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Has anyone here tried either of these dynamic mics from AliExpress? Fifine K669D Maono PD100 They look like solid bodies, I'm curious if they come apart easily and how good they would be as donor bodies. https://www.aliexpress.com/item/1005005510482582.html https://www.aliexpress.com/item/1005004887926822.html

Pondering how to choose SimpleP48 resistors, it suddenly occurred to me that we can use the techniques in FETbias.doc so I've updated that in my Files/Ricardo directory. It's so obvious with hindsight that I beg yus guy's pardon for my stupidity. Measuring at 9V is perfect cos we want 5 - 10V Mea culpa, mea culpa, mea maxima culpa.

I’ve been looking around to try to find some sources of material to enable me to learn about how amplifiers work. I’ve only got the most rudimentary electronics knowledge so end up floundering very quickly. I bought The Art of Electronics a while ago and have had a cursory browse through it. I was also recommended this paper by an old work colleague. https://1drv.ms/b/s!Ap5IR9dQ9eMPgfxAOWdiIkU-1cGvcQ "Audio power amplifier design" has also been recommended to me. What do you guys think / recommend to enable learning about these things? It seems that a lot of you are well versed in the ways of coercing electrons

Is there a way to connect a 3 pad electret (ground/source/drain) to the Linkwitz 2 wire solution? Thank you!

Hi all, a new ultrasonic microphone is now available on: https://www.dodotronic.com/product/ultramic-384k-evo High sensitivity and double MEMS sensor Cheers Ivano Pelicella

(First post) Hi, I have been experimenting with small electret microphones (from Primo) mounted on goosenecks as violin pickups for busking (including classical repertoire). Visibly similar to a DPA 4099 but orders of magnitude cheaper.... Results are quite good: not as nice as my external SDC in the optimal position (and probably not as nice as the DPA!) but way better than any piezo I've tried. I'm considering a next version with a slightly larger, FET-less capsule and an Alice circuit. The circuit would likely be too big to fit immediately next to the capsule, so would be distanced by around 15-20cm (6-8"). I am wondering how this separation of capsule and preamp would impact performance (e.g. noise, stability). Would it be better to stretch Alice by putting the 1G resistor and first FET with the capsule and the rest of the circuit downstream? I've seen the discussion on FET availability and the resulting OPA Alice. Are the 2N4416 and 2N 5087 still available (September 2024)? Would it be better to switch to an OPA circuit after the initial FET? For this application, it's a balance of sound quality (trying to amplify a good quality violin), directivity (to minimise feedback from amplifier), and practicalities (not getting in the way of the violin bow). Thanks for any comments! Jeremy

I have several 25mm Chinese electret capsules without internal FETs. How do I add a FET to one to make it like the TSB2590A?? And can I use any FET to do it ? Also , In another topic I see an SMD circuit board being used. Are these available from PCBWAY or are they not commercially available?? Thanks.... Charles

I'm thinking about maybe making a mic with 3 capsules to use as a stereo mic for recording instruments in my home studio. So a sort of flexible 2D stereo image mic, rather than a 3D soundfield. I don't need full soundfield, as the room is not so good that I often want much of the back, top or underneath of the mic. Mounting a full tetrahedral setup seems like overkill for my likely use. But I'm thinking of maybe front + left + right cardioid capsules, with a circuit to provide three outputs, which could then be combined in the daw to offer M/S or XY (at 45 degrees) or various form of mono multipattern. I'm interested in suggestions for how the capsules should be placed. If they are cardioid capsules they'll need some air space around them. Should they be in a vertical line? or with the front capsule in front in a triangle? Also suggestions for which inexpensive capsule would be most suitable. TSB2555 springs to mind but I'm not sure about the offaxis response, and maybe a smaller capsule would be better. any suggestions?

So far as I can tell, the best way to shield an XLR3 cable is by tying the shield conductor(s) to both the ground lug and pin 1 at both ends of the cable. This seems like the best way to ensure that the shield is connected to earth via a low-impedance path, which would provide the best shielding. But most commercial XLR cables seem to leave the ground lug of the XLR connector floating. I imagine this is done for cost reasons. Is there any reason NOT to short pin 1 to the ground lug at both ends of the XLR3 cable? Here are some references: Klaus Heyne recommends shorting pin 1 to the connector’s ground lug, back in 2004: https://repforums.prosoundweb.com/index.php?topic=3734.0 Gotham recommends leaving the connector’s ground lug isolated/floating: https://www.gothamcable.com/en/gothamcables/3conductormicrophone/10701gac3 I have a PDF from Neutrik, dated 2016, that says "In the course of the evolution of the AV industry, it has come to be that this tab is practically never terminated. This means, in turn, that the shell is not grounded. When in doubt, simply leave this tab unterminated.” Do these vendors assume that the housing of the XLR connector would be grounded once plugged in to whatever it gets plugged in to, meaning the microphone at the XLR3F end or mixer/console/interface at the XLR3M end? Because that approach seems compromised; whatever bare-metal mating surfaces exist between two XLR connectors would likely have much higher impedance than a soldered copper wire, no? Which is presumably what leads to this video recommending that RFI problems can be solved by MOVING the pin 1 conductors to the ground lug (!). Obviously the mic is shorting pin 1 to shield, or else the mic wouldn’t work at all… but this seems to improve XLR shielding at the likely expense of having the best-possible ground for the mic circuit. I wouldn’t ever recommend that but it’s difficult to argue with this demonstration: https://youtube.com/watch?v=Qj7bdZTwdv0 I am eager to hear insights about XLR cable shielding from the community. — matt.

The latest ZRAMO TH900 donor mics I bought from Amazon (BM-700 bodies and circuit boards with 1” CM-012 electret capsules) worked out of the box for once. Still “outa phase” with a Neumann, but otherwise wired correctly. A bit noisy by pro standards. This time, came in a glossy printed box with die-cut foam. Included a $11 metal shock mount and foam wind screen. $18 today. Deal. The ZRAMO “104” style mics are sturdy metal handheld bodies. The 16mm capsule is OK. The circuit board is good for scavenging an FET or a 3-pin XLR insert, but garbage otherwise. A definite buy at $10, today they cost $16, still may be as good a deal on a handheld mic body as there is. Prices and included items from ZRAMO vary from time to time. (USA) https://www.amazon.com/s?k=zramo+mic

You remind me that Prof Angelo Farina at the University of Parma, Italy, has done a lot of research and design on sound reproduction in noisy environments. He might also have some research papers on sound pick-up. Links to his research an many of his papers here: http://pcfarina.eng.unipr.it/

I accidentally acquired a 482A 4 mA power supply made by PCB Piezotronics. For those of you not familiar with the company, they produce measurement microphones that are basically equivalent to Bruel & Kjaer. The system works by supplying a 4 mA current source from 24 volts which provides the power for the microphone electronics through a BNC coaxial cable. That allows you to acquire microphone cables of any length very inexpensively. The capsules themselves are electrets and thus don't require the typical 200 volt supply. The microphone returns a voltage signal through low impedance electronics. The 4 mA DC supply and low voltage signal do not interfere with each other despite being carried on the same conductor. I'd like to build a microphone for this supply. I have some circuit ideas but I'm wondering if anyone here has made such a microphone. What circuit did you use? How well did it work?