Would anyone have any recommendations on how to reduce the noise floor on the 7100? I've got about .5mV to .7mV going to my speakers even with nothing connected to the amp.

As a person with some EE education and years of video/audio technical experience, measurements that small lead me to ask:

Did you measure with a 'scope or a meter? If a 'scope, what did the display show?

Sheilded leads?

What voltage did you get from the leads when the leads are not connected to anything?

Were the fractions of a mV you reported AC, DC or a combined measurement?

Were the inputs to the 7100 open, with an appropriate terminating resistance, or shorted?

Were the speaker wires disconnected from the amp and the measured output terminated by something like a 10-ohm resistor?

I ask all these questions because there are reasons one might obtain readings in the 0.5mV range even if everything inside the 7100 case were ideally perfect.

I'm not trying to be a troublemaker!

BestBang. Handled like a true Engineer. No answers, just more questions. I get that complaint all the time. “Can’t you just answer the question?” People just don’t understand.

I've got an EE background, so I'm answering and saying some things that are obvious to you, but qualifying my statements for other readers. Hopefully I don't say anything incorrect.

I measured with a multimeter. But as far as relative measurements go, the voltage seems to match the dB levels. A scope would indicate frequency, but it's voltage that produces volume, not frequency.

Not sure what you mean by shielded leads. I'm using banana plugs on the floor-standing that measured .5mV, and bare wire on the center that measured .7mV. The floor-stander was measured at just the leads, not plugged into the speaker.

The mV were for AC. A DC current would not produce noise. It's change in current that induces a magnetic field.

The 7100 inputs were open but without anything on them to short or terminate them. Attaching my receiver pre-outs to the amp inputs doesn't modify the noise floor. Attaching my equalizer outputs to my amp inputs raises the noise floor a few dB.

I didn't run any measurements over the speaker wire.

Using a scope will also give you voltage, based on the amplitude of the wave. I did it in class about 2 weeeks ago.

Right. I meant that a multimeter is enough for voltage. No need for a scope.

So...I answered the questions but nothing further?

Short the inputs and measure the output.

I was away for a few days and had a couple thoughts about the “noise” level.

I’m not sure how Outlaw would run such a test, but if I were using some of my usual-at-home stuff, I would test like this, starting with the 7100 off:

Because the Outlaw 950 processor has an output impedance of less than 600 ohms, I would put a resistor with short leads and a value between 300 and 500 ohms on the input of the 7100 channel being tested, no input interconnect cables attached.

I would put a 10-ohm resistor with short leads across the output of the 7100 channel being tested, no speaker wires attached.

I would use two pieces of wire, about one or two inches long each, to go from the 7100 channel output to the meter, the meter being placed as close as possible to the output terminals.

With the amp turned off, turn on the meter and note the voltage reading.

With the amp turned on, what increase in “noise voltage” do you observe after the amp has warmed up?

If the 7100 is living up to advertised specs of a –119dB signal-to-noise ratio, and if the testing is ideal, you should observe no more than about a 0.03 mV increase in noise. I’m not sure without trying, and I’m not at home, but my digital multi-meter may not have that kind of resolution and accuracy of extremely low voltages.

I would check with Outlaw tech support if you have further questions.

I played around with some stuff and my noise floor is good now. Thanks for the help.

What fixed it?

Yes what fixed it Josuah?

Sorry, was late and was tired. So didn't provide details.

I'm not entirely sure. First thing is I was using an EQ between the receiver and amp. That was increasing the noise floor by a few dB and also adding a ground loop hum. I reduced the ground loop hum to the level of the noise floor by grounding all the chassis together and to a ground hole on the power strip. This noise floor, with the EQ involved, was barely audible from my listening position.

But, disconnecting all inputs to the amp still had a noise floor that while inaudible from my listening position, was there.

Anyway, I removed the EQ, and this resulted in removal of something else besides the EQ: the RCA to 1/4" TRS Hosa cables I was using for interconnects. I am now using RCA brand RCA to RCA cables for the interconnects that I bought from Home Depot (including one labeled my green component video, since I needed 7 instead of 6).

This combination has resulted in an extremely low noise floor. Lower than when I shorted the inputs using 12awg copper or when the inputs had no connections. It is currently only audible from some of the drivers, and then only with my ear against the grille, and even then, barely audible. The chassis are still grounded to each other and the ground on my power strip.

Summary is the EQ was a noisy component, but also connecting the receiver pre-outs directly to the amp inputs using RCA brand cables instead of Hosas. The RCA brand cables seem to have better shielding. But that could just be them trying to make the cables look nicer.

hmmmm...

No, that's Hummm

i was thinkin' if i should add my .02 but it's REALLY long and simple,few more,maybe.....

Was everything on the same circuit and did you try moving the EQ, but leaving it connected?

Yes, everything was on the same circuit. The raised noise floor was not ground loop hum. I'm sure those who have experienced ground loop hum know the difference in sound. The higher noise floor was still there when everything else was off and disconnected.

Unless it just happened to be something odd that one day. Because in previous testing, I thought removing all the inputs but leaving everything there did lower the noise floor quite a bit. Not as silent as it is today though. Based on what I can hear with my ear against the grille.

I did try physically moving the EQ, but only a little bit, thinking maybe it touching the DVD player or not touching the amp would make a difference. Turning off the EQ would stop it from generating any EM fields.

I am experiencing something like that in my speaker testing setup, since I am still waiting for my equipment to arrive from Outlaw.

I have a Bedini Class A amp connected to an old Nad which I am using to test my speakers and found I was getting a "noisy grill" effect as well.. (even though none of my speakers actually have a grill)

They are all on the same circuit and seem to be having some kind of inconsistant EM problem, cause if I move them around a bit, etc, it stops for awhile. I am also having problems with the pots in the NAD, so that could have something to do with it as well, but its just old and I am not going to fix it.

Does you EQ have pots or is it all digital?

The EQ I was using was all digital input, on sliders, so I'm guessing no pots inside. 1U for 8 channels digital. But I was still getting the noise floor with the EQ off.