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

[micolas]

No C12 on the 1.1 ORS 87 board?

C12 is a simple filter, it can be anything, like C10 actually.
In v1.1 you can put it or not.
I usually after Zenner put a higher value C12 = 47...100uF, and in series with Zenner I put a 100ohm resistor,
but that's just me.

On the other hand, @Khron suggested using fewer component values, for simplicity.

 

[homero.leal]

No C12 on the 1.1 ORS 87 board?

Oh my! I think I forgot to rename C7 cap to C12. It's the small round cap at the botom-left. Will update the name for V1.2. Thank you.

 

[cello4u]

No idea, but there's one on the version 1.0 board, and it was in my BOM. Couldn't find what it was in the thread by searching C12. Thank you for replying.

 

[cello4u]

Oh my! I think I forgot to rename C7 cap to C12. It's the small round cap at the botom-left. Will update the name for V1.2. Thank you.
View attachment 130508

I think this makes sense to me. Thank you!

 

[elskardio]

Today I received a pair of k67 capsules from the Getwin store on Alibaba. $45 a piece.

I just installed one for a quick sound check and I'm really impressed! They sound beautiful and the build quality is excellent. Highly recommended!
Cheers

 

[untamedfrontier]

@homero.leal quick question regarding the v1.1 board (thanks again for making it). I saw the schematic calls for the LSK189 now, where IIRC (and I may not), the v1 board was still for 2N3819.

If I'm reading the schem & PCB correctly, Drain should be going to Pin1, is that right?

 

[homero.leal]

Hi!
Both boards (V1 and V1.1) use LSK189. What changed from V1 to V1.1 was the additional caps for LFEQ and HFEQ, and the component names to make it equivalent to @OneRoomStudio schematic.

Regarding the drain pin, here is a pic showing the trace (light red):

Hope this helps!

Regards!

 

[Wordsushi]

Today I received a pair of k67 capsules from the Getwin store on Alibaba. $45 a piece.

I just installed one for a quick sound check and I'm really impressed! They sound beautiful and the build quality is excellent. Highly recommended!
Cheers

This post reminded me that I had an unused $26 aliexpress k87 sitting around and just a while ago, when I swapped it into an ORS 87 build, I was quite surprised how good it sounded. I had bought it just as a "tester" capsule for builds, but now I'm thinking it's far better than that, actually. And then there are these black-ringed BaiFei Li capsules that I had been using that are also pretty good, if not really good overall, and also quite consistent as they all sound the same despite being pulled from 3 different mics at 3 different times.

Now it has me thinking that perhaps these companies churning out these cheaper capsules have evolved their product to a higher level of competence/quality and perhaps better machinery and processes are creating a level of consistency that just wasn't there a few years back. I'd love it if these capsules had a little more of that Neumann-esque midrange purr, but really, that's all that seems to be missing. The sonics are pretty solid as far as I've been able to tell within the limited use I've given them.

So, are we in a new era of "cheap, really quite good" capsules? I could certainly gig with any of the aforementioned mics with these in them if I had to.

 

[Jedias]

Hey guys, does anyone here tried to make it on a stripboard?

 

[micolas]

Hey guys, does anyone here tried to make it on a stripboard?

... perhaps the following will help you to some extent:

https://groupdiy.com/threads/open-source-diy-mic-project-ors-87-stripped-down-u87.86814/post-1137386

https://groupdiy.com/threads/open-source-diy-mic-project-ors-87-stripped-down-u87.86814/post-1140723

https://groupdiy.com/threads/open-source-diy-mic-project-ors-87-stripped-down-u87.86814/post-1149987

 

[Jedias]

I'll do you one better. Here's the layout:
View attachment 124217
"X1/P-" at the bottom means "XLR Pin 1 and transformer Primary -." You can figure out the rest. The blue line is just used to show that it doesn't intersect the gray lines it crosses. All touching gray lines do connect.

Here's the BOM. Part names somewhat match the original U87 schematic for reference. Tweak to taste:
R7: 1G
R8: 1M
R9: 7k3
R10: 25K Trimmer
R12: 47k
R13: 330k
R14: 10k
R15: 300k
R16: 56k (for 24V zener, try 47k for 33V zener)
R18 & R19: 2k2 (closely matched!)

C5: 33n (can go as big as 330n if you want more low-end)
C6: 220p (treble cap - smaller = more treble, bigger = darker)
C7: 1u (can tweak to taste. smaller = less bass)
C8: 20u 6v
C9: 470n
C10: 4u7 35V
C11: 4u7 63V
C12: 10u 63V
C13: 10n

Q1: 2N3819

GR1: 1N4749A (24V zener - can try 33V instead with smaller R16)

Tie the XLR Pin 1 to the ground tab on the XLR connector. Film caps should be at least 63V. Use teflon-insulated pins for the capsule connections and keep those junctions "in the air." The board needs to be about 38mmx80mm. Careful not to short to the rails (I used electrical tape to insulate behind the board). Any K67/K87 type capsule should work. Any 8:1 through 12:1 OT should work.

Experiment!

