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I am looking to amp my home theater with QSC PA style amps, the issue I am facing is converting the RCA amp pre out on my Marantz 7007 to a signal that is usable for the QSC amps. Looking to convert it to balanced XLR with the cleanest sound possible without any additional distortion.

I have came across a Behringer ADA8000 Ultragain Pro 8-Ch A/D & D/A Converter.

http://www.parts-express.com/behringer-ada8000-ultragain-pro-8-ch-a-d-d-a-converter--248-6020

Is this the best unit to use?? If not please steer me in the right product direction!!!
 

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I am looking to amp my home theater with QSC PA style amps, the issue I am facing is converting the RCA amp pre out on my Marantz 7007 to a signal that is usable for the QSC amps. Looking to convert it to balanced XLR with the cleanest sound possible without any additional distortion.

I have came across a Behringer ADA8000 Ultragain Pro 8-Ch A/D & D/A Converter.

http://www.parts-express.com/behringer-ada8000-ultragain-pro-8-ch-a-d-d-a-converter--248-6020

Is this the best unit to use?? If not please steer me in the right product direction!!!

An A/D & D/A Converter isn't what you want. You'll need a device that converts unbalanced consumer levels to balanced pro levels, colloquially called a "match box", or "bump box". They run about $60 and up and handle stereo pairs in both directions, consumer to pro and pro to consumer. You only need consumer to pro, so half the box will go unused. The less expensive ones don't do the job quite as well as the expensive ones, but might be fine.

But a couple of questions: why the QSC Pro amps? Do you already own them? If not, there are less expensive, better matched amps for this purpose. The QSCs are great amps, and there's a chance you can connect them directly to your Marantz pre outs, crank the amp gains wide open, and you'll be fine. There's a possible level match issue, but not always. Can't find the Marantz specs to verify just now.

All QSC Pro amps have cooling fans that are fairly noisy for home theaters. In fact, most pro amps of all brands have them.

Just to be clear, there's nothing to be gained by the use of balanced lines other than noise immunity. If your cables are short-ish, that's not a problem.
 

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An A/D & D/A Converter isn't what you want. You'll need a device that converts unbalanced consumer levels to balanced pro levels, colloquially called a "match box", or "bump box". They run about $60 and up and handle stereo pairs in both directions, consumer to pro and pro to consumer. You only need consumer to pro, so half the box will go unused. The less expensive ones don't do the job quite as well as the expensive ones, but might be fine.

But a couple of questions: why the QSC Pro amps? Do you already own them? If not, there are less expensive, better matched amps for this purpose. The QSCs are great amps, and there's a chance you can connect them directly to your Marantz pre outs, crank the amp gains wide open, and you'll be fine. There's a possible level match issue, but not always. Can't find the Marantz specs to verify just now.

All QSC Pro amps have cooling fans that are fairly noisy for home theaters. In fact, most pro amps of all brands have them.

Just to be clear, there's nothing to be gained by the use of balanced lines other than noise immunity. If your cables are short-ish, that's not a problem.
I agree most Pro Amps are pretty noisy... My Yamaha P7000S is dead quiet though. :T
 

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For pro amps you should consider Crown. The XLS and XTi series are known to be quiet (they're the only series I know for sure that are quiet). The fans only kick in when needed.

Then you need some RCA to XLR connectors:
http://www.zzounds.com/item--HOSXRM

You might not even need a bump box depending on the voltage output of the Marantz. My Tascam PA-R200 (rebadged Integra 30.4) doesn't need a bump box.
 

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Discussion Starter #5
Does anyone know the pre amp voltage output of the Marantz 7007?

I previously tried using just some RCA to XLR connectors as |Tch0rT| suggested but the amp would not put out much sound!! I mean is sounded like a whisper.

I am not worried about how quite the amp itself is, they will be mounted in a room behind the theater room. What I was referring to was sound quality. I am planning on running the front mains on this amp and would like to confirm the amp had the same sound quality as the Marantz.

I was fairly sure that we need a device to convert consumer ohm output to pro ohm input.

This is the input Impedance for the amp:
Input Impedance 10k ohms unbalanced, 20k ohms balanced

What is the output Impedance of the Marantz 7007??

I was reading the RMX 850 has an Input Sensitivity @ 8 ohm 1.15V (+3.4 dBu). Does this mean the amp needs a signal of 1.15V to work efficiently?

Also the amp has Input Clipping 10 Vrms (+22 dBu). What does this mean??


Thank you very much for all your help.
 

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Does anyone know the pre amp voltage output of the Marantz 7007?
See Part 7 of my gain structure article for an easy DIY method to determine your AVR’s pre amp output voltage. You can find it at the link in my signature. As gazoink indicated, there’s a good chance you don’t need a signal booster.


I previously tried using just some RCA to XLR connectors as |Tch0rT| suggested but the amp would not put out much sound!! I mean is sounded like a whisper.
If you are able to determine that your Marantz has sufficient output, then something was wrong with those cables. Either that or you had the per-channel levels set really low.


I was fairly sure that we need a device to convert consumer ohm output to pro ohm input
Impedance isn’t the issue, signal voltage is.


