I actually came across the J113 when i started my solid-state guitar (pre)amp project prototypes, a few years back, and it was the cheapest available that filled the main
requirements
No NOS-nonsense going on here... 
OPEN SOURCE DIY Mic Project - ORS 87 - Stripped Down u87
- Thread starter Wordsushi
- Start date
Help Support GroupDIY Audio Forum:
I actually came across the J113 when i started my solid-state guitar (pre)amp project prototypes, a few years back, and it was the cheapest available that filled the main
No NOS-nonsense going on here... micolas
Well-known member
About 25 years ago, in the communities where we were active, we used 2N5457 and J201, for guitar preamplifiers, amp or cab simulators, effects pedals, etc. And now I still have these models, with very low Idss, in Shoeps or in the emitter follower, they are good.
I really don't remember if at that time we were considering J111...J113
(Also at that time, a friend came with a defective Rode NT1 (white-grey), I remember perfectly that it had J305 and the best quality parts, many green Wimas, it's a pity that the capsule was compromised. He later bought a Behri B1 and was satisfied. I'm sure the two had a lot in common)
Has anyone some information about Mic&Mod K87 capsule?
https://www.micandmod.com/microphone-parts/microphone-capsule/k87-capsule/
I'd love to choose Arienne Audio, but I try to find options in Europe
https://www.micandmod.com/microphone-parts/microphone-capsule/k87-capsule/
I'd love to choose Arienne Audio, but I try to find options in Europe
micolas
Well-known member
micolas
Well-known member
M&M is a rebranded capsule.
Is it possible that the 1.1 has this in the pcb? the middle leg is currently in a hole that has a trace going to the other hole? Or do I need to desolder the jfet to get the leg out?
micolas
Well-known member
Do not solder the middle pin(Gate) of the 2N3819 on the PCB. If you soldered it, you have to unsolder it the transistor completely, quickly heating all 3 pins simultaneously, so as not to destroy it thermally or mechanically.
Do not solder the end of R7=1G on the PCB either (opposite to the one that is soldered to GND)
Attachments
The middle leg of what? And which "other hole"?
As @micolas said - POST PICTURES.
Hopefully well-lit but glare-free, and please try to zoom in on them and make sure they're also half-ass ok-ish focused. We're not dealing with film anymore nowadays, so you can retry as many times as you need to / can be bothered to, until you get it right.
I still can't comprehend why @homero.leal chose to have that "as an option" (or even a possibility)...
untamedfrontier
Active member
My ORS87 works fine without having the middle leg isolated from the pcb. I may try it isolated on future builds, but to get a functional microphone you don't need to have it isolated. Feel free to check my prior posts for pictures of it
You may also want to check the datasheet of your jfet though, I found my 2n3819 had the same pinout as the lsk189, where it appears other manufacturers of the 2n3819 have it flipped
micolas
Well-known member
It would be helpful to read all the posts in the thread.
However, we offer an important part of our time and experience to give solutions, indications, help, in a completely altruistic way.
micolas
Well-known member
In many cases, for some jFETs, the Drain can be inverted with the Source and it works.
But for optimal operation it is good to respect the pinout.
untamedfrontier
Active member
I actually came across the J113 when i started my solid-state guitar (pre)amp project prototypes, a few years back, and it was the cheapest available that filled the main
requirements
Any other recommended/necessary alterations to the current BOM to sub the j113 for lsk189/2n3819? I have a few in my inventory and could pop one in.
Also the PCB layout you posted earlier looks very cool, but I don't think I'm quite ready to learn how to etch my own pcb yet lol
micolas
Well-known member
I am very convinced that in version v1.2 @homero.leal will give up those traces on the PCB.I still can't comprehend why @homero.leal chose to have that "as an option" (or even a possibility)...
They created a lot of confusion.
Well, i'm kinda divided on this particular topic
I (will) have my "full fat" U87A-like project available anyway, as well as a "FET847" board, while this "ORS87" is halfway between those two, on one hand. And on the other hand, i just wanted to "give something back to the community" (as i did with @rogs' RFmic board, and the initial FET847-for-BM800 some years ago) , and i'd be a bit conflicted about selling boards of this particular project. Unless, of course, @Wordsushi and/or @OneRoomStudio happen to give their blessing (and/or insist that i do)
micolas
Well-known member
Unohdit Neumannin!Well, i'm kinda divided on this particular topic
i'd be a bit conflicted about selling boards of this particular project. Unless, of course, @Wordsushi and/or @OneRoomStudio happen to give their blessing (and/or insist that i do)
Unohdit Neumannin!
They make enough money as it is. Or if they don't, it's Sennheiser's fault...
All I did was share a perfboard layout for a simplified version of the U87 circuit. I claim no ownership of anything.Well, i'm kinda divided on this particular topic
I (will) have my "full fat" U87A-like project available anyway, as well as a "FET847" board, while this "ORS87" is halfway between those two, on one hand. And on the other hand, i just wanted to "give something back to the community" (as i did with @rogs' RFmic board, and the initial FET847-for-BM800 some years ago) , and i'd be a bit conflicted about selling boards of this particular project. Unless, of course, @Wordsushi and/or @OneRoomStudio happen to give their blessing (and/or insist that i do)
....although, I still maintain that this being "GroupDIY" and all, folks would be better off trying to understand the circuit and building it themselves on perfboard than buying yet another PCB/kit and painting by numbers.
homero.leal
Well-known member
- Joined
- Aug 8, 2015
- Messages
- 129
homero.leal
Well-known member
- Joined
- Aug 8, 2015
- Messages
- 129
And... now that you mention about version 1.2, what additional changes would you like to have?
I expect to update it next weekend.
Regards!
I expect to update it next weekend.
Regards!
