Apart Zone4 Controller introduces irritating noise

[Lisa Lane-Collins]

Using a Zone 4 controller in an installation, notice there's an irritating high pitched buzz in the system, prominent at 9.4, 10 kHz but there are frequencies lower in that.

The signal chain is, working back from the amp, amp to mini DSP, mini DSP to zone controller, buzz box to DI, DI to pc. I systematically unplugged the components of this chain until the sound stopped and that didn't happen until the zone 4 was out. Plugging the zone 4 input straight into the miniDSP also fixed the problem however then I lose my user friendly zone controller so that isn't really a solution.

Wondering if anyone else has had this kind of experience before? Is it a faulty unit? Is there a work around? Do I need another buzz killing thing between the zone controller and the miniDSP? Is it reasonable to expect it to work and sound better out of the box? I was under the impression Apart was a good brand.

This is the 3rd time I've tried implementing the zone controller in this set up, twice it's gone back under warranty because there was bleed between the channels. The first time they replaced the unit, I'm not sure if it was replaced the second time but I've just gotten it back and plugged it all in and it's not exactly up to standard.

I've fixed the agitating high pitched hum for now using the parametric EQ in the miniDSP but the 'noise' still there, it's by far the noisyest piece of equipment in the chain. And I am interested to hear back from people.

 

[Craig Hauber]

Re: Apart Zone4 Controller introduces irritating noise

I am unfamiliar with the MinDSP (other than I thought it was a bare-board 2ch processor that you supply your own PSU for.) I would suspect that as a possible trouble-spot long before the Zone4.

How is the connection between the zone4 and the miniDSP? Balanced?. If so then try lifting the pin1 connection (either via the phoenix connectors if hard-wired or with XLR ground lifts if cable-patched) You may have to experiment with what end of the interconnect you have to lift.

You may need an audio transformer in between

If it's unbalanced then you're probably screwed (just kidding!) But your description of the noise sounds much like one I get using PC laptops with their power supply. (If run on battery only there's no noise, plugged in charging, lots of buzz!). I've found RCA jack equipped "Hum Eliminators" work great for that (Ebtech) and even the Radioshack transformer-equipped rca cable (car stereo) has solved the laptop problem in a pinch.

For some additional troubleshooting purposes only try connecting the Zone4 directly to the amps without the DSP.

Also try ground-pin lifting on the zone4 (temporarily for testing purposes only) -same goes for the MiniDSP and the amp. (don't float them all at once though)

I've spent hours tracing people's buzz problems before and it usually boils down to an underlying problem with wiring (either mains supply or audio interconnects) or a poorly designed and possibly faulty product -like some home-stereo grade stuff being used in the middle of an install of pro gear.

 

[Lisa Lane-Collins]

Re: Apart Zone4 Controller introduces irritating noise

I noticed after posting that the zone controller still has the fault of bleed between channels too. Sigh

The mini DSP is a one of these http://www.minidsp.com/products/minidsp-in-a-box/minidsp-10x10-hd

I don't think I've ever tried leaving the zone4 and cutting the minidsp out of the signal, I doubt it's the source of my troubles here as it's been holding the fort every time the zone controller goes back for repairs but in the name of thorough testing, I will try that when I go in next.

The connections between the 2 are RCA

Will definitely explore additional buzz kill too.

Thank you for the suggestions, good to have more things for me to try