Nostromo Posted March 31, 2015 Share Posted March 31, 2015 Hi everyone, Wondering if any of you techi type guru’s out there could help me with a very simple question ? . . . . well simple if you understand electronics which I have to admit I don't !! I’ve got the chance to buy a second hand Demeter VTHF-300M Power Amp and want to quickly use it with a preamp to check its working ok before I make my final decision on it one way or the other. A mate of mine has offered to lend me his Avalon VT 737 SP preamp so as to test the Demeter, but, looking at the two units, the Avalon’s output is by way of a balanced 3 pin XLR output (plus, minus and earth pins) whilst the Demeter input looks to be a simple unbalanced mono jack input. At the moment I dont have a lead that could connect one to the other ! Question is, will these two units work together, (one balanced and the other unbalanced ?) and how exactly should I make up or order a lead to go from Balanced XLR to unbalanced mono jack ? . . . ie, do the two unbalanced jack terminals connect with the balanced XLR plus and minus pins or plus and earth pins . . . . or, will these units not work together ? Sounds simple I know, but I don’t want to get the lead wrong and damage either unit by connecting them together incorrectly ! ! Also wondered whether there would be any background earth hum etc what with the preamp being balanced and the power amp unbalanced ? Any advice very much appreciated. Cheers, Quote Link to comment Share on other sites More sharing options...
Nostromo Posted March 31, 2015 Author Share Posted March 31, 2015 Just been searching google for more info on this question of cross-connecting balanced and unbalanced audio equipment. I found a Rane Corporation technical note “Rane Note 110 titled Sound System Interconnection”. Reading this note my intention of using a preamp with balanced output into an unbalanced power amp doesn’t sound like a good idea ? !.... here is an extract from the Rane Technical Note where they touch on the concept of cross connecting balanced and unbalanced components:- [i]“And what of those who think connecting unbalanced equipment into "superior" balanced equipment should improve things. [u]Sorry. Balanced interconnect is not compatible with unbalanced[/u]. The small physical nature and short cable runs of completely unbalanced systems (like home audio for example) contain ground loop noise currents. However, the architecture of balanced topography ensures currents in unbalanced professional systems never get large enough to affect the audio to the point where it is a nuisance. Mixing balanced and unbalanced equipment, however, is an entirely different story, [u]since balanced and unbalanced interconnect are truly not compatible”.[/u][/i] Any thoughts ? Quote Link to comment Share on other sites More sharing options...
Nostromo Posted March 31, 2015 Author Share Posted March 31, 2015 (edited) Just read that there would be a 6dB loss by connecting a balanced preamp out into an unbalanced power amp in ? . . . I have no idea why ? Still don't understand this subject at all . . . . obviously pre / power amps are just not plug and play ? Can't seem to find any general advice for the layman bass player ? . . . loads of "techi" stuff online but I'm lost before I've finished the first paragraph ? . . . Any advice very much appreciated . . . . am just realising that if I do get the power amp I'm going to have to get a preamp to go with it anyway . . . . and it looks like understanding what bass preamp will work with what power amp is a real difficult issue ? Grateful thanks for any advice ? Edited March 31, 2015 by Nostromo Quote Link to comment Share on other sites More sharing options...
Soulman Posted March 31, 2015 Share Posted March 31, 2015 Hi,you need something like this,ART do one that's around £40ish,http://www.radialeng.com/j4.php Quote Link to comment Share on other sites More sharing options...
gelfin Posted April 1, 2015 Share Posted April 1, 2015 This might be helpful http://www.presonus.com/news/articles/balanced-unbalanced Quote Link to comment Share on other sites More sharing options...
bertbass Posted April 3, 2015 Share Posted April 3, 2015 Here you go, http://www.mediacollege.com/audio/connection/xlr-jack-mono.html Or, if you want to buy a ready made lead, something like this, http://www.amazon.co.uk/kenable-6-35mm-Socket-Microphone-Cable/dp/B003OSLUR2/ref=sr_1_3?ie=UTF8&qid=1428058502&sr=8-3&keywords=xlr+to+mono+jack Or even one of these, http://www.ebay.co.uk/itm/XLR-FEMALE-Plug-To-6-35mm-Stereo-Jack-Socket-Microphone-Cable-Adapter-Adaptor-/400782214104 Quote Link to comment Share on other sites More sharing options...
bertbass Posted April 3, 2015 Share Posted April 3, 2015 Should add that if you get a lot of hum, an earth loop, then something like this will get rid of it, http://www.gak.co.uk/en/behringer-hd-400-2-channel-hum-destroyer/1140?gclid=CjwKEAjw9PioBRDdpqy0-ofG3DgSJAACe5NEFTld_ArTfLicPAR6RgFiEOPzym8JKXFUmuxRTtyRmRoCv9nw_wcB Quote Link to comment Share on other sites More sharing options...
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