Dual Output Microphone: 2x Schoeps Circuit + K87 capsule BM-800 Donor Body)

[mihi_fuchs]

Hi everybody,

i have another design for the BM-800. This time I jumped on the idea of a dual output microphone (see kingkorg's thread: Quick DIY dual output LDC ), which consists of 2 Schoeps circuits and records each side of the capsule separately.
The design is based on the Schoeps microphone circuit adopted for LDC capsules. I was studying several designs, but in my hands the pimped alice design worked best - so I went with a very similar circuit (Pimped Alice V.40 &amp and V.56 DC PCBs ). The design includes a LPF, which can be controlled with C17 in order to adjust the high end to the capsule used.
For the capsule, my pick went to the Maiku K87, as the capsule need to come with separated backplates for this design. For the connection of the two PCBs to the outer world I changed the connector to a 5-pin connector and used a break out cable that split into two 3-pin XLR microphone connectors.
I found it quite nice to play around with a few plugins which are around (twonsend lab sphere or polar designer by AA; see kingkorg's thread on this topic: Townsend Labs Sphere Hacking

You can find a detailed building guide as well as the BOM and some sound samples in the dropbox folder below:

Dual Output Microphone: 2x Schoeps Circuit + K87 capsule (BM-800 Donor Body)

Shared with Dropbox

www.dropbox.com

It is highly suggested to match the HFE of Q1 and Q2. In my case my DC-meter was able to do the job.

Here are some pictures of the built:




As can be seen from the description the built was highly influenced by kingkorgs ideas and also his comparison with the townsend microphone. Some solutions were taken over from others and the Circuit is based originally on the Schoeps design with very helpful informations found in the PimpedAlice description and this forum.

Thanks for all the positive input and the sharing of the ideas within this forum, maybe the sound samples can provide some useful information for others ...

Cheers
Michael

 

[mihi_fuchs]

Here's to the left-over PCBs on the black market: Dual Output microphone PCBs + Connector for BM-800 donor body

In addition I still have a few spare 5-pin-XLR connectors too ...

Cheers
Michael

 

[Tubemooley]

This design is friggin' brilliant. I own several of the Joly modified MXL 990's. The 990 is basically the Schoeps transformerless circuit. Using two PCB's and a K87 capsule is a great idea. I may have to order a couple of these from you in the Black Market. Thanks, Dana Walcott.

 

[bremusound]

Wouldn‘t it work with a non-isolated backplate capsule if the backplate is grounded and the diaphragms polarized?

 

[mihi_fuchs]

Wouldn‘t it work with a non-isolated backplate capsule if the backplated is grounded and the diaphragms polarized?

yes, it would. but u‘d need additional components.

 

[mihi_fuchs]

This design is friggin' brilliant. I own several of the Joly modified MXL 990's. The 990 is basically the Schoeps transformerless circuit. Using two PCB's and a K87 capsule is a great idea. I may have to order a couple of these from you in the Black Market. Thanks, Dana Walcott.

thanks, but the idea was initially by townsend and austrian audio has dual output mics too as well as softwar. also in this forum kingkorg (Quick DIY dual output LDC) started the idea and examined hardware and prototyped. so my role is very minor and this is just one step along a lot of other people‘s work and creativity.

nevertheless, it‘s a really nice built and the result i like very much too!

so if you like to try the design you‘re very welcome. just let me know if you have any further questions or also suggestions …

best regards,
michael