Author Topic: Valve help :o( (Read 6353 times)

chrisola · « **on:** January 02, 2006, 07:41:49 PM »

Hmm

I havent played my Fireball that much the last couple of weeks, with it being Xmas (and before that i was working loads). So i came and turned it on today, and it sounded strange... like some kind of interference\noise on the Gain channel, making the guitar sound weird and distorted\warbly.

I thought it might be my PC\monitor\wireless network so i turned it all off and unplugged it, and tried again... SAME weird sound.... then i clicked onto the normal channel.... and its just squelchy noise!!!

I've never heard something microphonic before, but i'm pretty sure thats whats happened, 1 or more of the valves in the amp has gone i think.

Pretty pissed off, now i got to phone the shop i bought it from (again) and deal with them (eurgh!) and try and get something sorted. Really bad going considering the amp is supposedly new, yet came with the valves in the wrong sockets and they were already looking fairly coloured and used!

Actual question:

I dont really understand what the different valves are...

What does FQ Selected, Standard and Selected mean?? Does it matter if the types are put into the 'wrong' sockets?

In the manual for my amp, it says:

Power Amp: V1 & V2: 6l6GC Matched Set
Pre-Amp: V3 (input tube): ECC83 /12AX7 FQ Selected
V4, V5: ECC83 / 12AX7 Selected
V6: ECC83 / 12AX7 Standard

Would i need to get 4x ECC83's or 4x 12AX7 valves? Or 1 12AX7 for the pre-amp and 3 ECC83's etc? (pretty sure only 1 valve is labelled 12AX7 at the moment, the others have both names on??)

Confused!

Thanks for any advice... :)

Bainzy · « **Reply #1 on:** January 02, 2006, 07:51:56 PM »

ECC83 and 12AX7 means exactly the same thing - just a different name for the same tube.

chrisola · « **Reply #2 on:** January 02, 2006, 08:16:51 PM »

cheers.. how about the FQ Selected, Standard and Selected bits?? :)

HTH AMPS · « **Reply #3 on:** January 02, 2006, 08:17:07 PM »

the 'selected' ECC83/12AX7 valve will be one that has been tested for low noise/microphonics since it's being used for the first gainstage in the amp.

:twisted:

dave_mc · « **Reply #4 on:** January 02, 2006, 08:39:24 PM »

check your pm box, chrisola!

tewboss · « **Reply #5 on:** January 03, 2006, 11:55:50 PM »

I'd suggest that V4 and V5 have to be matched, but it doesn't matter if V6 isn't.

HJM · « **Reply #6 on:** January 04, 2006, 11:02:51 AM »

I guess FQ is better quality...

It's not to much of an issue, if you go to Watford Valves all ECC83 valves come tested.

There's no way to tell if it is the valves without having a spare set to swap in, one by one until the problem goes..! It doesn't sound like a microphonic valve - they whistle and howl in a high pitch feedback kind of sound.

You could just get one new ECC83 and swap the new one in each of the 6 positions, then you should find the faulty valve. If it doesn't cure the problem it could be a fried output valve.

As the problem effects both channels there must be a fault in a part of the circuit that both channels run through, so reverb/fx loop/phase splitter/power valves/output transformer area.

I'd just get the amp back to the shop as it's so new. :(

_tom_ · « **Reply #7 on:** January 08, 2006, 12:14:01 PM »

Quote from: HJM

There's no way to tell if it is the valves without having a spare set to swap in, one by one until the problem goes..! It doesn't sound like a microphonic valve - they whistle and howl in a high pitch feedback kind of sound.

Errg mine do that when you are near to the amp, its an uncontrollable MEEEEEEP! Time for new valves for me aswell I guess..

Arent selected the ones that are matched to work best with each other? Thats what I heard anyway..

tewboss · « **Reply #8 on:** January 09, 2006, 09:39:39 PM »

Quote from: _tom_

Arent selected the ones that are matched to work best with each other?

yep thats correct. i don't understand physics enough to tell you why. Hotrox sell JJ tubes which are supposed to be damn good.

dave_mc · « **Reply #9 on:** January 10, 2006, 05:39:48 PM »

Quote from: tewboss

Quote from: _tom_
Arent selected the ones that are matched to work best with each other?

yep thats correct. i don't understand physics enough to tell you why. Hotrox sell JJ tubes which are supposed to be damn good.

i thought it's just because the valves are sold with a margin of error in the electrical values, and for some aplications, they have to be closer matched, so "selected" means the company just tested the valves, and coupled the ones that were closest/close enough in values/specs together.

That's what my uncle told me anyway, and he's a radio ham (valve radios).