RCA 12AX7

[Tmuggie]

I bought an RCA 12AX7 today from a guy that works on old radios. He said it tested at 130%, whatever that means. Are these good for a guitar amplifier?I have read some pretty positive things about them but not exactly sure which one I have. The writing is pretty faded. Most I can make out on it is RCA. Seems like I read on here somewhere that you could spray wd-40 on on old tube and make out some of the faded writing. Is that true? I don't want to risk taking anymore of it off.
Also, where would be the best place to put that tube? I have a f-100 combo.
V1 or V4.... Or which ever one is the phase inverter.

 

[MrMarkIII]

WD-40? Bad idea. Use it for door hinges and that's about it. It's bad news for electronics and guitars. Try to not even touch any lettering in any way, it only reduces the value. The tube should sound great in V1.
Hiope this helps.

 

[Tmuggie]

Thanks for the tip.

 

[thunda1216]

Put it in V1 and smile, smile, smile. The RCA long plate 7025 tubes are fabulous, as well.

ty

 

[212Mavguy]

+1

 

[Tmuggie]

I am looking forward to trying it. I also bought a couple of jj tubes from him. They are new manufactured I believe. They have short squaty plates in them and the RCA looks long in comparision. I didn't know there were so many differences with tubes. I am now just learning about them and it is pretty fasinating. There is alot to learn though!

 

[Tmuggie]

Here is a link to an article I ran across talking about different brands of 12AX7's. This guy hyped up the RCA so my exspectations are pretty high at this point.

 

[212Mavguy]

I predict that you will find that if your RCA is a strong one with no issues that it will be more likeable to your ears for more tones than the JJ's.

 

[Tmuggie]

Here is the link http://www.tgpwebzine.com/?page_id=83

yeah.... That's kinda what I gathered from this guy talking about the jj's.
I think I paid too much for the jj's too. 18 bucks a piece... And 18 for the RCA .
Did I get fleeced ya think? Maybe the RCA will make up for it.
I can see that this could turn into a expensive operation.

 

[MrMarkIII]

I've paid $30 for Mullards, so... $18 for an RCA blackplate ain't too bad.
I don't know if an AC-30 is the best amp for a tube shoot-out, but I always enjoy any tube trial/test/shootout. The guy doesn't seem to dig that a 5751 is lower gain than a 12AX7, though.

 

[MusicManJP6]

The RCA AX7 is a GREAT tube. I had one or two a while ago. Made a noteable difference in my Rectoverb combo in V1 and also in PI slot.

 

[elvis]

As I understand it, long plates are more prone to microphonics or noise than short plates. Is this:

A. True?
B. An issue for high gain amps?

I'd be looking for something for V1 of a studio pre that I run with high gain.

 

[MusicManJP6]

As I understand it, long plates are more prone to microphonics or noise than short plates. Is this:

A. True?
B. An issue for high gain amps?

I'd be looking for something for V1 of a studio pre that I run with high gain.

My understanding is that this is more true in combo amps than head amps due to additional vibrations.

 

[212Mavguy]

Yep, it's a tendency, not an absolute, though...

 

[Tmuggie]

Well, I put the RCA in an initially was very excited, I had it on the overdrive channel and it sounds awsome ,I can tell a big difference. It's smoother with more definition, if that makes since... Very impressed......but....
On the clean channel it sounds better too but I had it pretty loud and I am getting ALOT of noise, rattlles and squealing, so I can tell you that the long plates, in this instance, make a big difference. I am looking for a short plate now.

 

[dodger916]

I love the RCAs, but sadly I've had a tough time finding one quiet enough for V1. YMMV. Luckily they're pretty cheap.

 

[Tmuggie]

It does sound really good though if I have it turned down low on the overdrive channel, which is pretty standard for me.