2 Power Amplifiers 1 set of Speakers - Amp switch? - Page 2 - AVS Forum
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post #31 of 50 Old 07-25-2011, 07:21 AM
 
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Quote:


4PDT Toggle Switch # K402 (first pic attached) was a 20 AMP @ 125 VAC
and it did not work because of "an impedance mismatch (contact resistance) with the high current switch."

This is BS, who told you that?
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post #32 of 50 Old 07-25-2011, 07:49 AM
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The two attachments in post#28. The first one works, the second one does not.

Perhaps the reason is different but the first one did not work when connecting two amps and one set of speakers to switch between. The second one did.
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post #33 of 50 Old 07-25-2011, 07:54 AM
 
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The mechanical drawings of the switches don't tell you anything about them electrically.
Chances are you connected it wrong, which is why it didn't work.
There is no impedance matching here.
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post #34 of 50 Old 02-14-2012, 11:57 PM
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I made a DIY amplifier switch. It is a very simple project, no power supply required, only a few passive components. Here you can see more pictures of the project: DIY amplifier switch

visit my DIY web site http://www.apcc.tk
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post #35 of 50 Old 02-15-2012, 09:32 PM
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Quote:
Originally Posted by SAM64 View Post

The mechanical drawings of the switches don't tell you anything about them electrically.
Chances are you connected it wrong, which is why it didn't work.
There is no impedance matching here.

Yeah, there is no impedance matching to the switch.

However, if anyone is contemplating using a tube amp with a selector switch that could potentially put the amp in an unloaded condition you could damage the amp, possibly quite severely (output transformer ruined, etc.). I've seen some recommendations to put resistors, say 150 ohms, across the terminals used for the tube amp side just in case you turn on the amp with no load or change the selector switch and remove the load with the amp on. For SS amps this generally isn't a concern.

Just because there is a knob doesn't mean you should turn it.
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post #36 of 50 Old 02-16-2012, 12:42 PM
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Guys Niles A/B Amp Speaker Switch.They go for around $90 bucks.I have one and it works great.I have it hooked up to two AVR's and one set of Polk Monitor 70,s.Again it is well build.You hook up all the speakers wire's from the two AVR's,Amp's,and speaker wire that will run too the speakers also hook up too the A/B Amp speaker switch and your good.
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post #37 of 50 Old 02-16-2012, 12:53 PM
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post #38 of 50 Old 02-17-2012, 12:42 PM
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Quote:
Originally Posted by FoxHoleJoe View Post

Guys Niles A/B Amp Speaker Switch.They go for around $90 bucks.I have one and it works great.I have it hooked up to two AVR's and one set of Polk Monitor 70,s.Again it is well build.You hook up all the speakers wire's from the two AVR's,Amp's,and speaker wire that will run too the speakers also hook up too the A/B Amp speaker switch and your good.

A 4PDT switch and some terminals run less than $10. Granted not as pretty, but still foolproof as long as you get the connections right.

Just because there is a knob doesn't mean you should turn it.
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post #39 of 50 Old 02-17-2012, 02:46 PM
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Where do you buy the parts for $10?
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post #40 of 50 Old 02-17-2012, 02:56 PM
 
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try digikey for a start
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post #41 of 50 Old 02-17-2012, 03:06 PM
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OK, can you post a model number of a fairly large one since it's hard to work with smaller ones?
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post #42 of 50 Old 02-19-2012, 12:34 PM
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http://www.parts-express.com/pe/show...number=060-572

Just because there is a knob doesn't mean you should turn it.
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post #43 of 50 Old 02-19-2012, 12:50 PM
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That's the one I tried originally and it didn't work so I had to use a smaller one, if anyone else ever tries it, please posts if it worked.
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post #44 of 50 Old 02-19-2012, 01:41 PM
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Quote:
Originally Posted by c627627 View Post

That's the one I tried originally and it didn't work so I had to use a smaller one, if anyone else ever tries it, please posts if it worked.

Then the switch must be broken (and you should ask them to send a replacement) or it was connected improperly. Those are the only two plausible explanations why it didn't work.

Just because there is a knob doesn't mean you should turn it.
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post #45 of 50 Old 07-06-2013, 03:12 PM
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I'm considering connecting my two vintage 60's tube amps to the same speakers and same source (mp3 for example). I'd have an RCA to 3.5mm cable on each amp leaving me with two 3.5mm connections plugged into a Y adapter making one 3.5mm connection plugged into my laptop. Each amp would have speaker wire going to the same two speakers so each speaker would have two speaker wires in both the left and right. Wwo amps would be playing the same music from the same source on the same speakers.

Is this crazy or doable?
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post #46 of 50 Old 07-07-2013, 02:34 PM
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Sounds like a recipe for trouble.

What is it you're trying to accomplish by doing what you propose?

Just because there is a knob doesn't mean you should turn it.
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post #47 of 50 Old 07-07-2013, 07:59 PM
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Just trying to hear what using two separate preamps (both amps are integrated) sounds like. Also I plan to use each amp separately (one for TV/Mp3 and one for phono/tape) with simple wiring.
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post #48 of 50 Old 07-07-2013, 08:55 PM
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Hi Brandon,
Quote:
Originally Posted by Brandon3858 View Post

I'm considering connecting my two vintage 60's tube amps to the same speakers and same source (mp3 for example). . . Each amp would have speaker wire going to the same two speakers so each speaker would have two speaker wires in both the left and right. Wwo amps would be playing the same music from the same source on the same speakers.
I think I smell smoke . . .

If I understand correctly, then each amp will be driving into the other amp. They may both survive, but it would be similar o a tug-of-war, and one of them may end up in the mud. Even if using the same source, the audio would be distorted due to the differences between the amps (different phase-shift and non-linearities). Even if you plan to not use the two amps at the same time, you should have some kind of switch to prevent one amp from driving the other.
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post #49 of 50 Old 07-08-2013, 06:21 AM
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Quote:
Originally Posted by c627627 View Post

So 4PDT switch then?


Any particular 4PDT switch specs?

When we built and sold ABX boxes:



We speced the speaker switching at less than 0.010 ohms series resistance from banana jack to banana jack when that path was switched on, and infinite ohms when switched off.
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post #50 of 50 Old 07-09-2013, 12:10 PM
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Quote:
Originally Posted by Brandon3858 View Post

Just trying to hear what using two separate preamps (both amps are integrated) sounds like. Also I plan to use each amp separately (one for TV/Mp3 and one for phono/tape) with simple wiring.

Then I think you need a switching device to isolate to one amp/speaker pairing at a time. If the amps have tube outputs then you also need to provide for a load for each amp so neither operates unloaded when the other is selected/in use.

Just because there is a knob doesn't mean you should turn it.
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