b3groover

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #20 on: March 20, 2007, 01:17:40 PM »
Up because I just replaced the capsule to fet cap with a 1000pf polystryrene and the two .22uf caps with .22uf Xicon polyester caps, which I had originally bought to mod my MXL 603s but they are far too large.  I have some Panasonic polypropelyne caps coming on Thursday.

I recorded four different sources before and after the mod, using the same gain structure and using four different mic stands that were kept in the same place each time to ensure some kind of "control".  I recorded a Wurlitzer 206A electric piano going through a MusicMan tube amp, a drum set with the mic out in front, about 3 feet, my voice, and a Hammond going through a Leslie 21h.

Honesly, on the drums and the Hammond, I cannot tell the difference.  On the Wurli, there is a less "shiny" high end on the modded mic.  On voice I heard the biggest difference, but it was not good.  On the un-modded, it is overly bright and silibant.  On the modded mic, the silibance seemed to be gone, but it was replaced with weird distortion in the upper frequencies whenever I sang loudly or hit high notes.  Not pretty.  I'm not sure if that is due to the polyesters or what.  Come Thursday I'll replace them with the Panasonics and try again.

Even though they are the same circuit, the 990 doesn't really sound like the 603s.  Probably due to the capsule enclosure (both the ring around the capsule and the windscreens).

EDIT:  Just thinking out loud here -- could the distortion be caused by the polystyrene, which is only rated for 50v?


khstudio

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #21 on: March 20, 2007, 03:46:34 PM »
Quote from: "pucho812"
Quote from: "Gus"
What does garbage sound like?


sounds like rock music with lots of loops/samples and a female singer :green:


Now that's funny :razz:

What's up Gus... I haven't got to that V77 yet.
Soon.
Kevin ~ KHStudio

Gus

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #22 on: March 21, 2007, 10:33:38 AM »
b3groover

  Being a schoeps type circuit but missing a part or two, the high end rise of the capsule and the baffle, grill mess might be clipping a stage.

Maybe what you are hearing might have been masked by the stock parts.

I have a modded MCA microphone sd with a baffle I don't like it at all.

Schoeps and AT can use a baffle ring but maybe the capsules were designed to be used with a baffle ring.

b3groover

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #23 on: March 21, 2007, 12:24:45 PM »
Gus, thanks for the reply.  My Panasonics came today and if I have time inbetween running around with my three year-old daughter, perhaps I can put them in and see if they do any good.  If not, no big loss as I never really used the mic anyway (it was a freebie from Musician's Friend a couple years ago).

What is the purpose of a ring around the capsule like that anyway?  I would say "to make it look better" but I was not aware (until now) that Schoeps did (does?) it too.

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #24 on: March 21, 2007, 12:49:46 PM »
The capsule boosts highs, output emitter followers distort them, so most probably stock capacitor rolls off highs a bit so distortions in output followers are a bit lower.

Here is my thread about how I solved the problem:

http://www.groupdiy.com/index.php?topic=20144

I hope it helps.

Gus

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #25 on: March 21, 2007, 01:17:31 PM »
http://www.schoepsclassics.de/1953.htm

some cool pictures at the site.

b3groover

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #26 on: March 21, 2007, 05:17:40 PM »
Very cool pics.  I still don't know why a ring around the capsule is a good idea engineering wise.  I'm sure it is, since Schoeps did it, but obviously it isn't in the 990.

So, should I put the original ceramic back or replace the 1000pf polystyrene with a 680pf polystyrene or polypropylene or silver mica or whatever?

b3groover

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #27 on: March 21, 2007, 09:35:41 PM »
Okay, I'm an idiot.  After looking at my work today and debating going back to the stock caps, I realized I replaced the caps in the mic marked 223, which are the 0.022uf instead of the ones marked 224, which are the .22uf caps I was supposed to replace.

Duh.  So after putting the old ones in and replacing the 224s with .22uf panasonics, it is no longer doing the harsh high-end thing, at least as far as I can test it right now, which is not much.  My baby girl and wife are both asleep, so no loud singing for me tonight.  I'll do further tests tomorrow.

