Hello there! I was thinking about buying an old MC 7106 ($1150, like new condition) to power my LCR channels in bridged mode. It's a six-channel at 100 watts @ 8 ohms, 160 watts @ 4 ohms and can be bridged into 3 channels, effectively doubling the power. Anyway, the issue I'm running into is I was reading the amplifier doesn't like driving 4-ohm speakers in bridged mode, and I'm trying to drive Kef R7 meta & R6 meta, which are 4-ohm speakers. Can anyone verify if this is a terrible idea? Is there something I'm missing? Also, I could run all my speakers single channel, but that would be way less watts than I'm using now with the Emotivas, which is XPA 2 & 5 500+ watts each. The speakers are rated 15-250 watts recommended. I'm having a hard time deciding what to-do, so any input is welcome, thanks!
I have just checked the spec. You can not drive those speakers in bridged mode. If you do you will blow the amp fast.
Since this unit has autotransformers, I thought this might be possible. I checked the manual and it clearly states that the amp will only drive 8 ohm loads in bridged mode.
Your speakers actually drop lower than 4 ohms.
So, absolutely do NOT drive those speakers bridged.
I would not buy that amp. Like everything else amps have improved and by a decent modern amp. Class D amps are now excellent and I would recommend buying one.
Bridging is generally a very bad idea, especially these days when speaker impedances are lower than they used to be.
When it comes down to it, you really don't increase the power in real terms. If you bridge to an 8 ohm speaker, you will get the same power as bridging a four ohm speaker unbridged. So if you bridge to a four ohm speaker, it would be like driving a 2 ohm speaker unbridged and blow up the amp just the same.
There is only one amp ever made that would handle this and it is the Quad 303, which was guaranteed unconditionally stable under all loads. With that amp, you can even parallel the outputs!
The only bullet proof and long lasting vintage amps are the Quad 606 and Quad 909, but you would need two of them to drive your speakers and those amps fetch high prices on the used market, as many know of their great reputation. If you buy Quad gear make sure it is from the era when Peter Walker was alive and running the show. He was obsessed with making high quality gear that did not blow up. His current dumping circuits were pure genius.
