12ax7/12AT7 Recommendations

[kevinkr]

I'm confused based on multiple comments on this thread about 12AT7 and 12AX7, just because there are 12AT7s installed in the equalizer now does not mean that is the correct tube if ART Audio says it should be 12AX7.. So which is it?

SY is right on the money about those tube comments.. All rubbish..

[jim1961]

Originally Posted by kevinkr

I'm confused based on multiple comments on this thread about 12AT7 and 12AX7, just because there are 12AT7s installed in the equalizer now does not mean that is the correct tube if ART Audio says it should be 12AX7.. So which is it?

SY is right on the money about those tube comments.. All rubbish..

I just sent A.R.T. another email to clarify the issue as to 12ax7 or 12at7. Whats in the unit says 12at7, but their literature says 12ax7a.

[Palustris]

This gets weirder and weirder: the OP stated "I have an A.R.T Dual Tube Parametric EQ that uses 12AX7A tubes"

He somehow confounded the 8752 date code with a 8752 tube number which he believes for some reason is a 12AT7. None of my tube manuals list a 8752 and Fathauer's _Electron Tube Locator_ lists no 8752: there is no such tube!

This guy needs a 12AX7 not a 12AT7; he states it in his original post!

[jim1961]

Originally Posted by Palustris

This gets weirder and weirder: the OP stated "I have an A.R.T Dual Tube Parametric EQ that uses 12AX7A tubes"

He somehow confounded the 8752 date code with a 8752 tube number which he believes for some reason is a 12AT7. None of my tube manuals list a 8752 and Fathauer's _Electron Tube Locator_ lists no 8752: there is no such tube!

This guy needs a 12AX7 not a 12AT7; he states it in his original post!

Here is what the tube says that I pulled out of the unit, line by line exactly:

JAN 12AT7wc
Phillips ECG 8752 aja
34167 usa

I stated, initially i needed a 12ax7a because (before i opened the unit and pulled the tubes) i was going by what the instruction booklet says for the unit, which is:

12ax7a

Yes. The two do not match and I am trying to find out from ART which is right.

I am sorry for the confusion, but with the owners manually specifying 12ax7a, I expected to find a 12ax7a inside. I didnt, I found a 12at7 instead.

http://artproaudio.com/files/owners_...dualtubeeq.pdf - This is the manual for the unit.

[jim1961]

I bought the unit used, so its possible the previous owner replaced the original tubes with something else. So its possible that this unit should have 12ax7a tubes, but were replaced with 12at7 tubes. I will update when I hear back from ART

[jim1961]

Even with this issue in doubt, we can continue. Both are readily available. I have emailed Jim McShane and Galen Carol and they both recommended a Mullard CV4024/12AT7 NOS. I assume I can also get this as a 12ax7 if needed.

What do folks here think of this tube?

[rongon]

I think I see what the source of the confusion is. That EQ is a recording effects box.

Is it this piece?:
http://artproaudio.com/files/owners_...dualtubeeq.pdf

If it is, it uses "Hand-selected 12AX7a tubes."

If that's the case, you want to use 12AX7, 12AX7A, 7025, ECC83 or maybe even 5751. But using 12AT7 would be a "mod" - and would certainly not help make it any more "hi-fi."

--

[jim1961]

Originally Posted by rongon

I think I see what the source of the confusion is. That EQ is a recording effects box.

Is it this piece?:
http://artproaudio.com/files/owners_...dualtubeeq.pdf

If it is, it uses "Hand-selected 12AX7a tubes."

If that's the case, you want to use 12AX7, 12AX7A, 7025, ECC83 or maybe even 5751. But using 12AT7 would be a "mod" - and would certainly not help make it any more "hi-fi."

--

Yup. Same as the link I posted above. I am only trying to put into it what its designed to use. I already know what the manual says. But thats not what I found in it when I opened it up.

[tinitus]

and you dont know what else may have been changed
it may be 'readjusted' to the 12AT7
who knows

I think the recomended Mullard may be a special long plate
maybe its low microphonic, or something ?

[jim1961]

Originally Posted by tinitus

and you dont know what else may have been changed
it may be 'readjusted' to the 12AT7
who knows

I think the recomended Mullard may be a special long plate
maybe its low microphonic, or something ?

It sounded fine with the Phillips JAN 12at7wj. If it was modifiied, I see nothing on the circuit board (like messy solder points) that might suggest it.

Ive owned this unit 4 years, and having bought it used, no telling how much time was on the tubes before I had it. So I felt it was time to replace them. And lets upgrade to better tubes while im at it.

For clarity, I AM trying to improve the sound, but not through changing the 12xx type, but rather by an improved version of what the unit is suppose to have.

I have found the very tubes I pulled out of it for about $14 a piece. I will go up $40 a piece. Surely I can better the performance for this much?