Seeking electret cardiod capsule for diy
« on: July 10, 2020, 01:40:16 PM »
I remember people mentioning that the CAD e100s uses a certain Transsound capsule -- that's a supercardioid electret mic.

I have a DPA electret mic preamp section laying around that I would like to add a capsule to (it's an older one that doesn't take the current capsules).

Anybody recommend an electret cardioid or hyper/supercardioid capsule to use, and where they might be available?



Re: Seeking electret cardiod capsule for diy
« Reply #2 on: July 10, 2020, 02:18:34 PM »
Good lord, really? $3? Is that an electret and a cardioid? No specs really on the page. Would love to hear that one. Self-noise is key consideration.

Meanwhile I found the JLI sourced transsound capsules I was thinking of, but the specs don't match the CAD mic, so I'm not sure what they're like, but for the price, worth experimenting I guess. The self-noise spec looks terrible (66db s/n?) so I can't understand how this is the cap used in those mics that get 3db self-noise. Help me understand.  ???

https://www.jlielectronics.com/microphone-capsules/tsb-25axz3-gp
« Last Edit: July 10, 2020, 03:00:34 PM by szegedin »

Re: Seeking electret cardiod capsule for diy
« Reply #3 on: July 10, 2020, 04:26:29 PM »
Yes, cardioid electret. I can't give you  exact noise figures, they can be tricky to measure having in mind all the variables.

They have great low end response, and are not hyped at the high end. No crazy dips and jumps in the FR.

For the price i'd just test them. They became my favorite for handheld condensers i make.

Re: Seeking electret cardiod capsule for diy
« Reply #4 on: July 10, 2020, 05:29:08 PM »
For the price i'd just test them. They became my favorite for handheld condensers i make.

Cool, thank you for the tip. For $7 shipped, certainly worth a punt. I'm also looking at the Primo capsules now, which might assure decent specs for a reasonable price.  I want to get in at <18db self-noise.

Re: Seeking electret cardiod capsule for diy
« Reply #5 on: July 10, 2020, 07:17:27 PM »
I'd personally check out the Primo cardioid electret capsules, but they are on the pricey side (like $40 for the EM204). But part of that is because I don't like the sound of the E100S (I really like the M179 though), but I like the vintage E100 and E200. They used a pair of Primo EM200s I believe, or it's another incredibly similar Primo capsule.

The capsule Kingkorg linked looks interesting as well.

Re: Seeking electret cardiod capsule for diy
« Reply #6 on: July 10, 2020, 07:35:02 PM »
I'd personally check out the Primo cardioid electret capsules, but they are on the pricey side (like $40 for the EM204). But part of that is because I don't like the sound of the E100S (I really like the M179 though), but I like the vintage E100 and E200. They used a pair of Primo EM200s I believe, or it's another incredibly similar Primo capsule.

The capsule Kingkorg linked looks interesting as well.

That's interesting because I used to have an E100, and I thought it was very dark sounding, so I sold it.  But if the Primo ends up more hypercardioid that's a plus, and I'd be satisfied to have basically an e100 for $40. Just looking to put a spare preamp body to use. But truth be told I would prefer the e100s, and if I was 100% convinced they use the transsound capsule, I would just buy it. I don't want to end up with 26db self-noise or something. I'll pay $50.

It is a separate question about the preamplifier circuit of those CAD mics, with four op-amps. I wish it was the life goal of somebody with more skills than me to recreate that super-quiet circuit for a DIY mic.

Re: Seeking electret cardiod capsule for diy
« Reply #7 on: July 10, 2020, 10:00:55 PM »
Primo EM204 and EM200 are killer capsules. Flatest of any cardioid i have ever measured. However they have a built in fet, so be aware of that. Will they work with with your pre? There is a guy in the states selling EM204 affordable on eBay.

EM204 is the more sensitive one, be careful it can be easily overdriven into distortion. I tried  using it in a hand held, but it limits signal heavily with loud sources.

In a way i like it, it sounds like a mic into a 1176 on fastest setting, but it's definitely not all round  mic.

At 10cm+ distance it works marvelous and is very quiet.

