Hello everybody. I'm based in France and new to this (great) forum and I'm just starting to build my own mics... I ordered and received 2 multipattern polarization boards and 2 preamp boards in the Schoeps style from a nice guy based in UK (Thet). I've oredred a Ali Express cheap capsule in the first time to begin with but if success, I want to ordre 2 U47flat... So excuse my lack of knowledge and experience but I would like to know how to connect the U47flat. I assume that the front diaphragm goes to "+60v" and the rear diaphragm goes to "-60v" but since there are 2 backplates, how do I connect them? If necessary I can post the diagrams of the polarization and preamp cards...Thanks for your help !
Soliloqueen's k87(k67) and k47 capsules
- Thread starter kingkorg
- Start date
Help Support GroupDIY Audio Forum:
Pretty sure the K47 only has a single backplate. The K87 has two isolated backplates.
Connection of the capsule wires depends entirely on the (microphone) circuit you intend to use, and that's even before messing with extra bias boards.
You definitely do NOT want to connect things as you described.
Hi Khron, thank you for your answer... may I ask you to have a look at the schematic please ?
here is a link to the boards I got :
https://www.halfshavedyaks.xyz/pcb/BM700-polarisation.php
Yes, you're right : the 47flat does have only one backplate, sorry... but what's wrong with my intent to connect front & back diaphgrams to + and - voltage ? How would do ? (I've posted a link to the polarisation board but it's waiting for moderator approval...)
the schematic :
the schematic :
Attachments
rogs
Well-known member
Yuo should be able to see how I connected the K.47 in the photo I attached to the first post in this thread:
https://groupdiy.com/threads/dual-polarity-voltage-multiplier.86416
That is -- the central backplate termination to the preamp input, and the 2 centre terminals to the plus and minus outputs from the voltage multiplier
https://groupdiy.com/threads/dual-polarity-voltage-multiplier.86416
That is -- the central backplate termination to the preamp input, and the 2 centre terminals to the plus and minus outputs from the voltage multiplier
Thanks Rog ! As I said, front and rear diaphragms to voltages + & - and the backplate to the preamp input (signal)
So what do you think about the schematic I've posted ? (actually this is the board I ordered and received for my first DIY mic)
rogs
Well-known member
Your schematic is based on the well established 'Schoeps' circuit and should perfom well.
You will need to calibrate VR1 to obtain the best compromise between lowest distortion and symmetrical clipping.
I personally prefer to use an op-amp for the preamp.... It removes the need for calibration, and in the format I've used it is probably the simplest implementation of a good quality impedance converter. ( See here: https://www.opic.jp137.com/index-ldc.html )
Other hobbyists using a simlar op-amp configurations - like Jules Rykebusch and 'Thet' - have taken the decision to add a bit more circuitry, and regulate the supply to the op-amp. That's not strictly necessary -- although the voltage multiplier supply does need to be regulated.
I find the addition of extra resistors into the signal path, and/or adding a differential output stage, simply add to the circuit somplexity, and will add a little extra noise into the signal path
But we all have slightly different views on how best to address these things...... It's all part of DIY hobby mic building!
Wouldn't that mean hardwiring the mic to fig-8 pattern?
rogs
Well-known member
My original dual polarity schematic is really only a concept sketch.....
I have included pattern selection links on my prototype stripboard made for that schematic -- see attached image on this post: https://groupdiy.com/threads/dual-polarity-voltage-multiplier.86416/#post-1130296
I'm guessing there will be pattern select options on whatever voltage multiplier Emmathom is using?....
That's all fine and well, but you must admit, those brief connection instructions, when read by someone not as well-versed in electronics and mics as some of the rest of us are, COULD be interpreted literally which would result in a fixed / permanent figure-8 pattern. Would it not? Unless i'm horribly misunderstanding something...
Thanks Rog... and I will read calmly your link. Yes I know much diyers that use OPA instead of fet (like JLI for ex.)Your schematic is based on the well established 'Schoeps' circuit and should perfom well.
You will need to calibrate VR1 to obtain the best compromise between lowest distortion and symmetrical clipping.
I personally prefer to use an op-amp for the preamp.... It removes the need for calibration, and in the format I've used it is probably the simplest implementation of a good quality impedance converter. ( See here: https://www.opic.jp137.com/index-ldc.html )
Other hobbyists using a simlar op-amp configurations - like Jules Rykebusch and 'Thet' - have taken the decision to add a bit more circuitry, and regulate the supply to the op-amp. That's not strictly necessary -- although the voltage multiplier supply does need to be regulated.
I find the addition of extra resistors into the signal path, and/or adding a differential output stage, simply add to the circuit somplexity, and will add a little extra noise into the signal path
But we all have slightly different views on how best to address these things...... It's all part of DIY hobby mic building!
But about using a tranformer (UTM 0547F from Arienne I guess) what are pros and cons ? I know it willa add "its own colour" but will it low the ouput level ?
rogs
Well-known member
I must confess I only considered the connections I described from the 'dual backplate' discussion earlier...... I'm assuming that the commercial voltage multiplier PCB tht Emmathom is actually using will have appropriate pattern select options?....
I had not really considered my original dual polarity notes as a project as such - just a schematic for discussion.
As you say, there is no mention of pattern selection.
I then actually built one myself, and included the stripboard layout as an indicator of how a prototype might be constructed for testing.
That of course did include links for pattern selection.
Not really a beginner's complete project of course....just an idea for discussion. Maybe I should have pointed that out?....
@Khron : I've read and kept open your "Khron's cave X1S rebuilt" 'cause I got a pair out-of-order... I dedided to throw the original circuit away (full of cms I don't deal with) and build on stripboard (like most of all my realisations like mic tube pre) a "schoeps-like" pre board using Thet's schematic and a single voltage polarisation from Thet's too (the 2 circuits on the same board)
Attachments
rogs
Well-known member
It was the JLI shipping costs outside the USA that made me consider my own op-amp versions, following Jules identifying the OPA164* op-amp series as useful devices for an impedance converter.
I've not tried any of the transformer options ...I'm not one for adding 'colour' into the internal mic circuitry myself !
As for output level changes, that will depend on the transformer windings turns ratio, and the impedance it is designed to interface with....
Yes I've read Jules website too... and JLI are far too expensive on their shipping rates to Europe (you & I are concerned)
About these OPA's they are VSSOP-8 and need adaptater to DIP-8 (not easy to solder!) Mouser sells them and so OPA1642 jfet's one
elskardio
Well-known member
Maybe you guys should create a new thread for this whole discussion… it’s getting a bit off topic here.
Hee Jung Park
Member
You are probably asking how to connect the physical capsule.
If there are two plates (two independently front and back),
the line connected to the center becomes the front or back,
and the two lines connected to the edge
(the line connected to the ring) can be combined and used.
Similar threads
Latest posts
-
Pacific Recorders & Engineering ABX control room monitor upgrades?
- Latest: westernskystudios
-
-
Warm Audio WA-19 (AKG D-19 clone), mechanical HPF, phase issue?
- Latest: abbey road d enfer
-
-
-
-
