2 sources, one set of speakers....
Jul 20, 2003 at 5:55 AM Thread Starter Post #1 of 19
JMT

JMT

JMT Audio:PPA/META42 Amp Factory
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Is it possible to use a single pair of speakers when running a seperate audio/HT system? There are switchboxes to select multiple speakers for a single source, but is there a mechanism to select multiple sources for a single pair of speakers? I tried just connecting both amps to the speakers, but the HT receiver overloads and shuts down.

I hope I'm not destined to have to swap speaker cables whenever I want to listen to music, or watch a movie. And, another pair of speakers is not an option (according to my wife).
frown.gif
 
Jul 20, 2003 at 6:28 AM Post #3 of 19
You're a pretty handy guy (or so I'm told by about a million JMT Meta users) - I would think building a small, but high quality switch box for speaker terminals would be no problem. Simple two position switch (to control 4 wires each) with some high quality binding posts for input and output (assuming that the inputs would be from speaker cable, if they are line-level even easier). As long as you stuck with good quality parts and some high quality short runs of cable inside, I bet any quality loss would be minimal.

Is there any commercial product that would accomplish this? Not to my knowledge (at least a nice one, may be one at rat-shack or something), but my knowledge is a far cry from what's out there.

-dd3mon
 
Jul 20, 2003 at 2:29 PM Post #5 of 19
Quote:

Originally posted by dd3mon
You're a pretty handy guy (or so I'm told by about a million JMT Meta users) - I would think building a small, but high quality switch box for speaker terminals would be no problem. Simple two position switch (to control 4 wires each) with some high quality binding posts for input and output (assuming that the inputs would be from speaker cable, if they are line-level even easier). As long as you stuck with good quality parts and some high quality short runs of cable inside, I bet any quality loss would be minimal.

Is there any commercial product that would accomplish this? Not to my knowledge (at least a nice one, may be one at rat-shack or something), but my knowledge is a far cry from what's out there.

-dd3mon


A couple of relays, a rocker switch and a piece of protoboard would do the trick as well, but I haven't seen any commercial devices to accomplish this type of switching.

/U.
 
Jul 20, 2003 at 4:01 PM Post #6 of 19
Here's a link to Chu Moy's Passive Preamp/switchbox. What I've always wanted to know is if this same thing could be done without having to switch inputs (ie: I'm listening to music on my CD player and I want to hear alert sounds my laptop makes while listening). I've looked at Headwize's article on making an unbalanced summing box, but I don't understand why the ring connections have resistors and not the tips. Wouldn't it cause the left channel to be louder than the right?
confused.gif
 
Jul 20, 2003 at 4:28 PM Post #7 of 19
Quote:

[size=xx-small]Originally posted by CRESCENDOPOWER

Does your receiver have stereo line level pre-outs?
I'm having a hard time understanding what you are asking.
[/size]



Dave, what I am trying to do is feed two separate systems into one set of speakers. For all intents and purposes I want to keep my two channel audio system and my home theatre independent of one another. The only issue is the main speakers (I want to use the same pair of speakers for the HT mains and my two channel listening). Space and wife limitations prohibit an additional pair of speakers so I attempted to simply run both amps to the speakers. But, even with my stereo amp off the HT amp overloads and shuts down during intense audio (music, sound effects, etc.) portions of a movie. I hope that makes sense.

My HT amp is an old Yamaha HTR-5140 and does not have any line level pre-outs. It appears I am destined to cable swap when switching sources....what pain.
rolleyes.gif
 
Jul 20, 2003 at 4:48 PM Post #8 of 19
So, basically you hard wired both sets of cables from both amps to your front speakers, and now your home-theater receiver shuts down? If your stereo system is not turned on I don't see what could be causing your receiver to shut down?
 
Jul 20, 2003 at 4:56 PM Post #9 of 19
Quote:

So, basically you hard wired both sets of cables from both amps to your front speakers, and now your home-theater receiver shuts down?


Correct
Quote:

If your stereo system is not turned on I don't see what could be causing your receiver to shut down?


Neither do I. Funny thing is that it worked before I swapped out my Marantz integrated for a pre/amp combo that drewski lent me.
 
Jul 20, 2003 at 5:57 PM Post #12 of 19
Quote:

Originally posted by JMT
Funny thing is that it worked before I swapped out my Marantz integrated for a pre/amp combo that drewski lent me.


When you connect it like you did, the stereo amp is connected as an additional load across the outputs of the reciever. So the stereo amp is acting as a short-circuit to the reciever. Some amps have small emitter resistors (~1 ohm). If this is what the reciever sees, no wonder it's shutting down. Just a thought...


/U.
 
Jul 20, 2003 at 6:07 PM Post #13 of 19
JMT: QED is usually a good source for such stuff. In your case, the MA19 should work - more info here: http://www.qed.co.uk/acc/switch.html

Greetings from Munich!

Manfred / lini
 
Jul 20, 2003 at 9:21 PM Post #14 of 19
lini, thanks for the link. That looks like exactly what I need. Unfortunately there is no information relative to ordering and pricing, and I cannot find any U.S. retailers for their products. I did send a PM to one of our U.K. members asking for assistance.

Thanks again.

Nisbeth, that sounds like that is what is happening. Perhaps the amp that I am now using is configured differently than the Marantz that I was using before. Thanks for you insight, it's appreciated.
 
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