Carbon Microphones

[Tubetec]

try 'T-17 Radio Microphone' as search on Ebay .
The Greeks seem to have a pile of the green ones , some new some used but many in good shape , ex US army signals stock .
Seems like this mics manufacture was liscenced out to many companies over the years , including Shure .

Might be some more general info about the mic here ,
http://k4che.com/T-17/T-17.htm
I like the bit at the end , 'alternate uses of the T-17'

 

[Tubetec]

Theres a carbon button mic from the Clansman radio system available cheaply , its a respirator mic , could be a good replacement for a dodgy T-17 button . Even comes with a 7 pin bayonet connector which might be re useable in a tube mic project , the mating chassis mount sockets are available cheap on the surplus market also .

The T-17 is configured with a two core and screen cable , white is signal , red polarising voltage and black ground .

I was going to refer back to the previous discussion about carbon mics , but I see its already been mentioned .

The original capacitor in the T-17 is massive , it can safely be replaced with something modern that doesnt have to survive the direct impact of an airstrike or artillery fire . A small audio transformer can be mounted up in its place , a secondary center tap can supply the polarising voltage from 48v phantom , via a resistor to the capsule. .

So lets count the BOM damage for the project
mic $25 ,
replacement carbon button $5
transformer $5
XLR $5
cable $5

$45 not including shipping , which might vary a bit .

So what if you have to spend a morning tearing it down and putting everything back together ,
your left with a mic that takes the carbonyphoney thing out into the fields and well and truly kicks its ass for it .

You could hammer nails all day with a T-17 and it would still work . There also the satisfaction of having re-used pre existing stuff to the maximum extent possible , so what if the casing is all beat up on the one you find in the local pawn store , its means it has history , better than brand new in a box .

 

[amplexus]

So what if you have to spend a morning tearing it down and putting everything back together ,
your left with a mic that takes the carbonyphoney thing out into the fields and well and truly kicks its ass for it .

You could hammer nails all day with a T-17 and it would still work . There also the satisfaction of having re-used pre existing stuff to the maximum extent possible , so what if the casing is all beat up on the one you find in the local pawn store , its means it has history , better than brand new in a box .

This is 100% my view of all of these things. LoFi Mics, home brewed subkicks, all manner of old containers and cases repurposed as gear housings, Signal tracers as guitar dirt boxes.... There's something both satisfying and deeply authentic about repurposing something old and worn into a useful tool.

There's a time for buying new, modern, shiny, and with a warranty- I just don't feel these things are it!

 

[Newmarket]

This is 100% my view of all of these things. LoFi Mics, home brewed subkicks, all manner of old containers and cases repurposed as gear housings, Signal tracers as guitar dirt boxes.... There's something both satisfying and deeply authentic about repurposing something old and worn into a useful tool.

There's a time for buying new, modern, shiny, and with a warranty- I just don't feel these things are it!

I think this post "hits the target". This stuff is interesting, fun and (in a good way) silly.
It's also accessible to many who are interested.
To elevate it to a 'Premium' product with associated pricing sort of takes the fun out of it.
Obviously, people can make their own judgements.
But I have "one foot" in the guitar/bass world and it seems to me that there is an interesting parallel.
A local shop does interesting and high value stuff.
But it is also putting up "vintage" but budget stuff at what I think are elevated prices. I'm talking stuff like Kay / Eko / Teisco electric guitars/basses. And I do realise that they are setting stuff up well before sale and it's commercial retail in a "Bricks & Mortar" shop where you can plug stuff in and try it - so not expecting private/ebay type prices but still seems excessive to me.
I guess that, at the end of the day, you can make the argument that the value of something is what someone will pay for it. But it does sort of take the joy out of it ???

 

[Ricardus]

So, from an older thread I found this schematic. Is it confirmed that this works?

https://groupdiy.com/threads/telephone-with-carbon-mic-using-phantom-power.46185/#post-1012903

 

[Tubetec]

The dual button type mics were found to be more stable , plus the balanced output arrangement might tend to nul out noises produced within the carbon itself in a way a single button mic wont .

 

[Ricardus]

A friend sent me some classic Ma Bell tech for my builds.

 

[Tubetec]

Im not commenting on this thread any longer , the online is a fickle world , where scores of people pick up and drop gear because of negative reviews that try to discredit, and then we have dick sucking commercials like this thread was trying to do ,but failed badly and probably has people out of jobs , you really are they most stupendous tool at times Whoops ,

 

[Chrisfromthepast]

Is it confirmed that this works?

Yes, that circuit worked just fine with my scarlett interface. The output was much hotter than I expected. I included a tiny sound clip in that other thread you linked to.

 

[Ricardus]

Yes, that circuit worked just fine with my scarlett interface. The output was much hotter than I expected. I included a tiny sound clip in that other thread you linked to.

Yeah, I tested it real quick and definitely think using a PAD is a good idea. The Scarlett doesn't have one, but my other preamps do.

 

[Ricardus]

Maybe a mod to that circuit would be a good idea.

 

[Ricardus]

I'll pad it down with some bigger resistors.

 

[Whoops]

I'll pad it down with some bigger resistors.

you can use 3 resistor and do a 20 db's U pad at the output, should be good enough.

You check some example values for the resistors in this nice page:

http://www.uneeda-audio.com/pads/

 

[PermO]

So I tried the circuit that was posted on the previous page, the one with the 9V battery and the 600:600 transformer.


That works really well.

I was quite surprised, I expected it to sound rather harsh and upper midrangy, but it doesn't.

It has that "radio sound" but it's rather warm / midrange sound, I like it, I will make something nice / weirdout of this.

The carbon capsule is from an old military field phone.

 

[Ricardus]

So I tried the circuit that was posted on the previous page, the one with the 9V battery and the 600:600 transformer.

View attachment 92308
That works really well.

I was quite surprised, I expected it to sound rather harsh and upper midrangy, but it doesn't.

It has that "radio sound" but it's rather warm / midrange sound, I like it, I will make something nice / weirdout of this.

The carbon capsule is from an old military field phone.

Post an audio sample please.

 

[PermO]

So we can upload video on the site but we can't upload audio clips ?

 

[PermO]

So, from an older thread I found this schematic. Is it confirmed that this works?

https://groupdiy.com/threads/telephone-with-carbon-mic-using-phantom-power.46185/#post-1012903

Just did that, and yes that also works.

Great easy trick for a lofi "airwave" sound.

I think the circuit with the battery and the transformer sounds a little better, I think the carbon capsule is slightly more sensitive that way, but it could be me.
I get a nice average level from this.

The phantom power circuit provides a hotter output but there seems to be more uncontrolled peaking in the higher midrange at times.

 

[Ricardus]

Just did that, and yes that also works.

Great easy trick for a lofi "airwave" sound.

I think the circuit with the battery and the transformer sounds a little better, I think the carbon capsule is slightly more sensitive that way, but it could be me.
I get a nice average level from this.

The phantom power circuit provides a hotter output but there seems to be more uncontrolled peaking in the higher midrange at times.

Yeah, if your mic pre has a pad, the phantom circuit output definitely needs a pad. 20 dB might not be enough.

 

[PermO]

I'm going for the battery / transformer circuit, I have the parts, it just sounded better to my ears.

I just went to a thrift store and I found a beautifull mic body for 3 euro.

It's going to look expensive

 

[Ricardus]

I'm going for the battery / transformer circuit, I have the parts, it just sounded better to my ears.

I just went to a thrift store and I found a beautifull mic body for 3 euro.

It's going to look expensive

In what world do you find mic bodies at thrift stores?!??!