I'm running a second zone for fellow. It will have two crown amps. A CDI2000 for his top end and an XLS2502 for the sub. The XLS will only accept a mono signal through input one when you bridge it.

My plan is to split the RCA output. One pair will go into a Cleanbox Pro and then to the CDi2000, the other will be summed mono per this article:

[Link: rane.com]

And then fed to the sub.

My question is will there be any nagative side affects to having the signal split, and one pair being summed mono while the other remains stereo?

Is there another circuit I should build that sums the pair to mono but also allows for the use of the original stereo signal?

Thanks.

Craig.

The resistor network works but by the time you assemble the parts and close it up, you could have bought this-

[Link: edcorusa.com]

Read the rane article before you read the rest of this. It covers every detail of splitting and summing.


Not mentioned here is the crossover for the sub, nor the method of calibrating the sub output level with the high end output level.


That's true for any amp when it's bridged. I'm just sayin.'


The rane article clearly states you can just use a simple Y for that. So you now have two wires to go to the stereo amp and two wires to go to the sub. In fact you can split to more than two amps, but anyone who needs to do that should ask about it.

(From here on in, when I say "source" here, I mean whatever feeds the next stage of the system.) You don't mention what your signal source is, but your post makes me think it's unbalanced.


Theoretically necessary, in practice not at all, unless you're running a hundred feet from the source to the amp. Even then I've had success without such a device.

In practice, you connect the hot lead of the unbalanced channel to the + of the amp input and connect the ground lead of the channel to both the - and the ground of the amp input. We do this every time we connect a consumer unit to a balanced input on commercial systems and we never have noise problems.
Never.

Re the sub:

EXACTLY. Connect your unbalanced signals to the circuit shown in Figure 2 (or balanced per Figure 1).  If using Figure 2, connect the source hot lead to the + of the sub amp and the source ground to the - and ground of the sub amp. If using Figure 1, connect to +, - and ground of the amp.


No. Well, almost not. Since the Crown has an input impedance in the 20K range, I'd use 1K resistors in that network, but it will definitely work as shown. Those resistors might reduce the stereo separation from, say, 60 dB to 30 dB. That reduction of separation is probably inaudible. To hear it, you'd have to be able to tell if a signal at, say, -30dB in one channel is at -30dB or -60dB in the other channel, all while music is playing in both channels.


There are lots of other circuits that will accomplish the same thing, but there's no circuit you should build to do so. It's not necessary and won't improve things.

Sure!

Thanks Ernie.

I read the Rane article. I wasn't aware the lack of stereo separation wouldn't be very noticeable. This is a very big garage so that won't be too big of a deal anyway. Loud and clear is more important.

The source is Zone 2 unbalanced from a Marantz preamp.

The amps will be balanced with the front panel level controls and the master volume is controlled from the preamp. Cross over will likely be at 80hz.

I have never gone unbalanced into the CDi. A long time ago 3peddlemini said he used to go unbalanced in but started using the cleanbox pro to convert to balanced and heard an improvemt in sound quality. For $60 I figured why not.

You recommend replacing the 470 ohm resisters with 1k? Leave the 10k as is?

Because he provided the model of the sub amp anybody with half a brain could easily Google it to see it has a crossover and gain control!! Imagine that.....

a) for my free consulting time he could have written "the XLS2502 sub amp." Yes, that's right, please not only give the model number but also give a brief description if it's not any kind of specialty device.
b)my answers work for him as well as for anyone using a normal power amp, not just an amp designed to power a sub.

I almost commented that my answer was so long because I see this site as building a reference source, not just answering individual questions. I think it was worthwhile to point out the need for a crossover anyway. He's balancing it by ear, but that's good enough for most of us!

I said "xls2502 for the sub". I felt that clearly meant it was the sub amp.

Didn't think cross overs etc were relevant to my wanting a mono input.

Thanks again for all of the info guys. I have what I need to proceed.

Craig.

I got that you wanted to use it for the sub. I did not get that it had any special circuitry inside it especially for the sub. You could have said you wanted to bridge a CDi2000 and use it for the sub, but in that case crossing over is an issue.

I'm just sayin.' Sometimes it's puzzling being Mr. Literal.