2 amp 4 speaker conundrum

[nino11]

Nino11 here. I have a Mcintosh vintage setup. MI-3, MR 71, C-22, MQ101and a pair of MC2002 amps running ML 10 C's as mono blocks. Sources are a TD-124 TT and a Nakamichi CD player. It was running beautifully until..... I found a pair of ML 1C's for a good price and thought I'll run 4 speakers out the two amps as a stereo set up.

But, I've tried multiple connection set ups and can only get sound of the two right sided speakers, What am I doing wrong? Is it an impedance issue? Is it the equalizer? I would appreciate your advise in this matter. I am no physics guru just a music and vintage hifi aficionado.

Thanks in advance,

Nino11

 

[damacman]

Welcome! Nice gear!

If you have the Stereo/Mono switch on either MC2002 set to Mono, only the right input is utilized. This is correct when using the amps in mono.

For the new setup with two pairs of speakers, you need to set each amp to Stereo, run RCAs from the C22 to each amplifier (both Left and Right), connect the ML1Cs to one amp, the ML10Cs to the other amplifier, and you should be set.

Original C22s have only one set of MAIN outputs. So, you'll have to use RCA y-cords to connect both sets of RCA cables. I'm mobile at present so unable to comment on impedance matching between the C22 and the pair of MC2002s so I'll defer that to @62caddy

 

[62caddy]

According to Roger Russell, MC2002 input impedance is only 20,000 ohm while the the manual of the C22 states "input impedance of the amplifiers should be 50,000 ohms or greater".

That said, the jury is still out on whether this would harm performance to a significant or even audible degree. When I recently asked Roger about this, he said the effect "was minimal" but was unable to be more exact.

While the MC2002 lacks front panel gain controls, it does have an input sensitivity switch on the rear panel which may help the situation. I'd suggest trying both settings to see which works best.

 

[nino11]

Thanks, the way my set up is right now the main outputs both R and L are coming out of the MQ 101 Equalizer. So I guess I’ll need 4 Y RCA adapters for amps and the EQ?

 

[62caddy]

Thanks, the way my set up is right now the main outputs both R and L are coming out of the MQ 101 Equalizer. So I guess I’ll need 4 Y RCA adapters for amps and the EQ?

The owner's manual of the MQ101 also states minimum amplifier input spec - "47,000 ohm or greater". The MQ101's input spec of 60,000 ohm is well above the 50,000 ohm minum specified for C22 so no problem there.

However when connecting both amplifiers by way of Y adapter cables will result in a net impedance of 10,000 ohm which is significantly lower than the 47,000 ohm minimum specified for the MQ101. As before, I cannot comment on any penalty to SQ since nobody as yet measured the effects of these apparent impedance mismatches as the owner's literature would suggest.

 

[nino11]

Thanks, to be honest. Physics is not my forte and these things sometimes go a bit over my head but I will give it a try and report!!

 

[damacman]

You'll need but TWO single male to dual female y-cords sir. One to split LEFT ch signals output from the MQ101 and one to split RIGHT ch signals output from same. LEFT goes to each amp LEFT input, RIGHT goes to each amp RIGHT input.

 

[damacman]

The owner's manual of the MQ101 also states minimum amplifier input spec - "47,000 ohm or greater". The MQ101's input spec of 60,000 ohm is well above the 50,000 ohm minum specified for C22 so no problem there.

However when connecting both amplifiers by way of Y adapter cables will result in a net impedance of 10,000 ohm which is significantly lower than the 47,000 ohm minimum specified for the MQ101. As before, I cannot comment on any penalty to SQ since nobody as yet measured the effects of these apparent impedance mismatches as the owner's literature would suggest.

Someone send me a C22 and I'll measure its output impedance!

 

[nino11]

I figured it out last night! Success! Thank you for your patience.