Bryston 4B green clipping lights blinking


Hi,

Although not new to Audiogon (the site), I'm a newbie to both posting on the Forum and to equipment outside that created for the masses. 

That said, I'm looking to achieve better sound in the house and recently purchased an older rebuilt Bryston 4B amp, an upgraded Apt Holman Preamp (from the Audiogon classifieds), Mirage M1 si speakers, a Marantz TT-15 turntable and various semi expensive interconnects and speaker cable. I have this system set up in a room that measures 18 feet by 38 feet.

While the system sounds as good as I had hoped (even under extremely loud settings), the amp LEDs continuously blink green when under even the slightest load. This is true even when inputting digital music via a Bluetooth module. Further, I'm using a higher end power conditioner on everything but the amp (I understand Bryston recommends a direct connection) and a stand alone 15 amp circuit with a proper ground. I wrote the seller and he tells me that older 4Bs do this.

Can anyone tell me if this is an ok condition?

thanks,

Rick







rickdarling
I have an older 4B and had an even older 3B before that. What you’re describing isn’t normal operation. The front panel LEDs should be a steady-state green, and will flash red on clipping. You can verify this with Bryston for yourself - the company offers excellent support, even on older products.
Thanks. I'm going to try another preamp to see if it makes a difference.

If you find there is nothing wrong with the amp, it could be pre clip warning. 

The Mirage M1’ are a great speaker and this 4B should be fine, the M1’s do have a nasty 5ohm combined with -45 phase angle at 60hz but the 4b should handle this.

http://www.stereophile.com/content/mirage-m-1si-loudspeaker-measurements#PGAwhPPKQTyDfY5g.97

The Bryston is dc coupled, I think maybe you could be getting warp frequencies or subsonic rumble arm resonance coming through from your t/t phono stage setup, I don’t know what bass mode means on the Holman pre, but it looks like it maybe a rumble filter, see if that cures it.

If that’s no good, then try cd player and a different preamp see if it cures it.


Cheers George

Thanks for the info George. I tried the filters on the Apt, a different Adcom preamp and it's filters as well as a CD player. Still blinking green on load. I understand that the thresehold for clipping May be adjustable internally. Perhaps I need to explore this further.
I also wrote Bryston.

This is one of the reasons why I gave up on the Bryston 3BST awhile back because it didn't take much volume to get it to clip and I was using very efficient speakers at the time, figurer that one out. Go for a Conrad Johnson or McCormack amp (solid state), then you could put that problem behind you. Thanks for your time!
In this this instance, I suspect it may have more to do with the age of the unit and potentially the non-Bryston work done on it. It really does sound excellent and I'm hopping to resolve it and keep the unit. At this point, it's only the green lights blinking and I have not seen anything (anywhere) on line with a condition similar.

PHD, I owned both 3BSST and 4BSST, and never had a problem, even when I abused the 4B. Before I bought, I talked to someone at the factory, burned an hour of his time, and he invited me to call back if I had more questions. It was the president.

I guess that your mileage has differed. Sorry to hear that.
terry9, it could be that the earlier models of the Bryston amps (B, BST) did not have the headroom that the more current amps (BSST) have, but you said you also owned the earlier 4B and thought it did not have this problem. We need to look at the listening habits and go from there. Not everyone on Audiogon is listening to classical music at low volumes. Some other types of music demands higher volumes just to sound good.
Keep us posted -Rick.
PHD, I meant that it was the 4BSST which I abused. Yes, I did mainly play classical at low volume, but that abuse was a doozy, and the Bryston simply shrugged it off.