Connecting two amplifiers to one set of speakers.

mattjax05

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Is it acceptable to run two amplifiers to one set of speakers not for bi-amping though. I would like a home cinema receiver and a hi-fi amplifier both connected to my speakers (obviously only the one amp will be on at any one time) Would there be any interference problems with the speaker cables being linked together in the speaker terminals?

Hope someone can help - thanks, Matt
 

Andrew Everard

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[quote user="mattjax05"]Would there be any interference problems with the speaker cables being linked together in the speaker terminals?[/quote]

Yes!!!! DON'T DO IT!!! You're likely to blow the output stages on one or both amplifiers. You need a swtchbox (as the least good solution, in sonic terms), able to entirely isolate the two amps from each other.

The more elegant solution, assuming your receiver has preamp-level front channel outputs, is to connect these to the stereo amp, and use that to drive the speakers for both music and movies.

See this thread where I answered a similar query.
 

mattjax05

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Thanks for the good advise, Im not sure if my receiver has the preamp front channel outputs for this procedure. Its a DenonAVR1707 - would you know if it has? Nothing on the back seems to suggest that it does although im only going on memory as im not at home yet.
 
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Anonymous

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Denon AVR 1707. Sorry, no pre-out for front channels on it.
It does have CD-R/tape out though, which you can use. Not as neat as what Andrew suggested, but works without an upgrade. Connect it to tape input on your stereo amp.
 

nads

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[quote user="Andrew Everard"]
[quote user="mattjax05"]Would there be any interference problems with the speaker cables being linked together in the speaker terminals?[/quote]

Yes!!!! DON'T DO IT!!! You're likely to blow the output stages on one or both amplifiers. You need a swtchbox (as the least good solution, in sonic terms), able to entirely isolate the two amps from each other.

The more elegant solution, assuming your receiver has preamp-level front channel outputs, is to connect these to the stereo amp, and use that to drive the speakers for both music and movies.

See this thread where I answered a similar query.
[/quote]

i like that solution but it does not work if both amps are from the same maker and are both remote controlled, Ok get the blu-tack out to cover on sensor ;)
 

mattjax05

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I didnt think so - shame, how is your method different i.e will the sound be worse than Andrews suggestion. Does both options offer Dolby and DTS formats to be encoded via the receiver, transferred to the hi-fi amp(via interconnects) and then played through the two speakers or will it only be stereo sound? Could I connect the interconnect from CD-R/tape to dvd input on the hi-fi amp instead of tape input on the hi-fi amp?
 

Andrew Everard

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[quote user="ranjeetrain"]Denon AVR 1707. Sorry, no pre-out for front channels on it.

It does have CD-R/tape out though, which you can use. Not as neat as what Andrew suggested, but works without an upgrade. Connect it to tape input on your stereo amp.

[/quote]

No, that won't get over the problem of two sets of speaker outputs into one speaker, and is impossibly fiddly as the tape outs on an amp or receiver aren't affected by the volume control.
 
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Anonymous

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I was hoping that he will be able to drive them entirely through stereo amp, with the difference being the way volume control will be handled. At least that or buy a new AVR.
OR it could work the other way round. If his stereo amp has pre-outs, he could connect that to direct inputs on the receiver and he is ready to go.
 

Andrew Everard

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[quote user="ranjeetrain"]OR it could work the other way round. If his stereo amp has pre-outs, he could connect that to direct inputs on the receiver and he is ready to go.[/quote]

But that kind of negates having the stereo amp at all - might as well just connect sources direct into the AV receiver.

The best bet is an amplifier switchbox like this one on e-bay, the Niles DPS-1.
 

mattjax05

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Andrew, you say the switchbox is the least best way to go - is it still worth going down this route or could I just flog my current avr and purchase one with pre-outs (what way would you go?)

Also, lets say my avr had the pre-outs, would I be listening to the surround modes, that the avr can encode, at its full potential using the pre-outs route?

Regards, Matt
 

nads

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[quote user="mattjax05"]
Andrew, you say the switchbox is the least best way to go - is it still worth going down this route or could I just flog my current avr and purchase one with pre-outs (what way would you go?)

Also, lets say my avr had the pre-outs, would I be listening to the surround modes, that the avr can encode, at its full potential using the pre-outs route?

Regards, Matt
[/quote]

yes as you will still be using all the trick the box does as that is all done in the pre-amp phase.

But i will never be tempted. Keep it separate.
 

nads

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[quote user="mattjax05"]
Hi Nads, Im being blonde here but could you explain a little simpler for me please - What part of my question did you answer?

