Bizzarre buzz problems with Octopre LE

[CarlH]

Hi all

I'm having some new and strange problems with an intermittent buzz in my system.

I've got it down to an Octopre LE, with nothing at all connected to it apart from the power supply and a single balanced TRS lead going to a Rokit RP 8.

There is an intermittent buzz emitting from the monitor. It comes and goes, sometimes of its own accord. Turning on phantom power on the Octopre will usually make the buzz either better or worse. Turning the Octopre off and back on again will sometimes make a difference. But I can't find any definite recipe to make the buzz appear or disappear.

When it is present, the buzz appears to emit equally from all of the 8 outputs of the Octopre. It is configured to pass signal from the ADAT input to the analogue outputs.

I've tried cutting the signal ground at the monitor end of the connecting lead, but this makes no difference.

The monitors are (near enough) silent with nothing connected, or with the Octopre turned off.

Anyone with any helpful advice or condolences?

Thanks

Carl

[CarlH]

Further investigation seems to suggest that the buzz is coming from the D/A option board; it goes away when the outputs are switched to take their signal from the analogue ins. I've checked the D/A board connections and nothing appears to be amiss.

[adrian_k]

FWIW I have a similar problem with a second hand Octopre LE, making it unusable. A nasty buzz (in my case there all the time) that appears on mic channels when I use the digital out. I don't get this problem using my RME Octamic.

I contacted Focusrite but (quite reasonably) they couldn't comment unless they could have a look at the unit, which would be chargeable, so for now the box sits in the attic

To be honest I wasn't too impressed with this unit's preamps anyway even when connecting via the balanced outs, but it might have been OK for drums.

cheers
A

[CarlH]

Ah well, thanks for the note. I suppose I'll have to get it off to Focusrite at some stage