Gus

phantom powered follower
« on: July 05, 2020, 12:02:53 PM »
A cut and paste follower with some other ideas.
Output is set at about 1.8mA current
No HPF section because this has no DC to DC section it would reduce the capsule voltage.
An idea not built yet.

I would build a transformerless  follower if I wanted a follower however there seems to be interest in circuits like this


« Last Edit: July 05, 2020, 02:40:29 PM by Gus »


RuudNL

Re: phantom powered follower
« Reply #1 on: July 07, 2020, 05:42:38 AM »
What I in general don't like about multipattern microphones, is that often the rear membrane is always in parallel with the front membrane, even if the rear is not polarized.
This works in cardiod mode as a 'pad' (~ 6 dB) and degrades the signal to noise ratio.

R16 could be omitted if you raise the value of R14 and R15.

The same probably goes for R9, R10 and R12.
« Last Edit: July 07, 2020, 05:49:16 AM by RuudNL »
There is a solution for every problem!

http://www.vansteenisaudio.nl

Gus

Re: phantom powered follower
« Reply #2 on: July 07, 2020, 07:16:16 AM »
I understand your points

Things I did not write about in the first post
R12 is to make it easier to adjust the total current by changing one resistor that supplies current to the Zener and the rest of the circuit.
R16, R15 and R14. I did not share why I have R16 in the circuit.

I did post it is a circuit with some cut and paste parts
Bootstrapped drain follower with extra current from the NPN AKG. Sony does something like this without the bootstrapping in a phantom power follower
Pattern control AKG


Re: phantom powered follower
« Reply #3 on: July 19, 2020, 10:14:11 AM »
 Just wanted to say thanks Gus for posting this.     I appreciate ideas that beyond the usual cloning of old stuff.

Thanks. 
Note to self:  Don't let c**ts wind you up

Gus

Re: phantom powered follower
« Reply #4 on: July 19, 2020, 04:35:33 PM »
It has cut and paste design with some other thoughts two parts are from AKG 414 versions

The lower capsule voltage can be a FEATURE for loud sources like drums you might even want it lower. I don't like cap divider input pads.

A JFET (with a hint about using different ones in the screenshot)and NPN a low noise high beta one would be good and about 2:1 transformer with some caps and resistors.

You can reuse the about 2:1 China transformers from MXLs etc. or go higher in ratio for more of an output pad.

You can try different capsules and build it cardiod only with less parts

I posted the pattern section because it was different than what DIY cloners seem to build and

I like the bootstrapping of the drain there are different ways to design input followers
I picked this because people seem to like the 414 version first stage this is from

No osc. based DC to DC so no FCC type issues
I wonder how many people know about the FCC rules look up the EH case. How long before the FCC goes after microphones?
https://groupdiy.com/index.php?topic=56105.0

I posted this to see if it could get a discussion going but it seems to have failed.

As I posted I would build a transformerless follower but some people like transformers

Re: phantom powered follower
« Reply #5 on: July 19, 2020, 06:35:58 PM »
Thanks for the extra info Gus


I posted this to see if it could get a discussion going but it seems to have failed. 

As I posted I would build a transformerless follower but some people like transformers

I'd like to have a discussion about it but, honestly, everything you say makes good sense to me and,  without trying it, I've nothing off the top of my head that'd add anything to what you've already said. 

I had an idea along similar lines  (but only in my head) of trying my own J-Fet NPN pair follower except in a Sziklai configuration, but I have no idea if it was a good idea or not :D   You seem to have put more thought into it than me so I'd be inclined to give yours a go. 

I do like that you have no DC-DC oscillator and I can certainly live with the lower capsule voltage.  I didn't know about the FCC rules on these so, def something for mic manufacturers to be aware of.   

For me, I think I'd just use a higher voltage coming from an external supply if I wanted higher capsule voltage anyway.  Think B&K/DPA's  120V scheme except , not 120V but 60V or whatever it ended up at. 

I'll think on and look at your schema some more with the additional info you gave,

Cheers.
Note to self:  Don't let c**ts wind you up


 

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