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

[Rossi]

To be honest, I have to agree with Shane. This is a simple and effective mod, and forums such as this are meant to share such information. Of course Gus worked hard on this mod, doing listening tests etc. and should be credited for it (let's call it "The Gus Mod" henceforth), but the basic idea is upgrading the capacitors in the signal path. And that's not a totally new idea that ought to be protected. In fact, wouldn't it be great if manufacturers picked up on mods such as this and upgraded their products? Everyone should have nice sounding mics.

I'd also like to point out that Gyraf has been recommending styroflex/polysterene as the best capsule to FET capacitor material for some time (e.g. for his G7 design).

I really don't see why The Gus Mod should be kept from the public. Plus, the public knew already. As Shane says, the mod was described here and elsewhere (e.g. homerecording.com, if I remember correctly). So I don't think Shane did anything bad by sharing his pictures with us. He only illustrated a mod that was "out there" already. His only mistake was to give credit to the wrong person. But he simply didn't know any better and appologized for his mistake.

Gus, please don't be upset. You should be proud of your achievement and be happy for everyone improving the sound of their mics with your mod.

 

[Jonkan]

how would you guys think this 1000pf cap would work in this particular mod?

http://se.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=106067&N=401

Its the only polystyrene capacitor i have been able to find in sweden. If there are any swedes here that know of other places nearby to get these kind of caps feel free to speak up.

thanks!
/Jonas

 

[mike_relay]

[quote author="Jonkan"]how would you guys think this 1000pf cap would work in this particular mod?
[/quote]

I just took my 603s apart.. I don't think that capacitor will fit... I'm just estimating from the picture and the length they quote though....

-mike

 

[balluda]

Jonkan try at:
http://www.rsonline.se/cgi-bin/bv/browse/Module.jsp?BV_SessionID=@@@@1362597618.1111603825@@@@&BV_EngineID=cccfaddeegflfhkcfngcfkmdgkldfil.0&cacheID=seie&3289056644=3289056644&stockNo=0116262&prmstocknum=0116262&prodoid=7456009

Is that what you´ve been looking for ? / Balluda

 

[Jonkan]

yup, thanks!

but no use buying them if they wont fit. Anyone that has tried something similar who could report on their findings?

What about using metalized polypropylene caps instead, would that work? I found some at elfa.
Or is it strictly non metalized polystyren and polyproylene caps that sound good? Anyone?

edit:
Just found these aswell, would they work better?
http://www.rsonline.se/cgi-bin/bv/browse/Module.jsp?BV_SessionID=@@@@1362597618.1111603825@@@@&BV_EngineID=cccfaddeegflfhkcfngcfkmdgkldfil.0&cacheID=seie&3289057650=3289057650&catoid=-987196485

Only sold in multiples of ten though, i only need two
/Jonas

 

[asm]

wish i had a capsule for the 603, ive got a body here but no cap
so close. yet so far away.

if anyone for some reason has one, let me know please.


thanks.
taylor

 

[Milkmansound]

well, my caps came from mouser and they do not fit, no matter how I try and get them in there! I am having trouble finding any cap from mouser that will go into the mic body. Damn. I will use the caps on something in the future - so that dollar did no go to waste - but has anyone located a cap in the mouser catalog that will fit? btw - the polystyrene fits quite well! Something tells me I will need to scrap together an order from digikey and get those panasonic caps.

 

[tmbg]

there's nothing worse than having to put together an order for one or two things from digikey, with their stupid handling charge.

Mouser has a MUCH MUCH better website, and is a lot more convenient, but there's always that one part that they don't carry, like the Amveco toroids I like, or this CPLD that I need right now.

 

[wgtenor]

Shane,
Do you have the digikey part number for those .22uf panasonic caps.
I just got some in the mail and they are huge.
There is no way they'll fit in the body.
I got panasonic polyprops with the 50v rating.
I thougfh they'd be fine but I can't use them.
Here's the part number of what I got.

Part # P3880-ND

cap polypropylene .22uf 50volt 1%.

Any info would be great.

Thanks,
Aaron

 

[jeffrey_burr]

Hi everybody! I'm one of those "lurkers" you keep hearing about, but now I'm all signed up.
Before I get to my question about the 603 Gus Mod, let me say a hearty "THANKS" to y'all microphone hackers, from this newbie! This forum is awesome.

