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MCA SP1 Mod/upgrade PICS!
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optofonik
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Joined: 16 Jun 2009
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PostPosted: Fri Jun 26, 2009 5:37 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

In my ongoing research I have come across many postings such as this. I'm currently trying to cross reference the information but much of it isn't even as specific the following. So, I was hoping that some of you may be able to fill in some of the gaps in this excerpts from this particular post:

Hitachi 2sa1083 bipolar. (Bipolar what? Located where?)

Up the polarization voltage from 40 to 57 volts. (How, with what?)

Output caps are enlarged to allow 20 hz to pass and those are bypassed with more MIT caps. (Enlarged to what? Where do the MIT caps go? What encompasses the output stage?)

Dale RN55 resistors for the audio path. (What comprises the “audio path”? What differentiates it from???)

Panasonic FM electrolytics are used for long term reliability. (Where?)

Kimber black pearls silver teflon wire off the capsule. (No explanation needed)

J305 FET from Siliconix. (No explanation needed)
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Brian
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PostPosted: Fri Jun 26, 2009 6:19 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

optofonik wrote:
In my ongoing research I have come across many postings such as this. I'm currently trying to cross reference the information but much of it isn't even as specific the following. So, I was hoping that some of you may be able to fill in some of the gaps in this excerpts from this particular post:

Hitachi 2sa1083 bipolar. (Bipolar what? Located where?)
I guess you didn't search it on Mouser? Sounds like a transistor to me.
Quote:

Up the polarization voltage from 40 to 57 volts. (How, with what?)
Probably the capsule polarization with resistors, there is a polarization resistor and a leak resistor and since both sides of the circuit must be balanced, they'll be the same value.
Quote:

Output caps are enlarged to allow 20 hz to pass and those are bypassed with more MIT caps. (Enlarged to what? Where do the MIT caps go? What encompasses the output stage?)
You'd have to figure to "bigger than they already are, and "bypass" means soldered in parallel. The electros usually are values unattainable in other types of caps, the Mit caps are small values, when bypassing a bigger electro they help get rid of audible phasing effects from the electro not handling the audio spectrum equally in respect to time.
Quote:

Dale RN55 resistors for the audio path. (What comprises the “audio path”? What differentiates it from???)
From the power path. You have power coming in and ac in the form of audio coming out. You can use the good stuff on the power path too, but, most people think"why spend the money?".
Quote:

Panasonic FM electrolytics are used for long term reliability. (Where?)
Wherever you would use them. They don't like AC so probably the DC power. The filter caps.
Quote:

Kimber black pearls silver teflon wire off the capsule. (No explanation needed)

Quote:

J305 FET from Siliconix. (No explanation needed)

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optofonik
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PostPosted: Fri Jun 26, 2009 7:15 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Wow. this will keep me going for awhile. BTW, mouser didn't have the Hitachi BUT I did find a data sheet and you are right (but you knew that) it is a transistor. I'll research what a polarization resistor and a leak resistor are (don't tell me, at least not yet) and see what I come up with. Its been a long time since I took on a project that had such a steep learning curve for me.
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Brian
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PostPosted: Fri Jun 26, 2009 10:27 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

I'm no genius and I figured it out from a book, you'll do fine. Just hang in there and do all the math.
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Jim Williams
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PostPosted: Sun Jun 28, 2009 1:09 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Those are my comments taken out of their original context. They refer to the mods I do on that mic.
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Brian
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PostPosted: Sun Jun 28, 2009 7:57 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Jim Williams wrote:
Those are my comments taken out of their original context. They refer to the mods I do on that mic.

Hey Jim, it's always good to know when you've had a hand in something.

I think it should have been included in the quote.

What was their original context?
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Mustang Martigan
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PostPosted: Wed Mar 22, 2017 10:49 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Brian wrote:
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.


You're post interested me as I own a pair of MCA SP1's that I plan on modding tomorrow; I just bought an $8 kit on eBay that includes 3 higher quality capacitors.. the C3, C4 and C13.

Jim William's name sounds familiar to me...people used to send him their SP1's to be modded until he stopped preforming the mods, no? Was he the one that recommended replacing "the .22uF's with 1uF Panasonic films, and the tants with Wimas, and the .001uF tant with a Panasonic film."?

Is DCoyle the one who recommended you removing the D1 and D2, and C1 and C2 caps on the output? You said that you preferred the mic with these four caps still installed?

Are you familiar with the mod that I mentioned above? If not, here is the eBay auction where you can get obtain the mod: http://r.ebay.com/TgDt4n. It's gotten all good reviews; I have yet to read a bad one.

How did the tone of the mic change when you made the changes that Jim suggested? I've read that he really know's what he's talking about. I was gonna send my SP1 pair to him a few years back, but it was when he had just stopped accepting more mics (for modification).

I currently use my SP1 pair as drum overheads, acoustic guitar and vocals. They work alright, but I have nothing to compare them to; my mic locker is pathetic. It's basically the two SP1's, a SM57 and a crappy $40 Shure AXS2. I don't have much money to spend of equipment unfortunately. My next purchase is going to be a pair of monitors. I've always had to mix with a pair of headphones, or on a pair of Bose bookshelf speakers, which have no business being used on a mix.. they're WAY too colored.

