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I'm looking at creating an XY mic for some field recording. I have seen that the Audio Technica BP4035 is a popular choice in this regard. I've started to think about trying to create something of a replica to this. I have been looking at Primo capsules, as being in the UK I find it limiting getting hold of supplies that I often see on here. I have been drawn to the Primo EM204, as it seems to be sensitive for a cardioid. EM204 Cardioid -31 dB sensitivity 16 dB self noise 78 dB SNR Does anyone have experience of this cap and are you able to chime in with any observations or advice for this or other caps? Or for that matter advice in general for an XY mic build? Cheers Adrian
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(hi, this is my first post :) ) (picture taken from the internet for reference) just gluing it around the circumference of the capsule? or on the back of the capsule a rubber ring that presses against the enclosure? any other ideas?
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Hey, i've researched a lot about this, but i cant seem to find any explanation to what i'm dealing with... I'm using the simple P48 circuit and the PIU 5024 electret mic capsules, and i'm super impressed by their sensibility. I'm a fan. Just one thing is making my head hurt, when in direct contact with sunlight, the sensibility drops instantaneously, and if i get them back to shadow, the signal gain goes back to normal.... Is this normal? Even with the sponge windscreen on! Is this magic? Should I just make them little sunshades? Thank you for any info! <3
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New Ultrasonic USB microphone
13
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
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Stretched Alice
5
(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
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I am designing a "mic activator" with some design goals that are not satisfied by the simpler ones (e.g. FetHead, CloudLifter), but are possibly already done by the more complex ones like SE Electronics DM1 / DM2 (but I don't know the schematic of that one, if anyone knows, please share). In short, I want decent CMRR, PSRR and low output impedance. I have a schematic I could build, but the part count to satisfy these requirements is pretty high. So I don't think I can fit it into the regular XLR male-female "tube" adapter, e.g. this one on AliExpress, which is similar to what FetHead uses. The PCB that can fit inside that one is 13mm wide by 15mm long, but 5.5mm of that length are used by the XLR connector. I could have a second PCB ride on the first, but I'd lose some area for the header connectors between the two. Ideally, I would like a longer tube, e.g. like Audio-Technica AT8202, which is ~36mm longer than the FetHead. Even 10mm longer would probably be enough for this circuit. Is there any way to source such a body?
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Putting an "internal" FET on an electret capsule
3
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
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a partial soundfield stereo mic for studio.
6
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?
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I wanted to use a t.bone EM700 (which I believe uses a 797 AUDIO CY011C 16mm electret capsule) as a boom mic into a XLR transmitter, but it¡¯s sensitivity of about 8 mV/Pa was a bit low for my needs (and the XLR transmitter doesn¡¯t have massive gain I can play with). I wanted to get at least 20 mV/Pa out of it. So I wanted to replace its preamp with one where it's easy to add gain, which usually is a charge amp, but without the complications of a transformer. Here is the topology I arrived at, which I¡¯d like to call chOPA (pronounced cho-pah, of course). Because of the battery powered XLR transmitter, I used one OPA1641 and one ADA4084 to save 1.15 mA of the P48 current budget vs. using one OPA1642. OPA1692 doesn¡¯t come in singles, I would¡¯ve liked that instead of the ADA4084. The mic sounds fine and has the sensitivity I wanted, with no perceivable SNR degradation vs. the original circuit (although that¡¯s something I need to characterize more rigorously). Of course it will have a lower max. SPL, especially when considering the input impedance of the XLR transmitter. The original mic had pad and low-cut switches, I covered the holes with conductive tape (there's a layer of proper copper tape under the aluminium). Feedback and criticism are welcome.
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proper XLR shielding
15
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. ¡ª matt.
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Cheap mic body donors
4
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
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[allowed] Re: [MicBuilders] Active noise cancelling for microphones in noisy environments - techniques?
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/
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building a meaurement microphone with a 4 mA current loop
3
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?
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TA4F to regular XLR(M) wiring
5
Hello there, I'm currently facing the following issue - We have this mic: Shure Centraverse Lavalier Condenser Microphone CVL The thing is - the room were we plan to use it and the shure bodypacks we have are subject to to much interference/drops in signal. We tried everything - all posible channels - repositioning the receivers - nothing helps. The room is oddly shaped, lots of concrete, quite a few tv/radio transmition antennas around the place. I'd like to re-terminate the TA4F mic's connector to a regular XLR(m), so the mic can be hardwired via a 10 meters long cable run to a yamaha mixer with phantom power. Here Is the data sheet Here is the pinout for TA4 shure bodypacks/transmitters Looking for a diagram or pinout, quite a lot of different drawings popped up in my search, so: - How should I go about feeding Phantom power to the mic? I have little experience with mic building, but I've put six pairs of matched primo electrets using the simplep48 directions/circuit with great success. Is there any of you kind engineers/micbuilders willing to take a look at the spec sheet and sugest a circuit? The datasheet says 5 to 10v max at the capsule, so I'm guessing shure packs provide PiP voltages to the mic (seems like it from the shure pinout above). Maybe just a simple correct wire-to-pin connection is enough? - The other thing I've found in shure's FAQ: TA4 -> XLR Pin 1 -> Pin 1 & Pin 3 Pin 3 -> Pin 2 Pin 2 & Pin 4 -> Not used But no mention of phantom. Does that make any sense? I have 0 budget to do this, have the required neutrik XLR male connector, a few components left from the simpleP48 builds, the cable run from the mixer to the spot where the mic will be connected is already in place. Any light much appreciated!
