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I have drawn this out showing the basics of the mic preamp with the two 6.8K resistors. If you want to maintain the phase relationship of the incoming audio you actually want the "+" terminal of the capsule going to Pin3 of the XLR. The circuit will work connecting pin 2 or 3. [image: SimpleP48Explain.png] -- Best Regards, Jules Ryckebusch 214 399 0931 Linkedin <https://www.linkedin.com/in/jules-ryckebusch/>

I recorded a couple handclaps and snap sounds with the SimpleP48 wired with pin3 to the capsule "+" and this is the resulting waveform. -- Best Regards, Jules Ryckebusch 214 399 0931 Linkedin

Hi everyone, I am a cardiologist. For a fun activity, I am working on my own electronic sthethoscope design. Heart sounds are low frequency and low intense sounds. (About 20 to 1200 Hz). Are listened to by touching the skin surface, that makes them susceptible to motion artifacts. I am looking forward to the suggestions of the audio experts in this group on the following topics: Which mic capsule, amplifier circuit and ext. should I prefer? Is it better to make a diy circuit or are there commercial ones to handle my needs? I guess that mic sensitivity and frequency range is important, are there ways to electronically modify mic sensitivity? Which solutions can be made about motion artifacts? And what about noise cancelling? Thank you in advance?

Hello, I have just ordered a pair of em200 caps from Micbuilders and intend to use them with the simple P48 circuit. I have looked in the files section but can't find a recommendation for the resistor value and wonder if anyone suggest a value please? Thanks very much, Ross

Hey all - I'm curious if people here have any recommendations for cheap, makeshift parabolic reflectors? I'd like to experiment a bit with the idea, but I'm hesitant to spend $80 on some meticulously curved glass. Are there any interesting alternatives? Thanks!

Hello, Been lurking this group for a while and finally got around to actually building something! About 2 years ago I had some extra MDF lying around so I decided it would be fun to make my very own Binaural Head. I based the shape off of the Neumann KU-100 and used a projector to draft some stencils approximating the size of my own head (it ended up being a tad over-sized). After rough cutting/routing the 9 layers I needed to make up the width of the head I ended up with this monstrosity After some diligent work with an angle grinder, sanding flap disk, and an old can of urethane clear coat the head was looking pretty good. I then entered the final semester of my EE degree and became very busy with my senior design project so I put the head project on hold. Months turned into years and the head got kicked around my house as my attention turned to more pressing matters. All the while I could feel the hollow, blank stare of the binaural head-to-be piercing into my core. Well, free time finally made itself available to me once again and I decided to turn this 10 lb mannequin head into a proper microphone. The original plan was to base the impedance converter on a Calrec schematic given to me by a friend. After a few failed attempts I decided instead to modify the popular OPA design that originates from this forum. Since I had already purchased the transformers I opted for a paralleled amplifier configuration. Douglas Self covers this technique in Small Signal Audio Design and details its improved load driving capabilities and reduced self-noise compared to a single opamp. Now, I am not sure whether the noise performance is actually improved when the source impedance is so high. Someone here may have a better idea but I would think that this configuration would reduce the input Z of the amplifier and cancel out any reduction in noise you typically get from a parallel amp combo (corrections welcome). The capsules I am using are the Omni caps that came with my pair of Lauten LA-120's (good mics btw). They happened to be about the same diameter as a 7/8" Ryobi forstner bit I had so I simply marked their location and drilled holes on both sides of the head. I carefully disassembled the caps and soldered the shield of some mic cable I had to the threaded brass ring that holds in the back plate. After re-assembling the caps I soldered the twisted pair to the back plate connection. I cut this lead to be as short as possible and pressure fit the capsules into the head. After laying out the circuit in Kicad I etched and drilled a pair of boards. I used some metal 1-gang outlet boxes from HD and some scrap metal from an old receiver as shielding. I drilled a pair of holes in the back of the neck (using the same 7/8" bit) and wired up some Neutrik XLR bulkheads I had laying around. Overall I'm pretty satisfied with the result, I included a short recording of myself on drums as an initial test. I plan on dusting off my 3D printer and printing out a pair of human ears to help achieve that HRTF stereo image goodness. Update to follow.

Bought 8 of these ...Wired up and put on my drum overheads and was impressed ...Noticed a clarity I didnt get with Octava O12s or My AKG 451s with CK-1 capsules...Or My MXL 603s mics...S/N is at 69db so not as good as a lot of mics but they beat out all my other mics...Even on kick they sound fantastic...Also A very good vocal mic with windscreen...Recorded the drums and the sound was still there.....Used the schematic with one resistor from pin 2 to ground..