Anyways, back to the SP1 mod. Has anyone on here done the mod I'm about to do? If so, how did it work out for you? The seller told me that the three caps this mod replaces have the most to do with the mic's overall tone. I'll report back once I've finished this mod. I'm going to make a before and after acoustic guitar recording that I'll share.
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Jim Williams
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PostPosted: Thu Mar 23, 2017 11:52 am    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Don't expect much from 3 caps. SP-1's have a rather harsh sounding capsule, it gets worse with better circuits.

A replacement capsule solves those issues. Microphone-parts sells replacement kits and pcb's for those mics using my designs. I recommend those if you want to improve that mic.
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Mustang Martigan
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PostPosted: Thu Mar 23, 2017 10:17 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Jim Williams wrote:
Don't expect much from 3 caps. SP-1's have a rather harsh sounding capsule, it gets worse with better circuits.

A replacement capsule solves those issues. Microphone-parts sells replacement kits and pcb's for those mics using my designs. I recommend those if you want to improve that mic.


Huh, so you'd recommend no replacing those three caps from the mod kit I bought? I agree about the capsule being the most important part.
I'm familiar with the Microphone-parts kits, but they can get pricey...I think maybe $100 before you even get into choosing which capsule you want to replace the stock one with. They have quite a few capsules to choose from. Do you have a favorite from their selection, or does it all depend on what you're using the mic for?
Besides not really having the $3-400 to throw down on modding the pair, I was wondering if the end result is worth the cash spent, or if you could just use that money to buy better mics, or just one nice one.
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PostPosted: Fri Mar 24, 2017 11:03 am    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Extending the low end is the best result those parts can offer. I use the Mic Parts rk-12, k-87, k-67, k-47 and some EU capsules. All of them sound excellent and all are useful.

A stock MCA SP-1 with one of those capsules will easily beat a highly modified SP-1 with that stock capsule. Combine them and they hold up well against multi-thousand dollar mics. In that regard, I feel it's a good value and a low risk investment.
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Mustang Martigan
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PostPosted: Fri Mar 24, 2017 10:44 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Jim Williams wrote:
Extending the low end is the best result those parts can offer. I use the Mic Parts rk-12, k-87, k-67, k-47 and some EU capsules. All of them sound excellent and all are useful.

A stock MCA SP-1 with one of those capsules will easily beat a highly modified SP-1 with that stock capsule. Combine them and they hold up well against multi-thousand dollar mics. In that regard, I feel it's a good value and a low risk investment.


The SP1's frequency response is listed at 30Hz-20kHz. So when you say that replacing the three caps I mentioned will "extend the low end," will it just add an extra 10Hz and extend the low end to 20Hz, or will it improve the tone in the low end as well?
This would be contrary to your previous post stating that altering the circuit without replacing the mic's sub-par capsule would only result in a harsher sounding mic. Is this just the case when replacing the majority of parts, like some of the other, more pricey mods have you do?
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Mustang Martigan
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PostPosted: Sat Mar 25, 2017 2:30 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Brian wrote:
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.


The images are no longer loading, probably cuz of the post being old.
I recenly spent $8/per mod (I own a pair) for three better quality caps as replacements in the SP1's circuit. I mentioned this in a recent post on this thread and Jim originally wrote me back with a warning about replacing circuit parts without also replacing the capsule.. he basically said that improving.tbe circuit just makes the mic sound harsher if u leave in the stock capsule. He then replied a second time saying that replacing those three caps will actually extend the low end.
From your original post, it sounds like just by just upgrading the mic's circuit dramatically improved it's tone. You didn't also replace the capsule, right?
I'm sure that a capsule replacement would improve the tone 10x over, but my question now is if it's 100% nessacary, or if even worse, it could affect the mic's tone negatively.
Thanks.
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Jim Williams
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PostPosted: Mon Mar 27, 2017 1:36 pm    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

The Mic Parts circuits were designed to polarize the diaphrams and it takes the signal off the backplate. That eliminates the 1000 pf cap off the capsule, it's then direct coupled. Then you only have the interstage cap to worry about.
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Mustang Martigan
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PostPosted: Fri Apr 07, 2017 5:19 am    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

Jim Williams wrote:
The Mic Parts circuits were designed to polarize the diaphrams and it takes the signal off the backplate. That eliminates the 1000 pf cap off the capsule, it's then direct coupled. Then you only have the interstage cap to worry about.


Like I mentioned earlier in the thread, this 3 cap mod, http://r.ebay.com/nbrSSr is offered thru SilentSkyStudios (a seller on eBay), not Mic Parts. According to the reviews of this mod, replacing the C3, C4 and C13 caps smooth out the top end (less harsh), fatten up the low end and improve the midrange, by eliminating the honky/nasal tones. These improved attributes refer only to the cap replacements and the stock SP1 capsule.

With this new information, do you still believe that this cap swap mod will just make the SP1's tone harsher, or that it will improve in the areas mentioned above (which are excerpts of reviews from people whom performed this simple cap mod)?

Thanks,
Adam
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Jim Williams
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PostPosted: Fri Apr 07, 2017 11:10 am    Post subject: Re: MCA SP1 Mod/upgrade PICS! Reply with quote

I have found no salvation for the MCA SP-1 capsule, it's that bad. Replace it and you too will understand.
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