Valve advice

imalrightjack

Hi,

I'm going to buy the following a) as a back up and b) to see how it affects an 'issue' (which might not be an issue!) with my Engl Gigmaster 30:

V1 - ECC83/12AX7

V2 - EL84/6BQ5

V3 - EL84/6BQ5

V4 - EL84/6BQ5

V5 - EL84/6BQ5 

Any advice on brands or what to consider?  Are any 'warmer' than others?  E.g. gold ones?  I'm clueless and any advice is welcome.

thermionic

What is the issue? And there's only one preamp valve in that amp?

imalrightjack

The preamp is a double triode.

The issue is the amp is making a sound in standby. I thought it can't do any harm to try switching the valves, as it's no bad thing having a back up set.

imalrightjack

Any thoughts on good replacement valves?

ICBM

It won't be anything to do with the ECC83, that's in the preamp and is nothing to do with the standby circuit.

JJs are the best currently available EL84s for reliability, and do sound darker than most other brands.

I would get a set of these - it's always worth having a spare set of power valves, plus the correct fuses - and try them. If it doesn't fix the "problem", just leave whichever ones you like the sound of best in the amp and keep the others as spares. And stop worrying about it .

imalrightjack

Cool.  Thanks for that.  A couple of questions though: what 'fuses' are these and where are they found?  And can I bias the amp myself or does it need to go to a technician?

ICBM

There are individual power valve fuses (x4) - if they're not in holders on the back panel they must be inside.

The amp also does ideally need biasing - unlike many EL84 amps it's not cathode biased - and again if there is no adjuster on the outside (since there doesn't seem to be a sensing resistor or test point) you will need to do that from the inside.

Given the way a lot of modern amps seem to be designed deliberately to be non-user-serviceable, it wouldn't surprise me!

But, since it's probably running fairly conservatively by EL84 amp standards given the range of bias voltage listed on the schematic, it's unlikely to be critical and is safe enough just to put new valves in.

imalrightjack

Any recommended retailers?

ICBM

Karltone.