C-85 inverted outputs

stoutblock

stoutblock

"If it sounds good, it is good." Duke Ellington
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I know the inverted outputs on the C-85 are meant to be used to bridge a couple of stereo amps (assuming they have a common ground).

Is there a way to also use them to drive a second amp for horizontal bi-amp? I would like to try to bi-amp my speakers with a Yamaha M-4 for the HF and a Yamaha M-2 for LF. Is it a simple phase thing where I can simply switch the polarity of the outputs on the amp connected to the inverted C-85 outputs?

Or am I all wet here?
 
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You are not all wet. There are actually a couple ways to use them.

One is as you say, for just a second set of outputs, just reverse the speaker connection polarity at both speakers.

Second plan which would also work for you, is to use left channel inverted and right channel normal into one amp, then left channel normal and right channel inverted to the other amp. Then just reverse the speaker connection polarity on each of the inverted channels. Theory behind this is that load on the power supply during heavy transients common to both channels hits both sides of the rail instead of both channels hitting the positive or the negative rail simultaneously.
 
whoaru99 said:
You are not all wet. There are actually a couple ways to use them.

One is as you say, for just a second set of outputs, just reverse the speaker connection polarity at both speakers.

Second plan which would also work for you, is to use left channel inverted and right channel normal into one amp, then left channel normal and right channel inverted to the other amp. Then just reverse the speaker connection polarity on each of the inverted channels. Theory behind this is that load on the power supply during heavy transients common to both channels hits both sides of the rail instead of both channels hitting the positive or the negative rail simultaneously.
Click to expand...

Good to know I am dry...

Interesting input, thanks!
 
I hooked up both the M-2 and M-4 amps today to the C-85 and I have to say I'm impressed! I've always felt the M-4 was a little more musical in the mid/high frequencies than the M-2, but the M-2 really drives the the woofers on these Soliloquy 6.5 speakers. I am quite pleased, the best sound so far in this room...

Yamahaamps2net.jpg


Thanks for the help Whoaru!
 
whoaru99 said:
Did you try the one inverted and one regular polarity to each amp method?
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Yes I did. Tried it both ways. Not sure I could tell the difference but ended up using your recommendation. No complaints :yes:
 
Bridge an M2?

I have an M2. How do you bridge it? Didn't know an M2 could be bridged. Is it the same as a P2200, requiring an external transformer? I also have a PC2002 and two PC1002. With these you just move the rear slider.
 
I use a C-85 to drive a pair of amplifiers - to a pair of NS-1000's and a pair of NS-1000M's .One set of 1000's has the polarities swapped around at the speakers on the inverted amplifier.
 
boneaus said:
I have an M2. How do you bridge it? Didn't know an M2 could be bridged. Is it the same as a P2200, requiring an external transformer? I also have a PC2002 and two PC1002. With these you just move the rear slider.
Click to expand...


The M-2 doesn't have built-in bridging capability. The inverted outputs on the preamp he's using enable one to do it though.
 
stoutblock said:
Yes I did. Tried it both ways. Not sure I could tell the difference but ended up using your recommendation. No complaints :yes:
Click to expand...

Yeah, it's not something that makes a huge difference but if it one is taxing the amp every bit helps.

It would be interesting to see someone with the right test gear do a comparison and see what difference there might be in power at clipping or dynamic/peak power. It's the latter, as I understand it, where the benefit should be present.
 
boneaus said:
I have an M2. How do you bridge it? Didn't know an M2 could be bridged. Is it the same as a P2200, requiring an external transformer? I also have a PC2002 and two PC1002. With these you just move the rear slider.
Click to expand...

Most any common-ground output amplifier can be safely bridged.

Feed the L channel a regular signal, the right channel an inverted signal. Connect speakers to the L and R channel + terminals.

A few of the Yamaha pre-amps from the same era have the built in inverted pre-outs. The info is in the User Manual for the C-70/80/85. The lower models may also offer inverted outputs but I've never gone looking.

So one pre to amp it's Left to Left and Leftinverted to Right
The other is Right to Left and Rightinverted to Right

Left amp + is + to each speaker.

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