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#1
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RCA SK-45 Mic Impedance?
Hi Friends,
This mic is factory set for unbalanced high impedance, according to a sticker inside the body. The documentation says it can be modfied for low impedance though it does not say how to do it. There is a transformer in the mic-head with a green and a black output wire, the green originally to hot, and the black to ground. I tried attaching the green to pin 2/black to pin 3 into low imp input, but this resulted in a duller sound than the unbalanced config to a high imp input. Documentation he http://www.thuntek.net/~bk11/1955cat19.GIF http://www.thuntek.net/~bk11/1955cat20.GIF Any info or suggestions on how to set this mic for balanced low impedance much appreciated. Regards, Joe |
#2
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RCA SK-45 Mic Impedance?
Go he http://www.k-bay106.com/mics.htm
On Sat, 05 Nov 2005 23:08:13 GMT, Joe Kramer wrote: Hi Friends, This mic is factory set for unbalanced high impedance, according to a sticker inside the body. The documentation says it can be modfied for low impedance though it does not say how to do it. There is a transformer in the mic-head with a green and a black output wire, the green originally to hot, and the black to ground. I tried attaching the green to pin 2/black to pin 3 into low imp input, but this resulted in a duller sound than the unbalanced config to a high imp input. Documentation he http://www.thuntek.net/~bk11/1955cat19.GIF http://www.thuntek.net/~bk11/1955cat20.GIF Any info or suggestions on how to set this mic for balanced low impedance much appreciated. Regards, Joe Mike Cleaver Broadcast Services Voice-overs, Newscaster, Engineering and Consulting Vancouver, BC, Canada |
#3
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RCA SK-45 Mic Impedance?
"Joe Kramer" This mic is factory set for unbalanced high impedance, according to a sticker inside the body. The documentation says it can be modfied for low impedance though it does not say how to do it. There is a transformer in the mic-head with a green and a black output wire, the green originally to hot, and the black to ground. I tried attaching the green to pin 2/black to pin 3 into low imp input, but this resulted in a duller sound than the unbalanced config to a high imp input. ** The other (ie input ) connections to the transformer are the ones to use. The transformer can be dispensed with for Low Z use. .......... Phil |
#4
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RCA SK-45 Mic Impedance?
What weird little mic!
A ribbon without a ribbon... Or is it A dynamic without a voice-coil? Are there many of these out there? It certainly doesn't LOOK like it was really workable as much more than a booth talkback mic. It's not anything like the SK-46. On 11/5/05 6:08 PM, in article , "Joe Kramer" wrote: Hi Friends, This mic is factory set for unbalanced high impedance, according to a sticker inside the body. The documentation says it can be modfied for low impedance though it does not say how to do it. There is a transformer in the mic-head with a green and a black output wire, the green originally to hot, and the black to ground. I tried attaching the green to pin 2/black to pin 3 into low imp input, but this resulted in a duller sound than the unbalanced config to a high imp input. Documentation he http://www.thuntek.net/~bk11/1955cat19.GIF http://www.thuntek.net/~bk11/1955cat20.GIF |
#5
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RCA SK-45 Mic Impedance?
Yup, it's weird--there's an oval-shaped magnet surrounding an
oval-shaped diaphragm with a wire embedded right down the middle. Each end of the wire is connected to the transformer. It's an almost-ribbon, or a not-quite dynamic. Nicely voiced on a guitar amp. Haven't tried it on vocals yet, but it's not as boxy as the frequency specs would lead you to think. BTW, thanks for the link Mike--I've now learned that mine is actually a KN-1B, same element but different body, FIXED at high impedance. The KN-1A is fixed at low impedance Joe SSJVCmag wrote: What weird little mic! A ribbon without a ribbon... Or is it A dynamic without a voice-coil? Are there many of these out there? It certainly doesn't LOOK like it was really workable as much more than a booth talkback mic. It's not anything like the SK-46. On 11/5/05 6:08 PM, in article , "Joe Kramer" wrote: Hi Friends, This mic is factory set for unbalanced high impedance, according to a sticker inside the body. The documentation says it can be modfied for low impedance though it does not say how to do it. There is a transformer in the mic-head with a green and a black output wire, the green originally to hot, and the black to ground. I tried attaching the green to pin 2/black to pin 3 into low imp input, but this resulted in a duller sound than the unbalanced config to a high imp input. Documentation he http://www.thuntek.net/~bk11/1955cat19.GIF http://www.thuntek.net/~bk11/1955cat20.GIF |
#6
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RCA SK-45 Mic Impedance?
