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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
georgehifi's avatar
georgehifi
10,312 posts
 

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

rickdarling OP
6 posts
 
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.
rickdarling OP
6 posts
 
I also wrote Bryston.

phd
1,314 posts
 
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!
rickdarling OP
6 posts
 
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.

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