Mic preamp problem

kimarin · 29th October 2004, 11:14 AM

Hi . I buildt this mic preamp, and I loved it. sound very open as the author said. I mounted a jack input to the preamp, so i could use a bass and a guitar on it with a 5k6 ohm resistor i series (stole the idea from a mackie vlz1604 schematic). This sounds nice, except for the kind of a ground noise when I'm not touching the strings on the guitar. Seems like a ground problem. Anyone have a clue how to fix this problem ?

http://www7.taosnet.com/f10/ssmicpre.html

Cool preamp

moamps · 29th October 2004, 09:11 PM

Hi,

Output from a guitar pickup is usually unbalanced and high-ohmic. If you wish to connect the guitar to your microphone preamp, for best results you should use a di-box (or a microphone step-up transformer reversely connected). To direct connect the guitar pickup to the preamp, connect "3" and "1" together, replace R3 with 100k, C3 with 10pF and omit C1 and R1. Signal input is pin "2".

Regards,
Milan

29th October 2004, 11:14 AM	#1
kimarin diyAudio Member Join Date: Jul 2001 Location: Norway	Mic preamp problem Hi . I buildt this mic preamp, and I loved it. sound very open as the author said. I mounted a jack input to the preamp, so i could use a bass and a guitar on it with a 5k6 ohm resistor i series (stole the idea from a mackie vlz1604 schematic). This sounds nice, except for the kind of a ground noise when I'm not touching the strings on the guitar. Seems like a ground problem. Anyone have a clue how to fix this problem ? http://www7.taosnet.com/f10/ssmicpre.html Cool preamp

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29th October 2004, 09:11 PM	#2
moamps diyAudio Member Join Date: Oct 2002 Location: Croatia	Hi, Output from a guitar pickup is usually unbalanced and high-ohmic. If you wish to connect the guitar to your microphone preamp, for best results you should use a di-box (or a microphone step-up transformer reversely connected). To direct connect the guitar pickup to the preamp, connect "3" and "1" together, replace R3 with 100k, C3 with 10pF and omit C1 and R1. Signal input is pin "2". Regards, Milan

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