Preamp for Primo capsules in xlr
- Thread starter Fastunov
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rogs
Well-known member
I've built the circuitry on the attached schematic, using stripboard. Works well.
As I recall, the P48 circuitry which ricardo linked to above needs you to cut tracks on the capsule PCB itself? ...
Not always easy to do! (depending on the capsule type of course)
As I recall, the P48 circuitry which ricardo linked to above needs you to cut tracks on the capsule PCB itself? ...
Not always easy to do! (depending on the capsule type of course)
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I think what Fastunov is after is my SimpleP48 circuit. It uses only 2 bits to achieve SOTA performance for LN nature recording. The huge BOM doesn't need a PCB but is usually wired directly to the pins of the XLR. Several people have built SimpleP48 with the whole shebang, including capsule, in the XLR too.
Modifying the capsule for SimpleP48RCA, brings further improvements at high spl and makes it also blameless as a studio microphone. But the simple original is probably best for nature recording .. especially if you haven't got a preamp with SOTA noise performance like a Sound Devices
It's all in my SimpleP48 document on Micbuilders
Hmmm! It's possible, some of the 3 pin Primo capsules won't need modifying for SimpleP48RCA. Have to look into this.
Modifying the capsule for SimpleP48RCA, brings further improvements at high spl and makes it also blameless as a studio microphone. But the simple original is probably best for nature recording .. especially if you haven't got a preamp with SOTA noise performance like a Sound Devices
It's all in my SimpleP48 document on Micbuilders
Hmmm! It's possible, some of the 3 pin Primo capsules won't need modifying for SimpleP48RCA. Have to look into this.
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mhelin
Well-known member
I guess this is the simpleP48 circuit (or is this even simpler one?) used here: DIY Microphone: EM172 Capsule and XLR Plug
I built one like this but it was very noisy, but not when wrapped with aluminium foil tape.
Don't know if Rogs' circuit can be fitted inside XLR plug, maybe. You could use 0603 resistors and 2xBC860 and BC850 SMD transistors though. For capsules without FET the PCB layout could have IF4500 footprint, too, to replace the NPN.
I built one like this but it was very noisy, but not when wrapped with aluminium foil tape.
Don't know if Rogs' circuit can be fitted inside XLR plug, maybe. You could use 0603 resistors and 2xBC860 and BC850 SMD transistors though. For capsules without FET the PCB layout could have IF4500 footprint, too, to replace the NPN.
rogs
Well-known member
I hadn't noticed that it was all intended to be mounted into the XLR jack -- My bad ... sorry about that!
I don't think my schematic would fit into an XLR -- but I maybe wrong!
I used it primarily to interface Knowles ultrasonic MEMs microphones with my Tascam DR100Mk3 for bat echolocation recordings..
So all 'thru hole' on stripboard!
mhelin's link above to Tom Benedict's article is to the same circuit that ricardo is describing..... You just don't have to 'join' anything to see this version
I think it should be OK for Primo EM172/272 or EM200 -- not so simple for the 2 terminal EM158/258 or EM204s though.
Not easy to find the track to cut on those - as we used to do for the 'linkwitz mod' on the Panasonic WM61 capsules...
Probably the easiest way to use the 2 terminal capsules would be to simply buy a Rode VXLR+ --- or make your own perhaps?...
https://www.zachpoff.com/resources/testing-xlr-adapters-with-plug-in-power
I don't think my schematic would fit into an XLR -- but I maybe wrong!
I used it primarily to interface Knowles ultrasonic MEMs microphones with my Tascam DR100Mk3 for bat echolocation recordings..
So all 'thru hole' on stripboard!
mhelin's link above to Tom Benedict's article is to the same circuit that ricardo is describing..... You just don't have to 'join' anything to see this version
I think it should be OK for Primo EM172/272 or EM200 -- not so simple for the 2 terminal EM158/258 or EM204s though.
Not easy to find the track to cut on those - as we used to do for the 'linkwitz mod' on the Panasonic WM61 capsules...
Probably the easiest way to use the 2 terminal capsules would be to simply buy a Rode VXLR+ --- or make your own perhaps?...
https://www.zachpoff.com/resources/testing-xlr-adapters-with-plug-in-power
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Thank you so much for your answer and scheme! I was just planning to use EM 204. Thank you so much. And what element base do you recommend, maybe there are some features. I mean Part list (as you have on the site dedicated to RF. AMX10)
rogs
Well-known member
I haven't done any detail on this project, as I did for the AMX project. I did do a complete stripboard layout for my LDCX2 project (see here: http://www.jp137.com/lts/LDCX2.notes.pdf ) and that took forever! ...
I don't think anyone has ever bothered to build one of those, so I've not repeated the exercise!
There is some detail on how to modify the EM204 and change it into an EM200 to make it suitable for ricardo's 'simple P48' idea here: Primo EM204 to EM200 modification
I don't think I'd be brave enough to try that mod myself!
