Help With Impedance Matching (1 Viewer)

IBourgal · Feb 21, 2015

I have installed a Russound ALT-126R volume control and need help determining the impedance match setting.

The setup is this:

Yamaha R-s700(set to 8ohms)>Niles Audio SS-6 speaker selector.

From the speaker selector are 3 pairs of Infinity P162 (rated 8ohms)

1 pair of B&W 686 (rated 4ohms)

The Volume control is between the speaker selector and the B&Ws.

How do I determine the impedance setting on the volume controls?

The instruction manual includes a chart, but I cannot tell if the speaker selector changes things. Do I treat it as if the B&Ws are the only pair? Or do I include all of the 8ohm pairs?

Any help is appreciated. I can post the chart if it helps. thanks.

Al.Anderson · Feb 22, 2015

It sounds like the speaker selector is in series with a single set of speakers; if so the impedance is simply cumulative. What bothers me is they included a chart, so they seem to think it's more complicated than that. Checking their site, it appears they allow for multiple pairs of speakers to be attached to the device, so that is probably what complicates matters, which you aren't doing. But yeah, it would be interesting to see the chart.

IBourgal · Feb 22, 2015

Here is the link to the manual. The Charts are on page 4. Again, I have the receiver at 8ohms>speaker selector>then 3 pairs of 8ohm speakers and 1 pair of 4ohm (with the volume control). Thanks for the help!

Here is the link:

http://a248.e.akamai.net/pix.crutchfield.com/Manuals/543/543ALT126R.PDF

schan1269 · Feb 22, 2015

The chart is straight forward.

Treat the B&W as two pairs of speakers...so...you "have five pairs of speakers".

That is a typical speaker switch ran in parallel.

3 pairs of 8 ohm speakers ends up at 2. Throw in a 4 ohm pair, you are at 1.

1 ohm times 8...

8ohm.

Al.Anderson · Feb 22, 2015

What threw me off in the original post is this, "The Volume control is between the speaker selector and the B&Ws." But as Sam figured out, you really have the switch between (or connected to) ALL the speaker pairs.

So yeah, I agree with Sam, set the volume control to 8x. (Although I can't follow Sam's calculation; I was just using the chart.)

IBourgal · Feb 22, 2015

Thanks. Is it ok that I end up at 8ohms and not 4 (as the speakers are rated)?

schan1269 · Feb 22, 2015

IBourgal said:
Thanks. Is it ok that I end up at 8ohms and not 4 (as the speakers are rated)?

Yep.

Won't make any difference...to the speakers.

The only thing that matters is not making the amplifier crash and burn.

Al.Anderson · Feb 22, 2015

While I'm not positive, it appears that the control knob is just trying to make up for the fact that you're running speakers in parallel. If you did that without some sort of compensation you put a very low impedance on the amp, which would likely fry it (these days it would just go into protect mode, but it's fun to say "fry"). So to answer your question, yes it's okay (and doesn't have anything to do with the speaker, it's for the amp).

IBourgal · Feb 24, 2015

One more question.... Does anything change if the speaker selector says it is also "impedance matching?"

schan1269 · Feb 24, 2015

Ok. Is the volume control, before or after the SS6?

If after, don't set anything. That Yamaha, with the SS6, will be fine if only 1 pair is 4ohm.

IBourgal · Feb 24, 2015

The volume control is after the ss6, before the 1 pair of 4ohm speakers.

IBourgal · Feb 24, 2015

So, leave the volume control at 1x?

Al.Anderson · Feb 24, 2015

Set it to 2X.

Read the chart like this:

- 1st chart (for 8 ohm receiver).

- 1st col (y-axix) 1 pair of 4 ohm speakers

- 1st row (x-axis) 0 pairs of 8 ohm speakers

- the cell where they intersect says "2X"

IBourgal · Feb 24, 2015

Thanks

IBourgal · Jul 25, 2015

Well, everything was working fine and sounding great for months. Until last night. The computer that was connected to the line input crashed. Since this is a bar, an Iphone was used to keep the music going. The manager connected the phone to the phono input instead of the line input. After a couple of hours, the SS-6 (speaker selector) caught fire! I didn't think fire was possibility. Everything was working fine for 10 hours a day since February. Could this change have caused this? What do I need to change to keep these 4 sets of speakers working all day everyday?

schan1269 · Jul 25, 2015

IBourgal said:
Well, everything was working fine and sounding great for months. Until last night. The computer that was connected to the line input crashed. Since this is a bar, an Iphone was used to keep the music going. The manager connected the phone to the phono input instead of the line input. After a couple of hours, the SS-6 (speaker selector) caught fire! I didn't think fire was possibility. Everything was working fine for 10 hours a day since February. Could this change have caused this? What do I need to change to keep these 4 sets of speakers working all day everyday?

Yep. Overdrove the system...till something fried.

Make sure the amp isn't fried as well.

IBourgal · Jul 25, 2015

Thanks for the reply.

It turns out it was the Volume Control that burned up, not the speaker selector. What exactly "overdrove the system?" The overall set up or the iphone in the Phono input? Or both?

schan1269 · Jul 25, 2015

IPhone in the phono.

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