[dm]

Davey,

Which 2x4 board are you comparing this too?  unbalanced rev A, rev B or the balanced board?

I received Paul's miniDSP 2x8 board and also checked another one.  Both measure the same so I think we can assume this characteristic is normal.

There is a decent amount of high frequency noise on all the outputs........even relative to the output noise from the miniDSP 2x4 boards, which is somewhat higher than analog circuitry would create.  I have a theory on the cause of this, but it's speculative. 

Anyways, here's a couple of photos from the many I captured.
The first one is a 1khz sine input/output of 200mV RMS for both the 2x8 board and 2x4 board.  (200mV would be typical value these boards might see for normal operation.)
The second photo shows noise floor (no input signal) of the 2x8 output (blue) and 2x4 output (red) over a range of 0-300khz.  In the audio band the noise floors are similar, but it's easy to see the large increase in output noise above 50khz generated by the 2x8 board.

Cheers,

Dave.

[Davey]

Unbalanced.  One of the newer boards with selectable jumpers.....in the 0.9 volt position.

Dave.

[swantzilla]

Sorry for reviving an old thread. I just received a 2X8 and noticed that it is putting out a signal to my power amps when there is no input signal. I can accept that there may be some noise but I think this much is unacceptable. I e-mailed the company last Friday and have not gotten a response as of yet. The 2X8 board is a 1.3 rev. Anyone else seeing this much noise? The meter switch is in the -20DB position. The output is only there when the DSP is booted up with the blue LED flashing. It is not there when it first powers up.

[swantzilla]

Additional note; Adjusting the levels on the plug-in has no effect. Nor does any mute button.