Finished MXL 603 mod.. listen.

So i bought:
.001uf 50v xicon polystyrene (Mouser PN:23PW210)
.22uf 100v metal poly (Digikey PN: E1224-ND)

I dont know if the voltage rating are screwing something up and i was suppose to get lower ones or what but i dont think i like it. It feels like it rolls off alot of mids and lows. Please listen to the clips..

http://www.187audio.com/songs/MODDED603.wav
http://www.187audio.com/songs/UNMODDED603.wav

I dont believe anything i did could have caused this besides maybe a wrong voltage rating??? I wouldnt think so but im no expert. Maybe its the way the guitar sounds in this room. It was the same mic position, same preamp, same everything.

Is this how the mod is suppose to sound? ::shrug::

I feel like it definitely opens up the top end, but like its missing some lows

My ears prefer the sound of the attack in the modded microphone. It may very well be that the decrease in low frequency is uncovering the attack, but I'd take the modded sound over the unmodded sound. Thats my ears for ya!

Maybe change the .22 caps to .47 (or larger if you can fit em by leaving the leads long). The modded mic sounds a lot nicer to me.

I assume you replaced the capacitor that was in series with the top of the capsule and 1G polarizing resistor and the gate of the 2sk170 and gate 1G resistor with the .001uf? The original cap was probably a 680pf or 1000pf? Did you make sure that you cleaned up all the flux and debris around those connections?

Something is wrong with this mic. I modded my 2nd one and it has way more low end. What can cause a high pass on this mic? It seriously sounds like crap when ive been playing with it.

even from my mac pro speaker i can hear the unmodded as "cloudy" in a bad way. This may be fine on it's own but when u put that in a mix it will most likely get lost.

yah the 2nd modded one opens up too. but with way more lows.

Anyone know what would cause a high pass in this mic?
Heres the schematic: http://www.187audio.com/MXL-603S.gif

put the stock caps back in and it sounds the same still.

[quote author="imloggedin"]Something is wrong with this mic. I modded my 2nd one and it has way more low end. What can cause a high pass on this mic? It seriously sounds like crap when ive been playing with it.[/quote]

Did you swap capsules? The new 603s ain't the old 603s!

yah i tried swapping them. same thing

this is the 2nd mic before i swapped the caps:
http://www.187audio.com/songs/UNMODDED603.wav

this is the 2nd mic after i swapped them:
http://www.187audio.com/songs/2NDMODDED.wav

this is the 1st mic after i swapped them, and it sounded like this so i put the original caps back in, and it still sounds like:
http://www.187audio.com/songs/backtooldcaps.wav

after i swapped the caps into the 1st mic it wouldnt work.. it had really low output. so i desoldered the poly cap and put it back on. then it worked but had this crappy sound it still has. ever since then its been like that.

http://www.187audio.com/scem.gif

I marked the dots where the XLR pins land. On the good mic i have 35.5 on both.. on the bad mic i have different voltages. Does that mean C20 or C10 is bad, or can components down the line change the voltage there?

someone help plz. im racking my brain!

im sure no one cares but, i put new caps in C20 & C10 and now theres alot of distortion, so i put the old caps back in and theres still distortion. gonna try and replace the transistors if i can find them locally i guess.

Are you sure there are no shorts? Could you have bypassed one of the 1G resistors accidentally? Also, what sort of condition is the styroflex cap in. they melt very easily during soldering if you leave too much heat. try replacing that one (if you haven't already). Get a magnifying glass and go over that board with a fine tooth comb looking for broken traces, shorts, or other molasses.

You said you cleaned the flux off the board with isopropyl. Could you have gotten some on the styroflex capacitor? (Great Scott!) Those things are easily eaten by solvents too.

yah i replaced the styroflex cap twice (bought extras). same thing every time. traces look good. no alcohol on the cap either. havent found a place to get the transistors sooo... it still sounds distorted. maybe it was too hot when i was soldering it but the 2nd mic went smooth as buttuh.

Can you define "too much heat" for a styro cap? How can you know you've cooked one when soldering? I know this is somewhat vague question, but can anyone give me some kind of general knowledge on destroying various components due to too much heat from the iron? How much is too much, in a general layman's practical application type of knowledge. :grin:

[quote author="Category 5"]Did you swap capsules? The new 603s ain't the old 603s![/quote]

Do you know when these changed over? Thanks!

[quote author="zebra50"][quote author="Category 5"]Did you swap capsules? The new 603s ain't the old 603s![/quote]

Do you know when these changed over? Thanks![/quote]

Nope. I have 2 pairs though. one four years old and one less than a year old. they are the same circuit but not the same mic. THe bodies on the old ones were heavier, and nickel plated and the new ones are thin, painted, and the capsules just don't seem the same.

My old pair is a perfect match, but the new pair has some variances. That's not to say the new ones sound bad. they are good sounding mics. The consistency has changed. They are still fast and smooth after the mods, but something aout them seems just a bit less sweet.

Of course, the old pair was $300 and this one was $100 so...

Also, the old ones are 603s and say Mogami on them. the new ones are just 603 and that's it.