Matt Nolan

I'd like to make something clean and linear, low distortion and very low noise floor, but without breaking the bank. SDC for recording small metal percussion instruments in isolation, and not necessarily at high SPLs, but there will be high transients.

I think I have figured out a nice circuit to try, but I am wondering what might be the best mic to start out with in terms of keeping the body and the capsule. Cardioid, I think, as I'm not recording large sound sources and there may be background noises and less than ideal acoustics that I'd like to avoid picking up too much of, though omni with a pressure sphere might be worth looking at also.

I know that an LDC would make my SNR life easier, but it's not going to help on the linearity / accuracy front. Perhaps an SDC on the larger side of things might be worthy of consideration though or, that rare beast, the MDC? What are your thoughts, people?

Rode, T.Bone, Behringer, Oktava, something else?

The Oktava bodies don't leave much room to manoeuvre...

I want a real condenser capsule, not an electret. I don't want to be beholden to somebody else's FET right from the start.

Thanks in advance. Go!


gyraf

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #1 on: March 28, 2021, 11:08:31 AM »
Look at Rogi's RF-microphone project?
..note to self: don't let Harman run your company..

Matt Nolan

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #2 on: March 28, 2021, 12:04:09 PM »
Look at Rogi's RF-microphone project?
Thanks. I think you mean Rogs' and I assume this thread - https://groupdiy.com/index.php?topic=71586.0 and this web page - http://www.amx.jp137.com/

I had thought about an RF capsule approach - I have less than ideal moisture conditions in my recording environment also, though not outdoors.

I will go and have a peruse. That gives me another option, if my own hare-brained scheme doesn't work as well in the real world as it does in LTSpice.

kingkorg

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #3 on: March 28, 2021, 05:28:43 PM »
SDC by nature has higher noise.

You can combat this by rising polarization voltage. I have used capsule of Takstar at 100vdc polarisation volatage. However i am not sure if it's possible to mod the existing CM60 circuit to go that high.

CM60 capsule is pretty linear with a peak at 8K which can be addressed with RLC filter, or external eq.

CM60's rear rejection is exceptional.

Matt Nolan

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #4 on: March 29, 2021, 09:12:22 AM »
Thanks kingkorg.

The Takstars have mixed reviews, but I guess a lot of that could be down to the amp rather than the capsule. Looks like the same body as the MXLs and the Micparts - do you know if the capsules are compatible - thread and connection wise?

At that price it is certainly a no-brainer for doing initial experiments.

kingkorg

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #5 on: March 29, 2021, 09:20:11 AM »
The threads should be the same, but sometimes they just dont fit, have no idea why, they seem to have wide tolerances.

Update.
Btw, I can't see any issue with the amp.
« Last Edit: March 29, 2021, 10:46:48 AM by kingkorg »

Matt Nolan

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #6 on: April 01, 2021, 12:02:29 PM »
Update.
Btw, I can't see any issue with the amp.
You're right. I bought a CM-60 on Ebay and it turned up today. It is basically the classic Schoeps circuit with some very small deviations.

I don't suppose you know what the conformal coating in the high impedance area is, or if you have been successful in removing it? It is tempting just to do minor mods on a pair of these.

Thanks,
Matt

kingkorg

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #7 on: April 01, 2021, 12:59:33 PM »
Unfortunately i don't :(

RuudNL

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #8 on: April 02, 2021, 06:39:17 AM »
I have modified a couple of CM-60 microphones, and in all cases the FET bias wasn't optimal.
(It seems they use the standard values for all microphones.)
There is a solution for every problem!

http://www.vansteenisaudio.nl

Joekkel

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #9 on: April 02, 2021, 07:18:59 AM »
i know this is slightly ot, but have you guys allready heard about the nevaton mc59. they have managed to build an incredibly low noise sdc. Heres a comparison to a Sennheiser MKH 20 an 8020:

https://fieldrecording.net/2020/01/13/mkh40-mkh8040-mc59c/

i wish the price hadnt gone up last year..


rogs

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #10 on: April 02, 2021, 07:38:08 AM »
i know this is slightly ot, but have you guys allready heard about the nevaton mc59. they have managed to build an incredibly low noise sdc. Heres a comparison to a Sennheiser MKH 20 an 8020:

https://fieldrecording.net/2020/01/13/mkh40-mkh8040-mc59c/

i wish the price hadnt gone up last year..

I'm guessing the Nevatron uses conventional Hi-Z mic circuitry, rather than the Lo-Z RF bias  circuitry of the Sennheiser?
Maybe not that useful for outdoor recordings then -- unless you can be certain that moisture is not going to be an issue of course! 
www.amx.jp137.com - A DIY RF condenser mic project

Matt Nolan

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #11 on: April 02, 2021, 12:08:55 PM »
I have modified a couple of CM-60 microphones, and in all cases the FET bias wasn't optimal.
(It seems they use the standard values for all microphones.)
I see that there is an option on the PCB to swap out the fixed SMD divider for a trimmer pot. Likewise, I think, for adjusting the DC-DC converter polarisation voltage.

Does that mean you have had success in removing the conformal coating? What did you use?

Matt Nolan

Re: Best SDC donor mic for upgrades, easily available in Europe?
« Reply #12 on: April 02, 2021, 12:29:45 PM »
i know this is slightly ot, but have you guys allready heard about the nevaton mc59. they have managed to build an incredibly low noise sdc. Heres a comparison to a Sennheiser MKH 20 an 8020:

https://fieldrecording.net/2020/01/13/mkh40-mkh8040-mc59c/

i wish the price hadnt gone up last year..
Interesting, but expensive. See also http://mics.nikfi.ru/en/products-and-services/kmn15-kmn16-studio-condenser-microphones/ - not as quiet, but still pretty low noise for (presumably non-RF) SDCs


 

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