Questions on the C-85 'Invert Output' running two amps

Frank Sol · May 24, 2013

Will most conventional stereo amps work properly if hooked-up as described in the C-85 manual -- one stereo amp driving the left speaker , the other stereo amp driving the right ?

I read that some amp designs wont work... What are the particulars ?

Specific example: would two Adcom GFA-535 (twin power trannies) work ?

Thanks :thmbsp:

avionic · May 24, 2013

Frank Sol said:
Will most conventional stereo amps work properly if hooked-up as described in the C-85 manual -- one stereo amp driving the left speaker , the other stereo amp driving the right ?

I read that some amp designs wont work... What are the particulars ?

Specific example: would two Adcom GFA-535 (twin power trannies) work ?

Thanks :thmbsp:

As in "bridging" ?

Frank Sol · May 24, 2013

I think so Dave... The manual says , 'This allows you to run ordinary stereo amps monaurally'

Then it shows how to connect... using amp 1 + & + to drive left ch then amp 2 + & + to drive right ch

avionic · May 24, 2013

What does the Adcom owners manual say about bridging ?

Frank Sol · May 24, 2013

I'm scanning that page now... Will post it in a second

Frank Sol · May 24, 2013

I'm asking about Fig. 1 configuration

avionic · May 24, 2013

Frank Sol said:
I'm asking about Fig. 1 configuration

Some Adcoms have a "bridging" switch like the 555.To allow for mono l operation.

brutal · May 25, 2013

"Common Ground" is the key to bridging stereo amps that do not have built in bridging capability. You can check around, but a quick google fu shows the GFA-535 as a common ground amp. YMMV and I take no responsibility for magic blue smoke leakage.

For obvious reasons, this generally won't work on internal monoblock designs that don't have built-in bridge capability.

stoutblock · May 26, 2013

As long as the amps LH and RH channels have a common ground the inversion method off of the C-85 will work with two stereo amps. If your amps have a mono switch, you don't need to use the inversion outputs on C-85, Just use the normal connection to the terminal on your amp that is used when the mono switch is on (the other one is not used).

What is not well known is the use of the inverted method with a single stereo amp as explained in fig. 2. Someone else can explain this better than I, but this method will reduce the load on most stereo amps resulting in better performance.

Frank Sol · May 26, 2013

Thanks everyone :thmbsp:

I'm just trying to understand the concept more-so for curiosity than application

stoutblock , I ran the 'Fig 2' hookup some the other day w/Behringer A500 amp I modified... I believe the bass is tighter at louder levels :scratch2:

Behringer A500: http://www.audiokarma.org/forums/showthread.php?t=519320

stoutblock · May 26, 2013

Frank Sol said:
Thanks everyone :thmbsp:

I'm just trying to understand the concept more-so for curiosity than application

stoutblock , I ran the 'Fig 2' hookup some the other day w/Behringer A500 amp I modified... I believe the bass is tighter at louder levels :scratch2:

Behringer A500: http://www.audiokarma.org/forums/showthread.php?t=519320

I tried the same with an M-4 and later an M-2. I agree that it seemed to let the amp push the speakers a little harder at high volumes. I think the amps also worked a little cooler? I assume this mostly has benefit when the amplifier channels use a common power supply?

Questions on the C-85 'Invert Output' running two amps

Frank Sol

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avionic

" Black Knights "------- F-15 " Wizard "

Frank Sol

Lunatic Member

avionic

" Black Knights "------- F-15 " Wizard "

Frank Sol

Lunatic Member

Frank Sol

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avionic

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brutal

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Frank Sol

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stoutblock

"If it sounds good, it is good." Duke Ellington

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