DIY RF Condenser Mics

[Fastunov]

Please check
Resistors
47R x 2 - https://uk.farnell.com/multicomp/mf12-47r/res-47r-1-125mw-axial-metal-film/dp/9343288
1k x 1 - https://uk.farnell.com/multicomp/mf12-1k/res-1k-1-125mw-axial-metal-film/dp/9342400
4k7 x 1 - https://uk.farnell.com/multicomp/mf12-4k7/res-4k7-1-125mw-axial-metal-film/dp/9343253
10k x 3 - https://uk.farnell.com/multicomp/mf12-10k/res-10k-1-125mw-axial-metal-film/dp/9342419
100k x 2 - https://uk.farnell.com/multicomp/mf12-100k/res-100k-1-125mw-axial-metal-film/dp/9342427
220k x 2 - https://uk.farnell.com/multicomp/mf12-220k/res-220k-1-125mw-axial-metal-film/dp/9342850

 

[Fastunov]

Capacitors
C1, C4 and C8 - https://uk.farnell.com/vishay/k101j15c0gf5tl2/cap-100pf-50v-5-c0g-np0/dp/2860078
C4 ("K67") - https://uk.farnell.com/vishay/k680j15c0gf5tl2/cap-68pf-50v-5-c0g-np0/dp/2860140
C8 ("K67") - https://uk.farnell.com/vishay/k470j15c0gf5tl2/cap-47pf-50v-5-c0g-np0/dp/2860125

C5 - https://uk.farnell.com/multicomp/mcpbsfc-1j224ka45/cap-0-22-f-63v-10-pet/dp/1685477
C6 - https://uk.farnell.com/multicomp/mcpbsfc-1j105kb45/cap-1-f-63v-10-pet-through-hole/dp/1685481
C9, C13 - https://uk.farnell.com/multicomp/mcpbsfc-1j102ka45/cap-1000pf-63v-10/dp/1685470
C10 - https://uk.farnell.com/multicomp/mcpbsfc-1j224ka45/cap-0-22-f-63v-10-pet/dp/1685477
C11, C12 - https://uk.farnell.com/multicomp/mcpbsfc-1j103ka45/cap-0-01-f-63v-10-pet/dp/1685473

C7, C15 - https://uk.farnell.com/panasonic/eca1hm470/cap-47-f-50v-20/dp/9693785

 

[rogs]

Looks OK apart from C6 - which should be 0.1uF (100nF) and not 1uF

C6 - https://uk.farnell.com/multicomp/mcpbsfc-1j104ka45/cap-0-1-f-63v-10-pet/dp/1685476

I need to repeat that this is not a full blown 'kit' project for a complete beginner. It is an experimental project.
If all goes well, you should be able to get a useful outcome, but if you possibly can, get someone with some knowledge of electronics to help you out.

 

[Fastunov]

Thank you for noticing my mistake, I guess I got a little confused.

Of course, I will attract highly qualified specialists to help me and will not be engaged in self-assembly, I have little experience for this.

I only needed your help in preparing a list for the purchase of all the components.

After completion, I will post the full Bom list

 

[rogs]

Of course, I will attract highly qualified specialists to help me and will not be engaged in self-assembly, I have little experience for this.

That is the bit I find strange. You say you will have 'expert' help, yet they don't have the ability to advise you on obtaining the right parts?.....

 

[Fastunov]

That is the bit I find strange. You say you will have 'expert' help, yet they don't have the ability to advise you on obtaining the right parts?.....

Any expert is usually very busy, I save and appreciate his time and I do the preparatory work on orders of all components myself.

 

[rogs]

Any expert is usually very busy, I save and appreciate his time and I do the preparatory work on orders of all components myself.

You do seem to be treating this a bit like a commercial enterprise?
I need to repeat, this is an experimental hobby project, not a complete 'kit' project .
I have built several versions - and they seem to work well - but I can't guarantee that all the 'bugs' are out of the design. There may well be alternative circuit configurations - possibly using different component values for different capsules, for example - that may work better.
The kind of thing you would expect from a DIY hobby forum project.
But it's not really a beginners one - neither is it a complete commercial design.
I know I have mentioned this several times before, but I should not like to feel responsible for you spending a lot of money, without understanding what you are getting involved with...

 

[Fastunov]

You do seem to be treating this a bit like a commercial enterprise?
I need to repeat, this is an experimental hobby project, not a complete 'kit' project .
I have built several versions - and they seem to work well - but I can't guarantee that all the 'bugs' are out of the design. There may well be alternative circuit configurations - possibly using different component values for different capsules, for example - that may work better.
The kind of thing you would expect from a DIY hobby forum project.
But it's not really a beginners one - neither is it a complete commercial design.
I know I have mentioned this several times before, but I should not like to feel responsible for you spending a lot of money, without understanding what you are getting involved with...

