2 preamps into 1 amp?

[zingo]

Here is my idea (Illustrated in confusing picture). I want to combine my HT and 2 ch to create one system that fits a little better in a house, yet still sounds as good as my 2 ch. As good as my Marantz pre/pro sounds for HT, it's not very musical and 2 ch is not its forte. So, what if I built two "Y" interconnects that went from my pre/pro and preamp to my main amp and my subwoofer amp. Those are the only two systems that would be used for both music and movies, so all the rest of the equipment would be independently controlled by the pre/pro. Would a "Y" IC create any problems as long as only one pre was on at a time?

[Gaara]

Sending a output to another output sounds like a bad idea to me even if only one was on at a time. You can't run your HT through your 2ch pre and run that direct to your amp?

[jakelm]

Just get a switch. Video and audio switch should pass anything right through.

[tcrossma]

I don't know if it'd work or not, but it sounds risky. How about picking up a pre-amp with an HT Bypass (unity gain)? That's what I do, and it works great.

[zingo]

Hmmm... that is a good idea with the pass through. I'll look at my pre/pro and see if it has a function like that. Do they make a "Hifi" interconnect switch box? I just don't want to pass my 2 ch signal through some junky little box that bottlenecks my system.

[zingo]

Would a tape in-out work, or does it specifically have to be something else?
Here's what the back looks like if you're interested:
http://pic6.audiogon.com/i/c/f/1202761838.jpg
http://pic6.audiogon.com/i/c/f/1202761837.jpg

[Face]

How about upgrading your pre/pro that also sounds good in 2ch. mode?

[pearsall001]

I just sold my CJ PV14LS2 tube preamp w/ HT bypass that would have fit the bill perfectly for you. It sounded & worked great. Your best bet to do it right is to buy a separate 2 channel pre w/ HT bypass. That way your 2 channel & HT are kept completely separate.

[Face]

You don't need separate components to do it right. It can be done right with the correct components, but it'll cost you.

[venomclan]

I just sold my CJ PV14LS2 tube preamp w/ HT bypass that would have fit the bill perfectly for you. It sounded & worked great. Your best bet to do it right is to buy a separate 2 channel pre w/ HT bypass. That way your 2 channel & HT are kept completely separate.

I 2nd that idea.

[zingo]

Those do sound like spendy options. Is there anything I can do with my current equipment...

What if I just built my own little two-way hifi switch box?

[tcrossma]

I think you might be able to use the tape loop to do something like what an HT Bypass does. I honestly don't know the difference between the two -- I only know that my HT Bypass works great.

It may be that the tape loop doesn't leave the signal unprocessed, so the fronts when using it for HT might not sound as good. Or there may be some other difference, which someone else can chime in about. Might be worth a shot of experimenting though.

[zingo]

What if I created a two-in two-out audio switch? I could input both my preamp and prepro like a regular switch box. But split the output to two sets of jacks, so each source would get sent both amps. I would just buy a Radioshack two-way switch and rewire it. Would splitting the signal like that work?

[GV#27]

Why not just connect the pre outs of your Marantz into an unused input on your preamp?Then set the preamps volume to the appropriate level.Having the pre in the chain should not degrade the HT sound discernably.

[zingo]

I feel confused, but I don't think that would do it. The issue is that each amp only has a single set of inputs, and no outputs. So I would still be running an output from each pre to a single amp. Or did I miss something...

[GV#27]

Sorry can't do a scetch but here is what I mean.

Marantz front L and R pre out to aux in on Pre amp.

Preamp L and R out to main amp in.


When you want to watch a movie select aux input on the pre amp and set the pre amps volume control about half way.This will allow the Marantz's output to feed through the preamp.You will likely have to readjust the balance between the fronts center and surrounds with the reciever.
Does that make sense?

[zingo]

Oh. That just might work good sir! So the 2 ch pre would end up being a control for the main speakers and subs when I watch movies, but runs independently when I listen to music. I'll have to try it out...

[adam2434]

Sorry can't do a scetch but here is what I mean.

Marantz front L and R pre out to aux in on Pre amp.

Preamp L and R out to main amp in.


When you want to watch a movie select aux input on the pre amp and set the pre amps volume control about half way.This will allow the Marantz's output to feed through the preamp.You will likely have to readjust the balance between the fronts center and surrounds with the reciever.
Does that make sense?

