don't run them straight in.
If you put a pair of dpdt(double pole, double throw) switches in between, and the center pole is the wires going to the speaker terminals, one side of the switches is one amp, the other sides the other. fine.
So I gather this cannot be done with quality speaker cable? We're talking about plain ole 16 guage speaker wire or the like? I wanted this for a hi end rig. I suppose it cannot be done with these double pole/throw switches with audiophool speaker cable? Is my thinking wrong? I have no idea what these switches are about. I am an electric doofus.
With respect to your question about wire -- yes, you can use high end wire with Elizabeth's switch idea. Most high end speaker wire comes terminated with spade lugs, so just make sure that the switch you buy can accommodate the size of spades on your wire.
Do you have an extra line level output on one of your amps and an extra line level input on the other? If so, you can connect them at the line level, assuming they are close enough together.
Any audiophile approved speaker cable can be used with the switches.
BUT, you would need to have some 'extra' wire of the same type. (a few feet would do.)
Locate your 'switchboxes' right up close up to the speaker, one behind each speaker.
The dpdt switches would be in a small box from Radioshack.
The side of the box could be quality 5way binding posts WBT would be good. Then a bit of audiophile wire soldered from the 5way to the switches, then use a longer bit hardwired to the switch (Remember, this is from the center terminals of the three pairs on the switch bottom) to terminate with spades or whatever right on your speaker terminals.
Two small aluminm boxes about 1.5"x2"x3" from Radio Shack.
Two DPDT switches rated 120v are fine, also from Radio Shack. (you could go for some really expensive silver contact dpdt switches, but I do not know where you could find them?)
(expensive parts:) EIGHT pair of binding posts. You can go cheap from Radio Shack, or go for WBT at up to $40 each.
The extra speaker cable you need about 3 to 6 feet of cable (but you want the box on the floor right behind the speaker, so whatever it takes to go up to the binding posts from the floor.) (mine are TWO FEET off the floor)
Any electrical type person can drill the holes in the boxes, wire up the wires to the binding posts, switches and the straight from to output of the switch (the center pair of three pair on each switch THIS IS IMPORTANT) with spades or whatever to connect directly to the speaker posts.
one set of the receiver A right speaker goes to the right side box posts A. The other receiverB goes to the right side box posts B. the switch in the box uses the receiver output you select and leaves the other circuit OPEN (which is fine if you accidentally leave the other receiver on.
So both are never shorted to each other, but only one at a time is powering the speakers.
You could also use a SPEAKER SELECTOR SWITCH but would have to install it "Backwards" As you want 2 receivers and one speaker pair, instead of one Receiver and TWO speaker pairs.
Elizabeth, are the switchboxes required to use as a safty feature in case both amps are left on? If one amp is off why would their be a problem connecting both spades directly to the binding posts of the speaker?
If you leave both amps connected to the speaker, the one powered up will likely damage the output stage of the one powered off. That's why you need a switch.
Also, if either amp uses tubes in the output stage be sure that the speaker is connected to the amp before powering up or you could damage the output transformer. No such problem with solid state outputs.
May I add that the switch you seek should have a 'break before make' not the 'make before break' type circuitry.
Here are the make before break/break before make definitions:
In a make before break type, a contact will not open it's primary output circuit until it has closed it's secondary circuit. Conversly, in a break before make type a contact opens the circuit to one output before it closes the circuit to a second output.
Also a DPDT with a "OFF" center position will work.
Ghostrider, I understand now the reason for the switch. One of my integrateds is tubes. Wouldn't you hook up the spades with power off for safty, anyway? Once the tube integrated is hooked to the swith box, powering up is not a factor, correct? It would seem that this, once the deed is done, to be a good way for me to have tubes and ss. I'm a little concerned that the switchbox is a kink in the signal--amp to speakers. Am I over reacting?
This electrical stuff is a bit intimadating. Would it be possible to find an audio repair shop to construct the two switch boxes with binding posts, etc. for me. Then all I would have to do is hook up the speaker cables? I could call Zu and get a few feet of their Ibis cable. Would that be cool? Maybe a bit more expensive, but less heatburn.
You should be a bit intimidated. If you do this wrong, you risk serious damage to your amps. In addition, to what was said above, I've heard that some tube amps do not like having no load on the outputs while the amp is on. That would be a problem if you switched over to the transistor amp while the tube amp was still on. Yes, you might be able to find a shop to make up a switchbox with what you need. Or, you might consider putting dual banana recepticles on the end of the speaker wires and bananas on the end of the amp wires, put the ends in a handy place and hook them up like an old-time telephone switchboard operator. If you describe why you want to do this, there might be other and better solutions.
You can get an automatic switch from someone like Niles Audio for this exact purpose.
Rwwear, very cool. Looks just like what I need. I probably could rewire the interior (or have it done) with Ibis cable. That would keep the continuity/wire DNA in sync, don't you thin? One or two of those switch boxes? I suppose the binding posts are on the back? thanks for the tip. warren
The reason why really doesn't really matter, but there is a major factor which nixes this idea. The bottom line is that the swithch box, no matter how you look at it, is a pothole on a perfect highway. I believe regarless of the connections and workmanship there will be inherent factors that have a slight, but, deleterious effect of the signal. Total isolation is impossibe. I'm going to let this idea go. The reason btw, was since I have an SET amp, and my speakers, though 101db, can handle up to 500 watts per. I just wanted the ability, on the rare ocassion I want my ears to bleed..lol...to pump in 100 or 200 watts. I have heard what these babies can do with a 100 watts per and would like to have that capability. Look, I can always have the speaker spades right next to the speakers and unhook and rehook. A bit of a pain in the ass. something I know I would not be into. My fellow audiophools, thanks for your tips. peace, warren
Interesting thread. I actually do this with my set up, without a switch box. So far, no problems noted. I've got the Gallo sub amp hooked up to the secondary voice coil input speaker terminals, and my tube amps connected to the primary voice coil inputs. If I'm going to leave the system on all day and not be in the room critically listening, yada, yada, I'll sometimes save tube life and swap the sub amp leads into the primary voice coil input on the speakers, switch the low pass filter off on the amp, and turn the tube amps off. I terminated the speaker cables form the sub amp in banana plugs for ease of operation when doing this. Is it a general consensus of opinion that I may be damaging my very expensive Bruce Moore tubed power amps by doing this? I always have them OFF when running things this way.
Thanks in advance for the replies,
In case anyone else stumbles across this thread, as I did, I just talked to a friend who's a former Bruce Moore engineer, and he confirmed, even with the tube amps off, the transformers will send a high AC signal to the plate and screen grids on the tubes. The tubes are designed for that, but not with the power off.
So, I'll end this practice.
Rolloff, glad to hear that my orignal thread may have saved you from disaster. Seems like it has...peace, warren :)