BEC Posted July 17, 2005 Share Posted July 17, 2005 You guys are going to a lot of trouble to avoid buying the $49.99 mixer. I think you can get around the phantom power problem with just 3 or 4 9volt batteries and a 10Khom resistor in series with them for feeding the mic. I know that the mic uses almost no power because when I turn off phantom power the mic continues to work for minutes. What I think you would miss more is the nice volume control features of the mixer and in my case I would really miss the little overload LED,s that let me know I have the gain low enough to avoid overload with just a glance. Also some day you may want a real Specturm Analyzer and you would have to have a line level signal for most of them which is what you get out of the mixer. Bob Crites Quote Link to comment Share on other sites More sharing options...
scriven Posted July 17, 2005 Share Posted July 17, 2005 Gee Bob, there you go raining on our little parade by injecting reality! Of course, as usual, you are completely correct in every respect. But, and you knew there would be a but, Who is a starving collage kid and I happen to like to make the few items in or near my stereo system that I am capable of building. (Building a power supply is approaching the limits of my capabilities!) While I won't presume to speak for him I have the impression that the good Doctor enjoys DIY. Also, we are located in the same graphical area and have discussed getting together before; this project would make an excellent excuse to do that. I am chalking this up to being part of the hobby so the $ and time issues dont have to be rational. Quote Link to comment Share on other sites More sharing options...
scriven Posted July 17, 2005 Share Posted July 17, 2005 ---------------- On 7/17/2005 3:40:48 PM BEC wrote: ... Also some day you may want a real Specturm Analyzer... ---------------- Bob, You seem to be stating that there are some deficiencies with the computer - soundcard - software implementation of a spectrum analyzer. Is that true? If so what are they? (Or am I just reading too much into your post?) Quote Link to comment Share on other sites More sharing options...
BEC Posted July 17, 2005 Share Posted July 17, 2005 ---------------- On 7/17/2005 10:22:08 PM scriven wrote: ---------------- On 7/17/2005 3:40:48 PM BEC wrote: ... Also some day you may want a real Specturm Analyzer... ---------------- Bob, You seem to be stating that there are some deficiencies with the computer - soundcard - software implementation of a spectrum analyzer. Is that true? If so what are they? (Or am I just reading too much into your post?) ---------------- Actually, with the right software and sound card, a computer should be able to go a good job on spectrum analysis. Most of the free software RTA's that I tried were too limited to do things I wanted them to do. Probably some of the more costly programs are up to the job, but free or trial versions I tried a couple of years ago left me wanting them to do more. When I bought the Wavetek Spectrum Analyzer, I found that it did everything I wanted it to do, but it is far from being easily portable. It stays tied up on the bench ready to test crossovers and drivers after building or rebuilding them. So, I bought a PC based scope and spectrum analyzer to go portable with a laptop. Still trying to decide it that gadget was worth the $250.00 I spent on it plus the laptop. Software that came with it is sort of clunky. Bob Quote Link to comment Share on other sites More sharing options...
jim-analog Posted July 18, 2005 Share Posted July 18, 2005 Not exactly. Phantom power (P48) is a dc voltage run simultaneously over the +/- audio signal line (XLR pins 2 and 3)of a balanced system. This is referenced to ground via pin 1. There is a precise specification for phantom power, which is +48v through a pair of 6K81 resistors to limit the current to a maximum of 14mA. The precision of matching between these resistors significantly affects the CMMR of mic as the dc voltage powers an amplifier located inside the microphone, and may also be divided down to provide capsule polarization voltage. There may be a low and high range on any specific mic as to where this amplifier will operate, but to adhere to the specification it must function with the above circuit. Lowering of the voltage will adversely affect the SNR, FR and gain of the (internal) mic amplifier. Raising the voltage may damage the internal circuitry. Many console strip and outboard mic amps are designed with a phantom power circuit built in. Regards, Jim On 7/17/2005 2:14:00 AM DrWho wrote: Btw, phantom power is just sending a DC signal through the cable...it's basically a way of boosting the signal of the microphone who's diaphragm isn't moving far enough to induce enough current to send the signal down the line. The more phantom you give it, the lower your noise floor gets. Well at least that's what I've been told...I've never noticed much of any significant differences. Quote Link to comment Share on other sites More sharing options...
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