Ernie,

An L-Pad should present a constant load to the amplifier. Maybe you were smoking brownies back then.

Ahh. I missed the ebay link and confirmation by the OP. I had a display in my store that an autoformer on once side and a very intentionally overcooked L-Pad and surround wall structure on the other to demonstrate the disaster potential for the later. It worked very well.

Anyway, given that information and presuming the wiring is in decent shape, I'm with most of the others; replace the controls and speakers with known quantities and get very happy customer once they hear the improvements.

Yes, they should, no I wasn't (I could never get them in the pipe). Maybe they were the kind of control that disconnected the wiper in the zero position. Too late to look now.

You certainly can use the yamaha to drive 70V speakers.
I have a Rane 4ch unit that I typically use. Mostly in places that have
a good quality amplfier lacking the 70v/100v outputs.

Add this to the speaker outputs. You will have to mono the signal coming into the yamaha.

[Link: bhphotovideo.com]

Yes, you certainly can use the Yamaha to drive 70V speakers. It is not recommended because it is not the best use of the amp.

The amp is designed to deliver its full power to an 8 ohm load. When loaded with a 70V line, very little power is drawn from it.

A 70V amp delivers its full rated power at 70V. That's what the spec means. If we had an amp that could deliver 70 volts to an 8 ohm speaker, that amp would be outputting 612.5 watts. And that speaker would be freakin' loud!

But if you cannot draw 612.5 watts from the amp because, say, it's only capable of delivering a voltage that would give you 100 watts at 8 ohms (which is 28.28 volts), then you can't possibly match the volume that you'd get with the same wattage from a 70 volt amp.

My point is, just as you can use ten feet of CAT5 as speaker wire because it's buried in the wall and you simply cannot replace it, you should never take that as your starting point. You should never take an amp designed for 8 ohm loads as your starting point with 70 volt speakers.

If you must use 70V speakers and they have a variable transformer tap, setting the speaker's tap for higher power results in a lower impedance presented to the amplifier.

First of all, thanks for all the responses. Sound.SD in post 9 provided some good info on both the speaker and VC. I would have never thought to look in the Polish edition of eBay.

The photo of the VC is a different model, but the specs indicate the one I am referring to is 8 ohm. Sorry about the 70 volt conclusion.

Now for the Yamaha AVR, speaker wire, or what looks like lamp cord, is connected to the speaker b front terminals and to the surrounds. So, a connection for two speaker pairs, yet the house has seven volume controls and seven speaker pairs. It looks like a complete rewire is in order.

House was built in 1998, and current homeowners purchased in 2008. They say the “system” was in place when they moved in and was operating until recently. Some speakers do actually function.

Thanks for letting me share my “70 volt confusion”.

Mortronics VC model 816122 CL
Atlas Soundolier C10 speaker
Yamaha RX-V363 receiver

[

And the back of the Yamaha AVR. I had to practice my new found image insertion skills one more time.

I hate wire nuts. If there are more wire nuts in other locations, this could be why some of the speakers don't work.

Odd. I found info on both the speakers and the mortronics control by googling with no special anything. I was willing to look at a model number like C10c in addition to the one given, C10, which I've learned is often helpful.


Yeah, it was the TITLE of the thread, so we were going to jump on it!


same thing to many people

That's weird just because one would think of connecting to the A terminals. And what surround mode was the receiver on? You didn't start pushing buttons without noting the initial settings, did you?

If the system was used at low volume, that could have worked. An amp specced to supply, say, 100 watts into 8 ohms will be very happy supplying five watts into two ohms. When the wrong load impedance is connected, that doesn't mean the amp will automatically fail. It means you have to adjust your expectations of what the amp can do before failing.


You should trace out the wiring, as suggested, to see what's what. If you had seven pairs of home run wires, you could add a multichannel amp. It you have four home runs, you'll have to work out how they spread out to seven sets of speakers, then used impedance matching transformers to match the loads. You might be able to or have to use a two channel amp! Hell, if they want background sound at 60 dB, that Yamaha amp might suffice, in two channel stereo. or in 5 channel stereo using the channels that are used right now.

The preferred thing, of course, is an actual DESIGN that will allow the amp to be turned up all the way, playing the speakers loud, with no distortion due to overloading. In other words, making all parts of the system operate to the full extent of their specs.

Congrats on image insertion.