Matt
[/quote]

you asked about the AV process and if you would still be getting it all if you had the pre outs.

And i said YES.
 
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Anonymous

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[quote user="Andrew Everard"]
[quote user="ranjeetrain"]OR it could work the other way round. If his stereo amp has pre-outs, he could connect that to direct inputs on the receiver and he is ready to go.[/quote]

But that kind of negates having the stereo amp at all - might as well just connect sources direct into the AV receiver.

The best bet is an amplifier switchbox like this one on e-bay, the Niles DPS-1.
[/quote]

That solution comes for a price not with whatever is currently available.
I see a switchbox as an extra hardware. If I were the asker, I'd rather upgrade my AVR.
 

mattjax05

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I thought that signals such as Dolby and DTS can only travel through either an optical cable or coaxial cable but from the reveiver to the hi-fi amplifier the cable wont be either of these!
 

nads

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[quote user="mattjax05"]
I thought that signals such as Dolby and DTS can only travel through either an optical cable or coaxial cable but from the reveiver to the hi-fi amplifier the cable wont be either of these!
[/quote]

and it still will.
 

Andrew Everard

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[quote user="mattjax05"]
I thought that signals such as Dolby and DTS can only travel through either an optical cable or coaxial cable but from the reveiver to the hi-fi amplifier the cable wont be either of these!

[/quote]

Not a problem as you are only sending the front left/right channels after decoding in analogue to the hi-fi amplifier.

But we're getting terribly tied up in knots here.

The best way to do what you want is to have a receiver with front channel pre-outs, and connect from them to your stereo amplifier. You then connect your front left/right speakers to an input - let's say AUX 1 for the sake of argument - on the stereo amp, which now acts as the power amplifier for the front left/right channels, and all your other speakers to the AV receiver as usual.

Connect your DVD player and other home cinema sources to the AV receiver as usual, and the pure music sources, such as your CD player, to the stereo amp.

Set the volume control on the stereo amp to 10 o'clock, select the Aux 1 input, and balance up the surround system as usual using the receiver's test-tones.

Now when you want to watch movies and other surround sources, you just select Aux 1 on your stereo amp, and set the volume to 10 o'clock, and after that you simply use AV receiver as usual.

To listen to music from stereo sources, simply use the stereo amp as normal - all the AV processing is thus out of circuit, and you have the best of both worlds.

If you don't want to change your AV receiver to one with preouts - and we're probably talking the better part of £400 to get one so equipped - then the Niles switchbox is the most cost-effective solution to doing what you want to do with what you have now, as it should only cost you about £50 plus shipping, judging from the US price.
 
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Anonymous

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Hi;

I'm looking at a similar problem and this thread has gone a long way to answer my main Q.

Essentially, I'm currently running an Denon 2105 AV amp (which I use for XB360, Wii, and Sky+) but this currently has no speakers so simply goes into the TV.

I also have a stereo system (Rotel Pre/Power amps, MArantz CD63 and some Mission stereo speakers).

I want to have it so that I can either run it all through the speakers which this thread suggests I just plug the Denon preouts into the Rotels to solve that - however I also want the option of having the sound output from the Denon to be played independant of the Rotels either thrtough the TV or some future 5.1 speaker system/sound bar.

Would the use of the preouts render the other audio sound outputs in some way disabled or would they continue to be usable (if you see what I mean!?!) enabling me to have the audio output on the Denon AV coming through the TV whilst (for example) the CD via the Rotels comes through the Missions?
 

Andrew Everard

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No, the preouts won't disable the speaker outputs, but they will only output the same signal as is being sent to the power amplification and thus to the speakers.
 
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Anonymous

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[quote user="Andrew Everard"]

No, the preouts won't disable the speaker outputs, but they will only output the same signal as is being sent to the power amplification and thus to the speakers.

[/quote]

Cheers Andrew (I can't believe I've only just discovered your forum BTW! .... I'm a long time What Hifi reader so this is a very useful thing to discover!)

back OT ...... that scenario you set out is fine as my aim is to have to option to use the Rotel amps to play my CDs from the Marantz whilst also using the AV Amp at the same time to conduct the 360/Wii/Sky+ Video signal and audio to the TV.

AFAI can see this should be perfectly ok as the 2 amps are 'doing there own thing' independantly when the Rotel is set to another 'non AV Amp' input.

I'll give it a whirl but many thx for the pointers.... now to buy some nice new speakers and hifi furniture to contain the kit!!!!
 

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