Anybody know anything about the Danelectro Free Speech pedal?

[Mark Hammer]

I have one that I bought 2nd hand without the original mic assembly it came/comes with. I don't have a schematic so I don't have the info needed to make my own assembly from the electret capsules I have sitting around. I see from pics that the plug from the mic assembly going into the pedal is a mini-TRS type. However, probing around does not reveal if the additional contact is to somehow carry signal from the second mic capsule, or to provide DC power from the pedal to the two mic capsules. And, if the latter, which contact is carrying the DC power and which the signal?

[52 Bill]

I have one that I bought 2nd hand without the original mic assembly it came/comes with. I don't have a schematic so I don't have the info needed to make my own assembly from the electret capsules I have sitting around. I see from pics that the plug from the mic assembly going into the pedal is a mini-TRS type. However, probing around does not reveal if the additional contact is to somehow carry signal from the second mic capsule, or to provide DC power from the pedal to the two mic capsules. And, if the latter, which contact is carrying the DC power and which the signal?

I didn't realize that there are two mikes on these things. I have one and can look for you later today.

[Mark Hammer]

Thanks. Much appreciated. Take your time. I'm in no hurry.

[52 Bill]

Thanks. Much appreciated. Take your time. I'm in no hurry.

Sorry, it wasn't where I thought it was, but I did find it and checked it out.

The two mikes are connected by two separate shielded cables to the 3.5mm TRS plug. Each mike connects to the plug separately, one to the tip and the other to the ring. They share a common ground connected to the shield.

The circuit provides 4.5 vdc to each mike, which I assume is the bias voltage to the single supply TL072 op amp that connects to the mikes.

Hope this helps, let me know if there is anything else you need to know.

[Mark Hammer]

Thanks, Bill. You're a prince.
I had measured hat V+/2 voltage at the T and R lugs of the jack, and it made no sense to me. Or rather, it presented an ambiguous picture. You have disambiguated it for me.

I have several two-pin electret capsules. I'll try one out and see what I get.

[Mark Hammer]

More confused than ever, now. For 3 contact capsules (V+, gnd, out), it's not clear how they should be connected. I've tried several different two-contact capsules, assuming that the DC-blocking cap on the output, and current-limiting resistance feeding V+, are both provided internal to the pedal. No dice.

I've sent a note to Danelectro, requesting either a schematic or some clarification. As the great orange one says: We'll see what happens.

[Mark Hammer]

They wrote back indicating that they had no schematic and no technical info.

[dmeek]

I'll take a guess. Remember the 2-wire mics have an internal FET so they are polarity sensitive.

Can you post a few closeup photos of the boards, both sides?


https://music-electronics-forum.com/...1&d=1584043921

[52 Bill]

Mark:
I tried an old Panasonic 2 pin capsule on mine and it worked fine. The volume control on the top of the pedal controls the volume of the mic inputs.

Perhaps you have a problem with the input chip?

[Mark Hammer]

Problem solved! The pedal was being operated by an idiot.

Because the onboard speaker functions like a mini-amp, I naively assumed that I would hear something from the speaker, if I blew into the mic while it was in effect mode. It just dawned on me that maybe one only hears what the mic picks up at the output of the pedal. I finally plugged in a patch cord between the pedal and my amp, and lo and behold, sound!

Excuse me while I smack my forehead a few hundred times.