So, here's what I'm wondering about. These caps have fairly wide tolerances, at least +/- 10%. So ordering two caps to modify a matched pair of mics will be a hit-or-miss affair, no? How important is it that these components (specifically in this circuit, I mean) be matched, if one desires to preserve the matched-ness? If so, perhaps someone has already ordered hundred of these and already has maybe a few dozen pairs matched? Thanks in advance for enlightening replies.

 

[soundtrack2life]

The statement in the original post "After those 3 simple cap changes the already decent mic becomes wonderful. I will be using thes mics more and more. " What exactly dose this mod do that makes it worthwhile?
Joe

 

[dasbin]

I did this exact mod some time ago but with Panasonic polyprop instead of polystyrene on the capsule cap. I did some pretty meticulous before & after mod recordings on acoustic guitar and A/B'd the results. Noticed absolutely ZERO difference with the mod.
Recently changed the capsule caps to these polystyrenes and again noticed no appreciable difference, even on drum overheads, although I don't have my original A/B recordings to compare to anymore. If anything they may have gotten slightly thinner and less airy now.

For me this is a bit of a reminder that perhaps psychology plays a big part in the "sound" of mods, either that or something about me and my setup just sucks, even though I think my signal chain is decent (312 clone preamp, EMU 1212m converters, Yorkville YSM1p monitors).
I'll keep them the way they are now (modded to this guide) just because it feels better having a ton of people on here telling me it must be better, but I just don't hear it. I also know they must be theoretically/electrically better with these better-suited capacitor materials. My ears just don't jive.
I will say that if I didn't have the A/B I probably would have thought the mod did a lot. As soon as I plugged in the modded mic I was like, "ah! that sounds awesome now!" But then when I heard my original pre-mod recording it was, "wait, that one sounded equally as awesome..."

I wish I still had the files so you guys could hear what I heard, and tell me if I'm losing my mind.
If someone else is planning on doing this mod, I (and probably others here) would really appreciate it if you could do a similar before/after recording and post here...

There's also the (slim) possibility here that I am actually the kid shouting the emperor has no clothes.

 

[Rossi]

I don't own a 603, but I did similar mods to a couple of other mics, and I can say with confidence, that those mods do make a difference.

As has been pointed out before, the capsule to fet cap is the most crucial, and you must use either polysterene or polypropylen. Polyester will *not* make an appreciable difference *in this application.* I have a Studio Projects B1, which has nice WIMA polyester caps throughout, and I thought it probably wouldn't make a big difference to use polyprop for the capsule to fet connection. But I was wrong. The difference was just as big as the change from ceramic to polyprop. As I said, I did not expect that, because I like WIMA polyesters and use them a lot.

What to listen for: don't expect night and day differences that your sister or your mom would recognize immediately. Also, the improvement is not in bandwidth. The frequency response does not change. The difference is in what people like to call resolution or detail. Better caps remove artifacts that lesser caps produce and that you only begin to hear once they're gone, because you thought they were part of the signal. There is a certain nasal quality that disappears with polyprop or polysterene. It's probably something in the realm of distortion and/or transient response. I have no means to measure that, but you can hear it. I'm actually getting to the point of hearing what kind of capacitor is used for capsule to fet without opening the mic.

A good test is acoustic guitar (steel string). That's a wide band and transient rich signal. It helps to know the instrument well. Make recordings before and after the mod. Listen to the before mod file several times, then listen to the after mod file. Or do it vice versa. That will help you to direct your attention to what's different, and once you find what to listen for, the before mod sound "stinks", and you'll be able to discern that stink rather quickly thereafter.

Upgrading other caps helps, too. In fact, on some mics you have to upgrade bigger ceramics or small electrolytics in the signal path before you can hear the capsule to fet upgrade at all.

Don't mod stuff that you like a lot as is, especially vintage stuff. Even though it may sound more transparent after the mod, you may lose its signature sound.

@ jeffrey: the cap values are oversized so +/- 10 % won't make a difference. If you want to be absolutely sure, you can use even bigger polyester caps, provided they fit mechanically. 1000p polysterene and polyprop caps are sufficient and usually only +/- 1 or 2 % anyway.

