Help with Distortion

[olddude]

I'm wondering if anyone has insight into the cause of distortion I get with my digital playback. This happens in a periodic but regular fashion say every 30 seconds or so and lasts around 5 seconds. I get a loud raspy distortion that builds to a crescendo and then stops only to recur again…almost like a record skipping but worse! I am a noob at this and maybe someone knows right away what is wrong.

 

I am running iTunes on a Mac Mini with and without Audirvana+. This goes via a Halide Designs USB bridge into an original EMMLabs DCC2 convertor via the S/PDIF coax input.

 

Thanks in advance.

[esldude]

Really hard to answer with that limited info.

 

Just shots in the dark.

 

Have you tried using the optical out of the Mini to feed the Toslink input on your DAC?

 

Have you tried some other playback software like Decibel or Bitperfect? I think the latter works with iTunes and former doesn't.

 

Can you borrow a different DAC and see if it happens with that?

 

If you listen over the Mini using headphones does it happen?

 

These steps might let you narrow down where the distortion is coming from.

[olddude]

Hi ESL,

 

No I didn't even realize the Mini had an optical out. I will give this a try.

The distortion comes whether I use iTunes "natively" or with Audirvana so I don't think the software is the problem.

 

I have briefly tried another DAC that was fed via USB (no bridge). There was no problem but didn't sound as good as old EMM.

The DCC2 works with no problem with it's CDSD transport.

 

My suspicion is that there is something wrong with the USB bridge or how I am using it.

[esldude]

Hi ESL,

 

No I didn't even realize the Mini had an optical out. I will give this a try.

The distortion comes whether I use iTunes "natively" or with Audirvana so I don't think the software is the problem.

 

I have briefly tried another DAC that was fed via USB (no bridge). There was no problem but didn't sound as good as old EMM.

The DCC2 works with no problem with it's CDSD transport.

 

My suspicion is that there is something wrong with the USB bridge or how I am using it.

 

I think your suspicions are correct more than likely. But it never hurts to double check things like listening to the mini with a headphone.

 

Most (maybe all) Mini's have a combination headphone toslink output (later ones have a toslink input too). You need an adapter for that. Like the following:

 

Amazon.com : Recoton Fiber Optic Toslink to 3.5mm Mini Adapter : Electronics Cable Connectors : Electronics

 

Toslink Female to Toslink Mini Male Adapter - Monoprice.com

 

I guess the final thing worth trying is your computer and Halide bridge or at least the Halide bridge and any computer with another DAC if one is available to you for the test. But since you say it works from a CD player I would think that eliminates the DAC as the problem.

[acg]

It could be something else plugged into that power circuit either in your audio room or somewhere else in the house. It might help to figure out what else is on the circuit and then unplug all that are unnecessary for audio to see the distortion still occurs. Could be a bad lamp or guitar amp or something like that.

[One and a half]

What else is connected to the USB, mouse , keyboard, camera...iPhone ?

 

Also remove spotlight, email apps, that sort of pesky software.

[olddude]

Thanks for the further thoughts. The Mac Mini is a dedicated music server. When I set it up, I removed non-essential software as recommended by this or some other forum. My system power supply is fringe fanatical. I have the DAC plugged into a Torus isolation transformer (preamp, phono stage and turntable motor controller also plugged into this) which in turn is plugged into a dedicated line. The Mac is plugged into a separate dedicated line just because it is there.

 

Is there any other maker of a USB bridge device like the Halide? This is what I would like to try...