2 Pre-pros / 1 Amp

[schwock5]

Wasn't sure where to really ask this or even to do it in the Klipsch forum, but was wondering about something...(i'm not too technical)

 

I was looking into getting an older Sunfire Cinema Grand Amp (5 channel or 7 channel), but this could really apply to any amp with both balanced and unbalanced inputs.

For Home Theater i'd run a Marantz Pre-Pro through it for multi-channel.

I could run my turntable through the Marantz, however, is something like this possible:

If i obtained a Sunfure Tube Pre-amp (or some other stereo pre-amp) and ran my turntable into that as well as my CD player, could i do unbalanced inputs from the marantz to the amp and balanced from the pre-pro to the amp in the same input of the front channels?

If one pre-pro is off while the other is on would this cause any issues? What happens if both are on and sending a signal?

 

I've seen some threads mention running the fronts of the home theater pre-pro into a line-in of the stereo pre-pro and having to have both on and the the volume regulated for both, but i wouldn't want to run the stereo pre-amp unnecessarily.

 

Or do i send the stereo pre-amp into the L/R "external in" of the marantz and send the signal that way? (keeping it in pure direct and analog all the way through)

[babadono]

I am having a little difficulty following exactly what you want to do but I will say this emphatically: Do Not Connect 2 outputs together. Does the amp in question have a switch for unbalanced or balanced input? And if it does what does that switch do? Only a schematic or a talk with tech support for the amp could answer that question.

[wvu80]

44 minutes ago, schwock5 said:

If one pre-pro is off while the other is on would this cause any issues? What happens if both are on and sending a signal?

 

First of all, follow @babadono's advice directly upstream ^^^.

 

It sounds like you want to run a pre-pro for home theater, and another pre-pro for your TT and CD player.  You want to use the same amp for both pre-pros.

 

Bringing balanced and un-balanced into the picture is unnecessary.  For home gear used the unbalanced.

 

I suggest you use the AVR and a single amp and connect everything to that.  The AVR will do both 2.0 and 5.1 with electronic switching using your remote controller.

 

 

[CECAA850]

16 minutes ago, babadono said:

I am having a little difficulty following exactly what you want to do but I will say this emphatically: Do Not Connect 2 outputs together. Does the amp in question have a switch for unbalanced or balanced input? And if it does what does that switch do? Only a schematic or a talk with tech support for the amp could answer that question.

I think he wants to have one amp, connect one pre to the balanced inputs and another one to the unbalanced inputs of the same amp.

[schwock5]

3 minutes ago, CECAA850 said:

I think he wants to have one amp, connect one pre to the balanced inputs and another one to the unbalanced inputs of the same amp.

 

Correct! (in theory). Just postulating.

I know people usually have a dedicated 2 channel and dedicated home theater setup.

How would you combine to leverage 1 amp and 1 set of speakers?

Let's say you like the sound of a specific tube pre-amp and want to use that for music but still have your home theater.

 

I mentioned balanced and unbalanced since an amp can have both inputs and you can connect 1 pre-pro to each.

 

[pbphoto]

I just use Y-cables to the unbalanced inputs on my amp.

[schwock5]

59 minutes ago, pbphoto said:

I just use Y-cables to the unbalanced inputs on my amp.

 

so you run 2 separate pre-pros through a splitter to 1 amp input?

What happens if you have both running? do your speakers play both signals simultaneously?

[babadono]

If that worked well these would not have ever been invented:

[rplace]

Give a Niles ABA 1-D https://www.crutchfield.com/p_190ABA1DW/Niles-ABA-1D-White.html or something like it. They allow you to run 1 set of speakers driven by two different amps or 2 sets of speakers driven by one amp. It won't allow you to mess up and have both going at the same time.

 

I've used one for years to switch between solid state amps driving my home theater's Khorns and the same Khorns with tube gear for 2-channel listening.

[schwock5]

What happens if you run both at 1 time? My concern is blowing something up 1st and foremost.

[rplace]

Ignore my post about the Niles box I see you are trying to switch sources to the amp not 1 speaker driven by two amps.

