Shure M68 mixer mods

[billyz]

OK, this is way off my usual.
My daughter is getting into recording and she asked me for some help and mics etc.
I got her a cheapo Presonus usb mixer , but the gain is a bit low for a dynamic mic. So.
Being a cheap father, I picked up a Shure M68 for $9. But boy was it ever noisey. Hiss, hum , etc. Here is what I did and it turned out pretty good.
1. install 1/4 jacks in place of the rca in and outs . used a dremel tool to grind off the rivets.
2. Replaced the power supply caps and doubled the microfarad of the first cap, reduced most of the hum.
3. replaced the transistors with Hi gain/low noise MPSA18.
4. replaced the electrolytic coupling caps with Wima 4.7uf/63v film types.

Reduced a ton of hiss and hum. Very clean and fat sounding, tons of gain.
I intended to replace the resistors with Takman hifi types, but got impatient and went ahead with what I had. I may revisit it in the future.

These are real sleepers for a budget minded studio beginner.

[HeeBGB]

What? Now I gotta start a new area for digital audio and Recording? pfft!

Nice work Billy. Sounds pretty cool. If I get some time to play with recording gear I will follow your direction!

Got any clips?

[billyz]

What? Now I gotta start a new area for digital audio and Recording? pfft!

Nice work Billy. Sounds pretty cool. If I get some time to play with recording gear I will follow your direction!

Got any clips?

Please please, NO Digital anything section, EVER. I put it in the garage talk, cuz thats what I think it is. Ha Ha.

[Leo_Gnardo]

Next you're going to have to build a nice tube compressor with her. "Daddy why does the meter run backwards? Is it s'posed to do that?"

[billyz]

Next you're going to have to build a nice tube compressor with her. "Daddy why does the meter run backwards? Is it s'posed to do that?"

I was thinking to rob some of these little stepup transformers and build a tube mic pre. I think they are like 10:1 . A tube compressor might be beyond my skills.