OPEN SOURCE DIY Mic Project - ORS 87 - Stripped Down u87

[micolas]

OK, you helped me a lot, thank you very much

I tested the capsule above, applied more than 65v to it for quite a long time, it worked perfectly, without cutting the sound and did not collapse.

Start a new thread and we'll continue there, along with everyone who has had success with this exciting project.

 

[khalidgul]

So , I am new and read this thread and it made me interested to build it.so i got the Hula cow pcb from pcbways and built it. it worked, but partially, it has low sensitivity and narrow frequency response, i followed the hula cow BOM with the exception I used T-13 transformer, Takstar cts-2 capsule,C-5 33nf and CC-6 156pf, C-7 1uf,cc-9 1uf,fet biased at 8.2 volts and 7.3 volts though same output,pot used is 20kOhm, wiring checked for shortage etc, it seem fine, i have connected capsule front side to signal and bacck plat(blue wire) to pol and the voltage between signal nad pol reads -31v Dc, body from aliexpress.I am sharing the result of the built and seek your guidance to fix the problem.last but not the least I would like to thanks all those who are involved in this open source and are very generous to share their knowledge and making an effort and sparing time to contribute.you are all my heroes.Thank you very much indeed.
test audio is attached.looking forward

 

[Khron]

@Wordsushi - Would there be any interest in etch-at-home ORS87(-Plus) boards?

https://groupdiy.com/threads/feeler...rds-opamp-jfet-u87a-fet847.87606/post-1157363

I just uploaded the copper & silkscreen PDFs to the first post in my feeler thread. Blame @rock soderstrom

 

[johnchantler]

Well......

https://www.pcbway.com/project/shareproject/ORS87_Plus_Open_source_U87_mic_project_2922baaf.html

That being said, BOMs for Mouser and Digikey are still in progress (close to being done), but i'll only get to scrape together a build guide in a few weeks, after i get some blank boards made

went for fedex as its usually cheaper/easier with customs clearance, so my boards arrived here today (ridiculously fast!).

looking good. thanks for doing this @Khron

 

[AdamFrisen]

Are there any sound comparisons made between TSC-2 and Arienne K87 capsule? I didn't find any when I did a search.

 

[Wordsushi]

@Wordsushi - Would there be any interest in etch-at-home ORS87(-Plus) boards?

https://groupdiy.com/threads/feeler...rds-opamp-jfet-u87a-fet847.87606/post-1157363

I just uploaded the copper & silkscreen PDFs to the first post in my feeler thread. Blame @rock soderstrom

Thank you for asking. That's a great question. Though it's far above my ability level to know what to really do with that, there indeed may be interest, but what I'm seeing in the conversations I'm privy to outside of this group are increasing levels of interest from people who are essentially DIY beginners, so buying PCB's is what seems to appeal to them. But if it doesn't involve too many resources to offer an etch-at-home kit with directions, why not? I personally see this project as the gateway between Mic Parts and a Bouchard kit, but also with the possibility to be a foundation upon which to customize and personalize.
A great majority of the people I talk about mics with outside this group are involved somehow, or looking to be involved in voice work and a majority of them are all seeking an affordable u87 alternative, so anything 87 DIY related is probably going to attract some eyeballs. For me, the process of etching a board seems like a next-level way to really DIY it so you've piqued my interest.

 

[Wordsushi]

So , I am new and read this thread and it made me interested to build it.so i got the Hula cow pcb from pcbways and built it. it worked, but partially, it has low sensitivity and narrow frequency response, i followed the hula cow BOM with the exception I used T-13 transformer, Takstar cts-2 capsule,C-5 33nf and CC-6 156pf, C-7 1uf,cc-9 1uf,fet biased at 8.2 volts and 7.3 volts though same output,pot used is 20kOhm, wiring checked for shortage etc, it seem fine, i have connected capsule front side to signal and bacck plat(blue wire) to pol and the voltage between signal nad pol reads -31v Dc, body from aliexpress.I am sharing the result of the built and seek your guidance to fix the problem.last but not the least I would like to thanks all those who are involved in this open source and are very generous to share their knowledge and making an effort and sparing time to contribute.you are all my heroes.Thank you very much indeed.
test audio is attached.looking forward
View attachment 131887View attachment 131888View attachment 131889View attachment 131890View attachment 131891View attachment 131892View attachment 131893View attachment 131894View attachment 131895View attachment 131896View attachment 131897View attachment 131898View attachment 131899View attachment 131900View attachment 131901View attachment 131902View attachment 131903View attachment 131904

That's actually @homero.leal's board. Maybe someone can put some eyeballs on this.

 

[Khron]

But if it doesn't involve too many resources to offer an etch-at-home kit with directions, why not?

