogy than that. Fortunately, my friend gave me a good price on those.

It was quite surprising to hear just how much of a difference the preamp tubes were making in V1 alone. Really, really surprising! Unfortunately, we didn't have the luxury of time, so we had to stop after a short while. Otherwise, we could've continued for hours and hours. Here's a quick summary of my findings. 


*Short plate Blackburn Mullard* *(short plate) *: pulled from my SuperLead. It sounded harmonically congested, polite, and quite smooth. Laidback presentation.

*Tokyo Shibaura (Toshiba)* : My friend's go-to 12AX7 for testing amps. Wow! Incredibly creamy midrange, dripping with vintage vibe, like you're listening to old records... in a good way!
*RCA grey long-plate* : WOW!!! The amp sounded full, larger-than-life, had an addicting 3D sound that fills the room beautifully. Harmonically complex midrange. Always heard of those for Fender amps but in this JTM45, it was a match made in heaven.
*Tungsram* : My friend hyped this one but even he was quite underwhelmed with how it performed. Hairy, and forward-sounding in an abrasive way, this one didn't last long.
*RFT* : smokey in a good way, but was rather bass-shy. Of course, one can crank the bass, especially on a bass circuit like a JTM45 but I did not purely for benchmarking purposes. Good option for taming a bass-heavy amp and giving it a nudge in a vintage direction.
*Amperex* : clean, very good-sounding tube, single-line runs sounded very good. If I hadn't heard the RCA, I might've gone for this one but it lacks the richness and complexity of the RCA, IMHO.
*Unnamed Japanese tube* : I forget which brand this one was. Very forward presentation, it was a run-of-the-mill tube, nothing special. Adequate, but there's so much better out there.

We even tested some in V2 and noticed a subtle difference in presentation. Surprisingly, my current production Tungsol which I had pulled from my SL ended up among the favorites, but ultimately, I went with another ANOS tube. Can't even remember which one right now as I'm running on very little sleep. I can update the thread once I get back home. Don't think it's a mystery which tube I got for V1. The RCA, baby! Honestly, that thing sounded so good, huge, and rich, I'm thinking of trying it in my SL for kicks. I'll experiment once I have some free time.

Oh, and I'll also be purchasing a Toshiba tube on my own since my friend wasn't too keen on selling that particular one. They're relatively cheap as the prices seem to hover around the $40 mark. Not bad. I'll buy one if only to change things up, once in a while. It's a surprisingly great tube.


----------



## zdogma (Mar 21, 2006)

OMG...


----------



## zdogma (Mar 21, 2006)

Maybe we can keep it civilized this time....

I'll start. 

I find there is some difference in noise/gain/output between various tubes types, but the differences for me are a bit more subtle. The reliability of many NOS tubes is better as well, I have some NOS Siemens 6681 (mil spec 12ax7's) that have been totally bombproof for me, I've run them problem free for over 10 years and they still sound great. I find the Sovtek 12AX7's WA/WB are a bit noisier than some. I find the shiny plate chinese tubes have a bit higher gain etc. Most of the NOS tubes sound pretty good to me as long as they work.


----------



## Beano Addict (Jun 26, 2013)

zdogma said:


> I find there is some difference in noise/gain/output between various tubes types, but the differences for me are a bit more subtle. The reliability of many NOS tubes is better as well, I have some NOS Siemens 6681 (mil spec 12ax7's) that have been totally bombproof for me, I've run them problem free for over 10 years and they still sound great. I find the Sovtek 12AX7's WA/WB are a bit noisier than some. I find the shiny plate chinese tubes have a bit higher gain etc. Most of the NOS tubes sound pretty good to me as long as they work.


The differences were as subtle as a sledgehammer. The amps were not being played at volume 1 either.

My NOS tube love started with Fender amps. Thought I'd see what some people raved about. I was lucky to take heed in the advice posted by Mike from KCA and my Super Reverb sounded much deeper and lush than with the JJs that were in there. 

Fender Amp Preamp Tube Layout and recommendations | KCA NOS Tubes & Amplifier Repair

If I had landed on some run-of-the-mill nothing-special tubes, I probably would scoff at the idea of NOS tubes as well. But thankfully, that was not the case.


