Hey everyone,
I'm brand new to the forum and I'm trying to do something pretty basic. It's probably incredibly boring when compared to building an amp or something much more involved, but I need the ability to share 1 set of speakers between 2 receivers. So far I don't really like the any of the purchasing options that I've found, so I'm thinking about building a switch box.
I have a Carver MXR 150 that I use for stereo (vinyl only), and I recently bought a home theater receiver for TV and movies. The Carver is much better for my vinyl listening needs, so I don't want to do it all with the new AV receiver, and I only have one set of speakers: Klipsch RF series. Hence the need to switch sources.
I know this topic has come up a few times, but I couldn't find anything conclusive about circuit designs or the quality of parts that would be required, so forgive me if I just didn't look hard enough.
My thought is to use a pair of 4PDT relays and to trigger the relays using the switched output of the Carver. The relays would connect one receiver at a time to the speakers, and short the outputs of the inactive receiver through a high ohm resistor, just in case. I was also thinking of adding an LED indicator light.
I've attached a schematic of what I'm thinking about, and I would greatly appreciate feedback. Is this at all on the right track? And if so, what type or brand of relays would be appropriate? Is this just stupid and I should just buy something?
Thanks in advance for any info that you can provide, and like I said, I apologize in advance on the boring nature of my request! 😉
I'm brand new to the forum and I'm trying to do something pretty basic. It's probably incredibly boring when compared to building an amp or something much more involved, but I need the ability to share 1 set of speakers between 2 receivers. So far I don't really like the any of the purchasing options that I've found, so I'm thinking about building a switch box.
I have a Carver MXR 150 that I use for stereo (vinyl only), and I recently bought a home theater receiver for TV and movies. The Carver is much better for my vinyl listening needs, so I don't want to do it all with the new AV receiver, and I only have one set of speakers: Klipsch RF series. Hence the need to switch sources.
I know this topic has come up a few times, but I couldn't find anything conclusive about circuit designs or the quality of parts that would be required, so forgive me if I just didn't look hard enough.
My thought is to use a pair of 4PDT relays and to trigger the relays using the switched output of the Carver. The relays would connect one receiver at a time to the speakers, and short the outputs of the inactive receiver through a high ohm resistor, just in case. I was also thinking of adding an LED indicator light.
I've attached a schematic of what I'm thinking about, and I would greatly appreciate feedback. Is this at all on the right track? And if so, what type or brand of relays would be appropriate? Is this just stupid and I should just buy something?
Thanks in advance for any info that you can provide, and like I said, I apologize in advance on the boring nature of my request! 😉
Seems like a pretty well thought out idea.
So what happens with the amplifiers power while switching, do you intend to power them down before switching? I'm just thinking cautiously here.
As far as relays, I guess as a minimum you need one that will handle the higher wattage amplifier.
So what happens with the amplifiers power while switching, do you intend to power them down before switching? I'm just thinking cautiously here.
As far as relays, I guess as a minimum you need one that will handle the higher wattage amplifier.
In the schematic, S1 is the default source and when S2 is turned on, the relays activate S2's outputs and simultaneously deactivate S1's outputs. If I were to turn on S2 while S1 was on and playing some content, S1's output terminals would open suddenly and I understand that to be bad. So when S2 is turned on and the relays close, S1's outputs are shorted through resistors just in case S1 is still on.
S1's outputs would see infinite impedance for a short time (~25ms) and I'm not sure how bad that is. This is assuming that the relays are break before make. If they are make before break the problem of switching under power could be less severe, or non-existent... I'm not really sure.. That's why I'm here!😀
Thoughts?
S1's outputs would see infinite impedance for a short time (~25ms) and I'm not sure how bad that is. This is assuming that the relays are break before make. If they are make before break the problem of switching under power could be less severe, or non-existent... I'm not really sure.. That's why I'm here!😀
Thoughts?
Sorry I just realized that I didn't quite answer your question.
I'm not planning on switching while the amps are powered, but I'm assuming that at some point it will happen, and I want the setup to be safe.
As for the relays, my Carver is 150 watts per channel, so 10A relays should suffice.
I'm not planning on switching while the amps are powered, but I'm assuming that at some point it will happen, and I want the setup to be safe.
As for the relays, my Carver is 150 watts per channel, so 10A relays should suffice.
Oh OK, well solid statem amps should be able to handle switching like that. If you get some tubed gear down the road you may want to power it down first.
Carry on.
Carry on.
I don't think leaving the unused amp open-circuited is a problem. Most decent power amps and receivers already have relays inside that disconnect the loads to protect from power on/off thumps and DC faults.
Ok, so I updated my design in light of some feedback I received here and elsewhere. I ended up going with two DPDT relays; one for each channel.
I finished assembly of the switch box last week, and enjoyed the hassle free operation all weekend. I even operated the switch while content was being played through the AV receiver (my primary source) and there was no thump on the speakers. I'm not planning on switching like that, but it's good to know it won't break anything.
So here's the updated circuit schematic and a few pics of the finished box:
I finished assembly of the switch box last week, and enjoyed the hassle free operation all weekend. I even operated the switch while content was being played through the AV receiver (my primary source) and there was no thump on the speakers. I'm not planning on switching like that, but it's good to know it won't break anything.
So here's the updated circuit schematic and a few pics of the finished box:
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Somehow I screwed up the pictures. Here they are:
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I sometimes thought that I wanted to use my Sony instead of the Leach amp to the only speakers I have without the hassle of changing the wires.
The solution...
My leach has a speaker protection circuit and the relay has 2 changeover contacts. I am going to connect the NC contacts to the Sony output so that when the big(Leach) amp is off, it (the Sony) plays through.
The GNDs will be shorted.
In my case, the Leach will have priority when it is ON.
Gajanan Phadte
The solution...
My leach has a speaker protection circuit and the relay has 2 changeover contacts. I am going to connect the NC contacts to the Sony output so that when the big(Leach) amp is off, it (the Sony) plays through.
The GNDs will be shorted.
In my case, the Leach will have priority when it is ON.
Gajanan Phadte
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