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anonymous 30 July 2004

Hi there!.
I've made a phantom power supply to use with my samson c03, it works just perfect, but when i plug the out of the phantom to the mixers imput, the mic sounds too low almost inaudible.
Other mics as my Shure 8700 sounds good and the gain is huge, but this one samson, doesn't.
Any ideas?
Does it need another pre, before the mixer imput(it sounds crazy but..)
The phantom i'v made is this:http://sound.westhost.com/project96.htm

THanks.

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anonymous Fri, 07/30/2004 - 21:47

Hi, i already done that when i bought it, and it worked just fine the mixer on the test was a behringer with 2 channel imput but it worked.
It's really weird, i don't know what else to do.
I'm trying doffrent things but it still does sound too low tht makes me turn the gain all the way up to hear something.
can it be some impedance issues?
Thx

ghellquist Sat, 07/31/2004 - 02:33

Hmm. The Shure mic is probably a dynamic mic and does not use the phantom power, so using that is not really a test.

I suggest you check up the wiring carefully again. Plug in your cable and look at the mic end. Then test the voltages there (turn down volume on the mixer to zero first).

pin 1 to 2 should be around 48 volt (pin 2 should be positive)
pin 1 to 3 should be around 48 volt
pin 2 to 3 should be 0

Pin 2 is the one in the middle. Having that on top you have pin 1 to the left.

Gunnar

anonymous Sat, 07/31/2004 - 07:43

Hi Thx Gunnar, i got that values it all works good, i discovered something that i think may be the cause of the lack of volume, i used 2 capacitors polyester ( non polar) when i should have used something like bipolar capacitors instead ( the two at the second scheme, the one who rides the signal from xlr to mic pre.
The caps are 22 microfarads NP i guessed that NP means non polar, but the designer says that should be bipolar, i'm not sure if bipolar exist as i never see them before but i'll check it up.

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