A quick pre-amp valve query

Kalimna

Greetings folks,
Doing a spot of spring cleaning (i.e. sorting out a load of crap I no longer need), and I found a couple of valves I must have bought a while back. I'd like to know if there's anything they are likely to be useful for and also if they're likely to be worth much more than a couple of quid?
Valves in question (there's only 2) : 
a Mullard ECC82
a CVC ECC81

Visually they look in good nick, but I have no means of testing them short of sticking them in an amp if it happens to be suitable. I need a new electronics project, so if they *are* usable in an amp circuit then I'd be keen to know.

Ta muchly,
Adam

ecc83

Hi Adam, a couple of years ago I dabbled with an 83 and an 82 in a very low voltage, around 18V, circuit and got some er, 'interesting' tones from a strat clone. If you have a gash 12V+ wall rat supply kicking around you could waste a wet Sunday messing with that?

Dave.

randella

Some amps use the ECC81 (12AT7) in the reverb driver or phase inverter positions - Fenders amongst them.

ecc83

randella said:

Some amps use the ECC81 (12AT7) in the reverb driver or phase inverter positions - Fenders amongst them.

ICBM or Rifty etc will surely correct me if wrong but I seem to recall that the ECC83 is the only one of the Big Three that has the required heater/cathode voltage rating for the usual PI configuration? I shall look it up in my Big Book of Fender Circuits but I think they use an unusually low value 'tail' resistor?

OK as a tank driver, the anodes are generally strapped for extra welly?

Dave.

ICBM

ecc83 said:

ICBM or Rifty etc will surely correct me if wrong but I seem to recall that the ECC83 is the only one of the Big Three that has the required heater/cathode voltage rating for the usual PI configuration? I shall look it up in my Big Book of Fender Circuits but I think they use an unusually low value 'tail' resistor? 

They all do for a typical LTP phase inverter - and probably for a cathodyne as well - but not for a cathode follower.

The ECC83 and ECC82 are both rated for 250V - it’s just the ECC81 and the 12AY7 which are only rated for 90V.

ecc83 said: 

OK as a tank driver, the anodes are generally strapped for extra welly?

In Fender amps, yes - most others don’t.

I think the Mullard ECC82 should be worth about £20 if it tests good - they’re nowhere near the value of a ECC83.

The CVC (Chelmer Valve Co - an importer not manufacturer) ECC81 is probably a 90s Chinese valve and worth a tenner or less.

Kalimna

Thanks for all the info there - not especially valuable (as I suspected), and possibly useful in a few circuits. I'll hang on to them I think.
Out of interest, the CVC ECC81 had no other markings on it - not country of origin for example.
Cheers,
Adam