Topic: Mic mod questions

[kirk97132]

So I have a pair of Sansom Co2 mics that I want to try modding myself.  I was thinking that changing out the ceramics for metal film  would help.  Question is do I change out all five of the marked items?  And there are two surface mount components circled should I be concerned with them?  Is there any recommendations that y'all have.  The markings on the group of four say 102 and the single one is 220.  Are there any values and or manufactures that you'd recommend?  Thanks in advance, Kirk

[andromedanwarmachine]

hello-

what benefit are you hoping for in swapping out the ceramics for metal film...?

JimP

[kirk97132]

To smooth out the response in the mid to high range, tighten up the low end response, possibly extend the low end some and hopefully lower the noise floor. 

[Chuck]

Here is a good place to start reading:

http://www.prodigy-pro.com/diy/index.php?topic=35310.0

[kirk97132]

Here is a good place to start reading:

http://www.prodigy-pro.com/diy/index.php?topic=35310.0

Thanks for the link, dunno how I missed that with all the reading I've done.  I'm still hoping for someone to check in I'd like to ask a few questions about changing some values.  Thanks again Chuck, Kirk

[Chuck]

I'm in the process of doing a couple CAD GXL1200 (MXL 603 clones) right now.
It doesn't look like the exact same circuit. I know that by replacing some of the capacitors in the GXL1200's I can extend the bass pick-up a bit. I don't know how or if that translates well to the Samson mics.

[kirk97132]

Ah that is one of the things I was wondering about.  I also think that the Cad/MXL's are a true condenser not electrtet capsules, do you know if that is correct?  I had also talked(e-mailed) with Michael Joly and he says one of the best things you can do for these SDC mics in this class is to open up the vents.  Basically cut the ribs out of the vents and make it just a big opening which will help to alleviate the 5-7K bump in the response.   He says it is caused buy the mic body and really helps flatten the response out in the high end.    Any hints on getting the self noise down with these?  I'm getting ready to post in Mic builders for help, I think I'm starting to exhaust the reading available.  Have you ever considered changing out the mic capsules themselves?  Thanx, Kirk

[Church-Audio]

Ah that is one of the things I was wondering about.  I also think that the Cad/MXL's are a true condenser not electrtet capsules, do you know if that is correct?  I had also talked(e-mailed) with Michael Joly and he says one of the best things you can do for these SDC mics in this class is to open up the vents.  Basically cut the ribs out of the vents and make it just a big opening which will help to alleviate the 5-7K bump in the response.   He says it is caused buy the mic body and really helps flatten the response out in the high end.    Any hints on getting the self noise down with these?  I'm getting ready to post in Mic builders for help, I think I'm starting to exhaust the reading available.  Have you ever considered changing out the mic capsules themselves?  Thanx, Kirk

True condensers have a separate high voltage supply to charge the capsule.. All of the mics in this price range are electret.

Chris

[Chuck]

The MXL603s are condensers. I just got done modifying the capsules on mine last night. I've been corresponding with Micheal also. The MXL603 stock capsule is recessed too far. So I ground it down last night. I plan to make the vents bigger too. I'm still trying to decide on what electronics to replace. The mic starts out sounding pretty good. The mods just refine it a bit.

[Chuck]

Ah that is one of the things I was wondering about.  I also think that the Cad/MXL's are a true condenser not electrtet capsules, do you know if that is correct?  I had also talked(e-mailed) with Michael Joly and he says one of the best things you can do for these SDC mics in this class is to open up the vents.  Basically cut the ribs out of the vents and make it just a big opening which will help to alleviate the 5-7K bump in the response.   He says it is caused buy the mic body and really helps flatten the response out in the high end.    Any hints on getting the self noise down with these?  I'm getting ready to post in Mic builders for help, I think I'm starting to exhaust the reading available.  Have you ever considered changing out the mic capsules themselves?  Thanx, Kirk

True condensers have a separate high voltage supply to charge the capsule.. All of the mics in this price range are electret.

Chris

I don't know about the capsules in the Samson, but the MXL603 caps take much higher voltage than a typical electret.

[kirk97132]

Chris thanks for the input.   I have noticed that a lot of the mics being modded with these types of mods are the 603, 1200, Nady 80's.  The Co2 is consistently left off that list which leads me to believe that there is some sort of internal difference.  Where as the other mics are all based on the Schoeps CMC-5 design which does use a true condenser. 

Chuck did you just move the capsule up and radius edges or did you do other stuff too?   Inquiring minds want to know  

[Chuck]

Chris thanks for the input.   I have noticed that a lot of the mics being modded with these types of mods are the 603, 1200, Nady 80's.  The Co2 is consistently left off that list which leads me to believe that there is some sort of internal difference.  Where as the other mics are all based on the Schoeps CMC-5 design which does use a true condenser. 

Chuck did you just move the capsule up and radius edges or did you do other stuff too?   Inquiring minds want to know

I completely sanded the front ledge off where the screen sits. Then sanded the space between the front of the housing and the capsule to .040". That's a somewhat arbitrary distance based on what I was able to gleen from other moders. I radiused the OD (front) and the two smaller ID's. I found that the small ID on one of capsules was .020" larger than the other. So I also fixed that. I'm going to re-measure everything and maybe paint the housings before I re-assemble the capsules for good. I'm going to put in a Mouser order over the weekend for the electronic parts I want to swap out.
I want to paint them a different color too. I don't like the nickel finish. Oh, and I'm waffling on opening the vents. I like the wide cardioid pattern the stock capsules have. From what I read that is partially do to the small vents. I'll probably use them as is for a while before I commit to hacking the bodies up.

[Church-Audio]

Ah that is one of the things I was wondering about.  I also think that the Cad/MXL's are a true condenser not electrtet capsules, do you know if that is correct?  I had also talked(e-mailed) with Michael Joly and he says one of the best things you can do for these SDC mics in this class is to open up the vents.  Basically cut the ribs out of the vents and make it just a big opening which will help to alleviate the 5-7K bump in the response.   He says it is caused buy the mic body and really helps flatten the response out in the high end.    Any hints on getting the self noise down with these?  I'm getting ready to post in Mic builders for help, I think I'm starting to exhaust the reading available.  Have you ever considered changing out the mic capsules themselves?  Thanx, Kirk

No I am talking about a polarization voltage of 200v or more. And I dont think thats the case with any mic made by Cad or MXL. You see these kinds of voltages  in some B&K mics, Anything that has a fixed charge on the capsule is electret anything with an external supply not for the FET but for the polarization is a true Condenser.  Its much more expensive to make a mike this way its much simpler to use a electret capsule then to build a external supply.

True condensers have a separate high voltage supply to charge the capsule.. All of the mics in this price range are electret.

Chris

I don't know about the capsules in the Samson, but the MXL603 caps take much higher voltage than a typical electret.

[kirk97132]

This has basicly jumped into the
http://taperssection.com/index.php?topic=127204.0
mic mods thread.   There are some differences between the CO2 and the mics being discussed but you'll get the idea.