Joe Kramer wrote: Yup, it's weird--there's an oval-shaped magnet surrounding an oval-shaped diaphragm with a wire embedded right down the middle. How's the diaphragm suspended? Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#7
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RCA SK-45 Mic Impedance?
Bob Cain wrote:
Joe Kramer wrote: Yup, it's weird--there's an oval-shaped magnet surrounding an oval-shaped diaphragm with a wire embedded right down the middle. How's the diaphragm suspended? Bob The edges are more-or-less sandwiched between the surrounding metal frame. It's essentially suspended the same way as a dynamic mic diaphragm, but it's an elongated oval instead of round. Looking at the grill, the diaphragm takes up the top 2/3 of its length inside, and the transformer takes up the remaiming 1/3, sitting just underneath the diaphragm. I was mistaken before to say the magnet surrounds the diaphragm; its apparently behind the diaphragm somewhere. The metal frame surrounding the diaphragm is only very weakly magnetic. Joe |
#8
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RCA SK-45 Mic Impedance?
Joe Kramer wrote: The edges are more-or-less sandwiched between the surrounding metal frame. It's essentially suspended the same way as a dynamic mic diaphragm, but it's an elongated oval instead of round. Looking at the grill, the diaphragm takes up the top 2/3 of its length inside, and the transformer takes up the remaiming 1/3, sitting just underneath the diaphragm. I was mistaken before to say the magnet surrounds the diaphragm; its apparently behind the diaphragm somewhere. The metal frame surrounding the diaphragm is only very weakly magnetic. Hmm, this seems mechanically to be more of a one turn dynamic than a ribbon. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#9
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RCA SK-45 Mic Impedance?
Bob Cain wrote:
Joe Kramer wrote: The edges are more-or-less sandwiched between the surrounding metal frame. It's essentially suspended the same way as a dynamic mic diaphragm, but it's an elongated oval instead of round. Looking at the grill, the diaphragm takes up the top 2/3 of its length inside, and the transformer takes up the remaiming 1/3, sitting just underneath the diaphragm. I was mistaken before to say the magnet surrounds the diaphragm; its apparently behind the diaphragm somewhere. The metal frame surrounding the diaphragm is only very weakly magnetic. Hmm, this seems mechanically to be more of a one turn dynamic than a ribbon. Bob That's about it--no coil, just a wire. You could almost call it a "straight wire with gain." Or maybe a ribbon mic on crutches. Joe |
#10
Posted to rec.audio.pro
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RCA SK-45 Mic Impedance?
Joe Kramer wrote:
BTW, thanks for the link Mike--I've now learned that mine is actually a KN-1B, same element but different body, FIXED at high impedance. The KN-1A is fixed at low impedance Right. I would bet that you could replace the transformer with the Lundahl 1:37 ribbon mike transformer if you want a low-Z output. As it is, you can rewire this mike for a high-Z balanced output, which might be okay into a lot of preamps. You can also add an additional step-down transformer after it (although you are still then fighting the top end loss from distributed capacitance in the secondary of the RCA transformer), and get a low-Z balanced out. But I'd bet that if you actually wanted to use the mike that the Lundahl would be an improvement. On the other hand, it would probably devalue the mike for a collector. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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