MXL 603 -> KM84 Replacement PCB

[GraemeWoller]

A bit of odd question: Can anybody recommend a good replacement for the Mogami wire in the 603/991 mic bodies? I've accidently burned a few of these and would like to replace. I've tried what seems a 24 G wire from a mic cable but these wires are very stiff and a bit hard to work into place.

Are you thinking about the PCB to XLR wires?

 

[chappyclark]

Are you thinking about the PCB to XLR wires?

Yes Graeme, I am talking about PCB to XLR wires.

 

[Beatpeat]

Preparing the Parts…

 

[chappyclark]

Suggest fitting traffo before soldering. You may have to file small amt off PCB to get it to fit.

 

[Beatpeat]

Thank you @chappyclark. This two Trafos fit already perfect…

 

[Beatpeat]

modding my MXL 991…

The first is already working.

 

[gtroc71]

Hello @GraemeWoller, I am another with a low post count
I would like to purchase one of your boards and possibly another two in the future.
If you could please contact me when you have a chance.
Thanks

 

[Ricardus]

Hello @GraemeWoller, I am another with a low post count
I would like to purchase one of your boards and possibly another two in the future.
If you could please contact me when you have a chance.
Thanks

The solution to low post count is to go into the new member forum and just write a welcome message to a few people.

 

[MusoGreg70]

This is a great find. I too best get my ten posts in.
Long time lurking only it’s time to wake up and sniff the solder.
Well done that Kiwi Man.
Btw both the 603s and two Carillon Axis 1 ( same mic it appears) are prone to an annoying whine? Stock.
I was going to do a basic capacitor mod to try and get rid of that, and try a 3U capsule, then saw this excellence.
Very pleased. Cheers!

 

[GraemeWoller]

Yay, a fellow Kiwi!
Yeah, there's certainly no whine with this one, Greg, and I'm just so happy everyone seems to have had such a fun time putting them together. It's been a really cool project! Are you wanting to get a hold of one?

 

[MusoGreg70]

Yay, a fellow Kiwi!
Yeah, there's certainly no whine with this one, Greg, and I'm just so happy everyone seems to have had such a fun time putting them together. It's been a really cool project! Are you wanting to get a hold of one?

Yes most definitely. . Thank you. Will P.M. G

 

[DSpenceATL]

Hey @GraemeWoller , another lurker here looking to buy a few boards
I PM’d you on Reddit a couple years back, but I don’t think it did a great job of alerting either one of us when we replied lol.

 

[GraemeWoller]

Hey @GraemeWoller , another lurker here looking to buy a few boards
I PM’d you on Reddit a couple years back, but I don’t think it did a great job of alerting either one of us when we replied lol.

Man, I don't have a clue what's going on there sometimes!! I love Reddit, but things get lost!!
I'll send you a message.

 

[joulupukki]

@GraemeWoller I may also be interested in a couple boards but can’t figure out how to send you a message.

 

[joulupukki]

3U sells two different contact length sizes for the capsule: 3mm and 0.5mm. Which one fits these MXL donor bodies?

 

[Chrisfromthepast]

3mm for the MXL 603s, 840, v67N, 604, 991, monoprice 600700 and likely more.

 

[joulupukki]

3mm for the MXL 603s, 840, v67N, 604, 991, monoprice 600700 and likely more.

Excellent. Thank you!

 

[joulupukki]

Using the 3U cardioid capsule and their GZT-84 (7:1) transformer would this be closer to a Neumann KM-84 or a KM-184 in terms of frequency response? Looking at the 3U cardioid frequency response (at the bottom of 3U Audio Microphones,Condenser Microphones) it’s got a bump between 5-10kHz that it seems like a KM-84 doesn’t (http://cdn.recordinghacks.com/images//mic_extras/neumann/KM84-KM184-frequency.png).

 

[Chrisfromthepast]

You are correct. You won’t be building something with the resale value or exact specifications of the km84.
Having performed this mod a few times, Im always happy to end up with a lovely sounding mic in the end, which gets more use than the stock 603s I keep around as a control group. That said, I think the real value in the part selection and building and trouble shooting, is in the learning experience more than the mic. I bet you can’t build just 1…

I don’t have the km48 to compare with, but took some rudimentary measurements last year, and will hopefully make more measurements soon with various small diaphragm capsules.
At the very least, you can see why I prefer the 3u transformer from these graphs.

The km84 capsule and circuit have been discussed here quite a bit, sometimes separately. This build is very DIY.

 

[joulupukki]

You are correct. You won’t be building something with the resale value or exact specifications of the km84.
Having performed this mod a few times, Im always happy to end up with a lovely sounding mic in the end, which gets more use than the stock 603s I keep around as a control group. That said, I think the real value in the part selection and building and trouble shooting, is in the learning experience more than the mic. I bet you can’t build just 1…

I don’t have the km48 to compare with, but took some rudimentary measurements last year, and will hopefully make more measurements soon with various small diaphragm capsules.
At the very least, you can see why I prefer the 3u transformer from these graphs.

The km84 capsule and circuit have been discussed here quite a bit, sometimes separately. This build is very DIY.

Thanks for the great info. I can see how this rabbit hole could quickly be similar to the one where I built five different vacuum tube amps from scratch (cabinet and all). Fortunately I've sold off at least one of those (since I don't need them all). But wow, it was very educational and fun!