apex 460 pics and some info for Gus

[pucho812]

PSU pics

Capsule pics. it's 32 MM diameter 4/8 MM thick

PCB #1 pic

PCB #2 puc

 

[Gus]

looks like the same power supply as the nady 1050

6. something fil voltage and about 200 V B+

Is the fil reg a 7806 with a 1n400X in the ground circuit?

Are both 1/2s of the tube used or is one side grounded out like the se5000 schematic that was posted yesterday?

I think I saw a AKG the tube schematic on the web at one time one might want to check that schematic

With a 12ax7 one might not want to change the 200meg grid to ground to a 1gig.

I have a number of things one can do to that microphone, simple to a rebuild. Problem now is that someone will take them a make money. Look at the post from E T K

http://www.groupdiy.com/index.php?topic=7546&start=30

Edit is the diaphram wrinkled or is the distortion from what it is reflecting?

 

[pucho812]

Gus
IMO it's almost identical to the nady.

THe wrinke is distortion from my crappy digi camera. :sad: it was worse when I was trying to take a shot with the flash on.

 

[Bluzzi]

Could that Power Supply be used for the G7 without mod? And the mike body as well? I don't think the transformer or capsule is worth keeping. But....

This might be a great way to get the G7 going. You can replace components as they come in (transformer, capsule, tube and electronics). You would hear the sound as it progresses from stock to complete G7.

I am not crazy about building power supplies for some reason but I love the audio part.

Jim

 

[DrFrankencopter]

Construction looks pretty flimsy on that mic...I wonder if there's alot of body/frame resonance. Also, how does the grille look? Open, or closed, how many layers of mesh?

If I were redoing this mic I'd want to make the plate that the capsule attaches to thicker. Also, I think I'd try to swap the position of the circuit board and the tube. Make a real short wire run from the cap to the tube. Toss the stock transformer and put in a lundahl, jensen or cinemag.

Probably would want a different tube/amp in there as well...I've never heard of a good 12Ax7 based mic. 5751, 6072 12AT7, or 6922 may make more sense.... 6072 is what AKG used in the C12, which seems to be the vibe that Apex is going for with this mic.

Who makes a good CK-12 style capsule now?

Cheers,

Kris

 

[dale116dot7]

Yes, there's some body resonance, but it's not terrible. The grille is three layers - if you remove the inner layer it opens the sound up and that helps a lot. The tube to PC board distance is not terrible, and you'd have to rebuild the two side channels to pull that off - you'd almost be better off starting with brand new mechanical bits.

Josephson engineering makes a CK-12 style capsule used in one of the Manley mics though I don't know if they'd sell individual capsules, Telefunken USA makes one for his 251 clone, and of course there's the 'teflon' capsule (which is really made of Nylon or Delrin or something like that, and not Teflon) 2072Z0005 from AKG - it was used on a lot of the C414EB mics, as well as the newer C414BULS. It's not the greatest CK12 around but it really isn't that bad either. The Peluso edge terminated capsule is closer to a K67 but in an edge terminated style. It may sound fine (I have not heard it) but a CK12 it ain't.

One caution when working with this mic is that the original capsule is a high-output one, probably greater than 20 mV at 94dB (at the grid), so most any other capsule that has a pretty flat frequency response will bring the noise up. For example, a Sony C37A capsule has an output of about 1 mV at 94 dB and the hiss becomes almost unbearable, even if you go through a box of tubes and find the quietest.

I have had luck with a 12AT7 and about 10 or 15 pF of capacitance from plate to grid, but the 6072's seem to be consistently quieter. A 12AU6 (without that feedback capactitance) actually sounds pretty good but they are also noisier than the 6072.

The 6072 amp is pretty fussy on the impedance of the output transformer, so I'd be tempted to try the Cinemag.

 

[pucho812]

The pics I took are from my first Apex 460. With that one I have only changed the tube froma cheapo chinese to a high quality at7. It sounds pretty good. A friend of mine has been loaning it for this session he has been recording with a female vocallist and he loves it. I wanna put on a better trafo I am thinking something like this. opions/ suggestions are always appriciated...

http://www.cinemag.biz/mic_output/CM-2461NiCo.pdf

 

[wgtenor]

I am kinda new to microphone mods although I have soldering experience just not mic modding experience. Anyway, I would like to upgrade my Apex 460, this mic intrigies me. I had planned on putting in a JAN 5751 tube and doing at least a partial recap of the mic circut. Also, would the PSU benefit from any simple modding without changing the circut.? On the mic itself which of the circut parts would most benefit from any higher grade components? I had also thought about changing out the capsule for a 32X14 MM DUAL 6 MICRON DIAPHRAGM by peluso but was a little concerned abou the output on this capsule. (I had read that the output on the stock capsule was a little high and that other capsules didn't put out enough for the stock circut.

BTW Gus thanks for all your input. and everyone else, I've been reading the forum quite a bit lately and I am learning alot. :grin: :?

 

[dale116dot7]

Personally, I'd stay away from any of the Chinese 32mm capsules. I haven't met one that I like yet, though I have not tried the Peluso version. Most of the sound is in the drilling, not the skinning. The 34mm capsules are better but they have a lot of high end. You can probably use it but you'll need to roll off the high end by about 5 to 10dB for it to sound normal. You will need to get the mount for it though.

I would pick the Cinemag T14 clone - it's cheaper and use a 6072 or 12AY7 (or maybe even the 12AT7) and eliminate the cathode follower stage.

-Dale