U87 (Revision A) in BM800 microphone donor body

[Jarbcd]

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

 

[Khron]

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.

 

[Jarbcd]

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

 

[Khron]

I wasn't sure what qualified as "audio-grade" or not, so I thought it best to ask.

"Audio grade" is just a BS term to "justify" adding a 100-5000% premium to the price of a component.

[Edit: grammar]

 

[MicMaven]

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

 

[mihi_fuchs]

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

 

[mihi_fuchs]

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

 

[hteo]

@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.

 

[cholmes777]

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

 

[cholmes777]

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?

 

[Khron]

For some reason I dont have the option to pm anyone

https://groupdiy.com/threads/private-messages-conversations-permission-update.82401/

 

[theo mack]

Also want to purchase mihi-fuchs u87 pcb boards.
If someone could reach out to me that would be great

 

[k4343011]

This is a live video recorded with fuchs' u87. The capsule is 3u audio's k87 capsule and the transformer is also 3u audio. This is the 8th single by Korean singer-songwriter Jo Jin-young. The title in Korean is "Mido" and the English title is "timeless haven:Mido." If you're curious about the sound, take a listen.

 

[RBeTT]

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



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

Here follows the final build inside and out.




| 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?

---


I appreciate your time, tips, and help

Best,
RB

 

[Dimon]

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.

 

[RBeTT]

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 |



Thanks for responding.

Best,

RB

 

[RBeTT]

HI everybody @mihi_fuchs

| FOLLOW UP |

Just to inform 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 |

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

 

[mihi_fuchs]

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.

nobody said you didn‘t. as far as i can tell there are few things you can try:
- actually and most likely it is a resonance of the body - they can vary and i hope dampening will help. if you use them in stereo, dampen both bodies the same way
- you have no ground connection to the body. as you used zip ties to connect it the holes have no electrical connection to the rails? check if that is true. it can be that they are different it that way. this connection is important for shielding the pcb.
- you can use a test tone to adjust bias of the fet.

| 2nd U87 Fuchs Mic |

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

so far - nothing obvious to me …

Thanks,

Best,
RB

 

[mihi_fuchs]

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?

that‘s fine for firing it up.

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

assuming you measured correctly that‘s perfect.

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.

well done.

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‘m sorry, but you have to measure and compare to the schematic. for a start you can also try with cables and crocodile clamps.

I appreciate your time, tips, and help

no worries, always welcome,
have a nice evening …
br
michael

Best,
RB

 

[RBeTT]

Hi @mihi_fuchs

- actually and most likely it is a resonance of the body - they can vary and i hope dampening will help. if you use them in stereo, dampen both bodies the same way

Yes, I will do.

that‘s fine for firing it up.

- you can use a test tone to adjust bias of the fet.

I have checked the U87 Building Guide and for my understanding, to refine RV10 for the best sweet spot is to generate a tone via J4. How can I do that without special equipment?

If not, which cheapest kind of machine should I be looking for?

Or preferable a portable digital tone generator or portable digital oscilloscope will do the trick for this and bullet proof for future projects?

assuming you measured correctly that‘s perfect.

I used GND on Capsule/body which i took a cable from XLR pin1 and J9, is that correct?

for a start you can also try with cables and crocodile clamps.

Good idea, let's see if I can figure it out.

----

| QUESTIONS |

1. I must give a lot of gain to have a reasonable level of sound, is this normal?
2. When I activate phantom power and start giving gain, I hear some crackling which goes away after a few seconds ON. Is this anything with the transformer? Does it need to break in on order to have normal results?

---

Always very helpful. Thank you so much @mihi_fuchs

Best Regards,

RB