Gus' MXL 603s mod - Pictures/Part numbers -thanks Flatpicker

[synthetic]

I just saw the new MXL 604 in Electronic Musician, they must be showing that at AES. It's a 603 with a rolloff, pad switch, screw-on omni capsule and wood box. I wonder if there's still room for mods inside?

 

[Rossi]

Philips/BC components MKT caps might fit. .47 u certainly will. Not sure about 1 u. They're smaller than WIMA. But you have to be careful the sides don't touch the metal housing as they're not insulated.

 

[bitman]

Hey!

So I bought 2 MXL 603s Mics and before they arrived I was off to
DigiKey to get caps. I bought the .22uf Metal Film/50v caps and some
1000pf polyprops.

I just moded them.

Here are the results.
The mics were run though my A DEE A 8K (best I've got) to a tear a tech ews88d.

The Guitar is a Seagull, the mics are pointed at the sound hole and the 12th (or so) fret.

Before Mod:
http://www.mtrecording.com/603s_before_cap_mod.mp3

After Mod
http://www.mtrecording.com/603s_after_cap_mod.mp3

And I like them better now.

Thanks to everyone involved.

Ron

 

[rodabod]

The links work fine.

Just remoce the from the beginning and end and the...copy and paste the address into your browser.

 

[bitman]

Thanks for the help with the links rodabod.

:wink:

Ron

 

[Rossi]

Thanks bitman, I think the files capture the sound change quite well. :thumb:
Before mod is a bit nasal and flat. With mod sounds more detailed and "deeper", you'd almost think it's a different guitar with a bigger body. It's exactly what I experienced when I modded some SD mics of mine (somewhat different design than MXL 603)-

 

[jeffrey_burr]

Please, I'm trying to find a way to fit big caps in for C4 and C9. I was thinking of replacing C3 (47uF 50v) with a smaller size part, but I was concerned this might affect the FET bias. I don't think so, but I'm not certain. Anybody please care to comment? and yes, I'm already aware that I'm in over my head - I try to compensate by always being polite. Thanks.

jeffrey (not an engineer, just another control-freak musician)

 

[bitman]

Dude, 50v caps should slide right in, right to the top!

My .22uf-ers are

Digikey PN P4667-ND

 

[jeffrey_burr]

Thanks dude. I'm trying to fit at least 1uF film caps for C4 and C9 (the stock .22uF guys everyone is having so much fun with). The BF-series polyesters from AVX are pretty small. I'm wondering about replacing C3 (that first electrolytic) with a slimmer version - the stock piece is ~8mm across. I need more room. But I don't want to open a can of worms by disturbing the operating point of the active device. I guess this wasn't a concern for those folks who were bypassing the DC converter section though.

It seems the zener "regulates" the DC after a fashion but I've never been too sure how that works... I was speculating about replacing C5 with a low ESR piece as well. Maybe this is not such a great idea?

My 603s will probably never be used for anything but drum overheads, with the only other mic on the bass drum (jazz sessions). I'd like to optimize the low-end as best I can.

 

[q2audio]

Hi,

Maybe this should be a new topic... but I just got a pair of 604's and of course want to open them to see what's going on inside. The problem is the rolloff switch, it's in the way of sliding off the body and I'm not seeing a way around this, but there must be. I can't seem to pop the cap off of the switch, and I can't think of another way. The three set screws are easy enough to screw in and the body will slide about 1/4" and then the switch/cap stops it from moving any further. It might be possible to slightly move the XLR, but I don't think it will do any good.

The mic does sound nice "as is", but I have nothing to compare it with.

Any ideas??

Thanks,

Tim

 

[q2audio]

A friend figured it out. The switch cap needed to lift off at an angle so the skirt would clear the hole. Smart guy, that guy.

Anyway, it appears that some of the "standard" mods are stock on these:

1G resistors, 2SK170BL FET, 1n/100V (white box, no name) film cap to connect capsule to gate of FET, film caps in other places (presumably audio coupling). Nice quailty double sided PCB. There are three electrolytics branded "Chang" that might benefit from an upgrade. There are two 220uF/16V and one 47uF/50V. These are all quite small caps (physically): 8mm dia., 8mm height, 4mm lead spacing (approx.)

Tim

 

[eatcrapandie]

I'm trying to remove this case and i see no other option other than pulling on the xlr pins with a needle nose pliers, is this how you guys remove the insides from the case??

 

[Jonkan]

if you mean the 603s, just screw the small screws on the side of the mic a bit in and then you can easily pull out the innards.

/J

 

[Flatpicker]

[quote author="eatcrapandie"]I'm trying to remove this case and i see no other option other than pulling on the xlr pins with a needle nose pliers, is this how you guys remove the insides from the case??[/quote]

:shock: :shock: NO! (see next post...)

 

[Flatpicker]

[quote author="Jonkan"]if you mean the 603s, just screw the small screws on the side of the mic a bit in and then you can easily pull out the innards.[/quote]No, you are thinking about the Oktava MC012 - The MXL 603 comes apart by simply un-screwing the end where the XLR connects and sliding the PC board out of the body. On the newer ones, the capsule screws off the same way.

 

[Jonkan]

Atleast on my mxl603s you have to screw in the screws and pull out the pcb. I have one of the very early ones i think though. Maybe they changed it later.

 

[eatcrapandie]

aha! Thanks, I tried twisting the bottom earlier, but it didn't budge, so i guess i must have not tried hard enough but the second time through I got it off, now off to digi-key, and mouser!

So I'm gonna try this mod on my 603, 991, and 2 990's i currently own. I've also been trying to research this for the 2003 and have found that you can buy the boards itself but can I just install the new caps in that as well and have it give me good performance?

 

[Flatpicker]

[quote author="Jonkan"]Atleast on my mxl603s you have to screw in the screws and pull out the pcb. I have one of the very early ones i think though. Maybe they changed it later.[/quote]Hmmm I didn't realize the early ones were that way. Anyhow, they are really easy to take apart now.

 

[Gus]

read ALL the Metas

http://www.groupdiy.com/index.php?topic=1155

 

[nisios]

Hi guys...

I have just finished modding 3 Mxl603 and i made a clip.
I wont tell wich is the moded and wich is the stock for now.....

The moded has .22uF Wimas and a 1000Pf Polystyren.

http://www.yourfilehost.com/media.php?cat=audio&file=MXL603_Teste.wav

By the way.... does anyone know a better place to host files......one that gives you a direct link to download the file and not this publicity crap?

And thanks alot for this mod guys.....