this is something i have vaguely worried about when designing multichannel mikes in one body, and then phantom powering them. in the classic wurtke circuit, the phantom voltage powers the output transistors, and you need it to be on for the transistors to work (right?) doesnt the core sound ppa also have a transistor driving the transformer. if it was just a transformer with a resistor to the centre tap to draw the phantom voltage, connecting only one channel would actually be better. otherwise you have four ten k resistosrs, four five volt zeners and four capacitors which are going to be paralleled. (talking from memory so probably through my hat) umashankar
i have published my poems. read (or buy) at http://stores.lulu.com/umashankar > From: jnarve...@wesleyan.edu > Date: Sat, 16 Apr 2011 09:18:42 -0400 > To: sursound@music.vt.edu > Subject: Re: [Sursound] TetraMic and/or Sound Devices 788T question: weird > noise at record start? > > > Hi, John (and Dave) - > > Ah - I haven't tried using just channel 1's phantom power. I *did* try taking > the 788T off of AC power, turning off all the phantom power on it, and > putting AA-batteries in the PPAs as the phantom power source. With this > set-up, I still got a weird noise about 12 seconds in to recording, but not > as severe. A bit mysterious. > > I haven't tried other mics yet - not sure I *have* any other mics at the > moment, since I had a bunch of stuff stolen last year (which indirectly led > to my TetraMic purchase this month). I certainly don't have any condensers... > perhaps I'll try it with line input just out of curiosity. > > thanks again, everyone, > > -jascha > > > On Apr 16, 2011, at 4:53 AM, John Leonard wrote: > > > Jascha, > > > > You only need phantom turned on on Channel 1 - try turning it off on all > > other channels and see if the noise goes away. The Baby Ball Gag does work > > with the TetraMic, by the way; not perfect, but so much better than the > > foam & furry set-up supplied with the mic. I believe that Rycote now do a > > special set-up for TetraMics with a modified lyre-suspension and the > > extended BabyBall gag, but that really is expensive. > > > > On the subject of Rycote prices - my thought is that if it enables me to to > > my job effectively, it's worth the money. Rycote is a genuinely innovative > > company, run by people who care passionately about what they do. And it's > > British! > > > > Best wishes, > > > > John > > > > On 16 Apr 2011, at 01:44, Jascha Narveson wrote: > > > >> The four XLR inputs are routed to tracks A, B, C, and D in the 788T, and > >> 48V phantom power is active on each channel. > > > > _______________________________________________ > > Sursound mailing list > > Sursound@music.vt.edu > > https://mail.music.vt.edu/mailman/listinfo/sursound > > > > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20110416/abcfb7b7/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
