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Hi everyone, does anyone know if the Ambi-Alice (GoPro mount version) will fit inside the Rycote "Baby Ball Gag" windshield? They make them to fit 20,21,22,and 25mm mic bodies. I think the GoPro mount diameter is 25mm? I can measure to make sure before I buy, but also want to make sure the basket will fit inside the windshield.

I got a chance to play with these and they are really nice. THis one is Cardiod https://www.jlielectronics.com/microphone-capsules/jli-160a11uc680/ And this one Figure 8 https://www.jlielectronics.com/microphone-capsules/jli-1660nb-38/ I wired the Cardioid one as a "two wire" by connecting the Source to Ground and using the Drain lead as my connection point for PIP power. I'm guessing they both have the same FET as the TSB2590 as they work well with a 100K Ohm resistor in the Simple P48 configuration. I put two Cardioids back to back, one facing front and one back in a quickly 3D printed holder with the Figure 8 at a 90 degree angle to both. That makes a three capsule Double MS setup. I plan on testing this and getting some samples in the near future. They sound really good. Two of the Figure 8's will make a great Blumlien pair that can run into a small PIP recorder. Jules -- Best Regards, Jules Ryckebusch 214 399 0931 Linkedin

I Just had a really cool adventure recording Humpbacks with my hydrophones. See this: https://youtu.be/XrURPtL9zuk One challenge was the failure of two of them post build. I also had a couple board failures after initial testing of the boards prior to attaching the Piezo cylinders. There were two modes of failure. Complete failure of the Opamp causing a higher than normal current draw. Second, it still worked but with a lot of noise. The light bulb went off as I realised that I was directly connecting the cylinder to the Piezo element. I connected my Oscope to the cylinder and tapped on it. I could easily generate 15-20 volt spikes that were visible on the scope. Reviewing the literature, I realized I wasn't including any input protection. Yes there are internal diodes for this in the opamp. I suspect they are fine for "normal use". I am updating the circuit as seen below: This includes a series resistor and two diodes to shunt anything to ground and the supply pins. Conveniently there is a .1uF cap across the supply rails of the opamp that will act as a low Z source for this too. I have my first boards back from PCBWay and will commence testing shortly. Love any advice or feedback here. -- Best Regards, Jules Ryckebusch 214 399 0931 Linkedin

Hello, is there any way to reduce the sensitivity of an electret microphone capsule with a built-in fet transistor? Something like a -10dB or -20dB pad? Thank you. M.

Hello, A while back I purchased a used MTG MV203 measurement mic to use as comparison/testing for any of my future projects. After researching the MTG documentation I built a rack-mounted power supply/preamp to go with the mic. Everything was working fine (PSU functioned nicely & super clean/healthy output from the mic). I moved the PSU into a new enclosure to make things more portable and started having issues with the mic. Sometimes I would get no output, sometimes very distorted, sometimes functioning perfectly. After thoroughly troubleshooting my PSU I found no issues with it at all, which led me down the harrowing road of cracking the mic body open and prodding around with my DMM. Here are pictures of the internals and my best shot at the schematic. Output was disconnected to verify the cable was not causing issues. Had to replace a 6k8 resistor that took flight when I was desoldering the adjacent mystery component. I used the component codes, DMM, and educated guesses to determine most of the components and I plan on measuring the unlabeled caps. I'm fairly confident the High Z section under the resin is two 10G resistors in series and a 0.2 pF cap (input impedance is specified at 20G and 0.2 pF). However, I am not sure what the black mystery components are. Intuition tells me they are resistors, but they must be on the order of >>10M because my DMM cannot read them. I will have to carefully remove them and employ something like this method to measure them on a separate board. Luckily I had also taken a look inside while it was working. I know from my first measurements that, when functioning, the output sits at around 65V DC offset. It now sits around 40V DC (sometimes as low as 24V) and I measure no signal regardless of sound source. Prime suspect is the 1uF tantalum cap as I understand they are prone to damage and considered somewhat unreliable. The dual diodes, MOSFET body diodes (not sure I understand why they are used here), and Both BJTs measure ok with the DMM diode mode. I'm posting this here mostly for general interest, but if anyone has suggestions on troubleshooting the circuit I would greatly appreciate any insight.

Hello, long time lurker here. Thanks for all valuable info in this group. I have an idea to build KM84 circuit with Primo EM200 capsule (theres inernal FET in this capsule). So I sketched basic schematic. I want to ask you if theres something to change or if theres mistake somewhere in schematic. I like the idea of transformer based electret mic, hope it is not totaly nonsens. Best regards Milan

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?