UDA - Scratching noise with DAC when using Optical Cable

[aimlink]

Just got my Ultra Desktop Amp:

-Intermittently I am hearing a scratching sound in the music while listening. It's difficult to describe. It's like listening to a CD with scratches on it which aren't bad enough to severely interrupt play. However, you hear scatchy glitches in play. It's not just a simple interruption or a pop, but a scratching sound created by a sudden and transient distortion of the sound which lasts less than half a second (like a tenth of a second).

- this happens every 1 to 5 minutes or so. At times I think it's gone and then I hear it again, so there's no fixed periodicity to it.

Any ideas or advice about this concerning issue? I just switched from my Ultra Micro Stack, to this new unit. I had no such issues with the Ultra Micro Stack that has been working perfectly. I connect to the Ultra Desktop using an optical digital cable. I'm also using a DPS that I was also using the with Ultra Micro Stack. In between the scratching noise, the sound is fine.

[twsmith]

I think the problem may be the source or the connection -- you're possibly hearing noise or even micro-dropouts in the digital signal which could be causing a scratchy or crackling sound. There are several things you could try -- first, the connection between the cable and Ultra Desktop and/or CD player could be faulty or loose, so you could pull it out and reconnect again, or try a different optical cable. You could also try using a coaxial instead of an optical cable (if this is possible in your set-up). Finally you could try a different source - switch out your CD player for another or a DVD player. Doing all of these things may help isolate the problem before calling the HR help desk -- they will probably ask you the same questions. Hopefully you don't have a defective unit.

[aimlink]

I have only one possible source to use here, i.e., my iMac. I have no CD or DVD player. I can't use coaxial since the iMac doesn't allow this. I've had the Ultra Micro Stack for over 6 months and no problems at all... ever when connected to the iMac with the same optical cable.

It may well be possible that there's a problem with the optical cable connection. Hmmm. I'll get a new cable and see how things go. For the time being, I'll switch the connection ends around.

Interestingly, the problem was occurring while playing 96Khz/24bit, high resolution music from HD Tracks. Now that I've switched to 44.1Khz/16bit resolution music I've not heard any scratching sounds for a long time of listening. It may well occur any moment now anyway. I'll continue to listen.

Anyway, I LOVE how you're talking in that you're proposing little technical issues. I'd hate to have to go through the process of returning etc. It's not the nicest process as an International customer.

[aimlink]

I got a hold of a USB cable and tried a digital over USB connection. It's without any issues so far. So it would seem that there's a problem with the Toslink cable.

[TheSloth]

Originally Posted by aimlink

I got a hold of a USB cable and tried a digital over USB connection. It's without any issues so far. So it would seem that there's a problem with the Toslink cable.

Some optical cables are woefully inadequate. The best way to test is to use Audio MIDI setup to increase the bit rate to 24/96. If there's a connection problem, this should make it considerably worse and more audible.

[aimlink]

Sloth,

That MIDI setup is what I was using with my Ultra Micro Stack. I had no problems with it and the same optical cable.

BTW, after using USB, the scratching sound is there but far less infrequent, hence my initially feeling that it wasn't occurring with the USB connection.

I'll be getting another optical cable and giving it a go.

The Ultra Micro Stack is supposed to be similar but I'm now having trouble making the Ultra Desktop tango with the same digital signal source that my Ultra Micro DAC worked OK with.

[aimlink]

Just for everyone's information, I had to return the amp to have the DAC replaced. It's now working perfectly. No more zapping/scratching sounds.

[plonter]

Originally Posted by aimlink

Just for everyone's information, I had to return the amp to have the DAC replaced. It's now working perfectly. No more zapping/scratching sounds.

so, in the end it was a defective unit hah..? as an international customer also,every time i get something I pray that everything will go smooth and the until will be in 100% shape just not to get into a returning process.
anyway,glad you had you unit fixed..now you can enjoy a blissful sound.

[aimlink]

It's a very unpleasant and expensive process when you're an International customer. The wait periods for shipping are long.

[Gamerphile]

Hmmm.. might have heard the same in some rare cases - was on USB input however and changed with source so suspect my source gear...

[aimlink]

Yeah. My problem didn't care about the source, whether USB or Optical. What had me thinking it did was that I'd often switch sources after letting it rest for a while, not knowing that the problem really became evident only after the amp warmed up.