My MiniDSP 2x4 HD exibits massive RF interference when connected to my Denon AVR X-4300H's subwoofer outputs (x2) via RCA cable.

MiniDSP is an active crossover/EQ device:
[Link: minidsp.com]

If I disconnect the RCA, then the RF interference goes away.
I've tried two different types of RCA cables and both had the issue.
I tried both RCA outputs on the AVR (sub1 and sub2).
I don't have this issue if I bypass the MiniDSP and plug the RCA from my AVR directly into my amps.
I tried a different PSU for the MiniDSP and still had the issue.

It's caused me to go down to a single RCA instead of two.
That helped a little.
I then ensured the RCA isn't running lengthwise with power cables, which probably helped.
In the end, I had to put the MiniDSP in a really weird position to get the RF interference to be low enough not to interfere with my URC remote's RF.

Do you folks know of any tricks I can use to further minimize the RF interference?
I've already posted on the MiniDSP forum and a 3rd party MiniDSP forum thread but not gotten any help.

Questions.

Are you basically using the MiniDSP as a low-pass filter for the sub? Since the Denon has that built in, what are you trying to get the MiniDSP to do?

What is the name of the output of the MiniDSP?

How does the "RF interference" manifest itself? Does it sound more like white or pink noise, or more like buzzing 60Hz?

"If I disconnect the RCA, then the RF interference goes away." I may be being simple-minded, but your descriptions so far lead me to think you're stating that there is no sub sound when you disconnect the sub signal... which seems obvious. Are you saying something different from that, or is that simply to tell us that the MiniDSP isn't simply buzzing (or whatever) on its own?

Is the noise constantly on? Does it go up and down with the Denon volume control? Does it go up and down with the amp(s) you're using to amplify the sub signal? Does its behavior change if you change inputs on the Denon?

Ernie,
He said RF interference, not audible interference. At the end of his 4th paragraph, he hints that it is causing interference with the URC remote's RF reception.


CZ Eddie,
URC antennas are notorious for picking up interference. A high speed processor (like what is in the MiniDSP) creates a lot of RF interference by nature.
Need to know 'which' URC base station you are using, to recommend some remedies.

Try using some ferrite beads on cables connected to the MiniDSP, including the power leads.

Brad, I have the RXF-250 and MRF-250!
Everything is located in the same rack together, except for the RXF-250 which I had to move all the way over to the top of my projector just to find a spot where it did not get interference. It was not fun routing new cable through the ceiling to the projector for the RXF's cat5 cable (for power/signal not networking of course).

buzz, that's a neat idea. I'll see if I can locate some to purchase!


Ernie,

The RF interference has no affect on sound. It's interfering with my URC RXF-250 RF receiver. Causing the second red LED to be constantly lit.

I use MiniDSP for two-way subwoofer where one plays up to 50hz and the other takes over from there. One sub is a pair of 18" (Dayton UM18) tuned to 15hz that are firing into the back of my couch. The other sub is a single 15" pro-audio (Eminence Kappalite) which is commonly referred to as a "mid bass module". It plays from 35hz up to 120 hz and anchors the sub "sound" up front.

I also use the MiniDSP for Auto-EQ using REW.
[Link: minidsp.com]

And I also use it for Bass EQ to add missing LFE back into movies which have filtered it out of the soundtrack.
[Link: avsforum.com]

I think you mean RFX-250 (the active antenna) with an MRF-350 (base station). The MRF-250 is a very old URC base station, that had a integrated antenna.

With the RFX-250 being already positioned so far away, it is weird you are still getting interference.
I would give Buzz's idea a try and see if it helps. But I would try the ferrite chokes on the antenna lead for the MRF-350 1st.

Sorry, yes the MRF-350!

Thanks for the suggestions.
Will try some ferrite chokes and see if it helps.
THere is certainly a lot of them to choose from.
[Link: amazon.com]

You could have google searched 'MiniDSP and read the manual int he time you took to write your reply and in the process, you might have learned what it can do. It's pretty cool, if you like geeky things.

It's not really even a geeky thing. It is pretty straight forward to use, with a pretty straight forward setup. The only quarky thing is keeping track of the software license you have to have to configure it.

There are several clones of this on the market now. And none of them (that I recall) require software licensing. Been meaning to try some of them out.

When someone can't bother to look it up online, it's geeky.

Have you looked into the Parts Express piece?

RCA cables running parallel to power cords isn't usually a source of this kind of interference but you need to verify the frequency range of the interference. 60Hz isn't RF.

Assuming you have a cable toner, use the inductive pickup to find the source of the noise- if it's the wire, find a way to shield it and if it's the wall wart, move it away from the MRF or find a way to shield that. Wall warts are a common source of interference.

Is the USB cable always connected to the computer? If it is, it could be the source. Disconnect it or try another one.

Have you tried setting the base station to a different channel?

Just for grins, try connecting the MiniDSP to the Front pre-out and see if it still does this. You're stacking crossovers and that must have (it would be unavoidable) some effect on the sound.