bruce Posted June 15, 2011 Share Posted June 15, 2011 CPC do a usb soundcard straight to XLR out. http://cpc.farnell.com/_/av17492/usb-audio-interface-usb-to-2-2/dp/AV17492?in_merch=Products%20From%20This%20Range&MER=e-bb45-00001003 Nice simple unit. but as I said in another thread, plugging it into something with phantom power enabled will fry it. (Speaking from experience) The identical unit with balanced jack connectors is far safer :) Link to comment Share on other sites More sharing options...
timsabre Posted June 15, 2011 Share Posted June 15, 2011 If your laptop is earthed through the power supply (check mains plug on power brick for 3rd pin), you nearly always need a DI box to get isolation, or you will get weird noises from earth loop problems. A soundcard with XLR balanced output will not help you here. Link to comment Share on other sites More sharing options...
jamesperrett Posted June 15, 2011 Share Posted June 15, 2011 does anyone know of any small usb/firewire audio interfaces with physical XLR outputs to do this instead. ART certainly used to do one but I can't find it on their website at the moment. James. You're more likely to blow your laptop or iPod by running at line level running over long distances as it puts the small amps in them under more strain than they are designed to handle. Sorry but that's just plain wrong. Headphone outputs can actually drive longer lines than line outputs as they generally have a lower output impedance and are designed to output more current than line outputs. iPod headphones have a typical impedance of 32 ohms while a line input usually has an impedance of around 10k ohms. The only way you will damage an iPod output is by feeding it to a device that has a voltage on the input connector or where there are unwanted voltages induced in the cable due to poor grounding or screening. The general reason for using long cables at mic level is for convenience - it is simply standard industry practice which has evolved over the years. Mic cables are usually balanced and the inputs work at a slightly lower impedance than line inputs, both of which make the connection less susceptible to interference. However, sending line levels to a balanced line input may result in less interference as the levels involved are much higher. James. Link to comment Share on other sites More sharing options...
chelgrian Posted June 16, 2011 Share Posted June 16, 2011 Sorry but that's just plain wrong. Headphone outputs can actually drive longer lines than line outputs as they generally have a lower output impedance and are designed to output more current than line outputs. Indeed the entire point is you are trying to make your connection function as an idealised transmission line and have no current flowing. Of course you can never do this perfectly. Even with everything balanced and ideal cables you can still run into interference problems in hostile environments...which is why the good lord invented StarQuad. Link to comment Share on other sites More sharing options...
Simon Lewis Posted June 16, 2011 Share Posted June 16, 2011 [Even with everything balanced and ideal cables you can still run into interference problems in hostile environments...which is why the good lord invented StarQuad. There are some specific benefits from using starquad, but these must be weighed carefully against the increased capacitance such a cable construction introduces... The LORD gave and the LORD has taken away; may the name of the LORD be praised... Job 1,21 Link to comment Share on other sites More sharing options...
Doug Siddons Posted June 16, 2011 Share Posted June 16, 2011 Just a quick comment as no one has mentioned it yet, the headphone out of a laptop carries left and right information so for best results two or a stereo di will be needed Link to comment Share on other sites More sharing options...
IA76 Posted June 17, 2011 Author Share Posted June 17, 2011 I connected the laptop to the XLR via a passive DI box and it works fine. Thanks Link to comment Share on other sites More sharing options...
Bobbsy Posted June 17, 2011 Share Posted June 17, 2011 There are some specific benefits from using starquad, but these must be weighed carefully against the increased capacitance such a cable construction introduces... Agreed. I've resorted to Starquad in the past but only for runs where there were very specific worries about noise. For example, for one programme we produced for the BBC, they wanted a bunch of mics in the reception area of our building and the only viable cable route was via an air conditioning plant room with some very heavy duty mains present--for that we used Starquad but for any "normal" interference risk ordinary balanced feeds were always adequate. Bob Link to comment Share on other sites More sharing options...
Bazz339 Posted June 17, 2011 Share Posted June 17, 2011 This is a good active stereo DI box powered by phantom or battery, it needs a 3.5mm stereo jack to 2 X mono jack lead. and this is a very good passive DI box, for PC interface, more expensive but used a lot by professionals. Link to comment Share on other sites More sharing options...
Simon Lewis Posted June 17, 2011 Share Posted June 17, 2011 Actually, I have come across a lot of noise and buzz problems with that particular Behringer DI, and have replaced quite a few with standard passive Behringer DIs when called to solve noisy laptop problems in churches... Link to comment Share on other sites More sharing options...
J Pearce Posted June 17, 2011 Share Posted June 17, 2011 Every DI120 has at least 3 snakes inside. You can hear them hiss when you plug it in... Link to comment Share on other sites More sharing options...
bruce Posted June 18, 2011 Share Posted June 18, 2011 Snakes? I thought it was pixies frying sausages! Link to comment Share on other sites More sharing options...
themadhippy Posted June 18, 2011 Share Posted June 18, 2011 your both wrong,its an undocumented feature.A built in white noise generator to aid setting the system up. Link to comment Share on other sites More sharing options...
TonyMitchell Posted September 14, 2011 Share Posted September 14, 2011 CPC do a usb soundcard straight to XLR out. http://cpc.farnell.c...e-bb45-00001003 Nice simple unit. but as I said in another thread, plugging it into something with phantom power enabled will fry it. (Speaking from experience) The identical unit with balanced jack connectors is far safer :) Bought one of these recently... will cut off the nasty, cheap jacks that have a tendency to unscrew themselves and replace with Neutriks when I get a spare half hour. But a question for the more computer-savvy... any idea why it works perfectly on a Windows 7 laptop, but doesn't want to know when hooked up to a Macbook Pro (have tried several different, recent MBPs with OS higher than the minimum they specify (9.04)? The LED illuminates, so it is powering up, but no audio.:( Link to comment Share on other sites More sharing options...
ramdram Posted September 14, 2011 Share Posted September 14, 2011 Any chance the distance to the lappie from the sound desk would allow you to use the usb "a" out of the lappie into the usb "b" on the desk, assuming it has one of course? Info on max length about halfway down page: http://en.wikipedia.org/wiki/USB Saw this method used in a recent production from a visiting company; no messing around with DI boxes, ground lift, just straight into the usb "b" skt on our A&H Zed 436, "route" the channel, job done. Link to comment Share on other sites More sharing options...
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