Noise on 7B2

[AVfile]

I’ve seen a lot of nice stories on Facebook lately of people getting their older 3B and 4B amps tuned up by the factory. My 7BSST2 are only 9 years old but there has always been some buzzing noise audible if you stand close to the tweeter/mid. Knowing that big amps can do this it does not really bother me, but it is different than the usual hiss (white noise). So I decided to measure the output at the speaker terminals.

Amp 1:
0.4 mV AVG
Min -2.5 mV
Max +2.5 mV

Amp 2:
-7.4 mV AVG
Min -11.5 mV
Max -3.6 mV

I don’t think this is anywhere near the specified -117 dB SNR which should be less than 0.1 mV by my calculations. Also looks like Amp 2 has a significant DC offset. What have others found?

Can Bryston fix this?

[hdvidguy]

Originally Posted by AVfile

I’ve seen a lot of nice stories on Facebook lately of people getting their older 3B and 4B amps tuned up by the factory. My 7BSST2 are only 9 years old but there has always been some buzzing noise audible if you stand close to the tweeter/mid. Knowing that big amps can do this it does not really bother me, but it is different than the usual hiss (white noise). So I decided to measure the output at the speaker terminals.

Amp 1:
0.4 mV AVG
Min -2.5 mV
Max +2.5 mV

Amp 2:
-7.4 mV AVG
Min -11.5 mV
Max -3.6 mV

I don’t think this is anywhere near the specified -117 dB SNR which should be less than 0.1 mV by my calculations. Also looks like Amp 2 has a significant DC offset. What have others found?

Can Bryston fix this?

Sure they can. Send in for warranty. Most likely a bad capacitor(s). I had my 14B SST with one channel bad. They replaced a bunch of things and got it back to factory specs.

[AVfile]

Originally Posted by hdvidguy

Sure they can. Send in for warranty. Most likely a bad capacitor(s). I had my 14B SST with one channel bad. They replaced a bunch of things and got it back to factory specs.

OK thanks. I called Bryston and was told to email Mike because he is working from home so now I’m just waiting for his reply.

[hdvidguy]

Originally Posted by AVfile

OK thanks. I called Bryston and was told to email Mike because he is working from home so now I’m just waiting for his reply.

Where Bryston is located in Ontario, we just came out of full lock down due to COVID. Stereo stuff is non essential. So may be some long delays getting things fixed.