I'm having a tough time getting a noise-free signal from my XM radio into the Empeg aux input. I've tried additional grounding, ground loop isolator, power line filter, better cables, pre-amp, etc. I don't think it's XM... if I unplug XM and ground the signal lines at the plug, I still get unacceptable noise. If I mute the empeg - absolute silence. Also MP3's sound great, so I don't think it's the empeg->amp path.

This is frustrating because I'm trying to get music from one digital device to another. What I really need is a digital toslink->toslink connection. Toslink is available on the XM side, but not on the empeg.

There were a few discussions a while back, and it seems the hardware is possible, but would require software hacking. I'm a hardware guy myself (chip designer), but I have done some software work in the past and would be willing to help out in any way possible.

Is anyone currently working on this?

A digital output board is already available for the empeg. As for digital input, I do not know if anything is in production. Check out the S/PDIF link in the header - you might want to give Stu (maczrool) a PM or email.

If you want to collaborate on this, let me know. Either through the website "contact us" link on our website at the S/PDIF link above or PM. The next model of sound card we make for the Empeg, if there is one, will be full duplex digital. We just need someone to help with the software side.

Stu

How are you going to interface the digital input? I tried to enable the tuner I2S input but it doesn't seem to work for some reason. Not much documentation about what tuner lines do what when in I2S mode as well so I may not be enabling it properly.

I was planning to use the tuner I2S lines. The DSP only has two sets of I2S inputs, so I guess that's the only option.

I believe Hugo said it wouldn't be easy to write the software to get it done. It will definitely take some time to work out.

Stu

Yeah. It's easy to make the DSP switch to the CD_2 I2S input instead of CD_1. You just need to modify the empeg mixer code to allow it to select the other input. The register definitions to select the I2S inputs is on page 63 of the DSP docs.

I'm not too sure how to make the empeg connect CD_2 to the tuner lines though which is main problem. Anybody from empeg know?

Have you tried to ground the AUX in shield to car ground? If you don't do this, you will get noise. A ground loop isolator will make it worse.

Hugo

Yes, that was the first thing I tried. Grounding the aux shield with the XM plugged in definitely made the noise worse. I know the aux input is supposed to be floating, but I think the ground loop isolator made an improvement. In any case, it is still not satisfactory.

I think my primary noise problem is not a ground loop: I have unacceptable noise even if I unplug the cable from the XM unit and ground the aux shield and two signal lines to the empeg ground.

It just seems wrong that I'm running analog FM into a digital input and digital XM into an analog input.

I'm considering adding the Eclipse unit w/ digital aux-in and running both empeg and XM digital into a S/PDIF autoswitcher. This would give me an all-digital solution (of course for more $$$).

-Jon