[babadono]

3 hours ago, CECAA850 said:

I think he wants to have one amp, connect one pre to the balanced inputs and another one to the unbalanced inputs of the same amp.

Ok. So it depends on what the particular amp in question does with the two different inputs.

[babadono]

31 minutes ago, schwock5 said:

What happens if you run both at 1 time? My concern is blowing something up 1st and foremost.

 

[JohnA]

I suspect it will work, but each preamp will see a lower impedance (the other preamp paralleled with the power amp impedance).   The lower load impedance may or may not affect the performance or sound quality of your system. 

[pbphoto]

8 hours ago, schwock5 said:

 

so you run 2 separate pre-pros through a splitter to 1 amp input?

What happens if you have both running? do your speakers play both signals simultaneously?

Yes.  I have a passive-pre for my two-channel listening.  Basically a switch box between my DAC and TT with a volume attenuator.  The other pre is an AVR for movies and the kids' PS4, appleTV etc.  The two are never used at the same time but the passive pre's volume attenuator is always part of the equation.  In other words, when playing a move with the AVR, I make sure my two-channel passive pre's volume is set at a consistent level - like 12 o'clock - and this makes the volume of my L/R speakers match the rest of the center/surround speakers.

[schwock5]

11 hours ago, pbphoto said:

Yes.  I have a passive-pre for my two-channel listening.  Basically a switch box between my DAC and TT with a volume attenuator.  The other pre is an AVR for movies and the kids' PS4, appleTV etc.  The two are never used at the same time but the passive pre's volume attenuator is always part of the equation.  In other words, when playing a move with the AVR, I make sure my two-channel passive pre's volume is set at a consistent level - like 12 o'clock - and this makes the volume of my L/R speakers match the rest of the center/surround speakers.

 

is this the only way to do it?

[wvu80]

I misunderstood the original problem.  I think I'm clear now, use two pre-pros simultaneously with a single power amp using the balanced inputs to the amp for one pre/pro, the un-balanced inputs for the other.  I have two comments.

 

1.  Don't do it, for one simple reason; the amp was not designed to be used that way.  One pre-pro, one amp.

 

2.  The ONLY thing that would change my opinion on that is if you contact the manufacturers of each and get their EXPRESSED approval.  If ANY of the companies say no, then it's "no."  Don't ask us, ask the company that made your amp.

 

The common way to do what you want to do would be to get a switch to completely separate the signals.  The first time you power two pre-pros into one amp, I would anticipate lots of blue smoke, maybe for all three pieces of equipment.  And hope that they don't take the speakers with them.

 

Unless you are independently wealthy and can afford to buy new amps and pre/pros every time you do something crazy and blow everything up, don't do it.

[babadono]

21 minutes ago, wvu80 said:

The common way to do what you want to do would be to get a switch to completely separate the signals

Or one of these

[schwock5]

i'm not trying to mix the signals, i want to ensure they are separated to exactly prevent this issue from happening :-)

 

1 hour ago, wvu80 said:

I misunderstood the original problem.  I think I'm clear now, use two pre-pros simultaneously with a single power amp using the balanced inputs to the amp for one pre/pro, the un-balanced inputs for the other.  I have two comments.

 

1.  Don't do it, for one simple reason; the amp was not designed to be used that way.  One pre-pro, one amp.

 

2.  The ONLY thing that would change my opinion on that is if you contact the manufacturers of each and get their EXPRESSED approval.  If ANY of the companies say no, then it's "no."  Don't ask us, ask the company that made your amp.

 

The common way to do what you want to do would be to get a switch to completely separate the signals.  The first time you power two pre-pros into one amp, I would anticipate lots of blue smoke, maybe for all three pieces of equipment.  And hope that they don't take the speakers with them.

 

Unless you are independently wealthy and can afford to buy new amps and pre/pros every time you do something crazy and blow everything up, don't do it.

 

[USNRET]

I use a 7 channel amp with 5 fed by prepro to the HT and 2 fed by preamp for the two channel. I use a Niles SPK-1 to select the L&R Corns. Default is HT channels and when preamp is on it triggers the Niles to use channels 6/7 of the amp.