Stereo Dual Sided LDC?

[kingkorg]

Previous discussion thread about mic moddeling got me thinking a lot about one capsule stereo LDC. Now that i have tried free plugin
https://townsendlabs.com/products/sphere-l22/
with pair of my mics i am very impressed by some aspects.

Please be aware that i am not talking about modeling other mics, nor making a copy of their own mic, but about using single stereo LDC to manipulate stereo field and some other stuff this free plugin provides. And maybe two stereo mics? Yes i can use stereo rair for this, i have tried, but it is so cool to have one stereo.

There was a thread about stereo LDCs, but no one came up with project. I have one Studio Projects C1, and it has place for another board inside. So the questiin would be, if i put dual sided capsule inside, and another identical PCB how do i get dual output from the capsules.

Should i electronicaly separate backplates and treat them as individual capsules? Should one PCB be wired as usual and the other one be conected to central terminal of back diaphragm? Should i conect two backplate wires coming from two PCBs together? What would be best way to do this?

 

[ln76d]

Should i electronicaly separate backplates and treat them as individual capsules? Should one PCB be wired as usual and the other one be conected to central terminal of back diaphragm? Should i conect two backplate wires coming from two PCBs together? What would be best way to do this?

Rather it should not work that way - otherwise there will be some commercial releases with single capsules instead of two (or someone did that?).
Ok, for now i'm only after two coffees, but let me try
Even making two completely, electronically, separated halfs of the capsule, still you should get leakage from both sides and other issues.  But maybe  separated fig.8? hmm... For example +60V and -60V apllied to both backplates and both diaphragms connected to the gates?

 

[kingkorg]

Hi Piotr.
Please dont bother too much. It's anyways easiest to put two mics against each other. It's not worth spending too much time on it.

However original L22 mic seems to have dual sided k67 in it. I guess software compensates for leakage or something...

I have c12 with separated backplates, works really well with the software.

 

[ln76d]

This is quite interesting
I started to thinking about simple dual triode "stereo" mike with single capsule for drum room ambient

 

[lampas]

https://groupdiy.com/index.php?topic=65920.msg835115#msg835115

 

[ln76d]

https://groupdiy.com/index.php?topic=65920.msg835115#msg835115

Thanks Vili for reminder, i forgot about that topic
Anyway i'm rather thinking about "softwareless", simple solution for walls tracking

 

[kingkorg]

Great! Thanks. But how did you connect the capsule? Are backplates insulated? Did you just join backplate leads from pcb?

 

[lampas]

Hi,

yes I have capsule with connected backplates... I just put another amplifier in the other side of the first one and connect outputs from both pcbs to 7pin xlr and that's it. 

 

[tonzauber]

5pin XLR should be enough.

It is available e.g. as a small diaphragm mic, the Sennheiser MKH800 twin.
I built myself a few based on modern AKG C414 capsules.

However: This is not really interesting forStereo, because no real stereo is coming out of it: Two Cardioids facing back to back are basically an omnidirectional,  if you invert one you have a fig of 8.  If you play that back over two individual speakers instead of sum them together as it's done to derive a variable pattern LDC microphone output, you end up with some replay artifacts.
There are of course some directivity cues, but they don't make any useable stereo image.

However, the idea is nice do build a microphone where you can change the polar pattern in postpro by mixing the front and back channel together.

 

[emrr]

The thing it's great for is dual mid-side. 

 

[zebra50]

The Josephson C720 does exactly this. It's a great microphone.

http://www.josephson.com/pdf/720booklg.pdf

 

[emrr]

Plus the Lewitt, the two Pearl models, and the Sennheiser.  I'm very curious about the long capsule Pearl with it's pattern difference horizontal/vertical. 

Agreed it would be much less 'cloney' to adapt some of the various clone pursuits here to this, since it's not commonly available or terribly affordable in the market. 

I did this to a TLM67:

https://groupdiy.com/index.php?topic=68096.0