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pioneer sx 1250

I have a pioneer sx1250. I see where it has connections for A, B, and C speakers. I tried setting up with 3 sets of speakers but only 2 sets will play. either A,B A,C B,C etc. when I engage the C speakers all the speakers shut off. Disengage any set , A B or C and the other 2 sets begin to play again. I am asking if this is as it is intended to be ? Thank you, Mark

Re: pioneer sx 1250

Hi Mark,

It is dangerous to run more speakers in parallel than recommended. Because this is a high power receiver it operates at very high supply voltages. If you connect more speakers in parallel, output impedance becomes low and the power dissipation of the output transistors goes very high and may result in the failure of these devices.

One more note, usually the heatsink grease on the older receiver dries up and the output transistors may not dissipate all the heat very well, so better not to connect more than 1 set of speakers unless a fresh heat sink grease is applied.

It happened to me once, and most of the output transistors of my Luxman M-4000 gone bad.

Re: pioneer sx 1250

Yes, this is normal. There are 3 sets of speaker outlets but the amp can only drive 2 sets at a time.

Re: pioneer sx 1250

JaS, Thank you for this info. I just assumed I could use 3 sets of speakers on such a big amp. My next question ( as you might guess ) is can I safely hook up additional speakers to run simultaneously. We like our music rather loud and the goal is to lighten the load on the other speakers while attaining a wall to wall affect. Of course we do not want to loose sound quality or beat up the SX 1250 in the process. Your help is appreciated, Mark

Re: pioneer sx 1250

Personally I'd stick to a maximum of two pairs of 8 ohm speakers as recommended in the manual, but in theory you can attach as many speakers as you like, as long as the combined load on each channel is 4 ohms or more. The protection circuit should trip in if the load becomes too great or you are driving the amp too hard, but it's safer to follow the manufacturer's recommendation.