Can U Split a pre-out?

[swingin]

Was woundering if you could split a pre-out on an reciever, like you can on a sub?
I have a pioneer VSX model..

 

[bandphan]

Was woundering if you could split a pre-out on an amp, like you can on a sub?
I have a pioneer VSX model..

What are you looking to do?

 

[swingin]

Add a second amp

 

[bandphan]

Add a second amp

Could you be a little more clear? And yes you can

 

[swingin]

I have 1 two channel amp running my fronts, and was thinking about adding a second amp for the other 5 channels.

 

[bandphan]

I have 1 two channel amp running my fronts, and was thinking about adding a second amp for the other 5 channels.

What speakers are you running, which Pioneer are you using and which amp are you going to add?

 

[TLS Guy]

I have 1 two channel amp running my fronts, and was thinking about adding a second amp for the other 5 channels.

Don't you have preouts for the other channels? If you do what you are planning the rear speakers will play the same as the fronts, which is a mess and not what you want at all.

 

[highfigh]

Was woundering if you could split a pre-out on an reciever, like you can on a sub?
I have a pioneer VSX model..

You can but some are more tolerant of this than others. Doesn't most of the VSX line have pre-out for all channels, or is it just the top models? If you do this, it won't be surround, just a lot of channels, in stereo.

 

[swingin]

Cerwin Vega, all around. Pioneer VSX-1017TXV-K, I have a behringer EP2500 for the fronts, and was thinking about the emotiva XPA-5 for the other speakers. I believe only 1 pre-out.

 

[TLS Guy]

Cerwin Vega, all around. Pioneer VSX-1017TXV-K, I have a behringer EP2500 for the fronts, and was thinking about the emotiva XPA-5 for the other speakers.

Yes but do you have preouts for those other channels? If not it will be a mess.

And how to propose to get the center for instance, as if you combine the L/R preouts everything will be mono.

The other issue is that you would have three amps to each preout, in my view that is one too many splits and requires a buffer amp.

In any event if you don't have discrete pre outs for the other channels what you are proposing is a big step backwards.

 

[bandphan]

your speakers all extremely sensitive, so for the effects channels Id say no need, and as mentioned if you dont have preouts for those channels its a mess.

edit TLS beat me to it

 

[swingin]

My bad, I guess I do have separate pre-outs for all channels.
It helps to read the manual, lol..

 

[sawzalot]

My bad, I guess I do have separate pre-outs for all channels.
It helps to read the manual, lol..

Not only do you have the pre-outs , I think that your AVR delivers 150 watts x 7 channels , exaggerated or not that should be plenty enough power for your rears and surrounds, by adding the amp to the fronts I believe you will take some of the work load off of the AVR which in turn should give you great performance and allow you to have a great set-up, I always liked that receiver, it's a beast.

 

[TLS Guy]

My bad, I guess I do have separate pre-outs for all channels.
It helps to read the manual, lol..

Or even look at the back panel?

 

[Johnny2Bad]

Yeah, use the pre outs if the preamp or receiver has them.

But, to answer your specific question ("Can U Split a pre-out?"):

Generally speaking; you can always split outputs but you should never combine them (ie don't connect two outputs into one input).

Occasionally you might get some impedance mismatch by splitting outputs but most home hifhi gear has plenty of allowance for that.

Never hurts to check the spec though. Make sure the output impedance is lower than the combined input impedances of whatever you're splitting to; (it can be equal as well, although most home gear isn't designed that way).

In your case pre out impedance low --> power amp input impedance high.

Since you're splitting, add power amp input impedances and divide by 2*
If the resulting value is still higher, that's probably good to go without further worrying about it. A lot of power amp inputs are 10x the pre out impedance.

This usually is not an issue, unless you're mixing solid state and tubes.

* There's a much better formula, but as long as the amps are similar and it's still higher than the pre out, it's no biggie. But, if you insist, you can punch numbers into this: (Zin of Amp 1 X Zin of Amp 2) divided by (Zin of Amp 1 + Zin of Amp 2)

 

[swingin]

Or even look at the back panel?