EM200 takes 10db more, it's the exact same capsule. They also have different output impedances. Worth considering when designing pre.

Both are unidirectional, and certain well known manufacturer whom i respect very much  specifies mics made with these subcardioid. Which is one step from cardioid towards omni rather than f8 which is hypercardioid.
« Last Edit: July 10, 2020, 10:09:13 PM by kingkorg »

Re: Seeking electret cardiod capsule for diy
« Reply #8 on: July 10, 2020, 10:38:28 PM »
Primo EM204 and EM200 are killer capsules. Flatest of any cardioid i have ever measured. However they have a built in fet, so be aware of that. Will they work with with your pre?

Hmm, will it? I was under the impression that any electret capsule would work on any electret preamp. I have a pair of DPA preamps from what was a 4015TL. I mated an old Bruel&Kjaer capsule from one of the measurement mics to it and it works beautifully. No FET in that of course. I want a cardioid for the other one - that's the idea here.

EM200 takes 10db more, it's the exact same capsule. They also have different output impedances. Worth considering when designing pre.

Both are unidirectional, and certain well known manufacturer whom i respect very much  specifies mics made with these subcardioid. Which is one step from cardioid towards omni rather than f8 which is hypercardioid.

Okay interesting. Which manufacturer-made mic is that? I thought that the CAD e100 (original one) had that Primo capsule and it was listed as "supercardioid." I'm not too picky for this money, but the narrower the better. Thanks for this insight.

Re: Seeking electret cardiod capsule for diy
« Reply #9 on: July 11, 2020, 07:58:20 AM »
In that case EM200 and EM204 won't work, they have a fet and some electronics around it built in. There might be some other Primo which are hypercardioids, but these two are not. Unless they used some acoustic manipulation around the capsule to alter that. Like AKG c1000 does with a plastic hypercardioid adapter.

If i remember correctly the original capsule from e100 is no longer produced, which is the reason why original e100 got so pricey on the used market.


Re: Seeking electret cardiod capsule for diy
« Reply #10 on: July 11, 2020, 11:20:45 AM »
In that case EM200 and EM204 won't work, they have a fet and some electronics around it built in. There might be some other Primo which are hypercardioids, but these two are not. Unless they used some acoustic manipulation around the capsule to alter that. Like AKG c1000 does with a plastic hypercardioid adapter.

If i remember correctly the original capsule from e100 is no longer produced, which is the reason why original e100 got so pricey on the used market.

Okay, that's a bummer but I'm glad I talked to you about it -- because the trannsound capsules also have a FET (and probably the alibaba cap), so I'm back at square one looking for a single available electret cardioid cap.

How do these work? They're electret but they need voltage to the diaphragm? So there are two leads plus the ground? Are you quite sure these capsules don't work with the electret preamps from DPA, Earthworks, or the AKG 451, to name a few?

Re: Seeking electret cardiod capsule for diy
« Reply #11 on: July 11, 2020, 08:00:08 PM »
This is over simplified answer, but in a nutshell: Several components that follow a capsule which is usually coupling capacitor and some resistors and a fet are built into some capsules.

For example here is a schematic. The part marked in red is built into the capsule. So you get ground, drain and source connections.

Here is a schematic that will work with EM204 capsule for example. The upper part of it is for regular mic. The lower part is if you want a M/S mic. In this one only two connectors from the capsule is used, the following BJT is splitting phase of the signal.


https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.jp137.com/lts/MS.EM204.Schematic.BC560.pdf&ved=2ahUKEwjT1aHOs8bqAhWswqYKHeMcC0sQFjAAegQIAxAB&usg=AOvVaw3t9_uX6O_sSBUgDR-bJ5Yq&cshid=1594512152587

I don't know what kind of schematic DPA has, so i don't know what kind of capsule it needs either. 

EM200 type capsules will not work with AKG 451. The voltage is used for the built in fet, not for polarizing the diaphragm.  Electrets dont need polarizing voltage, but electrets with built in fet need it for the FET. Download spec sheet for EM200 and you'll se what's built into the capsule.
« Last Edit: July 11, 2020, 08:11:32 PM by kingkorg »


 

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