Connecting AV Amp to Stereo Amp

c11ve

Standard Member
Hi, I read on this forum that I could retain my stereo amplifier for music and add an AV amplifier for movies, connecting the front preouts of the AV amp to the stereo amp. I have a Marantz PM7200 stereo amp and have just bought a Marantz SR5002 AV amp. My question is what do I connect to on the PM7200. There are pairs of input sockets marked 'Aux 1' and 'Aux 2', or there are 2 pairs of sockets marked 'Processor in' and 'Processor out'. The manual says use these latter sockets 'to connect a graphic equaliser or other analogue audio processor'. So which connection do I use? Sorry if this is a dumb question.
Thanks,
Clive
 

davepuma

Distinguished Member
You connect the FL and FR pre-outs to a source input, e.g. Aux 1 and obviously the front speakers to the hifi amp. The rest are driven by the AV receiver. I use the Video input on my hifi amp. Then set the hifi amp volume at 12 o'clock (memorable position) and calibrate the AV receiver. Just remember to turn the volume down when you're listening to any source directly connected to the hifi amp or you risk damaging your amp/speakers and hearing!
 

c11ve

Standard Member
Advice needed. I finally got round to setting up my system. I connected the FL and FR preouts on the SR5002 AV amp to the Aux 1 input on the PM7200 Stereo amp. When I turned the amps on I got a loud humming noise from the front speakers. The noise was there even when I turned off the SR5002. It got quieter if I turned the volume down on the PM7200, but only disappeared when the volume was set to zero. I've tried changing the phono lead, no improvement. Am I doing something wrong? (I am a bit of a novice).
Clive
 

-Matt-

Active Member
I'm not familiar with your specific equipment but I do something similar with my setup.

A possible source of the noise that you are hearing comes from the fact that your audio signal is being passed through two pre-amp stages.

From this image...



...it looks like you could use the processor-in connections to bypass the pre-amp in the PM7200.

I.e. Connect your sources to the SR5002 and let this handle all of the switching and pre-amplification/volume control. Connect the FL and FR pre-outs of the SR5002 to the processor-in on the PM7200 (remove the links first). You may also have to disable the source direct feature to hear anything.

Hopefully this should improve the sound quality a bit and should be more convenient. You will essentially be using the PM7200 as a power amp so you won't have to use two separate volume controls - just the one on the SR5002.

If you are still hearing a hum after this make sure your power leads do not run parallel to your speaker cables or interconnects (eliminate 50Hz pick-up). Failing that try searching for information about ground loops.
 
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xmb

Well-known Member
Most AV equipment is Class II (double insulated) and so has no connection to earth, but if say an item connected to your PM7200 is connected to earth (such as a turntable) then all the mains leakage current of all the devices connected to your SR5002 (such as DVD, TV etc) now pass down the screen of the connections you made between the two amplifiers and causes the buzzing (hum) you now hear.

This leakage current can be quite large if you have quite a few Class II devices connected together (each device can have up to 0.25mA leakage and a Class I (earthed) device can have up to 3.5mA). It is these leakage currents that cause the buzzing sounds. (Leakage currents can also be induced in to wires that run parallel with mains leads but are normally much lower than the mains leakage mentioned above.)


Just some technical information as a background to your potential problem.
 

Mark.Yudkin

Distinguished Member
Hum: let's try the most common ground loop cause first to save some time; otherwise you're in for some long evenings of unplugging and replugging.

Unplug all cable, satellite, antennna or whatever cables allow you to listen to the radio or watch TV broadcasts, regardless of how they're connected (you now cannot watch TV or listen to the radio). Does the hum stop?
 

c11ve

Standard Member
Thanks for all the replies. I did decide to disconnect everything until I found the culprit. It was my Pure DRX-701ES DAB Tuner. With that unplugged the hum has gone. Is there anything I can do about that? I've left it unplugged for now.

Onto my next problem. I have connected my Virgin V+ box by HDMI cable to the SR5002, then connected by HDMI from the SR5002 to my TV (a Sony KDLW5500 I've just bought, fantastic picture). However, I'm only getting stereo sound out. The display on the front of the SR5002 only shows the front left and right speakers being used. If I press the surround mode button it cycles through the various dolby modes and on most of the these the sound switches to the centre speaker only.

I have done a manual speaker set up, and when I manually cycle the test tone it cycles correctly through all the speakers. I have a centre, front pair, surround pair and sub-woofer connected. I have all the speakers set to large.

Am I missing something here, I thought that HDMI carries both video and audio signals, or do I need an optical lead from the V+ box to the AV amp for the audio?
 

dante01

Distinguished Member
Thanks for all the replies. I did decide to disconnect everything until I found the culprit. It was my Pure DRX-701ES DAB Tuner. With that unplugged the hum has gone. Is there anything I can do about that? I've left it unplugged for now.

Try using the same mains outlet to power both your receiver and the Tuner. Using a multi way trailer to power all your components can sometimes get rid of grounding issues that creae hums.

Onto my next problem. I have connected my Virgin V+ box by HDMI cable to the SR5002, then connected by HDMI from the SR5002 to my TV (a Sony KDLW5500 I've just bought, fantastic picture). However, I'm only getting stereo sound out. The display on the front of the SR5002 only shows the front left and right speakers being used. If I press the surround mode button it cycles through the various dolby modes and on most of the these the sound switches to the centre speaker only.

You'll only get multichanel audio from the V+ box when it is present and DD encoded material is being played. You must also ensure that 'HDMI audio override' is "on" in the V+ box's audio and display settings.

The V+ HDMI interface carries both video and multichannel audio only if the 'HDMI audio override' is set to "on" and you only get multi channel audio such as DD 5.1 when it is present.
 
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Mark.Yudkin

Distinguished Member
Thanks for all the replies. I did decide to disconnect everything until I found the culprit. It was my Pure DRX-701ES DAB Tuner. With that unplugged the hum has gone. Is there anything I can do about that? I've left it unplugged for now.
Was it the DAB tuner per se or its aerial connector? If the second, just use a coax ground loop isolator. If it's the first, you need to figure out the other half of the problem: a ground loop needs two paths to earth before we can best solve the issue.
I have all the speakers set to large.
You either live in a mansion and can afford massive speakers, or you have this wrong. Set the speakers to small.

The rest is as dante01 says.
 

xmb

Well-known Member
I did decide to disconnect everything until I found the culprit. It was my Pure DRX-701ES DAB Tuner. With that unplugged the hum has gone. Is there anything I can do about that? I've left it unplugged for now.

Looking at the manual for the Pure I see it is a Class I earthed device and therefore as I said all the leakage for all your equipment is flowing through the screens of the RCA interconnects and to earth via this point. But as Mark said try disconnecting the DAB aerial connection with the Pure re-connected to your system to see if this is an alternate earth point as this may be causing a ground loop, if so it is the easy one to fix with an aerial isolator. (You may be surprised to know that not all grounds (earths) are equal as some are more equal than others!)


If you have an aerial connected to the receiver this may also be the cause of the problem if fed from the same aerial as the DAB tuner. Again an aerial isolator should be fitted (if you have a wall plate with aerial outlets on I bet the cheaper non-isolated type have been fitted).
 

Mark.Yudkin

Distinguished Member
if you have a wall plate with aerial outlets on I bet the cheaper non-isolated type have been fitted
Not if he lives over here is hasn't. As a result coax ground loop isolators are sold everywhere...
 

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