Cant get to it

 

[ski2xblack]

A - B for rears

Hola, Swingin, what's happnin'?

Now I'm not saying you should try what I did, but I thought I would share it here if you're curious.

Using just stereo pre-outs, you can derive a rear-fill or ambience signal from the amp powering the rear speakers by connecting the negative speaker leads together (+ on amp to + on rear speakers, but - on speakers connected to each other, rather than back to the amp). This would give you a 'left channel/right channel difference signal' or A - B, which is a mono signal composed of any musical info that is not in mono in the front, A+B signal; the more left or right a sound appears in the soundstage in the fronts, the greater it is produced through the rears. This essentially gives you the rear-channel signal from first generation surround sound, minus the delay/reverb/dsp effects of old Dolby Pro Logic. Assuming the amp you are using for the rears has gain controls, you want to turn them down quite low, so as not to be able to localize the rears, but high enough to expand the image coming from the mains. It's crude matrix sound compared to discreet 5.1, but if done correctly can pleasantly enhance simple stereo, and won't come with the deleterious effects of running full stereo signals throughout the room. As others have mentioned, that would be a total mess.

Now I don't know if it's advisable to connect your amps in this way, but I did it for years with no problems. I wouldn't invest a dime to do this if I were you, but if you already possess the amps...

It really sounds like you would be better off just getting a proper, modern pre-pro or AV receiver so you can do multi-channel the right way.

 

[TLS Guy]

Hola, Swingin, what's happnin'?

Now I'm not saying you should try what I did, but I thought I would share it here if you're curious.

Using just stereo pre-outs, you can derive a rear-fill or ambience signal from the amp powering the rear speakers by connecting the negative speaker leads together (+ on amp to + on rear speakers, but - on speakers connected to each other, rather than back to the amp). This would give you a 'left channel/right channel difference signal' or A - B, which is a mono signal composed of any musical info that is not in mono in the front, A+B signal; the more left or right a sound appears in the soundstage in the fronts, the greater it is produced through the rears. This essentially gives you the rear-channel signal from first generation surround sound, minus the delay/reverb/dsp effects of old Dolby Pro Logic. Assuming the amp you are using for the rears has gain controls, you want to turn them down quite low, so as not to be able to localize the rears, but high enough to expand the image coming from the mains. It's crude matrix sound compared to discreet 5.1, but if done correctly can pleasantly enhance simple stereo, and won't come with the deleterious effects of running full stereo signals throughout the room. As others have mentioned, that would be a total mess.

Now I don't know if it's advisable to connect your amps in this way, but I did it for years with no problems. I wouldn't invest a dime to do this if I were you, but if you already possess the amps...

It really sounds like you would be better off just getting a proper, modern pre-pro or AV receiver so you can do multi-channel the right way.

The OP has found pre outs for all channels. That Hafler system you have described, never was any good and will blow quite a few amps. So I would not go touting it.

 

[Johnny2Bad]

That Hafler system you have described, never was any good and will blow quite a few amps. So I would not go touting it.

I'm assuming you mean David Hafler, founder of Dynaco. They sold Dynaquad(tm) boxes that extracted out of phase information to simulate ambience beginning in the mid-60's, as well as a "4-dimensional" integrated amplifier that used the system.

Hafler originally started his ambient sound experiments by having a single third speaker connected across the two + terminals along with two conventionally hooked up speakers. The original Dynaquad adapter used four speakers, and the IIL version marketed briefly during the 90's used 5 speakers. All extracted the ambient information from two channels.

The system is essentially what was later introduced as the original Dolby Pro Logic, although they did it at the preamp stage.

It's not usually * a problem with tube amps with a common ground between the L and R amplifiers, but with SS there's a danger of creating a DC path between the amps, which can lead to damage.

You're right, though, to warn people away. It's experimental in the true sense of the word ... anything can happen, you gotta be willing to see stuff go up in smoke and if not, stick to what the manual says and don't play.

* "not usually" does not mean "never".