U87 (Revision A) in BM800 microphone donor body

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
As a thank-you, here is a link for the BOM (doubled quantities however, but should spare the endless copy and paste off the pdf) :)

https://pt.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=4930838ebd
Does this BOM still hold up? A few of these are either out of stock or no longer available.
I'm far from an expert, so I'd love some advice! What would make for good replacements for what's missing?

To make it easier, here are the Mouser ID's:
MF1/4DC1503F
60900213421
URZ1J100MDD
USA1H4R7MCA
RGP0207CHK1G0
271-560-RC
 
Does this BOM still hold up? A few of these are either out of stock or no longer available.
I'm far from an expert, so I'd love some advice! What would make for good replacements for what's missing?

To make it easier, here are the Mouser ID's:
MF1/4DC1503F
60900213421
URZ1J100MDD
USA1H4R7MCA
RGP0207CHK1G0
271-560-RC

Resistors - any 1% 1/4W metal film should do fine (hint: sort them by price, and tick the "in stock" box).
Not sure why there are 10uF AND 4.7uF separately in the BOM. They're likely the same physical size, and they'll work just as well as each other in this simple of a circuit, so why not get closer to the quantity-price-breaks? That being said, for electrolytics, stick with the good Japanese brands (Panasonic, Nichicon, Rubycon, Elna, United Chemi-Con).

[Later edit - You can use three 22uF / 63v just fine, one for the source resistor bypass, and the other two in the supply filtering. Same with the 470nF coming off the drain, you can use the same 470nF in the power filtering, instead of the two 330nF ones.]

The Wurth jumper you can replace with a piece of wire on the underside of the board, in a pinch. Unless you plan on routinely replacing and rebiasing JFETs, that is...

Mouser seem to have restocked the 1G resistors - 6709 in stock as of yet, with another 5000 expected in june.
 
Last edited:
Thanks for this! I wasn't sure what qualified as "audio-grade" or not, so I thought it best to ask.
Should all be on the way :)
 
EDIT -- OOPS!!! POSTED IN THE WRONG THREAD ... DUH! (But I will leave it because Mr. Khron liked it!) :) Um... ahem... er ... JHR

* Do you have to relieve some of the pressure before replacing the tap?

* Gee. It looks a bit like motor oil. What style is it?

I like a dark beer, Stout, Porter, Dopplebock, Eisbock, Dunkle, etc. Come to think of it, I ALSO like light Lagers, Pilsner, Amber Ale, ... In fact ... maybe, I just like beer!

(Seriously, however, I do NOT like most IPAs or murky sour Weiss styles)

Cheers! James
 
Last edited:
EDIT -- OOPS!!! POSTED IN THE WRONG THREAD ... DUH! (But I will leave it because Mr. Khron liked it!) :) Um... ahem... er ... JHR

* Do you have to relieve some of the pressure before replacing the tap?

* Gee. It looks a bit like motor oil. What style is it?

I like a dark beer, Stout, Porter, Dopplebock, Eisbock, Dunkle, etc. Come to think of it, I ALSO like light Lagers, Pilsner, Amber Ale, ... In fact ... maybe, I just like beer!

(Seriously, however, I do NOT like most IPAs or murky sour Weiss styles)

Cheers! James
Good pint of beer is welcome everywhere. :)

Cheers and salut,
Michael
 
Resistors - any 1% 1/4W metal film should do fine (hint: sort them by price, and tick the "in stock" box).
Not sure why there are 10uF AND 4.7uF separately in the BOM. They're likely the same physical size, and they'll work just as well as each other in this simple of a circuit, so why not get closer to the quantity-price-breaks? That being said, for electrolytics, stick with the good Japanese brands (Panasonic, Nichicon, Rubycon, Elna, United Chemi-Con).

[Later edit - You can use three 22uF / 63v just fine, one for the source resistor bypass, and the other two in the supply filtering. Same with the 470nF coming off the drain, you can use the same 470nF in the power filtering, instead of the two 330nF ones.]

The Wurth jumper you can replace with a piece of wire on the underside of the board, in a pinch. Unless you plan on routinely replacing and rebiasing JFETs, that is...

Mouser seem to have restocked the 1G resistors - 6709 in stock as of yet, with another 5000 expected in june.
Sometimes recently it was hard to find 1/4W resistors for some values with mouser. So just for completeness, higher watt rating is absolutely fine. Just check if the dimensions are fine with the footprints or vertical application is possible.

The values are actually those of the schematics of rev a. Sure the suggestions are fine - but i never tried to alter those (the bom is not too pricy anyways - capsule and transformer will be main points of cost).

The wurth jumpers i found very handy for troubleshooting. If it is your first build you may consider those or at least bit of longer wires so you can easily remove the pcbs in case first powering up gives you troubles. Biasing the FET is working even without opening - you have a 2.54 connector on the board which you can put eg. pins.

Awesome - i wasn‘t aware of the restock as i was busy with 500 gear. Cool, definitly will make it on the next mouser order. Thanks for the info. :)

Best regards, happy soldering,
Michael
 
@mihi_fuchs if you still have some of the PCB for this mic available, I would preferably like to purchase 2 of this PCB from you to make a pair of microphones. Thanks.
 
In case anybody is interested, I put the remaining PCBs on the black market.

here is the link:
https://groupdiy.com/threads/pcbs-for-u87-in-bm800-microphone-donor-body.78373/
here is another link to leftover Styros for the built - maybe somebody is interested:
https://groupdiy.com/threads/left-o...ne-builts-mostly-630v-capacitors-in-eu.79796/
I'm also open to exchanging them against other projects you may have elaborated - just drop me a note if you're interested.

