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V67G mic mod
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Travst



Joined: 15 Jul 2008
Posts: 9535
Location: Birmingham, AL

PostPosted: Tue Jan 15, 2013 10:59 am    Post subject: Reply with quote

Mike Aimer wrote:
I don't suppose there happened to be a schematic of the V67Q stereo mic wherever you got the schem for your mic?


Unfortunately, no. This is only the 603 listed with the V67:

http://www.sdiy.org/oid/mics/
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Travst



Joined: 15 Jul 2008
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Location: Birmingham, AL

PostPosted: Tue Jan 15, 2013 11:19 am    Post subject: Reply with quote

After some poking around, I found an STK .01uf polypropylene cap and soldered it into C1. This is the original value, but a better cap. It sounds good to me, but I'll record a clip when my wife gets home so it will match the others.

Tangelo, what type of film cap do you suggest for C4? I assume that the stock cap is 22uf.



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tangelolemon



Joined: 26 Jan 2009
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Location: Brooklyn, NY

PostPosted: Tue Jan 15, 2013 4:29 pm    Post subject: Reply with quote

Travst wrote:


Tangelo, what type of film cap do you suggest for C4? I assume that the stock cap is 22uf.



Yes, that is going to be tricky. You may not be able to find a film cap in that size, though the low voltage rating certainly increases the chances. If you can't, a good radial electrolytic like a Nichicon (the ones specified as "audio grade") Panasonic, Elna, etc. would likely be an improvement over the tantalum. In fact, not a bad idea to replace all the tantalums with these.

WIMA made a 22f 16v film cap in the MKS-2 series, but those were discontinued a year or two ago. Shame, too, because they were perfect for this application and would've fit.

Maybe another manufacturer makes something comparable? But I haven't seen it.

Another option would be finding someone who had some old stocks of those WIMA caps. Here's the link to the "obsolete" page for them on Mouser--

http://www.mouser.com/ProductDetail/WIMA/MKS2-XL-22-16-20/?qs=sGAEpiMZZMv1cc3ydrPrF4mqn9uxydoMN%2fjRSPeiqJ0%3d

here's one lead for you if you had the inclination to hunt some down on the surplus market--

http://www.diyaudio.com/forums/swap-meet/178855-new-22u-16v-wima-film-caps-mks2-xl.html
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Travst



Joined: 15 Jul 2008
Posts: 9535
Location: Birmingham, AL

PostPosted: Fri Jan 18, 2013 8:11 am    Post subject: Reply with quote

Tangelo, how about this cap? Electrolytic, but the correct value.

http://www.allelectronics.com/make-a-store/item/NC-22/22UF-100V-NON-POLAR-CAPACITOR/1.html
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tangelolemon



Joined: 26 Jan 2009
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PostPosted: Fri Jan 18, 2013 9:12 am    Post subject: Reply with quote

nonpolar electrolytics can definitely perform better in audio circuits than conventional polarized electrolytics.

However, they tend to be physically larger (many are essentially two polar electrolytics back-to-back). Given that and the 100v rating, I doubt that axial-leaded cap would fit in that microphone.

This cap would be the one I'd choose to replace that tantalum, if I couldn't find that out-of-production WIMA film cap I linked above:

http://www.mouser.com/ProductDetail/Nichicon/UFG1E220MDM/?qs=sGAEpiMZZMtZ1n0r9vR22e0BBN1kF1oiBHYj4L1%252b1a4%3d

Inexpensive, and this brand is very good when compared to most other electrolytics in audio applications (it is specifically rated for audio performance). Its radial lead spacing would also most likely fit the tantalum's footprint near-exactly.
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tangelolemon



Joined: 26 Jan 2009
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Location: Brooklyn, NY

PostPosted: Fri Jan 18, 2013 9:20 am    Post subject: Reply with quote

By the way, if you have the means or desire to print out an article and read it at your leisure (it's a bit long to stare at a computer screen), then you will likely enjoy Cyril Bateman's series of empirical tests on capacitors. These tests are 15 years old now (1997, I think) but they're by far the most comprehensive and objective work on the subject... I consider this series to be the definitive text when talking about how a capacitor can impact the sound of equipment, and when it is less likely to do so. Complete with full methodology and oscilloscope measurements!

Parts "1" and "2" deal mostly with his methodology, and if you believe he's trustworthy, you can skim those sections. The real 'meat' comes later.

http://www.scribd.com/doc/2610442/Capacitor-Sound

Here's a link with different sections broken out, and also some notes (published later) and other articles.

http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=153&start=2

There are many people on internet fora who turn up their noses at the very idea that a capacitor's make or form factor could make a difference in the way it affects the fidelity of an audio circuit. I feel that those who hold this viewpoint are likely are either unaware of or have not taken the time to read and understand this series of articles, which I feel is definitive on the subject.
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Travst



Joined: 15 Jul 2008
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Location: Birmingham, AL

PostPosted: Fri Jan 18, 2013 9:58 am    Post subject: Reply with quote

You're giving me homework? Laughing

Thanks, I'll give it a read. I suspect you are right about the size of that cap. I do like the sites like Mouser that give me the dimensions.
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tangelolemon



Joined: 26 Jan 2009
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PostPosted: Fri Jan 18, 2013 10:45 am    Post subject: Reply with quote

Haha! Read only if extremely interested. It's rather dense and dry.
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Travst



Joined: 15 Jul 2008
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Location: Birmingham, AL

PostPosted: Fri Jan 18, 2013 10:46 am    Post subject: Reply with quote

tangelolemon wrote:
Haha! Read only if extremely interested. It's rather dense and dry.


As am I.
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Little Bit



Joined: 20 Aug 2003
Posts: 2840

PostPosted: Mon Jan 18, 2016 4:29 pm    Post subject: Reply with quote

Hello three year old thread.



Snagged an odd ball at Goodwill, labeled "Vibrato" no V67 type numbers.
In fact no numbers at all.
But it is clearly a V67 type.



Man, that Gearslutz thread is about as bulletin board as it gets.
Thanks, this will be a fun and easy re-FET re-cap. Going to try to put a trim pot on R7 for FET Bias.

Funny, I found this thread searching for V67 Mod's.
Hello Re-Ranchers one and all!
Long time.
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Travst



Joined: 15 Jul 2008
Posts: 9535
Location: Birmingham, AL

PostPosted: Sat Jan 23, 2016 8:03 am    Post subject: Reply with quote

Heya Little Bit. I found that the mod improved things but never got around to recording clips of the differences because of a distinct lack of singing talent. Then I went on to buy a few good mics and haven't used the V67 that much since.
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Little Bit



Joined: 20 Aug 2003
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PostPosted: Sat Jan 30, 2016 3:41 pm    Post subject: Reply with quote

Cool, I figured for the money it could be fun to play with.
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