Flatpicker

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #28 on: March 22, 2007, 10:36:14 PM »
Quote from: "b3groover"
So after putting the old ones in and replacing the 224s with .22uf panasonics...

You should be able to fit some good metalized polys up to 1uF in the 990 for the .22uFs - lots more room there than in the 603S.

b3groover

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #29 on: March 22, 2007, 10:54:38 PM »
What would be the advantage of putting a higher uf cap in there?  I bought some .47uf Panasonics just the the heck of it.


Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #30 on: March 22, 2007, 11:43:54 PM »
Quote from: "b3groover"
What would be the advantage of putting a higher uf cap in there?  I bought some .47uf Panasonics just the the heck of it.


From output emitters to the ground?

More distortions on highs.

But they are 22 nF, not 0.22 uF

0.22 uF are capacitors from FET to emitter followers. Almost nothing changes if you double them. Also, in series with them are 15 nF capacitors that are shorted by HPF switch. The switch is a toy: it rolls off 6 dB / Oct frequencies that depend on beta of output transistors and load impedance.

Gus

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #31 on: March 23, 2007, 07:13:06 AM »
The bases

Flatpicker

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #32 on: March 23, 2007, 05:54:37 PM »
I was talking about the .22uFs between the FET and emitter followers. I tried 1uFs in the one I modified (which did not have a switch) and it opened up the low-end a tad more to my ears, but YMMV.  I'm sure the 1uFs are way over-kill and the .47uFs would work fine.

b3groover

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #33 on: January 29, 2008, 12:53:01 AM »
Seems to me this mic would be a good candidate for a Royer mod! :)

Marik

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #34 on: January 29, 2008, 01:47:22 AM »
Quote from: "b3groover"
Seems to me this mic would be a good candidate for a Royer mod! :)


Well, it might except of one thing--the capsule sucks... I mean... there are only very few mics on the market I'd honor this way... another one would be AKG C1000, if it says something.

Anything, even 32mm Chinese capsules would be a much better choice, IMHO. Don't waste your time with this one. But that's maybe only me...
Samar Audio & Microphone Design

www.samaraudiodesign.com

The Art of Ribbon Microphones

tony dB

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #35 on: January 29, 2008, 03:26:25 AM »
AKG C1000? Are those similar to C3000? I happen to have some of those what could use some pumping up as teh last years they only get used when we run of of other options on very large drumsetups...

b3groover

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #36 on: January 29, 2008, 10:04:34 AM »
Quote from: "Marik"
Quote from: "b3groover"
Seems to me this mic would be a good candidate for a Royer mod! :)


Well, it might except of one thing--the capsule sucks... I mean... there are only very few mics on the market I'd honor this way... another one would be AKG C1000, if it says something.


So the ring around it really messes it up, eh?  It has the same capsule and electronics as the 603s.  I recently did a Royer mod on the 603s and it sounds fantastic.

Flatpicker

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #37 on: January 29, 2008, 08:19:39 PM »
Quote from: "Marik"
...another one would be AKG C1000, if it says something...

It does coming from you. So, did you Royer-mod one of these? Details! :green:

Marik

Help! cheap MXL 990 sounds like garbage. Any modifications?
« Reply #38 on: January 30, 2008, 02:20:22 AM »
Quote from: "b3groover"
Quote from: "Marik"
Quote from: "b3groover"
Seems to me this mic would be a good candidate for a Royer mod! :)


Well, it might except of one thing--the capsule sucks... I mean... there are only very few mics on the market I'd honor this way... another one would be AKG C1000, if it says something.


So the ring around it really messes it up, eh?  It has the same capsule and electronics as the 603s.  I recently did a Royer mod on the 603s and it sounds fantastic.


Not only the ring, but entire basket, etc.
I can't help but just get amused by the idea itself of putting SD capsule into LD body  :roll: .

Quote from: "Flatpicker"
Quote from: "Marik"
...another one would be AKG C1000, if it says something...

It does coming from you. So, did you Royer-mod one of these? Details! :green:


Yeah... go ahead... laugh  :cry:
Samar Audio & Microphone Design

www.samaraudiodesign.com

The Art of Ribbon Microphones



 

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