[FEELER] Are you interested on Phantom powered Tube microphone kit?

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ln76d

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As subject says :)

Is there any interest on P48 tube microphone circuit?
Kit could be including PCB and electronic parts, with tube or without.
If there's any interest - what microphone body would you like to use for it?

Am working in the free time on this circuit, idea is rather basic - cardioid (could be also used for electret capsules) or cardioid/omni.
If there would be more interest in multipattern i can think about DC converter for it but is there any need for another multipattern?
 
Multipattern with isolated backplates without DCDC converter would be cool. Or omni / card option.

That leaves C12 style for multi or isolated U87 style so optional de-emphasis would be cool.

What tube / setup are you looking at?

Thx,
jb
 
0dbfs said:
Multipattern with isolated backplates without DCDC converter would be cool. Or omni / card option.

That leaves C12 style for multi or isolated U87 style so optional de-emphasis would be cool.

What tube / setup are you looking at?

Thx,
jb

Tube - typical battery powered for hearing aids :)
Going after Audio Technica or Gefell i'll be trying 6418 or DL65-67 (or any similar) since they were tested for this application and works well.

I can always make additional tracks for isolated backplates multipattern - this is no problem.
Definately no deemphasis circuit :D
For now i didn't make any working in tube microphone. Tried similar topologies to U87 but it didn't work. U67 type of demphasis is screwed up and utilize specific transformer so also no. Anyway i want to add tracks for cap from plate to ground.
I will try first circuit with P48 powered capsule, but if there would be necessary for higher polarisation voltage i will use something similar to U87 DC converter or schoeps.
 
How would you supply heater current off of phantom power? I would think even a submini would draw more current than could really be supplied through many typical phantom setups, especially ones that use doublers or triplers from a 12- or 24-volt supply.

I seem to recall a recent post about a submini powered on phantom, maybe 6 months ago? I don't think it went anywhere.

Don't get me wrong, I would absolutely love to see it done, but I'm sure you understand my skepticism. :)
 
I think you'll need a DC-DC converter in there as, even drawing only 10mA for the 6418 heater, that's going to pull your 48V down to 14 or less.
 
midwayfair said:
How would you supply heater current off of phantom power? I would think even a submini would draw more current than could really be supplied through many typical phantom setups, especially ones that use doublers or triplers from a 12- or 24-volt supply.

I seem to recall a recent post about a submini powered on phantom, maybe 6 months ago? I don't think it went anywhere.

Don't get me wrong, I would absolutely love to see it done, but I'm sure you understand my skepticism. :)

http://www.microtechgefell.de/index.php/en/microphones/broadcast-a-recording/large-membrane-tube-mics/340-um900-roehrenmikrofon
 
Interesting!
But... maximum current (when shorted!) using 48 V phantom power is:

48 / (6800 : 2) = 48 / 3400 = 14 mA.
  But in this case the remaining voltage = 0 V!
Even tubes intended for battery use need a filament current of  50 mA.

Curious how this will develop!
 
micaddict said:
midwayfair said:
How would you supply heater current off of phantom power? I would think even a submini would draw more current than could really be supplied through many typical phantom setups, especially ones that use doublers or triplers from a 12- or 24-volt supply.

I seem to recall a recent post about a submini powered on phantom, maybe 6 months ago? I don't think it went anywhere.

Don't get me wrong, I would absolutely love to see it done, but I'm sure you understand my skepticism. :)

http://www.microtechgefell.de/index.php/en/microphones/broadcast-a-recording/large-membrane-tube-mics/340-um900-roehrenmikrofon

I am simultaneously baffled and amazed.
 
0dbfs said:
Very interesting to see a schematic because UM900 specs state 4mA current consumption from phantom.

Cheers!
-jb

Audio technica says 3mA :D
http://www.audio-technica.com/cms/wired_mics/187139bf88c8539d/

Gentelmans!

Don't ask how, why etc.

Question is:

Are you interested on Phantom powered Tube microphone kit?

;)
 
Blasphemy!!! That UM900 uses an... **gasp** op-amp(!) to drive the output transformer ;D

But a supposedly tube mic all on 4mA? That's... indeed quite the achievement :|
 
UM900 is the one of the best sounding microphones in the whole world!
I had only opportunity to make a quick test... Amazing mike!

As i said before 3mA in Audio-technica!
You would be surprised how simply it can be made :D
 
RuudNL said:
As far as I know the Microtech Gefell UM900 uses a DL651 or DL67 tube.
(Filament current 13 mA.) Must be a pretty fragile tube...

6418 filament current is 10mA but A-T circuit draw 3mA and the tube still get 10mA :D
 
Cost of course will be lower than with classic tube mike build - there's no external psu and multipin cable + connectors.
Anyway it wouldn't be cheap as typical tube mike without extra components ;)

Ok.
My proposition is cardioid/omni version only!
I need to simplify the circuit as possible :D

It need to be made with two PCBs!

Any propositions for donor microphone body?
Need to think about boards dimensions which will fit at least two-three ;)
 
How about something like the sE 2200A? I've just bought my 5th one (faulty) off eBay today ;D

Nice and roomy inside. I've actually started modding one to add a dc-dc converter inside and a pattern switch - still a work in progress though :p

ln76d said:
Cost of course will be lower than with classic tube mike build - there's no external psu and multipin cable + connectors.
Anyway it wouldn't be cheap as typical tube mike without extra components ;)

Ok.
My proposition is cardioid/omni version only!
I need to simplify the circuit as possible :D

It need to be made with two PCBs!

Any propositions for donor microphone body?
Need to think about boards dimensions which will fit at least two-three ;)
 
Years ago(2004?) at this forum there was a thread about a phantom powered tube DI mostly the same as a tube microphone circuit.
Think max power transfer not voltage.
I believe Thomas Holly was the thread starter.  I will try to find it.  IIRC different DC to DC converter chips were tried and other refinments.
EDIT found a thread http://groupdiy.com/index.php?topic=1195.0
 

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