 

[dasbin]

[quote author="Rossi"]A good test is acoustic guitar (steel string). That's a wide band and transient rich signal. It helps to know the instrument well. Make recordings before and after the mod. Listen to the before mod file several times, then listen to the after mod file. Or do it vice versa. That will help you to direct your attention to what's different, and once you find what to listen for, the before mod sound "stinks", and you'll be able to discern that stink rather quickly thereafter.
[/quote]
This is precisely what I did, and I was listening for the "grain" rather than response. Must have went back and forth between the two recordings for two hours straight, straining to hear any tiny difference. I just didn't. I really don't think my ears are that bad, either.
Perhaps the fact that it was a cheap Yamaha acoustic had something to do with it, so it lacks a bit of detail/definition, and it always seems to sound good in this room.
Re: Polyester, I never tried that, only the original ceramic, polypropylene, and then finally polystyrene.

Ah well. Guess I am crazy. Thanks for the reply.

 

[Gus]

dasbin

Did the microphone have a trim pot on the pcb? I believe I read the newer models don't at another forum.

Brent posted at the PMI forum the early 603 capsules were different and (better?) the later ones changed to an easier to machine capsule design IIRC. PMI forum is off line.

Sometimes the change can be masked by the recording chain. I test with as simple a path as possable and use headphones.

It is possable your microphone had better ceramic caps like COGs.

I have not tried a newer 603. Mine were older ones.

 

[dasbin]

Mine are the older style with trim pots, yeah. I didn't check to see what the ceramics were unfortunately.

Good point about using headphones, I should have done that.

I did leave the mics outside in a forest overnight one time to do some nature recording, and obviously there was quite a bit of condensation on them in the morning... that might have something to do with it, although after they dried out they seemed to sound the same as before.
In any case I'm still getting absolutely fantastic results with them in the studio as drum overheads, just as I was before. So the good news is I still don't feel the need to ever upgrade to better overhead mics; these are getting me results in the treble that sound as good as any top-budget recording to me.

It's totally possible that my ears just suck at hearing these kinds of differences. One time I was cleaning the capsule my Rode NT1 and a good portion (about a quarter) of the gold sputtering fell clean off. I didn't even notice any difference in the mic's sound after that.

 

[Flatpicker]

I modified three of them - 2 older versions and one newer version from GC. The difference is the same on all of them and I was using headphones. I noticed that voices became less harsh in the upper mids. On acoustic guitar, the initial attack of the notes changed to a smoother sound. It's hard to hear at first, but once you do you can't not hear it. You need to use short sound samples (<10 sec ea.) and set them up so that you can play them immediately back to back. Listen to the unmodified version 6-7 times in a row and then play the modified version. Pay attention to the guitar note's attack.

 

[Rossi]

I second that. The difference is particularly apparent in loud attacks. Play something dynamic and use a pick so the attack is sharp. It's pobably harder to hear a difference on picking guitar. The unmodded mic makes the guitar sound a little nasal, narrow and compressed. When you switch to the modded mic, it's almost as if the guitar had a bigger body. I could hear the difference both on headphones (AKG K240DF) and JBL monitors.


BTW. I played with a simulation program last night, and it looks like bigger caps than the 220n polyesters would be good. 470n should improve bass response, even bigger (up to about 10u) would reduce LF phase shift. You won't find anything that fits larger than 470n, I'm afraid. The capsule to fet cap is large enough. Take this with a grain of salt, I'm new to simulation programs.

@ Dasbin: sorry about the polyester confusion, must have misread your post.

 

[Category 5]

I used .47uf instead of the .22 in a pair, and you just might be right about the low end response...and they do indeed fit, although a hair tight.

I did this on my pair of 990s too.

The difference is not only in the attack. After getting used to the modified mics the unmodified mics sound like the high end is drifting in and out of phaes or something. Almost like it has a bit of flange on it. The modification eliminated this. I didn't notice until after the mod...but once I heard it I couldn't "not" hear it.

Shane

 

[jeffrey_burr]

Rossi, thanks, but I think you misunderstood my question. I'll rephrase.

When upgrading these caps, how important is it to have matched pairs of caps, if I want my matched 603s to remain matched?