dc blocking

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guest2521

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dc blocking
« on: 2 Oct 2005, 08:59 am »
James,

Do the bryston power amps have a dc blocking mechanism such as caps or a servo?

Regards,

Nick.

Crimson

dc blocking
« Reply #1 on: 2 Oct 2005, 01:11 pm »
At least for the ST sereis, I'd have to say no. I had a preamp at one point that was putting out DC, and the 7B's reproduced it in all it's wonderful glory.

NewBuyer

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dc blocking
« Reply #2 on: 3 Oct 2005, 12:28 am »
I too would like to know if the Bryston amps block/filter-out DC on their input lines.  

I would also like to know if the Bryston amps will block/filter-out any DC component that may be present on the AC line.

Please advise?

ScottMayo

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Re: dc blocking
« Reply #3 on: 3 Oct 2005, 02:04 am »
Quote from: biovizier
James,

Do the bryston power amps have a dc blocking mechanism such as caps or a servo?

Regards,

Nick.


I kind of hope not - the amp should take the input waveform and make it bigger. Editing the waveform belongs elsewhere.

That said, it might be interesting if someone (not necessarially Bryston) made a small external device that eliminated DC offsets. I think this is as simple as a cap and a resistor; the only trick is you'd want nicely matched sets for all channels.

nicolasb

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dc blocking
« Reply #4 on: 3 Oct 2005, 02:24 pm »
I faintly recall reading somewhere that Bryston subjects their amps to a 100-hour burn-in process before they leave the factory, and the input signal during those hundred hours is a square wave.

James Tanner

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Re: dc blocking
« Reply #5 on: 3 Oct 2005, 03:41 pm »
Quote from: biovizier
James,

Do the bryston power amps have a dc blocking mechanism such as caps or a servo?

Regards,

Nick.


Hi Biovizier;

Thanks for your question.  No, Bryston amplifiers do not have DC blocking caps at their inputs.  However, Bryston amps have no gain at DC, so they will not develop large DC shifts even from 'leakage'  DC, should such occur.

All Bryston preamplifiers and related components do have DC blocking capacitors at their outputs, to prevent any inadvertent DC leakage or offset from affecting any amplifier.

Sincerely,
Chris Russell
Bryston Ltd.

NewBuyer

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dc blocking
« Reply #6 on: 3 Oct 2005, 09:45 pm »
Still wondering please: Do Bryston amps, including the B100 integrated, block/filter-out any DC that may be present on the AC power line?

James Tanner

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dc blocking
« Reply #7 on: 4 Oct 2005, 03:53 pm »
Hi NewBuyer;

Thanks for your inquiry about Bryston amps. Yes, our amps do have filtering to block any DC on the power line from entering the power-supply. This is a must, as it can cause noise in the transformers. The main source of offset in the power line is second harmonic from poorly designed power supplies in other equipment, and amplifier manufacturers are forced to contend with this by filtering the line.

I hope the above is helpful, but please let me know if you have any other questions. Thanks for your interest in Bryston.

Sincerely,
Chris Russell

Sebastiaan de Vries

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Re: dc blocking
« Reply #8 on: 11 Oct 2005, 05:47 pm »
Dear,

A non polair cap and a resistor do the job. Consider a value between 10uF and 47 uF as a rule of the thump. Put a high value resistor parallel to ground to discharge the cap.

An other solution would be a active DC servo. You make that with a opamp in unity gain. If you are interested in that I can search some schematic's ;)

Godthank Bryston don't have cap's in the inputstage!! :D

Kind regards,
Bas


Quote from: ScottMayo
Quote from: biovizier
James,

Do the bryston power amps have a dc blocking mechanism such as caps or a servo?

Regards,

Nick.


I kind of hope not - the amp should take the input waveform and make it bigger. Editing the waveform belongs elsewhere.

That said, it might be interesting if someone (not necessarially Bryston) made a small external device that eliminated DC offsets. I think this is as simple as a cap and a resistor; the only trick is you'd want nicely matched sets for all channels.