My 950 has always made a popping noise when switched on or off. Annoying but tolerable I thought.

The 950 has recently started a strange oscilating electrical noise through the left and right front channels. These L & R front channels are run (pre out)to a dedicated 2 channel integrated amp (Rowland Concerto). The audio signal fades in and out just faster than 1 second cycles. I am also getting a weird electrical popping noise as I adjust the Rowland's volume control. Plus as I switch the various inputs the popping noise is significantly louder.

I have tried swapping rca cables with the 5 channel amp (model 750) and it now makes a loud steady electrical buzz in all the channels.

I had been using a single ended rca cable to feed
the Rowlands L & R. The Rowland has a HT by- pass input but it is only a balanced xlr input. I went and bough an xlr to rca connector to try that just in case, but it made even more noise.

When the system first turns on, everything appears to sound ok, but after 30 seconds of playing it starts the oscilating noises. I get it through the test tones and regular signal sources.

What's up with this.?

Thanks,
Kenreau

I'm not entirely sure, but a few thoughts did occur to me...

The buzz with the Model 750 sounds suspiciously like ground loop troubles, either from interconnects running alongside to a power cord or problems with the cable TV service's ground. If you haven't done so already, I'd suggest double-checking your wiring to make sure power cords are getting too deeply entangled with interconnects and possibly even disconnect the cable TV service from the home theater equipment entirely.

Since the Rowland is an integrated amp, have you tried feeding it a source directly to see if the oscillating noise is coming from there? The popping noise from the Rowland's volume control made me wonder if some of the problem might be there.

Last "question answering a question..." - Was the popping noise at turn-on coming from the speakers or the 950 itself? If it came from the speakers, how do you turn on your amps? (Are they always on, or are they triggered somehow by the 950's 12v trigger?)

Thanks gonk.

The popping noise comes through any speaker being fed by the 950.

The Rowland only makes the noise(s) when its input is switched to the 950 source. For regular 2 channel listening I feed the Rowland direct from a sony 9000ES dvd/cdp on input 1 and it is dead quiet. For watching DVD, the digital out audio signal feeds the 950. The 950 in turn feeds the L & R fronts through the Rowland and the other 5.1 channels are run by a 750amp. The 750 is turned on by the 12v trigger from the 950. The Rowland is always on (no on/off switch).

I have all devices plugged in to a Monster HTPS 7000 balanced power conditioner, which is on a dedicated 20amp circuit. This includes the TV, sat. receiver, dvd/cdp, 950 and 750 gear.

I will re-do the signal and power wiring routing to see what that does. If its not that, I guess it may be a part failure inside the 950.

I will let you know if I discover something.

Thanks again,
Ken

Just getting back from work to investigating this noise issue more. I am fairly certain now, as gonk suggested, it is a ground loop issue.

I did re-route and formally put all the cables in their proper places and it made no difference. The one variable I have realized is I switched integrated amps about the same time the noise issue started. They were/are both Rowland pieces, but with significantly different internal power supplies (the new one uses the B&W Ice digital power supply). I contacted Rowland and they suggested I pull out the Monster balanced pc and try some different plug in scenarios. I will report back what happens.

Thanks,
Ken

Here is what I have found;

With nothing plugged into the Concerto integrated inputs, it is quiet across all 1 to 6 inputs. After plugging the power cords in to various electrical arrangements from the Monster 7000 and then directly into the dedicated circuit only, I found no difference in noise levels. I continue to get the warlbing in / out cycle of the audio signal in the "front" left and right channels when fed to the Rowland integrated.

What I did boil it down to is when ever the Rowland is getting the left and right "front" channel input from the Outlaw 950 pre/processor I get the warbling audio signal/noise. I even rotated the inputs from 1 to 2 to 3. If I use the XLR adaptor and run it through the balanced HT by-pass (input 6) I get a substantial electrical buzz along with the warbling.

I rotated the input from the various Outlaw outputs (surround left and right, rear left and right and finally the center channel only) and it sounds correct and quiet.

So, I guess I have to concluded there is something malfunctioning with the Outlaws950 L and R "front" channels. But I am still perplexed because if I take the Rowland integrated out of the set up and plug everything to run only through the Outlaw 950 pre and the 750 (5 channel amp) the front left and right channels sound and work perfectly fine. There appears to be some strange interaction between the 950 and the Concerto integrated.

Any further suggestions?

Thanks,
Ken