electronic modifications for the MXL 4000

Hey there. I did the search function and didn't find what I was looking for...

Has anyone done electronic mods to MXL 4000s? I checked the meta, and nothing for the 4000. I have one and I'm looking to "supe" it up. If anyone knows anyone who has performed one, or if you have any ideas, let me know!

I would recommend the following:  Replace the monolithic ceramic cap from the capsule to the first fet with a poly cap.  I use a .001 uf 630v poly here.  It's a trick fit, but the resultant sound is much sweeter than stock.  I also replace the .22uf coupling caps with metal film stacked polys and that helps too.  I just did a 990 set for a friend at work and he loves em'  Peace, C

  Send me a photo of the guts and I will tell you what you to do! 

working on it  8)

here you go man



let me know what you think and thanks again

  Okay, yer gonna have ta take da' ting apart!  Be brave: The ONE cap yer gonna wanna replace is on the back of the board with the 1KM resistors.  The monolithic capacitor that you will remove is soldered to the teflon insulated posts that go thru the board.  The rest of the caps and resistors are cool in this mic.  It's been my experience that this one cap can smooth out the mic.  Good Luck! 

Sounds good to me

can you circle which part needs to be replaced in your opinion? Also, could you provide a part number or a link to the part?

thanks!

The part mentioned will probably be on the upper circuit board (beneath the capsule).

I'm personally dubious about the improvement gained by replacing one cap, but hope you manage top get somewhere with it.

The PCB in the upper pic is the DC/DC converter for capsule bias. The said capacitor must be either on the PCB in the lower pic or on the round PCB below the capsule (which you haven't shown us). Actually, it could also be direct coupled (i.e. no cap at all between capsule and FET) because I only see one gigaohm resistor near the FET.

Other than that I agree with Roddy: Changing one cap won't make a world of difference. Yes, a better cap will improve the sound, but only slightly so. My recommendation (provided ther is a coupling cap between capsule and FET) is a 1000 pF polypropylene one. Some people prefer polysterene, but that's more difficult to solder. Polyester/Mylar won't make an improvement in this position.

if you guys are making suggestions, could you please load the pictures into paint and circle the parts you're suggesting replacing, and maybe link me to parts they would be replaced with? I got the soldering thing down, but I'm not so brushed up on my electronics

thanks dudes

  The monolithic cap will be obvious once you remove one of the circuit boards.  It is located on the teflon insulated posts.  This is THE cap that makes the biggest difference IMHO.  I can hear it and so can most mic novices.  DIY!

The out of focus pictures seem to show OK parts.  The capsule to gate cap might be OK if it has one.

Is the capsule a multpattern 32mm dia one?

What is wrong with it that you want to change it?  IMO that is how you should think about changing a microphone.  Sometimes the stock parts can work well.

Holy moly. Gus is a legend    (I actually plan on trying out your 603s mod )

yeah the mic is a multipattern condenser. My main issues with it was coloration and there is a digital graininess that comes out ever so often. For the most part, it's not a bad mic at all, but there are takes where I nail it and then when I playback I hear that graininess. Kind of frustrating.

For the coloration I took out the inner mesh in the headbasket (by the way, is it customary to take out the lining on the top of the headbasket as well?). I thought better electronics might clear up some issues in the grain department. Also, I kind of just wanna have fun and a mic I can call my own.

thanks!

Looks like the gain stage is a version of the Schoeps circuit One n channel JFET? and two PNPs.  I can not read the yellow caps to tell the film type and value.

Do you hear the graininess with higher level sounds?  This can help tell if it is the microphone or the stages after the microphone.

You might want to look for the work people Like Zapanspark have done at the Yahoo microphone group with that type circuit it goes beyond the cap changes.
http://tech.groups.yahoo.com/group/micbuilders/

Cap changes at the capsule to gate can sometimes be heard because of the DC voltage difference between plates.  Cyril Bateman had a good web site with very good PDFs of tests of distortion from caps but it seems it has disappeared from the web.