I was reading the RMX 850 has an Input Sensitivity @ 8 ohm 1.15V (+3.4 dBu). Does this mean the amp needs a signal of 1.15V to work efficiently?
It means that the amp can be driven to its maximum output with a 1.15v input signal. Virtually any AVR can generate more voltage than that.


Also the amp has Input Clipping 10 Vrms (+22 dBu). What does this mean??
That’s the signal level that will make the amp clip. Nothing to worry about, few (if any) AVRs can generate a signal that hot.

Regards,
Wayne
 

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Discussion Starter #9
Wayne A. Pflughaupt thank you for your reply.

What effect does input impedance play when connecting audio signals? The RMX850 has an imput impedance of 10k ohms unbalanced and 20k ohms balanced.

How will this affect the sound/signal from my Marantz to the pro amp?

The spec sheet for the 7007 says the Digital D/A output is 2V @ 0dB playback. Is Marantz referring to the voltage output of the pre amp?

http://m.us.marantz.com/DocumentMaster/US/SR7007_0511.pdf
 

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What effect does input impedance play when connecting audio signals? The RMX850 has an imput impedance of 10k ohms unbalanced and 20k ohms balanced.

How will this affect the sound/signal from my Marantz to the pro amp?
As far as I know it’s a non-issue; all modern audio electronics are compatible with each other, even when mixing consumer and pro gear. I can’t say I’ve ever heard of anyone having a problem with input/output impedances, and I’ve been trolling various home theater forums for 15 years, and reading audio enthusiast publications even longer.


The spec sheet for the 7007 says the Digital D/A output is 2V @ 0dB playback. Is Marantz referring to the voltage output of the pre amp?
Can’t say that I’ve ever heard of that particular specification. I’d strongly recommend doing the voltage-output test I suggested in my previous post to see what you’re really getting from the 7007’s pre amp outs.

Regards,
Wayne
 

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I have a QSC RMX 2450 and it is dead quiet. If you are clean at your sources that is the question . If you use cheap gear period, don't expect to get audiophile results. The best path to take is to sell what you have, and purchase a Marantz 8003, or a 7005 that already have XLR outputs to strait up jack from pre pro to your pro audio amps. That is your best bet, nice and clean. There can be additional distortion and noise introduced into your setup with these cheapie converters. There is a good one , but it is cheaper and better to go the route above stated! Hope this helps you! Good luck!
 

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Has anyone checked if it is or is not? I wouldn't believe that Marantz would do it in the cheapie fashion. Either way, it is clean, plenty of power , good headroom, not lacking for power in the pro amps. Thats kind of like comparing bargain basement to some good quality gear. I personally wouldn't touch those cheap converters like Sampson s convert or art clean box for main channels. Sure they are sufficient for squeezing some serious juice to a subwoofer, but no sir, not to my mains! It always comes out to this same debate. It would be nice if someone could really clear up what manufactures and what models of pre pros are truly balenced!
 

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Besides signal is what it is. When it hits the Marantz, or Anthem, krell etc. I would imagine that everything that goes thru its processors and out to the amps is nothing but purity in sound. Otherwise no one would even think of ponying up that much cash for a second rate central point of sound!
 

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If you really want a converter that is clean, Apex makes one with eight channels. It costs $850, and is as clean as it comes! .001 THD!!!
 

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I went to Guitar Center looking at Behringer stuff, the Employees there did not think to highly of that brand of gear. All in all, you usually get what you pay for. I tried that route before, never again!
 

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About a year ago, I did an experiment. I was using the Emotiva XPA 5 and I thought " I wonder what it would be like to hook up my Integra pre pro directly using XLR cables, to my QSC Amp to run my mains with?" So thats exactly what I did. SWEETNESS!!!!!! Wow! Now that was some good quality sounding stuff ! I tried radio, cd, then bluray movies. I was very impressed! It is like they woke up sonically. Clear as a bell, imaging was more defined, and yes the same listening level. Either way I know what I would do... The choice is yours. Good luck in your endeavor of sound, and good day !
 

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Has anyone checked if it is or is not? I wouldn't believe that Marantz would do it in the cheapie fashion.
Not saying the conversion isn’t be done well in the receivers, just sayin’ it’s more stuff in the signal chain. That kind of stuff bothers some people – me, not so much.

I’ve heard people report that the S-Convert was actually a pretty decent piece of gear. Assuming a converter/booster’s TDH is low and response is linear, the main issue is really the signal boosting itself. That’s where the noise comes from (at least in the main channels).


It would be nice if someone could really clear up what manufactures and what models of pre pros are truly balenced!
You bring up another good point that I almost mentioned in my previous post: From what I understand, some consumer pre amps with balanced outputs aren’t truly balanced, at least not by pro-audio standards. Don’t recall what the exact issue with them is, though…


If you really want a converter that is clean, Apex makes one with eight channels. It costs $850, and is as clean as it comes! .001 THD!!!
A cheaper way to convert the signal is to use something like an outboard equalizer, crossover, etc. Any piece of equipment like that (with balanced ins and outs) will deliver a balanced output with an unbalanced input.

Regards,
Wayne
 
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