Do not worry, I myself treat this as an experiment that I am very interested in. But in any experiment, there must be a starting point.

Please do not doubt your development.

 

[Tim Campbell]

I think we may soon find RF mics on ebay from Russia
This forum has been many a company's R&D lab.

 

[rogs]

I think we may soon find RF mics on ebay from Russia
This forum has been many a company's R&D lab.

That thought had occurred to me as well?... Well, they do say that imitation is the sincerest form of flattery! --

 

[Tim Campbell]

By the way I have managed to collect 4 Sennheiser MKH mics in the last weeks. 2 mkh 405T's, an mkh 435T and a mkh 415T. They sound incredible. I am surprised by how great the off axis signal sounds even on the supercardioid and the shotgun.

 

[rogs]

I like the story about the 415T being 'too long' on Recording Hacks: Sennheiser Electronics Corporation MKH 415 T | RecordingHacks.com

I also noticed the specific mention of a 'low tension' capsule in that article.
I have had my best results using a cheap edge terminated LDC which is supposed to be a 3 micron device? It certainly didn't like more than 50V DC across it, so I've always assumed it was quite a low tension capsule?

Sadly, with the cheap Chinese capsules, membrane tension parameters don't often appear in the specs -- so it's a bit of a lottery concerning that feature...

 

[abbey road d enfer]

By the way I have managed to collect 4 Sennheiser MKH mics in the last weeks. 2 mkh 405T's, an mkh 435T and a mkh 415T. They sound incredible. I am surprised by how great the off axis signal sounds even on the supercardioid and the shotgun.

Do you have areason to attribute that to the RF technique, or is it simply because Sennheiser are good at making capsules. If the latter, this could be observed on conventional condenser mics (MKE)...?

 

[Tim Campbell]

Sennheiser are great at making capsules. The headbaskets on the 435 and 416 contribute greatly to this. They incorporate directional elements into the later headbaskets.

 

[bremusound]

By the way I have managed to collect 4 Sennheiser MKH mics in the last weeks. 2 mkh 405T's, an mkh 435T and a mkh 415T. They sound incredible. I am surprised by how great the off axis signal sounds even on the supercardioid and the shotgun.

The 405 sounds suoer fat and rich!

 

[Fastunov]

Do not worry, I myself treat this as an experiment that I am very interested in. But in any experiment, there must be a starting point.

Please do not doubt your development.

And what is so possible? Thank you for the idea!
I did not think and did not plan to do this! This is not my way, I want to use this development exclusively for my own creative purposes.)

 

[Fastunov]

Q1 - https://uk.farnell.com/multicomp/bc549c/transistor-npn-30v-to-92/dp/1574382?st=bc549c
Q2, Q3 - https://uk.farnell.com/multicomp/bc557b/transistor-pnp-45v-100ma-to-92/dp/1574384?st=bc557b
Q4 - https://uk.farnell.com/on-semiconductor/j113/transistor-jfet-n-to-92/dp/1017713?st=j113 jfet
D2, D3 - https://uk.farnell.com/on-semiconductor/bzx79-c6v2/diode-zener-6-2v-500mw/dp/9844651?st=bzx79

X1 ("C12") - https://uk.farnell.com/iqd-frequency-products/lfxtal003156/crystal-8mhz-30pf-thd/dp/9712844?st=iqd
X2 ("K67") - https://uk.farnell.com/iqd-frequency-products/lfxtal003169/crystal-10mhz-30pf-hc49-us/dp/9713697

L1, L2 - https://uk.farnell.com/multicomp/mc...h-0-275a-choke-axial/dp/1864497?st=mcal0410a1

 

[rogs]

All looks OK.
Seems like the J113 is on back order until September though?...

 

[Fastunov]

Thank you so much for your help! I will buy and search everywhere I find, the main thing is that there is a specification, delivery to Russia is a real problem.

 

[Gerard]

What I have discovered is the ones that collapse when a polarisation DC of more than 50V is applied, seem to perform best for this RF type project.
(I'm guessing they're lower tensioned capsules?) .....
That is one problem with using cheap capsules of course -- there's no way of knowing what a detail like membrane tension is going to be!

It might be interesting to see how the capsules Ari in the MicBuilders forum ([email protected] | Interest check: LDC capsules?) is flogging would work with the RF circuit. The diaphragms are clamped, not glued (Re: Interest check: LDC capsules?, fourth photo down) , so is should be possible to play with the tension.

I think I might purchase one or two to try.