I posted something about the problem with using the DD 192 HD converters with unbalanced inputs. Like you said, if you connect those outputs to an unbalanced input, the signal will drop 6dB and the ground of the input will be driven with audio. Unless you have a pretty amazingly earthed ground plane, you will get some crosstalk. ...and For the 192s, we can't just lift "pin 3" (-) to solve the problem unfortunately. On the 192s the shield isn't the same, or connected to the audio ground. This means neither polarity can work by themselves using the shield as the ground reference, as normal unbalanced signals work. There is no audio output ground reference available.
If you want to keep the HD192s, the only solutions are to balance every input in your studio, or unbalance the outputs of your converters... Greg Norman Electrical Audio Recording 773.539.2555 www.electricalaudio.com My email address has changed to [email protected] Please update your address book. On Dec 2, 2011, at 11:58 AM, Matt Syson wrote: > Hi > If the 192 instructions tell you to lift the negative it suggests that the > outputs are not 'transformer like' but a simple amplifier out on the hot and > another amplifier out with phase polarity reversed for the negative. With > this scenario 'grounding' it will drive signal current into the ground > causing possible crosstalk, distortion and maybe even damage to the converter > outputs. > A 'simple' test for this type of output is to measure a continuous tone > signal at a convenient level, say 2 Volts on a multimeter, connected to > measure BALANCED (between pins 2 and 3 of an XLR or hot to cold). Now, while > monitoring the output level, short one side to ground. With a transformer or > 'electronically compensating' output the signal level will not change, or > only by a tiny fraction. Shorting EITHER hot OR cold should produce no > significant level drop. I suspect that with the 192 outputs you would see a > fall of 6dB (Half the original level). In this case you must connect the > signal into a balanced input or if you have no choice with an unbalanced > input, cut the 'negative' and accept the inevitable signal level loss. With > the negative cut you will not damage anything. > Matt S > > On 02/12/2011 17:12, Matt Boynton wrote: >> >> That's what my issue was. Sometimes lifting the shield isn't the answer >> though. For example, a digi192 suggests on the rear panel to lift the >> negative wire instead of the shield. Which is different than any other >> converter I've encountered. I have the studio wired with the shields lifted >> on the converters so whenever I plug into an unbalanced input on the neotek >> the signal is 6 db or so lower. To remedy this I'm getting a new converter. >> >> Matt Boynton >> Vacation Island Recording >> 90 Walton Street >> Brooklyn, NY 11206 >> tel: 347 225 3201 >> www.vacationislandrecording.com >> >> >> On Dec 2, 2011, at 9:43 AM, Tom G <[email protected]> wrote: >> >>> Hello Matt, >>> >>> Interesting. I do have some noise in my left master channel/monitor however >>> it is only the monitoring section. When I mix down to tape or digital the >>> signal is fine. I'll check into this too...I am >>> guessing its more of a power amp and may not be related to my preamp issue. >>> >>> Thanks! >>> Tom >>> >>> --- On Wed, 11/30/11, Matt Boynton <[email protected]> wrote: >>> >>> From: Matt Boynton <[email protected]> >>> Subject: Re: NEOTEK: Series 1 Noise Problem >>> To: [email protected] >>> Date: Wednesday, November 30, 2011, 3:51 PM >>> >>> I had a problem where my speakers had a fairly high frequency buzz in >>> them regardless of the position of the control room volume pot. I >>> isolated it to the convertors. I ended up lifting the shield wire on >>> the ins and outs of the convertors and the buzz was gone. Maybe its >>> something similar. >>> Matt Boynton >>> Vacation Island Recording >>> 90 Walton Street >>> Brooklyn, NY 11206 >>> Tel: 347 225 3201 >>> www.vacationislandrecording.com >>> >>> >>> >>> On Wed, Nov 30, 2011 at 3:39 PM, Ike Zimbel <[email protected]> wrote: >>> > >>> > Hi Tom, >>> > Do the channels have to be side by side, or any two at random? Does >>> > this >>> > mean that you are using two and only two pre-amps when this happens, or do >>> > you mean when it's a pair, like overheads, while using other channels for >>> > other inputs (IOW, can you only use ONE mic-pre on the Neotek at the >>> > moment?)? If that's the case, does the problem steadily get worse if you >>> > use >>> > more channels? >>> > I very much doubt this is a grounding issue (in the 60hz hum sense, >>> > anyway), >>> > but it MIGHT be an interface issue between the direct outs of the Neotek >>> > and >>> > the input of the converters. >>> > Best, >>> > Ike >>> > >>> > >>> > On 11-11-30 3:27 PM, Tom G wrote: >>> >> >>> >> Hello All, >>> >> >>> >> I have been battling an issue with my Neotek Series 1 console on and off >>> >> now for about six months. When I use any two preamps (of the console) at >>> >> the >>> >> same time, I get a noise on one channel. According to my frequency >>> >> analyzer, >>> >> it is approx. 4k and is high enough in gain to make the track unusable. >>> >> When >>> >> I use outboard pre's there is no problem whatsoever. >>> >> >>> >> I thought it may be a ground loop or something similar, but floating the >>> >> grounds did not help. I'm using SSL converters and it doesn't seem to >>> >> matter >>> >> what inputs of the SSL I'm using nor what channels on the Neotek I >>> >> use...still the same noise. But only when using two channels together. >>> >> >>> >> Any thoughts? I have not tried completely floating all grounds except for >>> >> the console. Once I get my tape machine back home and hooked up, I am >>> >> curious if I get the same result. Although as stated, floating the two >>> >> channels in question was no help. >>> >> >>> >> Thanks! >>> >> Tom >>> >> >>> >> >>> > >>> > -- >>> > Ike Zimbel, >>> > Zimbel Audio Productions Ltd. >>> > Toronto >>> > 416-720-0887 >>> > >>> > "Studio House Calls". Repairs and upgrades to analog audio equipment >>> > including: AMEK, dbx, Neve, Neotek, MCI, Soundcraft and more. Authorized >>> > Warranty service for Allen& Heath, Clear-Com, Drawmer, Soundcraft, SPL >>> > and >>> > Yamaha. Ask about our RF frequency co-ordination services! >>> > www.zimbelaudio.com >>> > >>> > ------ >>> > >>> > View the list online at: http://www.mail-archive.com/[email protected] >>> > >>> > You can unsubscribe at anytime by sending an email to >>> > mailto:[email protected] with "unsubscribe neotek" in the message >>> > body. If you have any difficulties, or questions --please send an email to >>> > mailto:[email protected]. >>> > >>> > The Neotek list is lovingly hosted by Catapult Web. Remember that any >>> > message or reply sent to the list will be automatically forwarded to all >>> > subscribers. >>> > >>> > Vive Le Neotek! >>> > >>> > Thanks. >>> > >>> ------ >>> >>> View the list online at: http://www.mail-archive.com/[email protected] >>> >>> You can unsubscribe at anytime by sending an email to >>> mailto:[email protected] with "unsubscribe neotek" in the message >>> body. If you have any difficulties, or questions --please send an email to >>> mailto:[email protected]. >>> >>> The Neotek list is lovingly hosted by Catapult Web. Remember that any >>> message or reply sent to the list will be automatically forwarded to all >>> subscribers. >>> >>> Vive Le Neotek! >>> >>> Thanks. >>
