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How to get the best match between a preamp AV processor and a power amp?

ririt

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I will set-up a mixed HC/HIFi 5.1 system based on a Preamp processor (either an Emotiva XMC-2 or an Anthem AVM 60) and a mix of class D amp from HYPEX (center, surround & zone 2) or Purifi (L,R). They will power Dali Rubicon LCR as front loudspeakers (Sensitivity 89bB). A Rel T9i will be used as subwoofer.
I had a look on the specs of the processors: the maximum output voltage of the AVM60 is 8.4V rms (XLR output) while the one of the XMC-2 should be around 4V rms. The purifi amp from Audiophonics has an ajustable input gain either +7.3 dB or + 12.3dB. With +7.3dB gain the maximum power output is reached with an input voltage of 4.2V while with a +12.3bB gain max power outpout is reached with 2.25V. Moreover the HYPEX specs for NC400 or NC250 modules indicates that maximum power is obtained with input voltages of 2.05V rms and 1.6V rms respectively.
In any case, the max output voltage of the preamps are above or equal to the max input voltage of the amps. To my understanding, it will be good to prevent any amp clipping. However, since I am not an expert of this field (my day to day business is biotechnology!), I would like to get your feedback about what would be the optimal gain to select for the Purifi amp to combine it with both other the other amplifiers and the processor. Moreover, especially with the AVM60, do I have to envisage the use of attenuators between the processor and the amplifiers to have a better match?
i am looking forward reading your feedbacks!
 

Abe_W

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I will set-up a mixed HC/HIFi 5.1 system based on a Preamp processor (either an Emotiva XMC-2 or an Anthem AVM 60) and a mix of class D amp from HYPEX (center, surround & zone 2) or Purifi (L,R). They will power Dali Rubicon LCR as front loudspeakers (Sensitivity 89bB). A Rel T9i will be used as subwoofer.
I had a look on the specs of the processors: the maximum output voltage of the AVM60 is 8.4V rms (XLR output) while the one of the XMC-2 should be around 4V rms. The purifi amp from Audiophonics has an ajustable input gain either +7.3 dB or + 12.3dB. With +7.3dB gain the maximum power output is reached with an input voltage of 4.2V while with a +12.3bB gain max power outpout is reached with 2.25V. Moreover the HYPEX specs for NC400 or NC250 modules indicates that maximum power is obtained with input voltages of 2.05V rms and 1.6V rms respectively.
In any case, the max output voltage of the preamps are above or equal to the max input voltage of the amps. To my understanding, it will be good to prevent any amp clipping. However, since I am not an expert of this field (my day to day business is biotechnology!), I would like to get your feedback about what would be the optimal gain to select for the Purifi amp to combine it with both other the other amplifiers and the processor. Moreover, especially with the AVM60, do I have to envisage the use of attenuators between the processor and the amplifiers to have a better match?
i am looking forward reading your feedbacks!
If you are dropping more money on AV pre pros, get a Yamaha, Denon or Marantz man and the matching multichannel class AB power amps from the same brand. You would have little to worry about after that....These Japanese guys know how to do things right (Emotiva and Anthem are unrefined sht that will break down on you in a year or two. Class D is sht in general...gnite).
 

yodog

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Anyone else got any knowledge on the op’s question? I was wanting some clarification in this subject.... every instructional video or article just says to trust your ears but honestly I really don’t trust my ears all the time so it would be nice to learn a more technical or methodical approach to gain structuring / setting the gain / optimizing the gain between source, preamp, and power amplifier.

please do share what you know to be true and has had wonderful results or please share what you know doesn’t work because you blew up your speakers or damaged your equipment. Thanks and cheers.
 

Blumlein 88

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I didn't see this when it was originally posted. And I must say the only reply was very poor information. Apologies to @ririt that you didn't get better responses.

Let us look at two extremely poor ways to do it.

Let us say your amp needs 4 volts to reach maximum power. And your preamp can only put out a maximum of 1 volt. Obviously you won't be able to get very much power from your power amp. You probably won't get your speakers to play as loudly as you wish unless you used a power amp that is vastly over-sized for your speaker's needs.

In the other direction your power amp is really sensitive and only needs 1.5 volts to reach maximum power. You are using a pre-amp that can output 15 volts at max volume. You would be in danger of accidentally clipping your amp very easily. Your volume control could only be used at very low volume settings. Low volume settings may be noisier and it may make setting the volume a very touchy overly sensitive thing to have to do. If this is an old analog volume knob you'd probably have to use it only over the lowest 10% of its range.

You would like for your preamp max output to be close to the value needed for max power from your power amp. In the example above the XMC-1 with 4.2 volt output would have been a better match for all the various amps the poster listed. It is a little higher than needed, but that would have been the best match. Setting the Hypex for 4.2 volt input sensitivity and attenuating the signal to the other amps would have been the best choice.
 
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