Hi, does te Capacitor voltages makes diference in this circuit? I saw you put:
C8: 20u 6v
C10: 4u7 35V
C11: 4u7 63V
C12: 10u 63V

 

[micolas]

Hi, does te Capacitor voltages makes diference in this circuit? I saw you put:
C8: 20u 6v
C10: 4u7 35V
C11: 4u7 63V
C12: 10u 63V

Only C8=20...22uF make a diference.
Reducing it slightly reduces the gain of the circuit and the bass
The others: C10,11,12 are filters for audio supply and capsule polarization voltage

 

[untamedfrontier]

I built a mic!!

I was pretty sure it wasn't going to work correctly while testing initially because I getting Oldies radio, a world of hum, and general wonkiness. Once I grounded the board to the body, everything sounded nice. I also just biased very very very unscientifically. Measured out to ~10.8v but I think I may have also switched 2N3819s between original biasing and finishing.

Oddball things about this build with my 1st board (I bought 5 of Homero's v1.1 boards:

• Used part values which lined up with the original BOM for the "vintage" specs.
• Used Central Semi 2N3918 (which weirdly enough is the same pinout as LSK189, not reversed like the Interfet made ones)
• Used 1u Wima cap for C7 because I had one lying around and felt like it.
• 220p for C6, 33n for C5
• BaiFeiLi k87 Capsule (black ring)
• Neutrik NTE 10/3 transformer
• Am using a screw from a fender electric bridge for to secure the mic jack because the included one wasn't long enough to reach.

Just did a few little tests with it but I'm absolutely floored that I was able to not only build a mic, but one that sounds pretty darn good. I'll probably post a sample or two at some point, but I think this probably can be re-biased. Huge shoutout to everyone in this thread, could not have done this alone.

 

[Wordsushi]

I built a mic!!

I was pretty sure it wasn't going to work correctly while testing initially because I getting Oldies radio, a world of hum, and general wonkiness. Once I grounded the board to the body, everything sounded nice. I also just biased very very very unscientifically. Measured out to ~10.8v but I think I may have also switched 2N3819s between original biasing and finishing.

Oddball things about this build with my 1st board (I bought 5 of Homero's v1.1 boards:

• Used part values which lined up with the original BOM for the "vintage" specs.
• Used Central Semi 2N3918 (which weirdly enough is the same pinout as LSK189, not reversed like the Interfet made ones)
• Used 1u Wima cap for C7 because I had one lying around and felt like it.
• 220p for C6, 33n for C5
• BaiFeiLi k87 Capsule (black ring)
• Neutrik NTE 10/3 transformer
• Am using a screw from a fender electric bridge for to secure the mic jack because the included one wasn't long enough to reach.

Just did a few little tests with it but I'm absolutely floored that I was able to not only build a mic, but one that sounds pretty darn good. I'll probably post a sample or two at some point, but I think this probably can be re-biased. Huge shoutout to everyone in this thread, could not have done this alone.

BOOM! YOU ROCKED THAT!
Congratulations! And welcome to the club.

 

[homero.leal]

I built a mic!!

I was pretty sure it wasn't going to work correctly while testing initially because I getting Oldies radio, a world of hum, and general wonkiness. Once I grounded the board to the body, everything sounded nice. I also just biased very very very unscientifically. Measured out to ~10.8v but I think I may have also switched 2N3819s between original biasing and finishing.

Oddball things about this build with my 1st board (I bought 5 of Homero's v1.1 boards:

• Used part values which lined up with the original BOM for the "vintage" specs.
• Used Central Semi 2N3918 (which weirdly enough is the same pinout as LSK189, not reversed like the Interfet made ones)
• Used 1u Wima cap for C7 because I had one lying around and felt like it.
• 220p for C6, 33n for C5
• BaiFeiLi k87 Capsule (black ring)
• Neutrik NTE 10/3 transformer
• Am using a screw from a fender electric bridge for to secure the mic jack because the included one wasn't long enough to reach.

Just did a few little tests with it but I'm absolutely floored that I was able to not only build a mic, but one that sounds pretty darn good. I'll probably post a sample or two at some point, but I think this probably can be re-biased. Huge shoutout to everyone in this thread, could not have done this alone.

Big congrats!!! Just be aware, once you enter the club... there is no way back. But is a nice addiction, many folks will confirm that!

 

[AdamFrisen]

Would the circuit board work with Arienne K47 flat capsule if modified somewhat?

 

[micolas]

Would the circuit board work with Arienne K47 flat capsule if modified somewhat?

Try disconnecting
C6=220pF (de-emphasis will remain on the bass), or
C9=470nF (flat circuit)

 

[untamedfrontier]

Here's a voice only sample, no EQ or other processing, ~8" away, doing my best Wordsushi impression.
Chain was ORS87 > UA Solo/610 (3 gain, 9 Vol) > Apogee One > Logic Pro
View attachment J87_demo_speaking.mp3

 

[micolas]

Here's a voice only sample, no EQ or other processing, ~8" away, doing my best Wordsushi impression.
Chain was ORS87 > UA Solo/610 (3 gain, 9 Vol) > Apogee One > Logic Pro

It doesn't work for me
You must press 'Insert' on the attachment image after uploading the .mp3 file

 

[micolas]

Here's a voice only sample, no EQ or other processing, ~8" away, doing my best Wordsushi impression.
Chain was ORS87 > UA Solo/610 (3 gain, 9 Vol) > Apogee One > Logic Pro
View attachment 130800

This is.