----------



## GTmaker (Apr 24, 2006)

I really like the effect of a 5751 tube in the V1 position...
As for different brands, as long as the tube has good life left, I have never noticed a difference.

I recently put an old set of Mesa EL84's in my Blues Junior and they sound as good as the newer tubes.

that's all I have to say about that.
G.


----------



## Beano Addict (Jun 26, 2013)

GTmaker said:


> I really like the effect of a 5751 tube in the V1 position...
> As for different brands, as long as the tube has good life left, I have never noticed a difference.
> 
> I recently put an old set of Mesa EL84's in my Blues Junior and they sound as good as the newer tubes.
> ...


That's because Mesa tubes are rebranded tubes, just like Groove Tubes'. Most of the time, they're Sovteks but occasionally, they're other brands. 

I'm talking about real NOS tubes. Current production tubes leave me cold. They sound sterile. Never thought I'd think that way but the difference is staggering. Trust me, I'd MUCH prefer keeping my money for other things but the difference was undeniable to me... unfortunately.


----------



## Budda (May 29, 2007)

I've never experienced NOS tube fan-dom from trying an amp.

I had a vintage fender for a few months, and I liked how it sounded. That said, I had no other vintage fender stuff to compare it to, I just know I liked the tone of the amp.

I went with a good set of tubes from the tube store for my JCM800 2203, because I wanted reliability in tone. Roughly two years later and I still have both those things. I'd retube the power section but it doesn't sound like it's going. I push it - it's never below 7 on the master.


----------



## jbealsmusic (Feb 12, 2014)

Interesting. This is one of those times I wish there was some objective data to look at. Or, at the very least, recordings of each one using the same input and signal chain so we can listen for the differences.


----------



## WCGill (Mar 27, 2009)

Have someone put the tube in and then listen without knowing what it is. It might be a little harder and you might be surprised. In amps with negative feedback, such as the JTM 45, differences may not be very noticeable. That's why the AC30 is a better choice, or the Marshall 18, to give two examples of amps with no feedback.


----------



## dtsaudio (Apr 15, 2009)

Unfortunately there is very little empirical data on the sound of tubes. I suppose you could put each tube on a curve tracer and test them, but it still wouldn’t totally explain things. 
I have many customers who swear by NOS tubes and just as many who don't care. Hearing is a personal thing, and if you can tell the difference, more power to you.
Personally, i may hear a difference 10 - 20% of the time and it is equipment dependent. My problem with NOS is reliability and quality. I see too many people spend large money on what are garbage tubes just because they're vintage.


----------



## High/Deaf (Aug 19, 2009)

I think if you are running the tubes, either pre or power, in their linear region, you would be hard pressed to hear the difference. That was true with hi-fi equipment and their owners many years ago. Everyone was aiming for and getting very close to transparent reproduction, no tone imprint on any of them, per se.

But running them non-linear, sure, they may have their own sound. But that is a very 'guitar' thing to do.


----------



## WCGill (Mar 27, 2009)

Randall Aiken tested some EL84's some years ago with a curve tracer and found 4db frequency response differences between a few different brands. I would think 4db would be audible. No feedback of course.


----------



## jb welder (Sep 14, 2010)

Agree with those above who hinted that a double blind set-up would be much more appealing.
And this may just be me, but I prefer more quantitative rather than qualitative descriptions of tone. We're not trying to figure out which ones we want to eat. 
Not trying to be critical, I'm not a big fan of modern production tubes either. And even less a fan of the hype/marketing.


----------



## Beano Addict (Jun 26, 2013)

Kind of strange to read these comments. Have to wonder if there's even a tiny bit of "too cool for school" type of mentality buried in there.

I personally wish I didn't hear a difference or such a trivial one that I could scoff at the notion of NOS tubes for the sake of being able to use my money on any number of other things but the reality is that there is a gigantic difference that I hear going from one tube to another.

The amp was turned to 6. The characteristics of the amp changed drastically in a matter of seconds by switching from one tube to another. VERY surprising to see the reaction here considering the subtlety we experienced was as delicate as a sledgehammer. Wish I could trade with some of you guys. My wallet would thank you!


----------



## Lincoln (Jun 2, 2008)

How exacting was/is tube manufacturing? Are there variables during assembly that would affect frequency response? Would all NOS GE tubes measure exactly the same? Do All modern JJ's measure exactly the same? Are the differences being heard the difference of one tube in a bad batch being compared to a good tube from another batch?