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U47FET audio fades to black
6
Hi everyone, I posted a question on the groupDIY build thread for the D47FET from https://vintagemicrophonepcbkit.com/DU47FET.html but have not received any response so I'm casting a wider net here. I built this mic from the above PCBs into the relatively new body described in this build thread with a K47 capsule from Arienne Audio. When I power up the mic with P48, I get audio then it fades to silence in a mere second or two. I replaced the FET, a 2N3819 with one I tested prior to soldering in, but same result. I always use a heat sink when soldering semiconductors, styros, etc. I inspected all joints under magnification and they look ok. All semiconductors were purchased from Mouser, if that means anything regarding the counterfeit semiconductor market we are enjoying these days. The schematic Dan posted on his site is here. My hope is this symptom is common enough in FET circuits that someone out there will have experienced it and can suggest likely culprits. Naturally getting the correct wording into a Google search is difficult so results are not helpful at all.
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Hello everyone, I've build very few microphones and they've all been Electret with two pads and pretty easy. But i'm looking to try and build a microphone with this capsule: https://www.jlielectronics.com/microphone-capsules/jli-160a11uc680/ I see on the diagram though, that an external resistor and compactor to make it able to work. Also, is there anything additionally that I need to do to make it compatible with phantom power? Sorry for all the probably obvious answers, but I'm super new to this whole realm of audio. Thank you all!
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Obit for Micbuilders member Les Watts
4
Here's an obituary for Les Watts that I posted on my website: https://bgilbertsound.wordpress.com/wp-admin/post.php?post=2687&action=edit
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[allowed] Re: [MicBuilders] New to building microphones, curious about what I need in order to make this microphone work
2
Yes, it needs a simple circuit in order to make it work at all ¨C basically to provide the voltage for the impedance converter (FET) and to isolate the voltage from the audio feed to the recorder. As Ricardo recommended, the simplest suitable circuit is SimpleP48 or SimpleP48RCA, which you will find in his folder on MicBuilders. A more complex circuit is the Alice circuit, originally by Scott Helmke, which can drive much longer cables (SimpleP48 is probably best limited to <30 m or <100¡¯); you will also find this on MicBuilders and many other places.
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Good day all, I am new to the group but learning much from digging through old posts and files. Microphones, specifically, is a relatively new area of interest. I have tinkered with electronic and electro mechanical devices for many years, mostly related to RF communications. What brought me here is an interest in what is often referred to as "natural radio" - listening to and recording the sferics, tweaks, whistlers and chorus of extremely low frequency (ELF) radio waves emitted by charged particles in the Earth's atmosphere and magnetosphere in the range of 10kHz to 25kHz ( plus and minus ). It occurred to me that the likes of electret and condenser microphones and their circuits are not that much different to something suitable for monitoring "natural radio" - the need to interface a very high impedance transducer, the electret or condenser capsule in the case of the microphone and the electrically very short antenna in the case of the receiver, to the much lower impedance electronic amplifier circuits which follow. As is often the case, my interest in a specific application area developed into a much broader interest in the very interesting and much broader subject area of microphones. In my tinkering with various types of microphones I have a need to boost the output of a dynamic microphone. Easy enough to do - just plug in one of those generic inline phantom powered microphone preamp/boosters - job done. However, plug and play just does not cut it with respect to learning and understanding. Opening up a couple of these inline preamps plus many hours of searching and reading online has helped in the learning and understanding but has also left many more questions. What brings me to my post today was prompted by my recent comparison of a Klark Technique CM-1 inline preamp and the Rodyweil AC-1 inline preamp. Certainly not high end devices but suitable for my current needs. On comparing the PCB's from these two devices it quickly became apparent that the designs of these two devices were exactly the same - same components ( 2x PNP BJT, 2x NPN BJT, same number of capacitors and resistors of same value) and similar PCB layout, almost as if these two devices used the same "common" or "reference design" circuit. I have yet to fully sketch out the circuit diagrams of these two devices but that will come with time. That was a long way around to the crux of my posting - Is there somewhere ( that I've not yet stumbled upon) a circuit diagram of these or similar devices ( i.e. phantom powered 4x BJT inline microphone booster/preamp). Is it or are they in fact some "common" or "reference design" of some older origin and now often copied and duplicated in these low cost Asian sourced implementations? cheers, Graham
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Geophone again - questions
Hello, A while ago I shared that I had picked up a GD-10J geophone component. I wired it up and had a bit of fun - nothing of much consequence. I have an opportunity to do some field recording at some frog ponds, in the middle of a massive industrial area. They are surronded by heavy roads and have half a dozen goods line train tracks in frequent use, and a cement plant beyond that. I thought it might be interesting to add another mic to record sounds from the ground. So I 3d printed an enclosure for the goephone, and added a bolt to the bottom so I can attach different ends, in this case a rod from a sacrificial tent peg. Here's a link to an image. I was testing it in the garden (just jammed into ground), with a Zoom F3, and was surprised to be able to my cat walk past! Super fun, but I noticed that any contact with the cable was also very detectable. Getting permission to access the site is a bit tricky (security escort), so I want to get it right. I was planning to put the F3 and power bank in a waterproof dropbag, but I'm not sure how to arrange the cable to minimize contact. My idea at the moment is : - use tape to fix some foam between the cable and enclosure - cable to point down to stop water running into the top cap which I will make water tight with some petroleum gel or similar. - add another tent peg about 6" away, and loop the cable to that to stop any slack hitting the device. - have the drop bag about arm length away from that. Any thoughts, ideas, advice? Regards Matt
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Sat 8:39am
Sat 8:39am