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Bi-amping - Conrad Johnson CAV-50 & McIntosh MC275

Need some advise on the setting of the McIntosh MC275 volume pot.
Earlier today I hook-up my Conrad Johnson CAV-50 (integrated amp with pre-out, max. 45 Watts/ch) to the bi-wire input to drive the tweeter of my speakers, and then I connect the preamp output of the CAV-50 to the McIntosh MC275 (power amp, Max. 75 Watts/ch) to drive the woofers. Since there are 2 Volume potentiometers on the MC275, just wonder where should I set them to. Here are more info:

From the CAV-50's manual:
"PRE-OUT:
Connect this output to the input of a secondary amp......We recommend the use of an amp with an input impedance of 50k ohm or higher.....
Specifications:
Hum and Noise (PRE OUT): 94 dB below 2.5V"

From the MC275 manual:
"Sensitivity
1.2 Volt unbalance (since I am using RCA's, so I assume it's unbalance)
2.5 Volt balance
While the name plate of the amp MC275 specify:
Input Sensitivity
Unbalance - 1.2 V variable, 60 kohm
Balance - 2.5 V fixed, 180 kohm"

Again, where should I set the volume knobs to? 1.2 V or 2.5 V; or even somewhere in between to get the right balance of sound.
pioneer48
4 responses Add your response
pioneer48 OP
11 posts
 
Thanks folks for all the ideas and comments.
What I did last night was:
1. using my regular preamp Joule Electra LM100MKII on the MC275 and get a feel of how it sounds.
2. Then put the CAV-50 back and adjust the MC275 to closely resemble the balance of high/low as with the Joule Electra.
I found the best balance is setting the volume control of the MC275 to approx. 3V around 10 O'clock position.
stanwal's avatar
stanwal
3,147 posts
 
The above post contains what I consider misinformation in that the poster states that ONLY using an electronic crossover is biamping. What he is describing is ACTIVE speaker drive rather than biamping. Any time you are using two amps to drive different sections of the speaker you are biamping whether you are using active or passive crossovers. I have often biamped using the internal crossover in the speaker but have not gotten into driving the speakers actively, that is with the crossover IN FRONT of the amp with the amp driving the speaker directly. This approach has many theoretical virtues but is much harder to do; it is only for the really experienced. I set out to do it last year and I had no idea of the complexity involved and I have been in audio almost 50 years.
yioryos's avatar
yioryos
723 posts
 
Please see this page for an inside information regarding bi-amping.
http://sound.westhost.com/bi-amp.htm

Regards
George
stanwal's avatar
stanwal
3,147 posts
 
You will have to do it by ear; you are using two different amps with different power ratings and input sensitivities into two different loads so you will have to use a variable input on the Mac to balance them. There is always the possibility that this will not work, that is that the Mac is less sensitive than the amp in the CJ even at its highest setting. The you are in trouble unless you can adjust the internal amp level as well. This sounds complicated but what I am saying is this; you will end up with 2 amps with different sound levels; AS LONG AS the louder one has the volume control so you can lower its volume you are all right. If the louder one has no volume control you have problems.
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