Can someone tell me the Class of my Tandberg amp

If your chassis gets hot during idling. It is more class A than not. If it get hotter when playing loud.. it is more class B. Class A is "on" 100% at idle, and actually uses LESS energy when playing music. Where class B is cool when idling, and gets hotter (but usually never as hot as a class A is) when playing hard.
Nearly all so-called Class A are just biased more toward class A and still go to class B when run hard. The big, true Class A are usually BIG heavy monsters that act as room heaters just being on.
So if you want a class A sound, but don't know if a amp is A or A/B, then the heat output at idle, gives a good clue.
Class D at idle is stone cold.

I too don't think that Tandberg ever made a pure Class A amplifier, and just a small minority of amplifier manufacturers have.

I suspect from your other recent post that you are referring to a Tandberg 3003, which is rated at 2 x 165 watts into 8 ohms, and 2 x 250 watts into 4 ohms, and weighs about 25 pounds.

Those figures alone indicate that it is not even close to being pure Class A. The Pass Labs XA160.5, for example, which is Class A and puts out 160 watts into 8 ohms, weighs 150 pounds for EACH single-channel amplifier. As Elizabeth said, true Class A amplifiers "are BIG heavy monsters."

Regards,
-- Al

'class' does not necc 'translate' to better sound...your speakers and room will be much more important ..tandberg is excellent vintage gear rated c for cool.

Sheesh, so much doubletalk and and so many red herrings in response to a straightforward question. Here's the straightforward answer - all the Tandberg amplifiers I've ever seen are Class B (Push/Pull configuration). There is no coupling capacitor in series with the speaker, which is a dead giveaway for a Class A or AB amp. There is direct DC coupling to the speakers, which is why there's a protective relay circuit which clicks out when the DC balance is off. (Why? If you send any appreciable DC current to your speakers, you'll blow them out.) Using direct DC coupling means you don't have (another) varying impedance in the line to the speakers. (The speakers themselves are a varying impedance, but hey, ya can't do anything about that!)

Old thread but felt compelled to correct the previous statement:

Tandberg amps are in fact class AB, not class B. The outputs are not shut off completely with no signal present, which would be required to meet Class B definition.

You wouldn't be setting bias adustments at 35-40mV otherwise :-)

They made receivers with capacitive coupling (in the TR 1000 series) and without (everything subsequent to those), and they made bipolar receivers & amps and later MOSFET amps in both integrated & component form, and one receiver (3080A).

All of those are class AB.

John