----------



## Beano Addict (Jun 26, 2013)

Lincoln said:


> How exacting was/is tube manufacturing? Are there variables during assembly that would affect frequency response? Would all NOS GE tubes measure exactly the same? Do All modern JJ's measure exactly the same? Are the differences being heard the difference of one tube in a bad batch being compared to a good tube from another batch?


Good questions. I'd have to think military-grade tubes would have a much stricter manufacturing guidelines and quality control, therefore limiting the change from tube to tube of the same model. But that's purely a hypothesis on my part. It would be an interesting study for sure.

To me, it's really (and I mean REALLY) puzzling to see the lovefest for JJs everywhere on the web. I've never heard a single one that didn't sound congested or sterile. Tried them in Fenders. Tried them in Marshalls. Always sounds boring and plain cold to me. Yet, lots of people seem to love them. Maybe they're reliable and as such wouldn't be a bad choice for a tube inverter but as a V1 tube? No way!


----------



## zdogma (Mar 21, 2006)

Strat-Mangler said:


> Kind of strange to read these comments. Have to wonder if there's even a tiny bit of "too cool for school" type of mentality buried in there.
> 
> I personally wish I didn't hear a difference or such a trivial one that I could scoff at the notion of NOS tubes for the sake of being able to use my money on any number of other things but the reality is that there is a gigantic difference that I hear going from one tube to another.
> 
> The amp was turned to 6. The characteristics of the amp changed drastically in a matter of seconds by switching from one tube to another. VERY surprising to see the reaction here considering the subtlety we experienced was as delicate as a sledgehammer. Wish I could trade with some of you guys. My wallet would thank you!


No, just experience I think. I've used (probably) hundreds of different 12AX7/ECC83 preamp tubes over the 30 years of playing, in various good quality amps (old marshalls, fenders, various boutique stuff). I probably have at least 15 types of NOS 12AX7's in my tube box ATM. There are differences, agreed, but there are so many other variables that occur between the guitar input and a band mix that the differences dilute to minimally perceptible. In a quiet room, with a simple amp I think there are differences, put em in a mix, not so much. I like tubes that are durable and non microphonic. I tend to use NOS because that's what I have but I have no issues with MOST new production tubes. I've used the new tung sol tubes with no issues in a couple of loud combo amps where the longer plates on some of my NOS 12AX7 were horribly microphonic. I liked them, they sounded just fine to me.


----------



## zdogma (Mar 21, 2006)

Strat-Mangler said:


> Good questions. I'd have to think military-grade tubes would have a much stricter manufacturing guidelines and quality control, therefore limiting the change from tube to tube of the same model. But that's purely a hypothesis on my part. It would be an interesting study for sure.
> 
> To me, it's really (and I mean REALLY) puzzling to see the lovefest for JJs everywhere on the web. I've never heard a single one that didn't sound congested or sterile. Tried them in Fenders. Tried them in Marshalls. Always sounds boring and plain cold to me. Yet, lots of people seem to love them. Maybe they're reliable and as such wouldn't be a bad choice for a tube inverter but as a V1 tube? No way!


Yeah, the JJ's haven't been my favourite either. I've had more dud, microphonic, red plating tubes (especially EL84's) with JJ's than any of the other manufacturers.


----------



## Beano Addict (Jun 26, 2013)

zdogma said:


> Yeah, the JJ's haven't been my favourite either. I've had more dud, microphonic, red plating tubes (especially EL84's) with JJ's than any of the other manufacturers.


I was specifically referring to their sound but I'm sorry you had bad experiences with them even performing their rudimentary duties.


----------



## High/Deaf (Aug 19, 2009)

WCGill said:


> Randall Aiken tested some EL84's some years ago with a curve tracer and found 4db frequency response differences between a few different brands. I would think 4db would be audible. No feedback of course.


I wonder if that means a +\- 2 dB freq response in the hearing spectrum compared to flat. That's a massive inaccuracy for electronics and more in the realm of what someone would expect a speaker FR to look like. I would not use any piece of reproduction electronics, either hi-fi or SR, that was that wonky.

