Schematic of the current APEX 460 ?

[blue_luke]

Hello all!... 
It's been a while since my last post and also I am returning back to the audio recording hobby...

I modified three of those 2010 or so and was very pleased with the results, having a real C12 to compare with.
So yesterday I bought a pair of Apex 460 and upon opening the box I found that the suspension that comes with it seems to be made a bit better.
The mic body is now black and fit and finish seems to be somewhat nicer... maybe just a feeling...

Opening the PSU I see the same crap as I remember it...

Now opening the microphone I am not too sure about the look as I remember it.

Also I searched the subject of moding this mic and read somewhere that the current crop use a slightly different schematic.
So what is the current schematic if any different than the one we can get easily from the web?

For the moment, as a first step, I will simply replace the tube and I have two RK-47 and two RC12 capsules from microphone parts.
Of course I understand that the stock circuit is not optimised for neither off these caps!
I just want to make an idea for myself as what capsules will go to my taste. To see the 'personnality trait' of each type.
The mics I moded sometimes ago were Peluso C-12 caps, better tube, better coupling cap and a cinemag transformer.
In this case I would like to experiment with so called 'pencil' tube that were made in the US and some Russian triode that are very low microphonic and very rugged.

We'll see!

 

[Khron]

Surely the circuitry can't be THAT complicated I'd imagine a 12A_7 and a handful of capacitros & resistors shouldn't be that difficult to trace out... Right?

I mean, since you have them in your hand already, and we can't know if or how many other people around here do...

 

[blue_luke]

No it's not that complicated indeed... And I do have an old schematic that i have used before.

The question was "has anything changed to the schema in late years?"

I did trace a few components and it looks pretty much the same to me... so there will be a replacement 'C8' for a film cap, remove C9 C10 or replace with something less 'violent' than 0,1uF !  I think a few hundred pF is enough there plus maybe some ferrite bead?  This is to kill RF pickup after all...

On the other hand, I think the B+ rectification in the power supply was half wave... now it seems at first view to be full wave... I have not even plugged it in as of yet, that is tonight schedule, check tha at least they turn on and make some noise!

 

[rodaffleck]

On the other hand, I think the B+ rectification in the power supply was half wave... now it seems at first view to be full wave... I have not even plugged it in as of yet, that is tonight schedule, check tha at least they turn on and make some noise!

I just looked at the old board that I pulled from my 2004 era Apex 460. It's a bridge rectifier for the B+ supply. Perhaps you were thinking of the original AKG N12 power supply? It does half-wave I believe.

That said, most of the images for the 460 power supply schematics up on the internet don't match up with what I see on mine, though they all have full rectification for both B+ and heater. So it's quite possible there are a few revisions out there.

As for the mic itself, that also seems to fall under "quite possible". The innards from mine look exactly like those shown in the M16 expose on recording hacks:  http://recordinghacks.com/articles/telefunken-m16-and-apex-460-comparison. Boards are labelled TCR-11-A and TCR-11-B.

But the innards on the recording hacks page for the Apex 460 indicate that there was a revision at some point, because the boards are now labelled TCR-11-A+ and B+. Layout appears to be identical, but the legible resisters are now all 1% tolerance instead of 5%.  http://recordinghacks.com/microphones/Apex-Electronics/460