[FEELER] C12 Clone Project

[chunger]

I did a bit more foolery with prototyping today. . . Russian K40y PIO 4700pf capacitors arrived via Ebay a couple days ago.  I also ordered smaller 200V versions, but since I now have a pile of 1000V ones, let's try to put 'em in even though they don't fit between the turrets  :

Perfect. . . looking more and more like a Star Wars pod racer with each step.  Trust your feelings, Harry, Warp speed, engage!  I think I have my movies all mixed up.

And, I decided to gut another Alctron PSU for conversion to our C12 circuit.

Luckily Matador explained how to mod the stock switch in great detail.  With the aid of my Hakko 808 desoldering tool, I was able to make a go of it.

I actually could not remove the stock knob because under the cap, there's a slotted nut that requires a special tool to remove.  I could cut the knob off of the post, buy the special tool, or just leave the thing in place and mod the switch in place which is what I did.

I think I will wait and build this psu with the 2nd revision PCB because it'll sound way better yellow.  Stay tuned.

 

[micaddict]

Stay tuned.

Somehow I have a feeling I will.

 

[Matador]

I had to destroy the knob to get it off:  I had to Dremel the plastic to expose the nut, then a regular metric hex socket took it off.

 

[0dbfs]

I've got a collet tool for those kinds of knobs and have used either needle-nose pliers or a pair of greenie's crossed in the middle to take them off. Sometimes they're too tight to get off without the tool.

Cheers,
jb

 

[pasarski]

First of all, great project, keep up the good work! 

One thing I don't quite get is changing the polar pattern switch resistors. Seems like a lot of work just for authenticity, and if I understand correctly, it's a different PSU anyway. Am I missing something here?

 

[Matador]

First of all, great project, keep up the good work! 

One thing I don't quite get is changing the polar pattern switch resistors. Seems like a lot of work just for authenticity, and if I understand correctly, it's a different PSU anyway. Am I missing something here?

They probably don't need to be changed, and it will just work fine.  The stock 150K values will work as well.

I did end up breaking the switch in my Apex460, so I would recommend changing the switch to a Lorlin or a 1M pot with center detent, as the stock switch hardware is truly craptastic (all of the other HW in the PSU is fine however).

 

[chunger]

In honor of the official planet-wide sound check day "12-12-12", some test samples from prototype 1 for your listening pleasure.  Signal chain is microphone --> Great River ME-1NV preamp --> apogee rosetta 800 --> Logic studio.  Console is MCI JH600.

acoustic guitar to digital


acoustic guitar to tape


for reference purposes, KM84 to digital


KM84 to tape

 

[tonycamp]

Getting a much more "in the room" vibe with the c12 (digi and tape)than the 84 on my monitors. Very nice indeed. C12 sounds very open and smooth on the top and bottom, the 84's are kinda bottom lerchy and nasally in my rig. That's a smokin good mic chung!

 

[micaddict]

The Neumann KM84 (not to be confused with the KM184) is probably the most respected acoustic (steel string) guitar microphone.
Brave choice for A/B-ing.

Getting a much more "in the room" vibe with the c12 (digi and tape)than the 84 on my monitors. Very nice indeed. C12 sounds very open and smooth on the top and bottom, the 84's are kinda bottom lerchy and nasally in my rig.

KM84 has a basically flat frequency response with added proximity (since it's a cardioid mike) when used anywhere near the source. Also, the (SDC) cardioid pattern is tight and smooth.
C12, by nature, is somewhat scooped with added air (and plenty lows; especially the big tranny ones, too). Also, even when set to cardioid, the (LDC) pattern will be less tight. Both attributes can account for the C12 sounding more roomy.

The guitar is a relatively small, mahogany topped, Martin (0-15?). Those are relatively midrangey and perhaps a little boxy sounding (in a good way), too. The C12, to some extent, will compensate. On a big, spruce topped, guitar the KM84 might (!) be the "winner".

That's a smokin good mic chung!

No argument. I want one (if that wasn't clear by now).

 

[Matador]

Fedex says the next round of prototype boards are in the area.  I also have all of the parts from Mouser, with the exception of a few parts from Just Radios.  In any case, I hope to begin a V2 build of the PSU in the next few days.  I'll post pics as well when I can.

 

[dandeurloo]

Very nice sounding!  Keep up the work.

 

[dmp]

prototype 1 has the T14 instead of the 2480?
Any other differences?

Thanks for posting the samples. I agree the C12 sounds really nice. I'm surprised at the difference between digital and tape - but like someone else said, that's a different discussion

 

[mulletchuck]

wow that C12 clone sounds great on that guitar!!  y'all gotta send it to NYC so I can try it on sax, and compare it to a MikTek CV4, which is another C12 clone 

 

[kidvybes]

a MikTek CV4, which is another C12 clone 

...is that sarcasm?...the CV4 bears little resemblance component-wise to a C12...center-terminated K67 capsule, pentode-tube and a big-a** transformer...

...but, I'd still like to hear the audio comparison...

...BTW, I do have a BeesNeez Shelise, which has Ben Sneesby's C12-style edge-terminated capsule and a Cinemag 2480 tranny...definately in the classic C12 ballpark...

 

[chunger]

prototype 1 has the T14 instead of the 2480?
Any other differences?

The current prototype (this recording) is running the Cinemag 2480.  I delivered the sample T14 to Matador for prototype #2 which will verify the revised (hopefully final revision) pcb.

 

[Scrappersa]

Is there any chance we could get a comparison of the km84 and c12 on overheads? I would love to hear the difference as I love your c12 overhead clip.

 

[mulletchuck]

a MikTek CV4, which is another C12 clone 

...is that sarcasm?...the CV4 bears little resemblance component-wise to a C12...center-terminated K67 capsule, pentode-tube and a big-a** transformer...

...but, I'd still like to hear the audio comparison...

...BTW, I do have a BeesNeez Shelise, which has Ben Sneesby's C12-style edge-terminated capsule and a Cinemag 2480 tranny...definately in the classic C12 ballpark...

but...but...!!!  the 9-pattern switch!  lol  forgive me, I'm a newb!

 

[Studio Mollan]

Hi guys!
I haven't read through the whole thread so I'm not sure about the status of this kit but I'm in for two.
If you got a list please write me down for two. Do you also supply the bodies?
/
Emil

 

[kevinkace]

Still in development. Check here for bodies: http://www.groupdiy.com/index.php?topic=50015.0 (there was talk of a complete package once the details are sorted, check the poll at the top).

 

[chunger]

we have all the pieces at this point for full kit except for the custom headbasket.  A factory has been solicited to tool up for this piece and build to my specifications and I should see a sample approximately mid-January.  After sample verification, I don't think it will take that long to be swimming in those puppies.  I suspect raw pcb's will be available for general distribution relatively soon. Matador will be building the 2nd prototype probably within the next week or so assuming Holiday schedules don't hold up the process.  The sample boards are already in his possession.  At the Chinese Labor Camp, we don't really stop for holidays, but I guess this sample will be a bit higher quality  .