Tape Op Omnis

agauchede · Post by **agauchede** » Sun Dec 18, 2005 8:21 pm

Thanks for all the help everyone! Glad to know there are others dealing with the same questions I have. I solved my ground problem by wiring from pin 1 to the ground tab of the XLR in the mic.

I also had trouble getting the right caps: 1/4w for the 1000pF. The only 10uF I could find for the power supply is 400v!! It works - could this cause problems? It sounds pretty good, however I've barely done any extensive testing. I'll build the second tomorrow.

Thanks again!
Chris

Phiz · Post by **Phiz** » Sun Dec 18, 2005 8:23 pm

A cap rated for 400V won't give you any electrical problems. It's probably bigger and therefore harder to fit where you want it.

phantom power · Post by **phantom power** » Mon Dec 26, 2005 9:14 pm

Hello, I am proud to say that I finished one of these just in time for Christmas. It was a gift for a friend and it was my first ever DIY project.

It's a rad feeling! I can't wait to start a pair for myself. All I need is the enclosures for the mic and PS and the 10uF caps then I'm ready. So, my questions now are:

1- For those of you that didn't use the xlr connector to house the mic, what did you use?

2- Where's a good place to look for cool enclosures? I would like to put both PSs in one box.

3- How's the Linkwitz mod? Is it something I should even be thinking about at this point? Is it difficult to do?

Thanks alot -AE

agauchede · Post by **agauchede** » Tue Dec 27, 2005 6:24 am

Linkwitz mod? Do go on. . .

Chris

MD · Post by MD » Tue Dec 27, 2005 7:24 am

agauchede wrote:1/4w for the 1000pF. The only 10uF I could find for the power supply is 400v!!

Hey, just a heads up that your conversion might be wrong. There are 1,000.000 picofarads in a microfarad (uF).

So, if you really only need a 1000pf, then you need .001 uF, rather than 10uF.

Of course, in a power supply, more capacitance is usually a good thing, and .001uF seems rather small.

Anyway, I hope I've helped rather than hurt, and let me know if not.

-MD

Scodiddly · Post by **Scodiddly** » Tue Dec 27, 2005 4:20 pm

agauchede wrote:Linkwitz mod? Do go on. . .

Chris

http://www.mp3forkidz.com/mic/mod.html

http://www.scotthelmke.com/mic-other.html

Skipwave · Post by **Skipwave** » Wed Dec 28, 2005 2:02 pm

Ha! I just posted the same link another thread.

I built my omnis into some plumbing pipe I found.

e-man · Post by **e-man** » Tue Jan 03, 2006 10:13 pm

i just got my mic working today.

it's been laying around in a box for about 8 months. i put it together and it didn't work, kinda forgot about it.

found it the other day and spent an hour today disassembling everything and reworking my circuit. all i had to use was a 4-1/2" X 2-1/2" plastic project box from radio shack to house it in.

turned out o.k. - sort of a bottle type design but not quite. i consolidated the mic and the power supply together in the box. used just the end of an xlr plug boot to hold the capsule. suspended it in the middle of some "O" rings stretched across some metal rings.

gotta get a way to get it on a mic stand now.

hope that doesn't take 8 months.

later...

Shane Michael Rose · Post by **Shane Michael Rose** » Sat Jan 07, 2006 5:39 pm

does anyone have a parts list for digikey? i know its not that big of a deal to look for the parts.... but being that im a newbie, when i see fifty different options for a part, im not sure what to choose.

e-man · Post by **e-man** » Sat Jan 07, 2006 6:40 pm

check the prosoundweb article. it has a parts list.

the link is in the second post.

later...

crookedsound · Post by **crookedsound** » Sun Jan 08, 2006 7:01 pm

Okay, I got the Knowles Acoustics mic (part # 423-1021-ND) from Digi Key as the replacement for the Panasonic cartridge.
As I look at the bottom, unlike the Panasonic cartridge there is no white positioning dot. There are only two green circuit looking lines going from one terminal to the outer edge. The other terminal has no such feature.

Can anyone tell me how to know which should be the ground and which the output? What happens if it is wired in reverse?

Thanks-

Eric

ubertar · Post by **ubertar** » Sun Jan 08, 2006 8:40 pm

I finally got all the parts yesterday and put it together, consolidating the power supply and mic and combining it with a ruby amp (http://www.runoffgroove.com/ruby.html) and out to headphones (ipod earbuds) to make a quasi hearing aid for my grandma. I had some electret capsules I got surplus a long time ago laying around, so I used those in place of the panasonic and it sounds good.

e-man · Post by **e-man** » Sun Jan 08, 2006 9:32 pm

crookedsound wrote:Okay, I got the Knowles Acoustics mic (part # 423-1021-ND) from Digi Key as the replacement for the Panasonic cartridge.
As I look at the bottom, unlike the Panasonic cartridge there is no white positioning dot. There are only two green circuit looking lines going from one terminal to the outer edge. The other terminal has no such feature.

Can anyone tell me how to know which should be the ground and which the output? What happens if it is wired in reverse?

the terminal connected to the outer edge or case is probably the negative or ground terminal. the other is probably your output terminal. hooking it up backwards will mess up the output level and the sound quality.

i'm pretty sure about the terminal thing, but you would be wise to seek info from the manufacturer about it.

later...

ubertar · Post by **ubertar** » Sun Jan 08, 2006 10:12 pm

Here's the datasheet for that capsule.

I'm surprised you went with that one-- the freq. response is only 100-10k.

crookedsound · Post by **crookedsound** » Mon Jan 09, 2006 4:36 am

Okay, seems like I shouldn't be using this one (the Knowles).

I'm pretty sure I was told it would be a good replacement for the Panasonic. I got them a year ago or more and just picked up the pieces to start the project last week.

What capsules will I want to use? Aren't the Panasonic's discontinued? I want to get the most out of these mics that I can.

Is this in that long string about it from the archives?

Thanks for pointing this out ubertar, I clearly wasn't paying close attention.

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