Rega brio bias setting - diyAudio
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Old 15th January 2015, 10:40 PM   #1
jimnich is offline jimnich  England
diyAudio Member
Join Date: Nov 2014
Location: Bristol UK
Default Rega brio bias setting

Hello everyone.

I'm new here so be gentle with me.

Recently fixed a dry joint on this "old friend" which solved an imbalance between channels. Somehow now sounds not quite 100%. Maybe needs to be re-biased? Has anyone got any information . I don't have a schematic or any knowledge of values or where to measure.

It is one of the first large clamshell models with the large feet.

Any help would be greatly appreciated !
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Old 15th January 2015, 11:40 PM   #2
sreten is offline sreten  United Kingdom
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Join Date: Nov 2003
Location: Brighton UK

The clamshell Brio is based on a very old "Texan" design.

The power amp is an op-amp driving a CFP configured with gain.

See p4.pdf here : (and the rest of the pdfs)
Rega Brio (one channel dead)

However there is a later larger clamshell (deeper) still with small feet.
Probably just doubled up output devices. Don't know a large foot version.

Whatever, identify output resistors and compare voltages
across them between the channels, adjust to match.

rgds, sreten.
There is nothing more practical than a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 15th January 2015 at 11:51 PM.
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Old 16th January 2015, 10:32 AM   #3
jimnich is offline jimnich  England
diyAudio Member
Join Date: Nov 2014
Location: Bristol UK
Hello Sreten,

Thanks very much for your reply. I will do as you suggest. I have only performed this adjustment on Sansui amps before . There service manuals are very user friendly. They always state a value in mv. I will post later how I get on.

Regards Jim
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Old 16th January 2015, 12:27 PM   #4
jimnich is offline jimnich  England
diyAudio Member
Join Date: Nov 2014
Location: Bristol UK
Left ch = 22mv . rch = 60mv. Adjusted both to 20mv.
The output resistors were 1 ohm ( measured 1.3 ).
Suggested IQ 15ma.
Any way sounds as good as I can remember it.

Thanks Sreten. Regards Jim
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