a question of noise!

[the_doc735]

....a question of noise!

Does anyone have experience of the sophia electric 91-01 300B? (monoblocks)

Is it in its nature for transformers to buzz and hum (vibrate)? (with hum trim pots)

I just wondered because my puresound 2A3 was really quiet i.e. silent/no noise! (with no hum trim pots)

[RothwellAudio]

No, transformers shouldn't hum/buzz. It indicates to me that the transformers are poor or the design is poor or there is a fault somewhere. If you're lucky it could just be a case of resetting the bias so the current drain is as it should be.

[the_doc735]

No, transformers shouldn't hum/buzz. It indicates to me that the transformers are poor or the design is poor or there is a fault somewhere. If you're lucky it could just be a case of resetting the bias so the current drain is as it should be.

many thanks!

I seller said: "I don't think it is a fault as it would be unlikely that both monoblock's have developed the exact same fault at the exact same time - yes?". "Although from your sound file, it looks like there is a 50Hz. frequency that should not be there!!". These are step down 230v - 120v action'ed by an airlink BPS0508.

Also, see this: https://www.audioaficionado.org/show...t=15595&page=3 POST 27. Sounds like my problem to!

sent you a sound file of the buzz via email.

[337alant]

You may have a problem with DC on your mains?
http://sound.whsites.net/articles/xfmr-dc.htm
Are you using any of those home plugs for networking they work on the earth network so could be a source of noise
Alan

[anthonyTD]

Make sure they are meant to be run on 240v plus, a lot of equipment made these days are 230v, even then, they may only need 220v on them for all the voltages on the secondaries to be correct, basicaly; the over voltage in some cases can cause the Transformers to hum.
If your not sure, get in touch with the manufacturers.
Hope this helps.
A...

[walpurgis]

If it is a DC issue, this recent thread may be of interest: http://theartofsound.net/forum/showt...rom-DC-Blocker

[RothwellAudio]

That sound file doesn't sound like transformer buzz at all to me - it sounds like humming coming from the speakers. A hum in the signal can have many causes but in this instance I suspect power supply ripple. I could be wrong about that though.
Of course, hearing the humming in isolation doesn't give any indication of the signal-to-noise ratio. That hum could be at a very low level or a very high level, there's no way to tell. Also, no indication of whether or not the hum goes up/down with the volume control.

Anyway, it doesn't sound like transformer buzz and isn't caused by DC on the mains.

[the_doc735]

You may have a problem with DC on your mains?
http://sound.whsites.net/articles/xfmr-dc.htm
Are you using any of those home plugs for networking they work on the earth network so could be a source of noise
Alan

I'll try unplugging them!
thanks!

[the_doc735]

Make sure they are meant to be run on 240v plus, a lot of equipment made these days are 230v, even then, they may only need 220v on them for all the voltages on the secondaries to be correct, basicaly; the over voltage in some cases can cause the Transformers to hum.
If your not sure, get in touch with the manufacturers.
Hope this helps.
A...

These sophias are 120v~ I,m using a step down transformer from 230v (i.e. airlink BPS0508) as stated above!

[the_doc735]

If it is a DC issue, this recent thread may be of interest: http://theartofsound.net/forum/showt...rom-DC-Blocker

thanks!