Still, getting good sound at a fraction of the price of a U87 is very tempting
OPEN SOURCE DIY Mic Project - ORS 87 - Stripped Down u87
- Thread starter Wordsushi
- Start date
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Yes, I believe that is where I got the BOM,https://groupdiy.com/threads/open-source-diy-mic-project-ors-87-stripped-down-u87.86814/post-1144040
That should be a pretty comprehensive bill-of-materials. Maybe attach a photo of the board so we can verify the component designators vs the values? I'm not gonna spend even more time digging through the rest of this thread for that
wasn't sure if they should be touching, or under the other side of the board?
Maybe a dual build like @Wordsushi did.Any reason you're looking at a FOUR-pin (or FIVE-pin) XLR insert?
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untamedfrontier
Member
Was mainly just looking for any compatible XLR insert, and this one is the only one I saw on mouser that looked appropriate, I didn't even notice the additional pin...Any reason you're looking at a FOUR-pin (or FIVE-pin) XLR insert?
I would have been really kicking myself when that showed up.Will edit and strikethrough that one in the previous post as to not potentially lead any others astray.
AC3-MIC appears to be the right part
Neutrik 3MC-I is also a similar standard XLR connector
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It is a 2-layer, 2-sided PCB.
The red pcb paths/traces are independent of the blue ones.
There are complex circuits that required PCBs with dozens of overlapping layers.
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oran.outan
Well-known member
Hi All,
thanks for all the share about that project !
I just start a build on the V1 version/PCB and I'm confused about the R8 resistor which is in parallel with the Trimpot... I understand that the 4K7 value was for simulation ! That mean on the PCB I need to keep it empty ! The R8 place is if I want to replace the trimpot value by a fix resistor/value ! right ?
thanks for the clarification...
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thanks for all the share about that project !
I just start a build on the V1 version/PCB and I'm confused about the R8 resistor which is in parallel with the Trimpot... I understand that the 4K7 value was for simulation ! That mean on the PCB I need to keep it empty ! The R8 place is if I want to replace the trimpot value by a fix resistor/value ! right ?
thanks for the clarification...
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@oran.outan
You got it right. Just be aware that the value of R8 at the end will not be 4.7kohm, but will be dependent on the Idss of the jFET and how you will make its BIAS.
You got it right. Just be aware that the value of R8 at the end will not be 4.7kohm, but will be dependent on the Idss of the jFET and how you will make its BIAS.
joulupukki
Well-known member
Am I understanding this right, that with a 2N3819 you could use a 33V zener and get more headroom? I’m curious if this same type of thing would apply to the standard U87 build. Like, could I modify the Dany Bouchard U87 build keeping the same FET but with a 33V zener and get more headroom out of that thing? That’s my only real complaint, especially after modding an AKG P420 and having it turn out so similar but with a lot more headroom. Haven’t yet built an ORS87 version, but maybe this is one thing I could adapt from the ORS87 project.
Yes, you will have more headroom, more signal output and the transformer will saturate a little faster.
Just put a 33v Zenner and reduce the resistance that feeds it (for example in ORS87 R16 - 22...33kohm , you have to experiment, the Zenner will stabilize effectively if you feed it with a few extra volts, also take into account the possible phantom voltage deviation +/- 4v). For Dani B. U87 get inspired by U87ai.
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Yes,Sir!!!Forgot to re-translate?
It's complicated on a smartphone to do things right, look for schemes, etc
joulupukki
Well-known member
Excellent, thank you for confirming! I’ll do some experimenting after I finish up with another experiment (changing the Bassman Micro tube amp I built to use a pair of EL84 power tubes instead – won’t be “micro” anymore once I’m finished).
oran.outan
Well-known member
Yes yes! This part was clear…
Thanks
There are many ways to BIAS the jFET.
Depending on the measurement equipment available (DMM, oscilloscope, signal generator, spectrum analyzer - hardware or software), depending on the purpose pursued, preferences (cleaner or more saturated sound),maximum signal with reasonable distortion, symmetrical half-sines, by ear with injection of complex musical audio signal, with sine signal, with high-level voice, etc., using equipment to visualize / measure the waveform, harmonic distortion (some prefer more 2nd order harmonic, which is supposed to make the sound more musical) etc etc
In general, opinions, preferences, tastes are divided, so BIAS is a purely personal decision, it is actually a compromise.
Many years when I was building guitar effects pedals, We considered that asymmetric clipping/saturation/distortion was closer to the character of tubes, so I used in overdrive,distorsion,fuzz etc, --many types of diodes (germanium, silicon, selenium), LEDs(of different colors and sizes) and junctions of different bipolar or mosfet transistors, connected anti-parallel. So it's possible that asymmetric distortions will produce a special sound in microphones.
In any case, from my personal experience, I can say that among the transistors, jFETs are the closest in sound to tubes.
Useful information about jFET's BIAS:
https://groupdiy.com/threads/neumann-vintage-u87-clone-build-thread.48030/
elskardio
Well-known member
I just finished the big brother! I went with the UTM0587 for this one.
It has the same exact circuit, it’s very well done, so there’s no reason to not sound the same.
It sounds incredibly good even without the tunning
Thank you so much for the tunning tips Ruud
What does C12 do?
