Inside the MXL 604 microphone

I took some photos of the inside of my MXL 604 mic for your enjoyment:



Click here for more pictures. I'm hoping to add the Gus mods to it, if I can find room. Those caps were a bit tight on the 603, so I imagine this one will be even tighter.

looks like there are films at the gate and to the output PNPs.
I did note the bias feedback pot is gone are there three resistors in the source leg of the fet? one 2k to 2.2k and maybe two of 220k or 270K with one end of a 1 gig at the junction instead of the pot?

Thanks for the pictures

Looks like some of the "Gus mods" are already there. MXL must have read that thread too. Wonder if the capsule is any better?

Yeah, the FET bias pot is gone, but it's all 1% metal film resistors inside. I can't see the values, it's packed in too tight.

The capsule looks identical to the 603 to me. There are two, of course, one cardoid and one omni.

Is it worth changing any of the caps? Is that a WIMA on the backside now? Should I change that to a Styroflex?

I'll do some A/B tests one of these days.

I would change it to styroflex.

All the 603s I modded with styroflex caps gave me mixed feelings when I tried them on acoustic guitar. Granted it wasn't harsh like the ceramic, but it lost that fast transient attack and just sounded kind of mushy to me. The styroflex rules on the Oktava MC012s but a good metalized polypropylene might be a better choice for this one. Just MHO. I can?t tell if this one is a metalized polypro or polyester. Either way would be an improvement over the ceramic in the 603.

I had forgotten about the 604 coming with 2 capsules. I may have to nab one during the next GC sale. :wink:

BTW, thanks for posting this. :thumb:

Is there anything to be said for having both? I've heard of multiple parallel caps in the power supply to give noise multiple paths to ground. But I suppose this doubles the capacitance, doesn't it?

I'll probably just keep it stock. :shock:

[quote author="synthetic"]Is there anything to be said for having both?[/quote]Yes, I'd give it a try. In fact, when I gave this same opinion to Gus way back when, he suggested the very same thing. I ended up selling all my 603s though, so I never got to test it out.

I'll probably just keep it stock...

Click to expand...

Doesn't hurt to try things. Besides, you can always put it back like it was. But having said that, it looks pretty good stock.

My 604 is not harsh at all...I was pleasantly suprised at it's performance. It was kind of a "stop gap" measure on the way to a 451 or Josephson but I can see this being used for a long time :thumb: ...

Cheers,
Ray

Update on the 604. I put the styroflex in parallel with the Wima (?) on the back of the board. It sounds very nice. Comparing it to my Gus modded 603, it seems to have more bass response but is possibly noiser. That's probably thanks to the loss of the FET bias, though I can't see where it would fit on that little board. All told, I prefer the modded 604 to the modded 603.

I'm very happy with the mic. Like all MXLs, especially after a few mods, it's a ridiculously good value. It gains a rolloff, pad, and an omni capsule. Now if someone would come up with some mods for my 960. Other than gutting it and using the chassis to make a G7, which is my ultimate goal.