24/192 Dac/Amp for custom in-ear monitors?

kwl · « **on:** 8 Feb 2012, 05:40 pm »

I recently purchased an iBasso D7 (24/192 asynchronous XMOS USB dac and amp; http://www.ibasso.com/en/products/show.asp?ID=77). Although music through the D7 is very promising, I am hearing electrical noise through my sensitive Ultimate Ears Reference Monitors (earphones) at low volumes; it also exists at higher volumes, but is partially masked by the music. I have tried 2 different laptops (using battery only) and 3 different USB cables. The noise makes the fairly new and expensive ThinkPad X220 unusable as it is clearly audible in quiet passages of the music. It is less of a problem on an older Acer laptop. I am sure that the noise is generated by the laptops; moving the mouse on the Thinkpad increases the intensity of the noise on the Thinkpad. There is no significant difference in noise between the different USB ports. The D7 seems not to be galvanically isolated from the computer. Do you have any suggestions to remove/reduce the electrical noise? Will a USB hub help? What are other owner's of custom in-ear monitors using for a portable (or non-portable) dac/amp?

Thanks,

Ken

randytsuch · « **Reply #1 on:** 8 Feb 2012, 08:49 pm »

Don't think a USB Hub will help, but they are cheap to try and see.
If the noise is coming through the PC, it will just go through the hub too, at least that's what I would expect.

I have seen galvonic isolators for USB, which should help, but I have no idea if they will fix your problem.

Quick search found this
http://www.circuitsathome.com/products-page/usb-interfaces

Good luck
Randy

kwl · « **Reply #2 on:** 10 Feb 2012, 07:22 pm »

Thanks, Randy. To my surprise, a non-powered USB hub in between the laptop and the iBasso D7 markedly reduced the electrical noise. I'm no engineer and can't explain it, but it is a doable workaround. That being said, I'm returning the unit. Ibasso will test it and send me a replacement if the original was somehow defective or refund my money otherwise. IBasso customer service has been incredible and I hope it works out. The D7 is an impressive little dac/amp.

TF1216 · « **Reply #3 on:** 10 Feb 2012, 08:39 pm »

I used to own the Ibasso D10 and it worked great for me. At that time I was running directly out of my laptop. The D10 was powering Sennheiser HD580 if I remember correctly. I then purchased JH13s and used a DAC and portable amp to power those. No noise issues ever. I now have the JH3A and things are still quiet out of a laptop.

I am guessing there was something up with your D7. Please keep us posted.

ecramer · « **Reply #4 on:** 10 Feb 2012, 09:28 pm »

Hello Kwl

Ultimate Ears Reference Monitors nice iem's if you get this straightened out would love to have you write a review. Might want to throw a shout out over in the discless circle they might have more insight into this. Why usb is the only input on this is a mystery
can you try an ipod to the dac and see how much noise is there that way

kwl · « **Reply #5 on:** 13 Feb 2012, 06:14 am »

The Ultimate Ears Reference Monitors (UERMs) are indeed quite nice. I admit that I'm relatively new to headphones/earphones. There is an adjustment to the music in the center of your head rather than projected as an image in front of you. The trade-off is more clarity and detail than these somewhat older ears have ever heard from speakers. My goal is to put together a high quality, semi-portable system for my serious 2-channel and hi-res listening. The UERMs are the first piece of that system. Why the UERMs rather than other custom in-ear monitors like the JH13s or ES5s? The simple answer was that I got a great deal on them. I would say that the reviews of the UERMs on Head-Fi are spot on; they are accurate and detailed without being sibilant or harsh. Bass is tight and well-defined, but on the lighter side. The UERMS are definitely not for bass heads. I have used the UERMs with an iphone 3GS (lossless ALAC), a 2009 TADAC dac/headamp, straight from a few laptops and most recently the iBasso dac/headamp. The quality of sound has been directly related to the quality of the dac and the recordings. The UERMs are very sensitive and don't really need separate amplification. The iphone with lossless files actually sounds quite good. With the exception of the iBasso D7, I have not had any noise issues with any source.

vigotone · « **Reply #6 on:** 23 Jun 2012, 04:05 pm »

Hello,

I have the exact same problem with the exact same setup. I just got the iBasso D7, and when upon listening with my UERM's, I'm hearing some digital noise when I move the trackpad on my MacBook Pro. I've emailed iBasso support to see what they say. I would hate to have to return the unit.

Thanks,

Lee

kwl · « **Reply #7 on:** 2 Jul 2012, 11:33 pm »

I returned the D7 and bought a HRT Headstreamer. Sound quality is really excellent, even more so considering the price ($139). The only negative is that there is very little room for volume control for the sensitive UERMs. The new Dragonfly ($249) looks interesting as an alternative as well.