I've only used my schematic to build stripboard versions for my MEMS ulttrasonic mics. They were fitted into plastic drainpipe enclosures ..
There are some photos of the construction here: http://www.jp137.com/lts/MEMS.bat.experiments.pdf
..and you can see, that the stripboard layout is not complex.
I think I still have a stripboard layout pencil sketch I used for that 'one off' project somewhere .. but it isn't necessarily going to be very legible.
As I say, it shouldn't be a difficult layout to do yourself.
The only other version I have done is for my M/S mic, which uses 3 x EM204s. (There is a photo of that project in post #11 of the EM204 conversion thread I linked to above.)
That time it was all fitted into a BM800 body, so there was more room for the stripboard.
Again, I only have rough sketches of that project layout. The time I spent on the LDCX2 stripboard layouts rather put me off doing a lot of detail for projects no one else was going to bother to build!
The AMX project was different. It generated a lot more interest, was not suitable for a stripboard, layout, and two group members very kindly did the PCB layouts. (Ruud did the prototype -- Khron did the several versions of the BM800 version).
There are several project PCBs for projects like the 'Alice' mic, and those can usually be adapted quite easily, to accommodate simpler internal FET electret capsule versions... like the EM204 for example.
Of course, I can imagine how much time it took you, just a titanic work and a lot of effort you put into it. I have been looking for a scheme for Primo capsules for a long time, I was interested in this when I met the site and the product from LOM. AUDIO , but they only have circular capsules, and I want to use a cardioid. That's why I took the path of search.I haven't done any detail on this project, as I did for the AMX project. I did do a complete stripboard layout for my LDCX2 project (see here: http://www.jp137.com/lts/LDCX2.notes.pdf ) and that took forever! ...
I don't think anyone has ever bothered to build one of those, so I've not repeated the exercise!
There is some detail on how to modify the EM204 and change it into an EM200 to make it suitable for ricardo's 'simple P48' idea here: Primo EM204 to EM200 modification
I don't think I'd be brave enough to try that mod myself!
I've only used my schematic to build stripboard versions for my MEMS ulttrasonic mics. They were fitted into plastic drainpipe enclosures ..
There are some photos of the construction here: http://www.jp137.com/lts/MEMS.bat.experiments.pdf
..and you can see, that the stripboard layout is not complex.
I think I still have a stripboard layout pencil sketch I used for that 'one off' project somewhere .. but it isn't necessarily going to be very legible.
As I say, it shouldn't be a difficult layout to do yourself.
The only other version I have done is for my M/S mic, which uses 3 x EM204s. (There is a photo of that project in post #11 of the EM204 conversion thread I linked to above.)
That time it was all fitted into a BM800 body, so there was more room for the stripboard.
Again, I only have rough sketches of that project layout. The time I spent on the LDCX2 stripboard layouts rather put me off doing a lot of detail for projects no one else was going to bother to build!
The AMX project was different. It generated a lot more interest, was not suitable for a stripboard, layout, and two group members very kindly did the PCB layouts. (Ruud did the prototype -- Khron did the several versions of the BM800 version).
There are several project PCBs for projects like the 'Alice' mic, and those can usually be adapted quite easily, to accommodate simpler internal FET electret capsule versions... like the EM204 for example.
I myself, too, would never undertake the modification of the primer by drilling, it is not for my hands and skills. I can easily ruin everything
MEMS microphones are still a big mystery to me and I'm just learning about them.
It seems six months ago on some resources or in a video on YouTube, I do not remember, I saw your M / S version and I must admit I was very curious. It is a pity that few people are interested in it, I think this is due to the M/S conversion. On an analog remote and recorder, this is a whole 3 channels and a lot of hassle with conversion. With a digital broadcast remote, everything is easier, there is an MS on button and that's it
I use the ms-Sennheiser 418s all the time. I would be very interested in this project! Then I found your website and the RF.Amx10 project and it caused me a lot of emotions. I am looking for a microphone with a large aperture and that it is positioned perpendicular to the body. I will definitely make myself some microphones.I apologize for the English, I use google translate
This is a good article with many useful practical points. But there are a number of errors which I've addressed in my MicBuilders article. Tom has corrected some of his errors but I'm not sure he's caught all of them. So if you are building one of these, do read his article/thread ... but get my 'original' too.
BTW, SimpleP48 is in no way a performance reduced circuit. It is truly SOTA for certain parameters
eg electrical noise is, in theory, rather better than any Schoeps copy. In practice, the advantage is from .. zilch for a noisy capsule like WM61 ... to maybe a dB or so for a very low noise Primo or Transound.
RFI immunity (which is vital for professional use) is better than some very $$$ big name Germans. For nature recording, about the only criticism for the SimpleP48 original (no capsule mods required) is I wouldn't use mike cables over 20m.
The SimpleP48RCA version (modified capsule) is difficult to fault by any standard.
