Modding A.I.R. Swordfish to Advanced Audio CM47

[Frank00]

Hi everyone,
This is my first post on this forum after quite some time spent as a reader only and it looks like this is a pretty awesome community, so here I am asking for your help.

I bought this microphone (A.I.R. Swordfish) a while ago and now I'm thinking about modding it to bring it to its full potential for my next project.
The capsule is a k47, the transformer a 6.5:1 ratio (bv8 style) and the tube a 6072a, and I've already decided what to swap them for (equivalents obviously).

The pcb components seem to be the same as the Advanced Audio CM47, so I contacted Dave Thomas (owner of the company) to help me figure out if that is actually true or not, and if any changes needed to be made in order to optimize the mic and psu circuits.
He was very kind and responded me, but he gave me (at list I think) an incomplete answer.

DISCLAIMER: I'm not here to discredit him or his company in any way. I'm sure he is an awesome guy, maybe he just didn't have the time to give me a more detailed answer.

Since some of his suggestion weren't really clear to me, I'll paste them here in hope that you guys can help me figure them out:

1) The Zener diodes must be changed in the power supply.
(Makes sense, since my power supply looks like the tipical Apex 460 psu. I've read those need a couple of 62v Zener diodes in D5 and D6 in order to place the correct voltage on the capsule).

2) 2-capacitors need to be removed and one need to be changed out.
(This one is not very clear to me).

3) the cathode resistor value needs to be changed on 1st stage.
(Not clear either).

I'll attach a couple pics of my mic and power supply to the next posts, as well as some CM47s I found online so you can better understand the situation (I can send more if needed).

I'll gladly accept any type of suggestion on the matter.

Thanks,
Francesco

P.S. I'm a total noob at electronics so please be very specific and patient.

 

[Frank00]

Here's the mic pcb.

 

[Frank00]

And the psu pcb.

 

[Frank00]

Here is the AA CM47 pcb.

 

[kingkorg]

Have you tried Google?

http://advancedaudio-europe.com/forum/viewtopic.php?p=72#.XdFQbdbTUXM

Any Apex 460 mod can be applied as well, there are tons of mods for these.

 

[Frank00]

I've been researching for weeks on the topic and you can be sure I've read every single post on the AA forum, but the info on the Nady 1050 haven't been helpful to me, since it's not the same pcb.
As I have already stated I'm a complete newbie at all of this, and that's why I'm here in the first place.

 

[Frank00]

Have you tried Google?

http://advancedaudio-europe.com/forum/viewtopic.php?p=72#.XdFQbdbTUXM

Any Apex 460 mod can be applied as well, there are tons of mods for these.

What circuit mods would you do if you had the mic?

 

[kingkorg]

I did exactly what was described in the link i posted, and the mic sounds killer. I kept stock zeners and added the ones sugested by Dave, so i get to switch B+ voltage for lower and higher polarization voltage. It didn't make any difference sound wise, but with stock zeners you get a bit less noise. However if you use CK12 style capsule you should change zeners for the ones sugested by Dave. For k47 capsule it shouldnt make any difference.

The pcb is the same component wise, the numbers might be swapped. You could easily compare Nady's PCB and see which component is which. I dont mean to put you off, but if you think that is still too much, maybe ask someone to do it for you. After all, there are some high voltages here.

 

[Frank00]

Thanks for the info.
Everyone has to start somewhere I guess.
I'll try to match my pcb to the Nady 1050 and change what I need on mine.

Still, if someone else wants to chime in and add some info, it'd be great.

 

[Icantthinkofaname]

These mics are basically all the same. It's the same circuit as the Apex 460, just in a different body. Of course I actually messed mine up so I can't say much (I salvaged the transformer, and still have the PSU and 7 pin cable, if anyone wants these I'll send them if the recipient pays the shipping).

 

[Frank00]

Thanks for the offer, but I got everything I need.

 

[rodaffleck]

These mics are basically all the same. It's the same circuit as the Apex 460, just in a different body. Of course I actually messed mine up so I can't say much (I salvaged the transformer, and still have the PSU and 7 pin cable, if anyone wants these I'll send them if the recipient pays the shipping).

I could actually use those--or at least the PSU and cable. You're in Canada, right? Shipping shouldn't be too crazy to the east coast.