Neumann Vintage U87 Clone : Build Thread.

[GhostlyStudio]

Hmm. I have a JLI TSC-2 that I just ordered and am wondering how to make this work since the backplates aren’t isolated. Ideas? Ripped off by the JLI?

I went with JLI after watching @Wordsushi 's YouTube vid recommending them and I suspect that in the past they've maybe had different capsules and have changed supplier maybe? I can definitely say that their capsule isn't a Takstar for sure.

 

[joulupukki]

I went with JLI after watching @Wordsushi 's YouTube vid recommending them and I suspect that in the past they've maybe had different capsules and have changed supplier maybe? I can definitely say that their capsule isn't a Takstar for sure.

Yeah, the capsule looks different from the picture they show on their website. If I could figure out how to eke out some more sensitivity so I wouldn’t have to turn my preamp up so high, that’d make it better, for sure. I mostly use cardioid and so not having Fig8 isn’t a huge downer. I’m going to try changing the Zener from 24V to 33V first and see if sensitivity improves a little.

 

[deanrichard]

I̶'v̶e̶ j̶u̶s̶t̶ f̶i̶n̶i̶s̶h̶e̶d̶ m̶y̶ U̶8̶7̶ b̶u̶i̶l̶d̶ u̶s̶i̶n̶g̶ D̶a̶n̶n̶y̶'s̶ b̶l̶u̶e̶ p̶c̶b̶'s̶ a̶n̶d̶ B̶O̶M̶, a̶s̶ w̶e̶l̶l̶ a̶s̶ a̶n̶ A̶M̶I̶ T̶1̶3̶ t̶r̶a̶n̶s̶f̶o̶r̶m̶e̶r̶, a̶n̶d̶ f̶o̶l̶l̶o̶w̶e̶d̶ t̶h̶e̶ b̶u̶i̶l̶d̶ g̶u̶i̶d̶e̶ o̶n̶ h̶i̶s̶ w̶e̶b̶s̶i̶t̶e̶. C̶h̶u̶c̶k̶e̶d̶ i̶n̶ a̶ T̶S̶C̶-̶2̶ c̶a̶p̶s̶u̶l̶e̶ f̶r̶o̶m̶ J̶L̶I̶ t̶o̶ c̶h̶e̶c̶k̶ e̶v̶e̶r̶y̶t̶h̶i̶n̶g̶ w̶o̶r̶k̶s̶ f̶i̶n̶e̶ w̶h̶i̶l̶s̶t̶ I̶ w̶a̶i̶t̶ f̶o̶r̶ o̶n̶e̶ o̶f̶ A̶r̶i̶e̶n̶n̶e̶'s̶ K̶8̶7̶'s̶ t̶o̶ a̶r̶r̶i̶v̶e̶ a̶n̶d̶ e̶v̶e̶r̶y̶t̶h̶i̶n̶g̶ a̶p̶p̶e̶a̶r̶s̶ t̶o̶ w̶o̶r̶k̶ a̶s̶ e̶x̶p̶e̶c̶t̶e̶d̶, b̶u̶t̶ t̶h̶e̶ o̶u̶t̶p̶u̶t̶ s̶e̶e̶m̶s̶ q̶u̶i̶t̶e̶ l̶o̶w̶?̶ P̶l̶u̶g̶g̶e̶d̶ i̶n̶ m̶y̶ A̶K̶G̶ P̶4̶2̶0̶ i̶n̶t̶o̶ t̶h̶e̶ s̶a̶m̶e̶ a̶u̶d̶i̶o̶ i̶n̶t̶e̶r̶f̶a̶c̶e̶ a̶n̶d̶ t̶h̶e̶ d̶i̶f̶f̶e̶r̶e̶n̶c̶e̶ i̶n̶ v̶o̶l̶u̶m̶e̶ i̶s̶ n̶o̶t̶i̶c̶e̶a̶b̶l̶e̶. I̶s̶ t̶h̶e̶r̶e̶ a̶ g̶o̶o̶d̶ p̶l̶a̶c̶e̶ t̶o̶ s̶t̶a̶r̶t̶ i̶n̶ t̶e̶r̶m̶s̶ o̶f̶ d̶e̶b̶u̶g̶g̶i̶n̶g̶ w̶h̶e̶r̶e̶ I̶'v̶e̶ l̶i̶k̶e̶l̶y̶ g̶o̶n̶e̶ w̶r̶o̶n̶g̶?̶