If he means a gain difference of 4dB from one set to another, that too would be surprising as I assume most of the gain parameters are set by circuit and not the device. This was done on purpose by the manufacturers so changing tubes wouldn't produce a significant difference in sound in what should be a flat reproduction system, irrelevant of the components regularly replaced for maintenance.

Guitar amps are a different beast though. They are production and not reproduction equipment - so the way they use tubes is different. Reproduction equipment is never designed to run well into distortion.


----------



## WCGill (Mar 27, 2009)

4 db 2nd harmonic it was.

JJ_EH_tube_tests


----------



## dtsaudio (Apr 15, 2009)

Lincoln said:


> How exacting was/is tube manufacturing? Are there variables during assembly that would affect frequency response? Would all NOS GE tubes measure exactly the same? Do All modern JJ's measure exactly the same? Are the differences being heard the difference of one tube in a bad batch being compared to a good tube from another batch?


 When you consider the manufacturing techniques from the 50's and 60's and the measuring techniques, 20% tolerance was the norm. A lot depended on who was on a certain step in the process and when. Just like the old saying when buying a car from that era - don't buy one made on a Friday or Monday. 
There is also materials and their tolerances as well. So things could potentially vary quite a bit. Tubes are very tolerant of the differences and will work in the majority of instances even if badly out of spec (not well but will work).
Step into the 21st century and you have automated QC, tighter tolerance on materials, and probably newer or at least re-furbished equipment to make the tubes. What you DON'T have is the expertise, and experience of what were in essence craftsmen who made the tubes in the early days. You also don't have the quantities or in some tubes the military standards, so tolerances haven't made any real progress and are still probably 20%.
What I'm getting at, is that it is possible to get good and bad from either NOS or new manufacture that may be in tolerance but at different ends of the spectrum and sound quite a bit different. I come across this on a weekly basis.
Just so you know where I'm coming from, I am on the fence about this topic. I can't afford NOS and don't have the time to look for good ones, so I buy and recommend to my customers new manufacture unless I can get NOS from a *reputable *supplier without selling my first born. It's less of a hassle for everybody. But if you like NOS and can hear the difference, go for it. Just make sure you know who you are buying from. Lots of crap out there.


----------



## High/Deaf (Aug 19, 2009)

WCGill said:


> 4 db 2nd harmonic it was.
> 
> JJ_EH_tube_tests


That makes sense. Second harmonic indicates they're being driven to clipping. The testing methodology confirms this:

"The phase inverter was designed around a 12AX7 stage to provide the proper drive levels for the EL84 tubes, allowing them to be driven to fully clipped levels before the phase inverter itself exhibited noticeable clipping."

In linear mode, I think it would be hard to hear much difference.


----------



## WCGill (Mar 27, 2009)

dtsaudio said:


> When you consider the manufacturing techniques from the 50's and 60's and the measuring techniques, 20% tolerance was the norm. A lot depended on who was on a certain step in the process and when. Just like the old saying when buying a car from that era - don't buy one made on a Friday or Monday.
> There is also materials and their tolerances as well. So things could potentially vary quite a bit. Tubes are very tolerant of the differences and will work in the majority of instances even if badly out of spec (not well but will work).
> Step into the 21st century and you have automated QC, tighter tolerance on materials, and probably newer or at least re-furbished equipment to make the tubes. What you DON'T have is the expertise, and experience of what were in essence craftsmen who made the tubes in the early days. You also don't have the quantities or in some tubes the military standards, so tolerances haven't made any real progress and are still probably 20%.
> What I'm getting at, is that it is possible to get good and bad from either NOS or new manufacture that may be in tolerance but at different ends of the spectrum and sound quite a bit different. I come across this on a weekly basis.
> Just so you know where I'm coming from, I am on the fence about this topic. I can't afford NOS and don't have the time to look for good ones, so I buy and recommend to my customers new manufacture unless I can get NOS from a *reputable *supplier without selling my first born. It's less of a hassle for everybody. But if you like NOS and can hear the difference, go for it. Just make sure you know who you are buying from. Lots of crap out there.


Yeah I don't put NOS in my amps either, just too hard to get replacements. The stereo mono blocks I recently built were a different story, all triode and new production doesn't exist. As well I used two of my remaining NOS GZ34's. They'll *never* need replacing. I do like a NOS Mullard in V1 of my VOX builds. They're the shit.


----------

