How to Adjust the Volume Between Two Sets of Speakers

The simple dirty way is to put a wirewound pot of say 25-50ohm and appropriately rated in circuit with the pair you want to turn down. Ideally one pot for each (ideally a 2 gang pot) speaker...or you could be really really dirty and join the speaker common terminals and run that through the pot and back to the amp.(Assuming we had stereo...it won't be quite the same any more)
Terms and conditions apply, mess with it at your own risk...nuffin' to do wiv' me guv'
Del

Since I mostly worked with lights, it crossed my mind to wonder if you could throw a cheap dimmer switch in the line that would have ohms in range? Of course the DC rectifier output to speakers may make this thought useless, and I mostly worked with AC power for lights.

In built in home systems there are room volume controls do this.

Then again you may wonder what sort of speaker wire you are running, and how long it is going.

Might be you want thicker wire for the B feed.

I shall defer to Del, here, for consider him much better than myself in this area.

All the dimmers I've ever seen are designed to work on power line voltage. Speakers work on very low voltage, so no- that won't work (unless I'm grossly mistaken).

I thought it was one of the easier tasks in electronics. My car stereo has a front/back control (even in the Tazz) And the hi-fi also had it. (until it broke because some of the speaker wires came loose)

There are products called L-Pads designed for this. Parts Express sells them. They will reduce power sent to one set of speakers so as to balance the others level.

Word of caution. You can easily fry these even though they rate them at 100 Watts. If you turn up the amp loud enough you can dissipate enough power to burn up the L-Pad. If this is just light background music, then you should not have an issue.

A better solution is to buy a second power amp like this and run the second set of speakers off of this amp. Balancing will be easy and both amps will operate better because their loads never change. You will not need the L-Pad with a separate amp.

While Parts Express is located in the US, there are plenty of like stores in the UK.

You can put one of these in line with your remote speakers for about $35:

http://www.smarthome.com/8256/70-Watt-Basic-Stereo-Speaker-Volume-Control-NX-V703C/p.aspx

Dear DCaD, Your suggestion is the one I would go with if I had a similar problem. My "Dimmer" suggestion for one thing would cost about the same, and is not really made for the application.

Still from what I know, a regular Lintron Dimmer is resistive.

If I had a Variac, I would always put that in the line to vary the light intensity over a dimmer, because a 500watt Lintron residential type dimmer would make noise that pissed the Sound guys off.

The hum from Florescents piss them off too.

In this case I will defer to both you and Del, and look forward to learning something, or have forgotten.

P.S. My NAD has twice been repaired, for dropping a stereo channel. I really loved it for it produced great sound, and had imputs and outputs I needed for Ear Movies I made there for awhile. Ran all to it and out of it through a Realistic equalizer and a Pioneer Reverb box so I could isolate sounds, and sometimes give depth. I was working with collections of cassette tapes, which we know are inferior. I used to carry a tape recorder around with me all the time. I didn't look like a nerd, but I guess I was one.

Hang on thar buddy (to be read in a pretendies agressive voice)...
No GA from DTC ???
That L pad link is good... (can you guess the next word?)
But... it DOESNT maintain a consistent load. And if you look at the wirewound device it looks to me like a regular pot.
In the L pad diagram with the wiper at the top the load is the Lpad in parallel with the speaker, with the wiper at the bottom the load is just the Lpad.
I think it may be a case of re-brand a regular pot and mark it up 400%
I've been robbed .
_{But a tough cynical cat like me is used to being POPO'd .... skulks off to secret cat nest.}

Del _{(Just kidding)}

Yeah, you are right of course.
_{( I do know that stuff...I worked in a component and Hi-Fi shop in Soho (the genuine one) after dropping out of uni. and was into building my own amps and speakers...weren't we all?Happy days...[except when my pre-amp was motorboating])}

My original suggestion is based on the observation that you are unlikely to f**k an output stage by increasing the load impedance, whereas reducing the load impedance can produce copious amounts of smoke.
Del

Good point!

So, did you build with tubes or transistors?

This question will seperate the men from the boys.

Transistors... from the wonderful Mullard Audio handbook.
That's how I started into electronics...well actually taking two portable valve record players sticking a stero cartridge in one and wiring the second chanel to the second deck. It worked of course, but there was the 'spare deck' rotating...so I took the deck off the spare and removed the rotor from the motor...
Ohhh look smoke!...
The rest they say is history, although my design process hasn't gained much in sophistication over the years.

Del

That's too funny!

it certainly sounds like an impedance mis- match to me..., as well , some amp's only recommend using 1 speaker output at a time

That's right, if you overload the system you will blow the output stage of the amp....its a common mistake of people who dont understand these things....LOL

From the original post, "Both run off the same amplifier,one pair from speakers 1 and one pair from speakers 2."

Seems to imply that the amp has dedicated terminals for a satellite set of speakers. However, it does seem clear that the output circuit feeds both Speakers1 and Speakers 2.

It is also possible that the impeadence of the two sets of speakers could be different and/or the speaker efficiencies are different.

not to belabor the point, : my amp has 4 sets speaker of terminals.. but still recommends only 1 set be in use at any given time

Hi Team

Thanks for the global response I think I will opt for the two amp solution.

All your comments have been very much appreciated.

Mart

Start with an impedance matched volume control for audio applications, a dimmer switch will not give you the desired results.

Also, the speakers may have a different resistance (between rooms) and this would cause a delta in the volume.

My NAD, and some other amps I've had over the years, had A, or B, or A&B so I could run 2, or 4 speakers, in one room, or in two rooms.

Maybe I needed a bigger house to have the problem.

Still to me I think it is excessive to buy multiples of amplifiers, when pots and or what I know as reostats, would do the equalization job, if the main amplifier was of any power at all.