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MCA SP1 Mod/upgrade PICS!
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Brian
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PostPosted: Fri Mar 13, 2009 9:22 am    Post subject: MCA SP1 Mod/upgrade PICS! Reply with quote

MCA SP1 Mod/upgrade

I'm posting pics.
before:



After:





You'll notice that some of the ceramics got replaced with wima polypro's, some of the electros got replaced with higher value, capacity, and low esr electros, The ceramic off th capsule got replaced with a polypro, mainly for beefiness, some of the ceramics surrounding an feeding the transistor got replaced with COG ceramics except for the one feding the main power which is a bigger value electro, there are bypas polypros sandwiched between the boards (not shown) under all the electros. The bias and leak resistors are also changed to a better quality 1 G ohm.
It's dead quiet and smooth on top with plenty of clarity but not thinness in the mids and some BEEF. It sounds VERY stable and strong now. Punchy and smooth.
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Last edited by Brian on Fri Mar 13, 2009 12:34 pm; edited 1 time in total
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Brian
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PostPosted: Fri Mar 13, 2009 10:18 am    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

In the Simple Machines forum, DIY > Discussion Forums > The Lab > Function of 2 caps in MCA SP1 (MXL 603) circuit?
This from Jim Wiliams:
Thanks guys! I'm the original poster.

I replaced the .22uF's with 1uF Panasonic films, and the tants with Wimas, and the .001uF tant with a Panasonic film.

I also took out D1 and D2, and C1 and C2 on the output. This was according to reccomendation from a guy named DCoyle on tapeop.

These mods are probably already detailed here under the MXL series mods, but I thought I'd mention that what is a little bit unique about these SP1 mics is they have 2 extra .001 caps right before the output transistors, shunting the highs to ground.

DCoyle reccomended taking these out as it opens the mic up a bit, and the other MXL mics don't have them.

I tried it with and without these caps, (replaced again with Panasonic .001 films) and I decided the mic sounded smoother with those caps in. Just going with my ears here. I imagine what may have attracted some people to this el cheapo mic in the first place is that it seems to lack some of the high end harshness of a lot of other cheap mics, and keeping those caps, but upgrading from the ceramic seems to retain that quality.

Anyway, just thought I'd share.
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optofonik
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PostPosted: Tue Jun 16, 2009 1:20 am    Post subject: I'm having trouble with your after pics... Reply with quote

I'm very much a newbie and am struggling a bit studying the circuit of my SP-1 and discerning what's what. Its just time, I know. Close up "after" pics, with the detail of the "before" ones would be a tremendous help. I also wonder if there is anything on the web that breaks down what each component contributes to the sound. It would be great if there was a primer on mic design that used one of the MXLs as the example. Sigh...
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RodC
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PostPosted: Tue Jun 16, 2009 8:15 am    Post subject: Re: I'm having trouble with your after pics... Reply with quote

optofonik wrote:
I'm very much a newbie and am struggling a bit studying the circuit of my SP-1 and discerning what's what. Its just time, I know. Close up "after" pics, with the detail of the "before" ones would be a tremendous help. I also wonder if there is anything on the web that breaks down what each component contributes to the sound. It would be great if there was a primer on mic design that used one of the MXLs as the example. Sigh...


Welcome to the board. Just start studying some basic preamp/amplifier design. You will get there. A condensor mic has to have a preamp at the capsule because its signal is so weak it must be boosted before you send it on down the line.

Basicly you have to provide some polerizing voltage to the capsule (Which is just a cap) then from there its mostly preamp circuit. There is a ton of stuff out there just Google Google, and read read read.

Try to learn how to trace the signal path, learn how a smal signal at the base of a transistor controls a larger current through the CE junction. Do some reading about negative/positive feedback.

Once you can determine the signal flow you should then be able to figure out what is in the path of the signal and what is the Power supply portions of the circuit.
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RodC
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PostPosted: Tue Jun 16, 2009 8:17 am    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

BTW, if your more energetic than I....

You may want to learn how to spell... I wasnt in line when that was passed out! Smile
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Brian
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PostPosted: Tue Jun 16, 2009 11:47 am    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

You can search this forum too, it's all here. I have a few posts up which contain observations I've made about what certain component material and size changes do to the sound of the mic preamp, also, read some Walter Jung on capacitors.
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optofonik
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PostPosted: Tue Jun 16, 2009 1:56 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

RodC wrote:
BTW, if your more energetic than I....

You may want to learn how to spell... I wasnt in line when that was passed out! Smile


???
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optofonik
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PostPosted: Tue Jun 16, 2009 2:00 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

RodC wrote:
BTW, if your more energetic than I....

You may want to learn how to spell... I wasnt in line when that was passed out! Smile


What was spelled wrong?
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optofonik
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PostPosted: Tue Jun 16, 2009 2:32 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

I understand that the schematic for the MXL-603s is also the schematic for the SP-1.
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PostPosted: Tue Jun 16, 2009 2:40 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

How is it that this mic can sound as good as everyone says?

I've never heard it but I have definately heard that mxl 990 or whatever the "Large" diaphragm mic is and it blows...

It's the same circuit right? How much better can this thing sound?
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PostPosted: Tue Jun 16, 2009 2:40 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

optofonik wrote:
RodC wrote:
BTW, if your more energetic than I....

You may want to learn how to spell... I wasnt in line when that was passed out! Smile


What was spelled wrong?



Nothin that I would be able to find in your post... I was commenting on my lack o spelling. I noticed some errors but I have been on the run all day, didnt get a chance to fix em.
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optofonik
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PostPosted: Tue Jun 16, 2009 3:48 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Electro-geniuses don't need no stinkin' spelling. Thanks for the insight, by the way. I've been studying the 603s schematic and, with the help of this great page:

http://www.kpsec.freeuk.com/symbol.htm,

am getting smarter by the minute.

Wink

PS: Shakes, as I understand it by gutting the PCB and replacing the components with better ones for a few dollars there is a significant improvement over the $50.00 mic that it was. Besides, soldering builds character. Modding mics from developing nations makes us better citizens and the rest of the world a better place for all.
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shakestheclown
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PostPosted: Tue Jun 16, 2009 4:45 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

I guess I should have mentioned that I was referring to a modified MXL.
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Brian
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PostPosted: Tue Jun 16, 2009 5:11 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Mine sounds a TON better, it's usable now. Makes a great room mic. Nice and smooth.
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PostPosted: Tue Jun 16, 2009 5:42 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

FWIW I have a pair and some CAD GXL1200s that I have done some electronic upgrades to...

Cutting away the front and gettin rid of the material that recesses the capsule made more of a difference to mine than the electronics did.
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