Tube Amp Archive

Yeah, the box to the Groove Tube 12AX7-M says made in China, and copyright Fender Musical Instruments. I really wanted to like it but found it a bit too aggressive for me.

Haha! If only I'd been that poetic in my descriptions! Matt - Ah, I didn't know that about the lower Ra of the 5751, I generally always thought it was just lower gain. Funny how preconceptions play with your head, I was all prepared to not like the 5751 I think because I'd read somewhere on a forum ...

Here’s a comparison I’ve just done of various new production 12AX7 valves in a Fender Twin. I thought I’d share my results incase anyone else was interested. The amp is a Twin Reverb Reissue with Celestion G12-65 creamback speakers and has all the stock Sovtek valves. I was plugging into the Vibrato...

So I got a balanced GE valve delivered today and took your advice Matt, just played them and compared it to the Mullards I have, and I seem to slightly prefer the sound of the Mullard... When it's being driven the Mullard just seems to be a little smoother and warmer, the GE still sounds really good...

Yeah however much I like a good ol' sine wave, I'll use a load box. A few questions; What volume should I run the amp at? Half way? The volume I normally like to play at? Secondly, Matt, if I measure it the way you describe then I'll be measuring the 'AC signal swing'. Is this measuring the voltage ...

Ok, thanks everyone! I'm going to have a good think about this and when I feel totally confident I can do it without turning myself into fried chicken, I'll do it. It may be a weekend job so that I can really take my time and make notes like you say Matt.

I'll let you know how it goes

Ah so that's why people say it's good to have a balanced phase inverter! I get it. Very well explained Matt, even I understood it! As for working inside valve amps...I'm comfortable with very easy stuff and I know not to go anywhere near the filter caps, I don't go poking around. If it's a case of j...

Yeah okay I'm curious, I have a multimeter and I can use a sine wave sound from my computer.

So I need to measure the AC voltage. Can you tell me where the PI outputs are where I'd need to put the connectors from the multimeter?

Thanks!

Ah ok, this is very helpful, I didn't know that. I think some experimenting is in order!

Do you know why people particularly seem to recommend a balanced valve at the phase inverter position? I've never heard it recommended in any other position...

Many thanks

Hm I don't really know... The dealer I use always seems to state if the valves are balanced, this one wasn't described as balanced, so I'm presuming it's not, I have no way of testing though...

Hm.. Might go for the GE ECC81 then

Thanks

I'm trying to get the best possible sound from my Twin Reverb Reissue, I've replaced the speakers and now I'm going through the valves but I'm not very experienced with different NOS valves. I have a very nice sounding 1965 Mullard ECC81 that I could use as a phase inverter but it's not balanced. Sh...