Well, offering a full etch-it-yourself is a bit outside my scope, actually. "Back in the day" (say, 10-15 years ago), that's all we DIY'ers had Before all these "$5 for 5-10 PCB" deals were a thing...

Anyway, even kitting up parts is one step further than i'm willing to go, but as mentioned earlier, Digikey & Mouser BOMs are almost done (just gotta triple-check everything, for my own peace-of-mind), and i'll try to scrape together some build guide as soon as i have some blank boards in hand Probably unwise to hope for the guide earlier than next month, though

 

[Khron]

Well......

https://www.pcbway.com/project/shareproject/ORS87_Plus_Open_source_U87_mic_project_2922baaf.html

That being said, BOMs for Mouser and Digikey are still in progress (close to being done), but i'll only get to scrape together a build guide in a few weeks, after i get some blank boards made

Mouser & Digikey BOMs added, along with ordering instructions- wanted to make it flexible but still quite clear. Lemme know if improvements / corrections are needed

 

[khalidgul]

Finally I fixed it.the problem lied faulty fet.now it works great. super satisfied and excited to experiment more. though I would like to under circuit analysis of the circuit.Is there any way I could read the circuit analysis of different mic builds.

 

[Khron]

though I would like to under circuit analysis of the circuit.Is there any way I could read the circuit analysis of different mic builds.

https://www.audioimprov.com/AudioImprov/Mics/Entries/2014/2/7_Mic_Electronic_Eq_Pt.1.html
https://www.audioimprov.com/AudioImprov/Mics/Entries/2014/2/7_EQ_Pt.2_-_Transformerless_Mics.html

Might be worth going through the rest of the posts there too: https://www.audioimprov.com/AudioImprov/Mics/Archive.html

 

[AdamFrisen]

The three PCB boards mentioned in this thread. Unfortunately no capsule/transformer arrived yet...

Khron's boards from PCBWay came much faster than Homero's but maybe that was because some different choice I might have selected. The shipment cost for Khron's was $25, Homero's $5. Considering the board itself costs $5 each. Minimum order was 5 pieces, but I got 6 pieces of Khron's ( I won't tell PCBWay...).

Now wouldn't it be fun to populate all these and measure them in Audio Precision One or Two with same capsule...

 

[Khron]

The three PCB boards mentioned in this thread. Unfortunately no capsule/transformer arrived yet...

Khron's boards from PCBWay came much faster than Homero's but maybe that was because some different choice I might have selected. The shipment cost for Khron's was $25, Homero's $5. Considering the board itself costs $5 each. Minimum order was 5 pieces, but I got 6 pieces of Khron's ( I won't tell PCBWay...).

Now wouldn't it be fun to populate all these and measure them in Audio Precision One or Two with same capsule...

View attachment 131981View attachment 131982

It's weird / uncanny to see a creation of mine "in the real world" - especially when "even" i don't have a real one in hand just yet

 

[AdamFrisen]

That is proper guard ring for high impedance circuit (I think I saw similar in application notes way back made by Analog Devices). I bet Khron's PCB might show best shielding and least noise when measured.

 

[Khron]

That is proper guard ring for high impedance circuit (I think I saw similar in application notes way back made by Analog Devices). I bet Khron's PCB might show best shielding and least noise when measured.

Pretty sure it'll be even more effective on the double-sided boards, but squeezing things down onto a single layer was a personal challenge i voluntarily chose

PS: On a side-note, i don't think i'll ever be able to comprehend the point of >160V capacitors inside a phantom-powered DC-DC-less microphone...

 

[khalidgul]

Hello all, I am seeking help regarding signal analysis for the U87.Could anybody please direct me which where could I learn ?Also I am sharing the recording for the build I just finished and fixed, I look forward for your feedback on the quality of sound.Thank you all very much indeed.

 

[micolas]

Hello all, I am seeking help regarding signal analysis for the U87.Could anybody please direct me which where could I learn ?Also I am sharing the recording for the build I just finished and fixed, I look forward for your feedback on the quality of sound.Thank you all very much indeed.

@khalidgul
Now it doesn't work.
In order to be able to post an mp3 file here, you must press the INSERT button on its image after uploading.

 

[AdamFrisen]

@Khron - Could you be kind to point out the schematics with values corresponding to references in your PCB?

Or just a list with references <-> values

Ah maybe you are working with the build guide where they will be noted?

 

[khalidgul]

@khalidgul
Now it doesn't work.
In order to be able to post an mp3 file here, you must press the INSERT button on its image after uploading.

View attachment test ORS87.mp3
microphone gain on ssl 2 audio interface, aprox 60% dialled in

 

[micolas]

View attachment 132068

OK, that's how it's done.
Now it works.