Buzzing sound when MC Phono Stage connected to laptop via USB

Posted by: Jason Milner on 29 December 2010

Hi all

I've recently switched cartridges from a very old (and recently broken, hence the upgrade) "hybrid" MM Linn K9 body/K18 stylus to a shiny new MC Dynavector DV-20XL. As you can imagine, the performance jump is huge, and I'm overjoyed. But…

There's one niggling problem (this is where the DA post becomes relevant). I've been gradually ripping my vinyl collection, using my Project Phono Box II USB phono stage to connect to a Windows laptop via mini USB -> standard USB cable. The Phono Box has an MM/MC switch, & set to MC it does a fine job sending the music to my 282, but as soon as I connect it to the laptop, a slight, but definitely audible buzzing sound starts. This is heard through the speakers, and also comes out on the recording (which is done using Audacity).

I suspect the issue lies with the interaction of the low level MC signal coupled with a potentially poorly built USB connection / circuit in the laptop?

Is this something any of you guys have ever encountered (and hopefully resolved)? Please let me know if you are able to help. Any hints / tips or suggestions for alternative connections gratefully received.

Many thanks,

J

Posted on: 30 December 2010 by Geoff P

Jason

I am ripping vinyl using a USB ADC sound card. This has built in 'ground lift' switches which help significantly to reduce hum but even so if I try to use the signal straight out of my phono stage there is background noise detectable.

I found I got the best noise /hum free result using the 'Tape out' on my 552. Try that with your 282. It could be quite a bit better.

regards
Geof

Posted on: 30 December 2010 by Jason Milner

Thanks Geoff.

At present I'm connecting LP12 -phono_cable-> Phono Box -USB_cable-> Laptop, i.e. completely bypassing the 282. The ADC is integrated into the Phono Box. To use the 282, I'd obviously need to add an ADC between it and the laptop (I'm assuming here that even if there's an ADC built into the laptop it won't be worth using, given that it would be unlikely even to match that in the phono box).

I have to confess I'd assumed there was no such thing as a decent add on sound card with ADC for a laptop, (in my ignorance, I'd thought they were only available for desktops) but a quick Google has shown me the error of my ways!

Do you have a recommendation for a (preferably both Windows and Mac compatible) laptop sound-card?

thanks again, J

Posted on: 30 December 2010 by Geoff P

Jason I use an EMU 0404 USB. Comes with quite a lot of sound editting software bundled. I run it with Cubase on a netbook with a USB HDD attached. Operating system is Windows XP,. I find 96/24 is the best for ripping. 192/24 is possible with the right software but it didn't seem to offer much over 96/24 except v. large file sizes.I am very happy with the results.

EMU has beta drivers out for Windows 7 , not sure if they work perfectly but should do by now. The biggy is that whilst they offer ASIO drivers and full resolution up to 192/24 for windows they only offer some of that for MAC. Read thru' their web info to get the latest.

Other USB cards may have better Mac support so check them out against the ADC and internal pre-amp specs of the EMU.

regards
Geoff

Posted on: 30 December 2010 by Jason Milner

Thanks Geoff. Will check it out. I'm using a Win XP laptop for recording in the living room, & an iMac for editing in the study, but at some time I'd like to replace the laptop with a MacBook, so will need something that works well with both.

One limitation I have is that (for now) most of my computer audio listening is done at work via iPod, which is limited to 48kHz/24bit. Longer term I'll be checking out the likes of the Akurate DS & Naim equivalents for home use, but that's at least a year away, so for now 48/24 will do. That said, my work iPod set up is pretty decent given its limitations. I use a line out, headphone amp & some decent IEMs, so I want to make my rips as good as I reasonably can.

I had a quick look at the EMU 404 USB. I think I'm missing something on the input side. They list coax & optical S/PDIF plus MIDI, but no RCA phono inputs. I guess the connection from EMU to laptop would be USB, but how would I connect the 282 into the EMU?

J

Posted on: 31 December 2010 by PureHifi

Try running on battery power rather than ac power pack on the laptop.

Posted on: 31 December 2010 by Geoff P

quote:
I had a quick look at the EMU 404 USB. I think I'm missing something on the input side. They list coax & optical S/PDIF plus MIDI, but no RCA phono inputs. I guess the connection from EMU to laptop would be USB, but how would I connect the 282 into the EMU?

Jason

This is where it is a bit of a fiddle with these sound cards which are typically tailored to take Mic signals and / or guitar amp outputs.

If you go to the EMU 0404 pages on the web site and choose the 'Product tour' tab and scroll down to the 'Inputs/Outputs' section the inputs id'd as 1) are so called Mic/Hi-Z/Line inputs. These multipurpose sockets can take analog line level either balanced or unbalanced via leads wired with std XLR plugs.

Each socket takes a single channel of a stereo pair. Cables with XLR to RCA unbalanced wiring can be bought for not too much ( try Flashback ) or with a bit of soldering expertise you can make up your own. You can then use RCA 'joiner' sockets to connect to an RCA to DIN lead wired for 'signal out' for your 282 tape out sockets.

Alternatively have a straight thru' DIN to a pair of unbalanced wired XLR sockets made to order.

Geoff

Posted on: 01 January 2011 by Jason Milner

Thanks PureHifi.

I'd already eliminated that one, but thanks for the tip. It used to buzz when the laptop was running on mains power even with my old MM cartridge.

Posted on: 01 January 2011 by Jason Milner

Thanks again Geoff. It shouldn't be too hard to get an appropriate cable then. Now I just need to persuade "'er indoors" that I need another gadget...