Gefell MV691/692 Mods

[alhe]

Did anyone try to mod these - Any ideas where to start, and what could easily be improved?

I have seem some of you do some real nice, complete rebuilds. Tubes etc. Not really looking too substitute a new circuit, but improve on the stock pcb.

 

[alhe]

I am going to bump this in hope that someone are familiar with these mics. 

 

[baadc0de]

I only did Oliver's Gefell m582 mod and that sounds great. Noise goes down quite considerably. So I'm saying, maybe take that circuit?

 

[alhe]

Sounds good, but I assume that is a complete rework, making it a tube mic. I don't have PSU's so I want to stay with phantom powering for now.

I haven't looked inside the mic preamp yet, but perhaps a new fet would yield results, plus new caps if needed?

 

[mylesgm]

I only did Oliver's Gefell m582 mod and that sounds great. Noise goes down quite considerably.

What's this mod?

 

[Sredna]

A KM84 circuit could be worth a try... (or KM54)

 

[alhe]

@Mylesgm: This mod, I assume, is actually a conversion to the tube circuit found in the Neumann/Gefell m582. Very similiar design, same capsules.

Did anyone try a KM84 circuit?

 

[mylesgm]

I realise it was referring to the m582 and I have three of them so I was interested in any modification for that mic body.  Any details on what that mod is?

 

[bezen4uk]

Hi alhe,
Last year I modded MV692.
The tube is russian 6S6B, which is close to AC701 family.
The circuit is simplified KM54.
Trafo is original MV692, but wired as 9:1 (primary windings in series).
Power supply has 120VDC and 5VDC.
The owner uses this mike mostly with UM70 capsule.

If you want phantom powered circuit, then you can try KM84 circuit.

 

[alhe]

Myles, I don't know the details, but the tube circuit is very simple. The MV691 transformer is 4.5:1, but if you put the windings in series you should have 9:1 which put you in the ballpark for a tube mic. You can do the circuit PTP.

 

[alhe]

Bezen4uk; Very nice! I'd like to do something like that if I weren't restricted to phantom power.

 

[mylesgm]

no, I already have the m582, I was wondering if there are mods for that circuit.

 

[alhe]

Alright, apparently I'm a bit slow  :  :

You're welcome, anyway.

 

[Marik]

Did anyone try to mod these - Any ideas where to start, and what could easily be improved?

I have seem some of you do some real nice, complete rebuilds. Tubes etc. Not really looking too substitute a new circuit, but improve on the stock pcb.

May I suggest, the MV691 and 692 are two totally different mics. As such, their mods would be completely different.