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Yamaha C-70 Preamp and 2 M-60s Power amps question

T

thefluffy

New Member
I recently aquired a Yamaha C-70, T-80, and 2 M-60s. I want to set it up so that each M-60 is powering two speakers. I have a pair of Klipsch Cornwalls and a pair of Klipsch LaScalas.

The C-70 has two outputs the regular output and the inverted output. What do I need to do to use the inverted output for one set of speakers? I know I will have to reverese the connection to the speakers but do I reverse both speakers on the amp plugged into the inverse output or just one? :scratch2:

Thanks,

Daniel
 
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Hi there,

First, congrats on a super-nice score! Yamaha gear is top-notch!

Regarding your question, depends what kind of setup you're going for. Will this be for a multi-room system? Or you want all 4 speakers to be in the same room?

For a multi-room system, you don't need to bother with phase as you won't be hearing both pairs at one time.

For a same room system, it gets more complicated. For one pair of speakers only, it doesn't matter wich pre-out you use, as absolute phase is inaudible. When it comes to two pairs of speakers in the same room, there are many issues that come into play. If the speakers are all on the same "end" of the room and fireing in the same direction, invert the connection to the speakers that are driven by the inverted pre-out to get them back into phase with the other ones, it should sound better in theory . For other setups, such as opposite-wall speakers, I simply suggest that you try it out both ways to see what sound best in your practical real-world setup.

Hope that helps!

az
 
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There are two ways to use the inverted outputs on the Yamaha pre-amps that provided them. One method augments the bass response using a single or pair of stereo amps, the other allows you to run a pair of amps bridged. You should look at the section in the OM that outlines the hookup options. The stereo option uses one regular channel, one inverted, then one speaker is inverted coming out of the amp. I'd post the images quick, but having trouble getting adobe to copy to my clipboard.
 
The setup will be in the same room. The Lascalas are in the front of the room and the Cornwalls are in the back of the room.

The amps will not be bridged. I am using each channel on each amplifier to power a speaker. I am looking at the manual now and it makes perfect sense to me. I don't know why it didn't make sense before. :scratch2:

The simple way would be to just reverse all of the speaker connections on the amp plugged into the amp using the invert output. But, I see two different ways of doing this.

Option A: Run one amp for one channel. Like one amp for the right channel and one for the left channel. I still have the option of running one side of the amp inverted this way. Basically set it up like the diagram in the manual shows for a bridged connection but use two speakers, one on the L output and one on the R output.

Option B: Run one amp per a pair of like speakers. So, one amp for the Cornwalls and one amp for the LaScalas. Again, I still have the option of running one channel inverted from the other.

Would there be any benefits of running one way or the other? Would reversing the phase on one side of each amp have any real benefits? I'm probably slitting hairs there, I really will never use more than maybe 20 watt spikes from these amps due to the efficiency of the speakers.

Thanks,

Daniel
 
The reversed phase trick to augment bass response will make it so that one channel draws current from the positive half of the power supply, while the other channel draws from the negative side at one moment in time. Reversal of the connections on one speaker re-establishes correct phase acoustically. I don't think you will notice any improvement with such sensitive speakers as you noted.

az
 
audiozaz said:
The reversed phase trick to augment bass response will make it so that one channel draws current from the positive half of the power supply, while the other channel draws from the negative side at one moment in time. Reversal of the connections on one speaker re-establishes correct phase acoustically. I don't think you will notice any improvement with such sensitive speakers as you noted.

az
Click to expand...

I'm also using that "bass enhancement wiring setup" in my system with my c-70/m-70 just because it's smarter overall, a better design I suppose on paper.

But I haven't noticed any improvements from the already shockingly great bass in my studio from various speakers. I suppose I'm not driving it into high watt territory so maybe no difference is to be found anyway unless pushed really hard. my room's small so I'd go deaf if it ran at 400watts total into my speakers LoL, even inefficient speakers.
 
thefluffy said:
The C-70 has two outputs the regular output and the inverted output. What do I need to do to use the inverted output for one set of speakers? I know I will have to reverese the connection to the speakers but do I reverse both speakers on the amp plugged into the inverse output or just one? :scratch2:

Thanks,

Daniel
Click to expand...

Yes, the connections to both speakers on the amp running from the inverted outputs must be reversed to bring them back in-phase to the others on the non-inverted outputs.

As to your other question about reversing phase on one side of the amp, I'm in agreement with audiozaz, likely won't make any difference unless you're really pushing the watts. I have experience with this on a C-80 and two M-80s (and two M-40s).
 
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