# Two Receivers for Vertical Biamping L-C-R



## mijotu (Dec 30, 2018)

I am currently running a 6.1 HT system with a Pioneer Elite VSX-72TXV and am curious about using my Arcam AVR300 as a second amp for the fronts. I’m assuming I would run the preouts to the Arcam, with it in Direct Mode. I’m concerned about possible phase issues, though I’m sure that’s just the beginning...

So, my question is: Is this routine enough that a solid guide is already available? How much correction should I expect, requiring REW, etc? Could MCACC address such issues? Would I be better off powering the HF or LF with the Arcam? Or, have I simply lost my mind?

I look forward to all that I can learn,
Michael T


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## ajinfla (May 10, 2009)

mijotu said:


> I am currently running a 6.1 HT system with a Pioneer Elite VSX-72TXV and am curious about using my Arcam AVR300 as a second amp for the fronts. I’m assuming I would run the preouts to the Arcam, with it in Direct Mode. I’m concerned about possible phase issues, though I’m sure that’s just the beginning...
> 
> So, my question is: Is this routine enough that a solid guide is already available? How much correction should I expect, requiring REW, etc? Could MCACC address such issues? Would I be better off powering the HF or LF with the Arcam? Or, have I simply lost my mind?
> 
> ...


What speakers? Presumably biamp terminals?
Your biggest concern shouldn't be "phase', it should be gain and ground loops. To maintain the original frequency response, it's critical that the LF and HF legs of the speaker XO (effectively a voltage divider) be fed the exact power they would have been fed by a single amp...but now using 2. Measuring and then matching the voltage outputs of each amp is key. Acoustic measurements using REW etc, would be tricky, because you need very high accuracy (in the order of 0.1db), something not possible outside an anechoic chamber with high precision measuring equipment. Then there is the possibility of having ground loops with the 2 amps interconnected, since it seems you wanted the drive the Arcam with the Pioneers pre outs.
Not trying to discourage you from just trying for the sake of it, but quite frankly, it's highly unlikely to result in "improved" sound outside of gain errors and/or pushing to very high levels where clipping/compression might be involved. Your time and effort, so YMMV.
Btw, thanks for joining and happy new year

cheers,


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## mijotu (Dec 30, 2018)

ajinfla said:


> What speakers? Presumably biamp terminals?
> Your biggest concern shouldn't be "phase', it should be gain and ground loops. To maintain the original frequency response, it's critical that the LF and HF legs of the speaker XO (effectively a voltage divider) be fed the exact power they would have been fed by a single amp...


I had read about gain matching. Is there a way to measure and adjust that on dissimilar equipment?

I think I had confused phase with time alignment. Surely the signals received by the LF and HF will have to be coordinated. What steps would one take to do so?

What steps does one take to address ground loops resulting from this arrangement?

My speakers are Polk RTi150 and CS400.

Thanks for your response. While there will be issues, I am interested in what it will take overcome those challenges.

Surely I am not pioneering this approach?


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## ajinfla (May 10, 2009)

As mentioned in my previous post, you would have to match the voltage outputs. Send both amps a 1khz test tone and measure their output terminals with an AC voltmeter with high accuracy. You would have to use the Arcam volume control to "match" the Pioneers outputs.
You don't have to worry about time/phase...unless it shows in your FR. 
Unless the Arcam creates some sort of long delay, it won't matter, as long as your measured FR using the Pioneer only driving the speakers (so NON biamp) matches the FR in biamp mode, all is well. Your "phase/time" issue worries don't exist.:smile:
Once again, not trying to discourage you, but there is not going to be any non-imaginary "improvements" if the gains are truly matched, unless the caveats in first post are met.
Good luck.


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