jimma Posted March 11, 2015 Report Share Posted March 11, 2015 I was just curious if anyone else has had this problem or knows what I might be doing wrong. I have a T powered 416 when plugged into the 633 with t power I get no signal yet when I feed it 48v with a 48v/12v adaptor it get signal. Could I be wiring it wrong? The reason I ask is that I seem to be getting a lot of high freq noise and doesn't seem as clean as p48 versions I have used in the past, I was hoping to remove the adaptor from the chain to rule that out and hopefully get my 416t sounding better. Any help is greatly appreciated. Quote Link to comment Share on other sites More sharing options...
Ryan Coomer Posted March 11, 2015 Report Share Posted March 11, 2015 The 633 has 12 volt phantom, and that isn't the same as 12 Volt T-power - that's why it doesn't work. You will have to us the 48V phantom to 12V Tpower adapter. Quote Link to comment Share on other sites More sharing options...
bmfsnd Posted March 11, 2015 Report Share Posted March 11, 2015 Your best bet is one of these guys: http://www.trewaudio.com/store/PSC-48V-Phantom-to-12V-T-Power-Barrel-Adapter.html Quote Link to comment Share on other sites More sharing options...
jimma Posted March 11, 2015 Author Report Share Posted March 11, 2015 Thanks Ryan I didn't know that there was a difference. Just out of curiosity what is the difference? I wouldn't mind checking that my adapter is a Tpower adaptor and not just a 48v phantom to 12v phantom as its not a PSC adapter. Quote Link to comment Share on other sites More sharing options...
VASI Posted March 11, 2015 Report Share Posted March 11, 2015 Hi Jimma, Check here: http://www.sounddevices.com/support/tech-notes/t-powering-basics Quote Link to comment Share on other sites More sharing options...
pkautzsch Posted March 11, 2015 Report Share Posted March 11, 2015 Try it with an old SQN or 302 mixer that actually provides T power to rule out the power converter barrel as culprit. Still noisy - faulty. Sputtering noise often is a sign of death with old 416s. Quote Link to comment Share on other sites More sharing options...
Glen Trew Posted March 12, 2015 Report Share Posted March 12, 2015 Thanks Ryan I didn't know that there was a difference. Just out of curiosity what is the difference? I wouldn't mind checking that my adapter is a Tpower adaptor and not just a 48v phantom to 12v phantom as its not a PSC adapter. I'm sure it's a 12T adapter, because I can't think of a reason to bring 48V phantom to 12V phantom. And if it's a T power mic, and it works, then your adapter is a 48V phantom to T power adapter. The difference between Phantom power and T power: Modern phantom power has positive DC voltage on pins 2 and 3, and negative (ground) on pin 1. This way, if a dynamic mic is plugged in to a phantom powered input, the circuit doesn't "see" the voltage, as if it's "phantom'. Another advantage of phantom power is that any noise on the powering voltage is cancelled out on pins 2 and 3. However, since modern phantom circuits use the mic cable shield as the negative voltage conductor, if the shield is broken or intentionally "floating" anywhere in the circuit, the mic won't work. (The reason I specified "modern" is because the origin spec for phantom power required 4 conductors and used 4-pin XLRs until connecting to the microphone, at which point the shield was connected to the grounding tab and the powering voltage negative conductor was connected to pin 1. The first broadcast facility I worked in in the 70s was wired this way, but this chances of every encountering this these days is zero. So forget I even brought it up.) T power has positive voltage on pin 2 and negative on pin 3 (though there was a time when different manufactures had reversed standards, which is why T powered mic users should always have a phase reversing adapter handy.} A disadvantage of T power is that any noise in the powering voltage is mixed and amplified with the mic signal. Therefore, T power requires an ultra low-noise power supply, which is difficult to obtain when using modern DC-DC inverters, which I believe is why most manufactures no longer include the option of T power with their mic preamps. Glen Trew Quote Link to comment Share on other sites More sharing options...
jrd456 Posted March 14, 2015 Report Share Posted March 14, 2015 One of the reasons that Kudelski used T power was that Nagra's had a positive ground.Also, T power is good for Batts. J.D. Quote Link to comment Share on other sites More sharing options...
David Waelder Posted March 14, 2015 Report Share Posted March 14, 2015 A little historical perspective on T-power might help with understanding its role. (I think I have this right but I'll defer to members, like Glen, with greater engineering expertise.) Phantom power for condenser mikes has been around for many decades. But, in the 60's and 70's, getting 48 volts of power to the microphone was a challenge. At that time, DC-to-DC converters were either unavailable or impractical for remote recording applications. Microphone manufacturers addressed the need by designing versions of their microphones to work with 12-volt T-power that works across pins 2 and 3. Although there was no protection for dynamic microphones inadvertently plugged in to the wrong input, the lower voltage was easily available from portable recorders and mixers. Protection for dynamic microphones is probably more important for a studio where many different people might set up a particular stage then with film sound equipment that is typically owned by the user. Development of DC-to-DC converters that can efficiently produce 48 volts from a 12 volt source made the T-power design unnecessary and manufacturers gradually moved away from it. David Quote Link to comment Share on other sites More sharing options...
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