The above is what I do and it works well. I set my 2ch pre's volume to a predetermined level that I have calibrated with the rest of the HT channels (about 1/2 way on the pre's volume knob) However, as others have said, a 2ch pre with a HT bypass is the ideal situation when you want a 2ch pre and HT pre/pro to share the same amp for L/R, since it bypasses the pre’s gain circuitry.

Trying to share the sub between the HT pre/pro and 2ch pre is going to be more of a challenge. Hooking things up like above and then running the sub with speaker-level connections from the L/R amp, and speaker level outs from the sub to the L/R speakers may work.

Most 2ch pre's do not have a line level sub out or bass management. For these pre's, you would need to run a 2nd set of pre-outs (assuming it had them) from the 2ch pre to the sub and adjust the sub's low pass filter and level to blend with the L/R.

Even if you used a switch for the pre/pro’s sub out and a 2ch sub out (or 2nd set of stereo pre outs), you may need to change settings on the sub for each. For example, if the sub has a low pass filter bypass, you would want to use that for the pre/pro since it has bass management, but you would want to use the sub’s low pass filter with the 2ch pre in order to blend with the main L/R (assuming the 2ch pre doesn’t have any bass management). Kind of messy.

[tcrossma]

The problem with that approach is that you'll not be able to get correct volume matching in HT. "About half way" isn't going to cut it when you really want your speakers calibrated within a db of each other.

And that's exactly what the HT bypass of a pre-amp will do for you, because it outputs a fixed level. It lets you calibrate for HT and not have to "guess" at the volume level each time you switch inputs. I'd still pursue the tape loop a bit if I were you -- it has a chance of working the way you want I think.

And also, as adam2434 mentioned, doing that would still route the signal through the pre's gain path, which means it'll get doubly processed.

[GV#27]

So the 2 ch pre would end up being a control for the main speakers and subs when I watch movies, but runs independently when I listen to music. Yes.

[GV#27]

The problem with that approach is that you'll not be able to get correct volume matching in HT. "About half way" isn't going to cut it when you really want your speakers calibrated within a db of each other. After he calibrates his levels he merely just has to set the volume on the preamp at the exact same spot every time he watches a movie.Mark it with tape or something.
.

And also, as adam2434 mentioned, doing that would still route the signal through the pre's gain path, which means it'll get doubly processed.As it will going through the tape loop as they are usually buffered with an an op amp.Anyhow the pre amps gain stage should be neutral enough that it does not degrade the HT sound noticeably.It won't hurt to give it a try.

[adam2434]

The problem with that approach is that you'll not be able to get correct volume matching in HT. "About half way" isn't going to cut it when you really want your speakers calibrated within a db of each other.

If you calibrate the L/R ch levels on the pre/pro with the 2-ch pre's volume at a specific point (say 1/2 way), and make a small mark on the pre (if it doesn't already have tic marks for volume levels that you can reference), and set it to exactly that same place every time, you can can have proper level matching every time.

I do agree that a pre with a HT bypass is the ideal though.

[adam2434]

Anyhow the pre amps gain stage should be neutral enough that it does not degrade the HT sound noticeably.It won't hurt to give it a try.

Yep, I hear no problems or degradation running my receiver's L/R pre out to an input on my 2ch pre with the volume on the pre at a predetermined level (1 tic over 1/2 way up).

In the grand scheme of things, with the equipment I have, this is the best compromise to get the best 2ch sound my system can offer without swapping cables around.

My next 2ch pre will have a HT bypass though, or maybe a pre/pro that has good 2-ch performance.

[GV#27]

this is the best compromise to get the best 2ch sound my system can offer without swapping cables around.


Yes it is a simple solution without adding cost or complexity.:)

[zingo]

I will try this first since it won't cost me anything. It seems like a pretty good solution, and I will try both the tape-loop and the pre-out. And I am not too worried about the subs as they have their own amp and an active x-over (thanks to GV#27s suggestion) with separate volume control.

[zingo]

I may be solving this problem. Right now I am looking at the Lexicon DC-1 and Outlaw 7100 combo. I feel like that would solve all 2 channel and HT problems...

(PS. Is the 7100 a common ground amp?)

[zingo]

Yes the 7100 is a common ground; I just measured it.

Looks like I'm pulling the trigger on the Outlaw 7100 & Lexicon DC-1 combo (Since I already have half of it now :)). I think that should be a nice upgrade, for HT and 2 channel.