Copying the wiring exactly from my Marshall 2x12. Right input supposed to be 8 ohm mono (left is for stereo - ignore that bit).
The speakers are 16 ohm and in this pic the right pair of wires go to one speaker (red positive / black negative) and the left do the same on the other speaker.
To my mind it's wired in parallel rather than series. Does that not mean that the impedance remains at 16 ohm for that mono input?
My H&K doesn't have an impedance selector but apparently puts out 25w into 16 ohms and 40 into 8 ohms. So, I'm guessing it's factory-set at 8. That make sense? I've always believed less into more (8 ohm amp output into 16 ohm speaker) was OK whereas the opposite isn't?
Cheers. I've no occasion to at the moment. Just setting up my new 212 with a couple of 16 ohm speakers and wanted to ensure it was 8 ohms for the new Boogie. Only tired it through my Boogie 412 so far but that's up for sale.
Yes - when two output sockets are wired like that they are wired in parallel to the same OT secondary. So if its a 16R secondary, then you would want to run 1 x 32R cab to each socket to get a 16R load (32R||32R = 16R). If you run 1 x 16R cab to each socket, that will be an 8R load in total, and therefore the reflected load back through the OT to the output tubes will also be halved - which means the output tubes won't work as efficiently or last as long (all other things being equal). But it usually doesn't do any immediate harm to run output tubes at half the optimum load.
Actually on second glance I think those might be switching jacks and I see there are two sets of red and black wires running to them. So I would want to see a schematic. If the red leads are coming from different taps of the OT secondary then you might have a switching impedance option built in. Can't really tell without details.
The left jack insertion disconnects the right one and connects to one speaker only. I don't use any stereo output stuff so that bit doesn't concern me. Cheers. Appreciate the replies.
