Moog Music Forum

latigid on wrote:Hi there,

I performed the mod myself. It requires just a few parts but will involve cutting a trace on the PCB. I got sent some directions, but "modified" them slightly to what I thought was a better method.

I'm not sure if I should give out the details. One condition on receiving the 104 Spillover Mod directions was that I kept the information private. I sent "rosser" at Moog my instructions, which I'm sure he'd pass on to you. I haven't asked, but if he says it's okay I'll post the directions on the forum. It isn't too much different from the 101 mod given above.


Cheers
Andy


P.S. Happy Thanksgiving!

Thanks Andy, I have one more question. Is your freqbox surface mount? I'm pretty sure mine is.

Hi there, yes, the FB is SMT. The sockets are through-hole but they used lead-free solder which made desoldering them difficult. But nothing is desoldered for the gate mod.

So I tried this mod, exactly as described, however applying signal to R5 doesn't seem to do anything. If I send it a CV, it works.

Am I missing something? Do I need to attach a ground wire from the jack as well?

Alien8 wrote:So I tried this mod, exactly as described, however applying signal to R5 doesn't seem to do anything. If I send it a CV, it works.

Am I missing something? Do I need to attach a ground wire from the jack as well?

Hmmm... Applying an audio signal into R5 should work... of course, any signal input, audio or CV must have a common return. If the CV signal you send works, what is different about the audio signal that you send?

Hi there,

I'm the original poster about the MF101 (Big Briar version) mod.

I assume that the problem you're having is with the MF101 mod, not a 107 mod. This being the case: yes, you need an audio ground path from the socket bringing in the audio signal to go to the envelope follower. If I remember correctly, this is as simple as running a wire from the ground of that socket to the ground of the main audio in socket. (Sorry, on the road at present, without MF101 to hand to check it for you.)

If you find that CV is working via the new socket (which isn't actually the point - it's meant for an audio signal, as the MF101 already has a cv input), then I would assume that somewhere in your setup there is a ground from whatever cv source you are using to the MF - possibly via a mixer or something, if your cv controller is a synthesizer (or theremin or whatever) with audio out going to a mixer to which the MF is also connected.

Assuming we're talking about the MF101 mod I originally described, I assure you it does work. It's been doing so on mine since 2001.

Please note, though, that the mod I originally described (as per instructions received directly from Bob Moog in 2000 or 2001) applies to the old (vintage?) Big Briar version of the MF101. I have no idea whether it can be applied to later versions - as I don't possess a Moog MF101.

Good luck!

Cheers,

Jim F.

Thank-you for the speedy replies!

It is the 101 that I am modding. And I agree that I must have stumbled upon a ground loop in the process, which made the CV signal work now that I think back.

The ground addition makes sense, and indicates the missing link! I will give this a go.

It's alive! Thanks for the help!

Glad the 101 mod worked out!

Cheers,

Jim F.

Just to clarify...

When using a switched jack like pictured above:

The ground goes to the sleeve lug like normal.

The switched connection, normally closed to the tip goes to ground. When nothing is inserted, all lugs are grounded.

The (now) free end of the resistor goes to the tip lug.

When a jack is not connected, the resistor goes to ground.

When a jack is connected, the tip breaks connection to ground and goes through the resistor to the circuit.