Bryston Amp question.

govcon · « **on:** 7 Aug 2005, 07:05 pm »

Since I'm a recent owner of a Bryston 6B ST, I was wondering something about the amp or any Bryston amp for that matter. I don't see any specs for the Bryston amps that indicate their power output anywhere below 4 Ohms. Are the amps stable with a 2 Ohm load and how far will they go down until it becomes a problem for these amps?

govcon · « **Reply #1 on:** 10 Aug 2005, 12:07 am »

No one has an answer?

James Tanner · « **Reply #2 on:** 10 Aug 2005, 12:28 am »

Hi govcon,

It depends on the type of load at 2 ohms.

If the load is very 'reactive or capacitive' in nature then we would not recommend the 6B. You would need the 7B or 14B. If the load is 'resistive' at 2 ohms then it is not as big an issue.

So we do not recommend the 6B below 4 ohms if 'reactive' but if the load has a small area of frequencies at 2 ohms then it is not usually a problem.

Do you have an impedance plot for the speaker?

james

govcon · « **Reply #3 on:** 10 Aug 2005, 12:34 am »

Hi James,

Thanks for the reply. Unfortunately, I don't have an impedence plot for my speakers. The speakers in question are a set of B&W Nautilus 804s. The minimum impedence specified by B&W for these speakers is 3 Ohms. I was just wondering how stable the amp is if say it saw a 2 Ohm load.

You mention reactive or capacitive. Could you explain the differences?

Thanks again for any info.

James Tanner · « **Reply #4 on:** 10 Aug 2005, 01:08 am »

HI,

The B&W 804 is a Resistive type load so the 3 ohms is not an issue with the 6B.

Most Dynamic driver type speakers are resistive- most electrostatic speakers are reactive.

james

govcon · « **Reply #5 on:** 10 Aug 2005, 03:19 am »

Thanks for the info James.

nicolasb · « **Reply #6 on:** 10 Aug 2005, 08:40 am »

Correct me if I'm wrong, James, but doesn't the "below 4 ohms" figure refer to the nominal impedance of the speaker rather than the absolute minimum value? B&W N804 speakers are a nominal 8 ohm load (and, if anything, I would think a 6B would be overkill).

James Tanner · « **Reply #7 on:** 10 Aug 2005, 12:01 pm »

Hi nicolasb,

Yes you are correct the nominal impedance is usually the main concern which is what I was alluding to when I said -- if a narrow band of frequencies falls below 4 ohms it is not an issue.

That said I would not say the 6B is overkill on the B&W's. I have always found that more power gives the sound a sense of 'dynamic contrast' at low levels that the smaller amplifiers do not.

james

Phoenix · « **Reply #8 on:** 10 Aug 2005, 01:11 pm »

Quote

You mention reactive or capacitive. Could you explain the differences?

Yeah, would be nice to know that!

James Tanner · « **Reply #9 on:** 10 Aug 2005, 02:20 pm »

Capacitive loads tend to store energy and ask the amplifier to provide more and more current.
Resistive loads require the amplifier to deliver more voltage swing and is easier on the amplifier.

james