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

[Khron]

Sorry, you should have seen the first one.

Well, in 2024, surely we can do better..(?)

Yeah, I'm just throwing in parts from the BOM.

Ok, but then why stop halfway through? And then wonder how and why things don't work...

And a picture of the 1.1, which until recently I had none.

What about this?

https://www.pcbway.com/project/shareproject/OPEN_SOURCE_DIY_Mic_Project_ORS_87_5bff5d94.html

 

[micolas]

@cello4u
We all started somewhere, without much knowledge. We joke sometimes, but as you already realized, we have good intentions and dedicate part of our precious time and our experience (acquired with efforts, sacrifices, sometimes failures and disappointments, investments, etc., in a life), to help totally selflessly.
The most important thing is to persevere, not to be defeated by problems, failures.
Step by step you will succeed and the satisfaction will be proportional to the difficulties encountered.

 

[cello4u]

Anybody have an open source 87 circuit for sale?

 

[cello4u]

Well, in 2024, surely we can do better..(?)



Ok, but then why stop halfway through? And then wonder how and why things don't work...



What about this?

https://www.pcbway.com/project/shareproject/OPEN_SOURCE_DIY_Mic_Project_ORS_87_5bff5d94.html

Yes, that is in my collection of pictures. Apparently not much help to me.

 

[Khron]

Yes, that is in my collection of pictures. Apparently not much help to me.

Assuming that by "that" you mean the PCB view on PCBway... The schematic (with component values, and matching component designators) is right below that, if you scroll down, so... What exactly is the problem, still?

 

[micolas]

Anybody have an open source 87 circuit for sale?

Do you want a PCB ready populated with components?

 

[cello4u]

Do you want a PCB ready populated with components?

YES!

 

[cello4u]

Assuming that by "that" you mean the PCB view on PCBway... The schematic (with component values, and matching component designators) is right below that, if you scroll down, so... What exactly is the problem, still?

It's me. I'm the problem.

 

[micolas]

YES!

To use it as a reference, clone it, or just use it to have a U87 style microphone?

 

[cello4u]

To use it as a reference, clone it, or just use it to have a U87 style microphone?

Mostly to use as a microphone. I have sold recircuited, reskinned transformer less Chinese 87's, and would consider selling them depending on the profit motive.

 

[mic test]

jeremynothman Thank you very much, I've just spoken to Haun/MBHO, they think they can repair it for around 100€ this nice (=​

 

[cello4u]

@Khron , in this case it is about the famous wireless BIAS, which we have all heard of)
(Sorry, couldn't resist)

Thank you. I think I installed the trimpot in the jfet, and then screwed the pooch trying to desolder it (if not before). It seemed to me like it was one or the other (that it would be used in biasing). I thought I read in the thread that the r* was optional, part of the biasing. Guess I was wrong about that. Not sure what part that is in the Mouser BOM. Thanks for pointing these out to me.

 

[micolas]

I've just spoken to Haun/MBHO, they think they can repair it for around 100€ this nice (=

MBHO builds capsules for Brauner,Soundfield, probably also Audix.
So it looks like you will solve the problem.

 

[untamedfrontier]

Thank you. I think I installed the trimpot in the jfet, and then screwed the pooch trying to desolder it (if not before). It seemed to me like it was one or the other (that it would be used in biasing). I thought I read in the thread that the r* was optional, part of the biasing. Guess I was wrong about that. Not sure what part that is in the Mouser BOM. Thanks for pointing these out to me.

R* is only optional if you don't use/remove the trimmer. Likely for most of us, the trimmer is the better option than using a fixed resistor, since biasing can vary a little bit depending on personal taste and parts used in the build.

I don't think there's any reason why you can't just use the trimmer to bias and leave in the circuit permanently, but you'll need to use either the trimmer OR the fixed resistor in R*.

I posted a couple screenshots of my build earlier using the v1.1 board if you need any picture based references.

 

[untamedfrontier]

Hello, can someone tell me why there is a CE mark on the tube mic from Brauner Valvet and not on the Phantoma without tube?
Doesn't it always have to be on the mic if it's a business? and that's good to read?

I think you might want to create a separate thread for that question, that doesn't seem to be related to this topic.

 

[mic test]

OK, sry, you're right

 

[Jedias]

Hey guys, I'm having trouble finding the zener 1N4749A, theres other alternatives there I can use instead? And also I cant find a 25k trimpot, but i have a 20k and a 50k wich is better to use? Thaks a lot!

 

[Khron]

Hey guys, I'm having trouble finding the zener 1N4749A, theres other alternatives there I can use instead?

Yes, virtually any 1/2w / 0.5w zener you can find, between 24v and 33v.

And also I cant find a 25k trimpot, but i have a 20k and a 50k wich is better to use? Thaks a lot!

Either one should be fine. Even with a 20k, you shouldn't need to reach the end-stop. But even if you do, just try another JFET (their tolerances are REALLY wide)...

 

[Khron]

PS: Anyone interested in a 53.5x38mm (~2.1"x1.5"), single-layer, multi-donor-body-compatible, etch-at-home ORS87, with pad & high-pass?



Although truth be told, it's not all that much of a "stripped-down U87" anymore...

 

[anvl]

View attachment Caminito miU87.mp3
Sound test done at home (birds included).
Left: MicParts capsule + 180pF on the top end.
Right: 797audio capsule + 220pF on the top end.
Both using Aliexpress T13 transformer. Raw file, no EQ no compression.