Sorry, cancel that... I think I misunderstood that the original U87 circuit has less output compared to the U87ai (which the P420 is modelled off). I'm able to give more gain and speaking normally into the Mic comes out fine / clean.

Regarding your low output, I can't speak to the TSC-2 capsule, but I have installed two of the TSC-1's in MCA SP-1 mics, and they seem very high output to me. They are maybe 2-3 db hotter than the JLI-103 and the Baifeili L81 that I put in my other two MCA SP-1's. Now I don't have a U87 for reference, and I wasn't trying to build a U87, just improve the sound of the old MCA SP1's I had laying around. For that purpose, I am very pleased with the TSC-1 capsules. I don't have any measurements to back up my opinion, but they sound good to me.

 

[joulupukki]

I wonder if it could be that it doesn’t have isolated backplates and I connected the backplate wire to the PCB using the RBK terminal and maybe it needs to be on the FBK instead?

Would there be a way with Dany’s PCB to make it so all three polar patterns (Omni/Cardioid/Fig8) would work on the TSC-2 since it has non-isolated backplates? Seems like I remember seeing a discussion on the Fuchs 87A board where you could make all polar patterns work regardless of whether the capsule had isolated backplates or not.

 

[OneRoomStudio]

If you use a DC step-up circuit, "AI" style, you can generated all patterns without isolated backplates (U87AI didn't use isolated backplates).


If you want to stick to phantom power, it's a little trickier. You could try putting half-voltage (~24V) on the backplate and 48V on the front diaphragm, then switch the rear diaphragm between 0V (giving you figure-8), 24V (giving you cardioid), and 48V (giving you omni). Since you'd only have a 24V differential between the backplate and the diaphragms, you'd loose about 6dB of signal compared to a "standard" U87.

 

[joulupukki]

If you use a DC step-up circuit, "AI" style, you can generated all patterns without isolated backplates (U87AI didn't use isolated backplates).
View attachment 138660

If you want to stick to phantom power, it's a little trickier. You could try putting half-voltage (~24V) on the backplate and 48V on the front diaphragm, then switch the rear diaphragm between 0V (giving you figure-8), 24V (giving you cardioid), and 48V (giving you omni). Since you'd only have a 24V differential between the backplate and the diaphragms, you'd loose about 6dB of signal compared to a "standard" U87.

Gotcha. I care more about a stronger signal in Cardioid. I can live without Fig8 on this mic.

 

[OneRoomStudio]

Gotcha. I care more about a stronger signal in Cardioid. I can live without Fig8 on this mic.

If that's the case, it's easy to get only cardioid and omni (figure-8 is the tricky one). Keep the front diaphragm at ground potential (feeding directly into the FET), put your polarizing voltage (P48) on the backplate, and then use a switch to either disconnect the rear diaphragm (putting you in true cardioid), or connect the read diaphragm to the font diaphragm (putting both at ground potential, giving you omni).

 

[joulupukki]

If that's the case, it's easy to get only cardioid and omni (figure-8 is the tricky one). Keep the front diaphragm at ground potential (feeding directly into the FET), put your polarizing voltage (P48) on the backplate, and then use a switch to either disconnect the rear diaphragm (putting you in true cardioid), or connect the read diaphragm to the font diaphragm (putting both at ground potential, giving you omni).

Yep. That’s how it’s working currently. It just suffers from lower output levels with the JLI TSC-2 compared with the Arienne Audio K87 v1 capsule. I ordered a 33V Zener and will swap out the 24V Zener just to see. Even just a few more dB would help it be a more usable mic so I wouldn’t have to turn the preamp up so high.