I've made enough stupid fuzz pedals during the pandemic to fill a drawer so it is time to move on to something new. I have been starting to research some mic mods to do at home. Starting this thread to discuss all things mic mod related. Where do I start on this adventure?

I've got an MXL990 that I want to change out the capsule on as a beginner project. I see micparts.com had mod kits & capsules for these, but I also see the same (allegedly) capsules for sale on Ebay for much cheaper.

Also, looking to gain an understanding of transformers and why Lundahl transformers seem to be what you need to have in a great mic. Any resources for dummies like me would be greatly appreciated.

Thanks!

look on groupdiy for ideas.
micparts is not a great idea imo, they are overpriced though there is some convenience in the kit format, and they may do some quality screening of capsules--I would hope at the mark-up.edit: looking at their sdc capsule;they have tripled the price of what it was 2 years ago.
what don't you like about the 990?
I'm not familiar with that mic.
what are you going for/what changes/what purpose?
the capsule is rather fragile and is the part that contributes to the performance most.
generally these budget large diaphragm condensers have used a copy of the u87 capsule--some are decent some are fizzy/hyped
there are cheep knock-off u47 capsules available now;something I'd try if a novice again...either from aliexpres or JLI electronics.
what model lundahl do you have in mind? there are other options depending what you are going for.
I would suggest a u47/m7 style or sennheiser 414 style capsule in the current circuit and then a flat transformerless circuit like the schoeps/alice or maybe a source follower circuit if you want to try something else.
remember the capsule is fragile and sensitive to any contamination from finger oil, solder flux etc.
I have built a few mics over the years and am willing to help.

Second GroupDIY. It can get a little heavy there and the learning curve can be steep, but there are a lot of helpful folks and some great project threads with people who know they're stuff.

There's probably some stuff on gearspace too, especially for the 990 as it's a common, affordable mic.

https://advancedaudio.ca/ is another good resource if you're interested in modding the apex 460 style tube mic, Dave Thomas is very helpful and also sells parts that can be useful for other mods as well, capsules and transformers. They have a forum but it doesn't get a lot of action, still some good info there.

http://foxaudioresearch.ca/ hasn't been updated recently, but they have some good info and I'm pretty sure at least one micparts kit is based on their mods.

Micparts.com is a common starting point, but I'd recommend you check out one of Matt McGlynn's other projects, the Microphone database http://recordinghacks.com/microphones might not be super helpful for mods, but it's a great resource on what's out there already.

Same goes for http://coutant.org/ Nice collection of info on mics all in one spot.

I've never modded a 990, but a capsule swap is an easy start if you want to try a different capsule, just be careful and don't put a screwdriver through the diaphragm.
quick search yielded this, which might be a good starting point http://www.audioimprov.com/AudioImprov/ ... ement.html

Let us know how things go.

Peluso is said to make really nice capsules. Might be a little pricey for such a sensitive part on your first DIY outing:

https://www.pelusomicrophonelab.com/parts/Capsules.html

Thanks everyone!