Cheers
Mike
Hi

Looking to buy these u87 boards Please asap. Let me know as soon as you can please

Thanks
 
For some reason I dont have the option to pm anyone or mihi-fuchs about the u87 pcb boards
I want to buy one if he has any. Can anyone help me please?
 
Also want to purchase mihi-fuchs u87 pcb boards.
If someone could reach out to me that would be great
 
Hello everybody and @mihi_fuchs

I have finished the build 🥳 yet I’m having some trouble with high-pitch noise around 1.2K ...

Here is the AUDIO SAMPLE | Audio File [Dropbox]

Here follows the AUDIO CURVE

131024_U87_Fuchs_1k Noise.jpg

I’m using Aurycle Body with a 3u Audio transformer and capsule.

Here follows the final build inside and out.

IMG_20241013_180600 (1).jpgIMG_20241013_182019 (1).jpgIMG_20241013_182030 (1).jpg


| QUESTIONS |

1. I’m unsure if I did something wrong adjusting RV10 [FET Bias] ... I just set it to 10.55V via Multimeter between GND and Q1 pin1. Is it anything to do with it?

2. To set RV24, I’m having +60.0V and -60.2V between GND and the Top PCBs, is this measurement correct?

3. For testing purposes, since I'm waiting for longer screws, I have set extra GND to capsule and J4 [1] on PCB from XLR pin1 via Jumper to the mic body.

4. As I understood, I have 2 external SPDT switches on the mic body. I want to connect Low Cut and PAD, but I don't know which pins go on SW2 and SW3. Which numbers from the photo below should I use to connect it?

141024_Aurycle Body_External Mic Switches_Order.jpg---


I appreciate your time, tips, and help 🙏

Best,
RB
 
Привет всем и @mihi_fuchs

Я закончил сборку 🥳, но у меня возникли некоторые проблемы с высокочастотным шумом около 1,2К...

Вот АУДИО ОБРАЗЕЦ | Аудиофайл [Dropbox]

Далее следует АУДИО КРИВАЯ

View attachment 138236

Я использую Aurycle Body с 3u Audio трансформатором и капсюлем .

Ниже представлена окончательная сборка внутри и снаружи.

View attachment 138237View attachment 138238View attachment 138239


| ВОПРОСЫ |

1. Я не уверен, что я сделал что-то неправильно, настраивая RV10 [FET Bias] ... Я просто установил его на 10,55 В с помощью мультиметра между GND и Q1 pin1 . Это как-то связано с этим?

2. Для настройки RV24 у меня есть +60,0 В и -60,2 В между GND и верхними печатными платами. Правильно ли это измерение?

3. В целях тестирования, поскольку я жду более длинные винты, я подключил дополнительный провод GND к капсюлю и J4 [1] на печатной плате от контакта XLR 1 через перемычку к корпусу микрофона.

4. Как я понял, у меня есть 2 внешних SPDT переключателя на корпусе микрофона. Я хочу подключить Low Cut и PAD, но не знаю, какие контакты идут на SW2 и SW3. Какие цифры с фотографии ниже мне использовать для подключения?

View attachment 138241---


Я ценю ваше время, советы и помощь 🙏

Лучший,
РБ

Hello!As we wrote above, if you have a BM800 case with a resonance in the region of 1 kHz+, this is the resonance of the case, you need to dampen it, there is a photo above of how.
 
Hello!As we wrote above, if you have a BM800 case with a resonance in the region of 1 kHz+, this is the resonance of the case, you need to dampen it, there is a photo above of how.

Hi @Dimon

I have read every single post in the thread. I will try anyways the method but


I’m using Aurycle Body with a 3u Audio transformer and capsule.

As I said on the previous post, I'm using a AURYCLE BODY.

I have done a 2nd mic using the exact same materials and I have a different result. I will try the method of dampening as described.

| 2nd U87 Fuchs Mic |

Captura de ecrã 2024-10-14, às 16.25.05.jpg

Thanks for responding.

Best,

RB
 
HI everybody @mihi_fuchs

| FOLLOW UP |

TO CLARIFY, I have
read every single post in the thread.
I have done a 2nd mic using the exact same materials and I have a different result from the previous one.

| 2nd U87 Fuchs Mic |

Captura de ecrã 2024-10-14, às 16.25.05.jpg



Aside of dampening the body, is anything on the build that might I have done it wrong?

Thanks,

Best,
RB


Hello everybody and @mihi_fuchs

I have finished the build 🥳 yet I’m having some trouble with high-pitch noise around 1.2K ...

Here is the AUDIO SAMPLE | Audio File [Dropbox]

Here follows the AUDIO CURVE

View attachment 138236

I’m using Aurycle Body with a 3u Audio transformer and capsule.

Here follows the final build inside and out.

View attachment 138237View attachment 138238View attachment 138239


| QUESTIONS |

1. I’m unsure if I did something wrong adjusting RV10 [FET Bias] ... I just set it to 10.55V via Multimeter between GND and Q1 pin1. Is it anything to do with it?

2. To set RV24, I’m having +60.0V and -60.2V between GND and the Top PCBs, is this measurement correct?

3. For testing purposes, since I'm waiting for longer screws, I have set extra GND to capsule and J4 [1] on PCB from XLR pin1 via Jumper to the mic body.

4. As I understood, I have 2 external SPDT switches on the mic body. I want to connect Low Cut and PAD, but I don't know which pins go on SW2 and SW3. Which numbers from the photo below should I use to connect it?

View attachment 138241---


I appreciate your time, tips, and help 🙏

Best,
RB
 
Back
Top