Bryston amp, pop sound at power down.

My 20 year old 4bST would send a quiet, dull thud sound to first the left speaker, then the right on shut-down, no matter what the preamp’s volume setting. I was told by my dealer and by Bryston’s James Tanner this is normal operation for that amp. I would not describe it as a “pop”.
I now have a 4b3, no more thuds on shutdown.
Send an email about it to James Tanner, he’s responded promptly to me in the past.
 

No tube preamp. I've tried the amp with two different solid state amplifiers and with no inputs at all and the pop still occurs. I noticed that it seems to be an equal pop on both left and right channels. 

I will perform the dc speaker terminal test tonight and report back

Thank you Erik.

I measured DC voltages at speaker terminals on the amp and both channnels measured .000VDC. This measurement was with a fairly decent fluke meter and had the volume set to zero on preamp and speakers disconnected. 

That's how to do it, correct?

bslon: I think my sound could be also described somewhere between a thud and pop. Interesting you had it on the older version as well. I'd be curious if anyone else who has the 4BSST2 has the issue. 

I will send an email to James tanner if I can locate the address on their website.

Thanks

I have 3 Bryston 7B ST's and all three give off a pop/crackle at power down, whether turned off at the pushbutton or due to loss of AC feed.  Since it is the same for all three, I guess it is normal.

While a bit disturbing, the sounds are not loud enough to endanger my speakers, and they no longer bother me as I am used to them.

I leave these amps on all the time, and so I hear the noises very rarely.