fsalter

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3240 on: March 23, 2021, 07:47:43 PM »
" That doesn't look right. On a 2N3819 L to R when the flat of the transistor is facing you the leads are S G D."
I agree. This is wrong. I'm pretty sure on most jfets you can get away with reversing S and D, but your gate (the middle leg) in the 3819 and NTE312 have to be soldered in the middle.


Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3241 on: March 25, 2021, 01:33:17 AM »
" That doesn't look right. On a 2N3819 L to R when the flat of the transistor is facing you the leads are S G D."
I agree. This is wrong. I'm pretty sure on most jfets you can get away with reversing S and D, but your gate (the middle leg) in the 3819 and NTE312 have to be soldered in the middle.

You're actually getting to the heart of the question.  I know that the middle is the gate on the 3819, but on the NTE312 the gate is one of the outer legs.  The drawing on the NTE312 data sheet is a little hard to follow so I'm not exactly clear which outer leg is the gate.

So in the picture, I have the leg on the left (which, if you were holding the JFET up to you by the legs with the flat side towards you would be the leg on the right) going to the isolation lug which if I understand correctly should be where the gate goes.

If anyone has a picture of how they connected their NTE312 maybe that would avoid further confusion.

Ricardus

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3242 on: March 25, 2021, 11:08:26 AM »
You're actually getting to the heart of the question.  I know that the middle is the gate on the 3819, but on the NTE312 the gate is one of the outer legs.  The drawing on the NTE312 data sheet is a little hard to follow so I'm not exactly clear which outer leg is the gate.

So in the picture, I have the leg on the left (which, if you were holding the JFET up to you by the legs with the flat side towards you would be the leg on the right) going to the isolation lug which if I understand correctly should be where the gate goes.

If anyone has a picture of how they connected their NTE312 maybe that would avoid further confusion.

 If you have the transistor facing you, with the FLAT side facing you, on the NTE312 the leads are G S D.

 That's enough info to solder this in correctly.
Audio mastering for hire..

joakimkarlthomas

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3243 on: March 27, 2021, 05:44:21 AM »
Hi! One of my DIY U87 built with DanyB pcbs have a multipattern capsule (RK87). I skipped the switch pcb but would like to insert a jumper installation to change to figure 8 and omni when needed. I tried to jumper the pads on the board ”CRD” and ”8”. Could not get it to work, is there anything more I need to do? Both sides of the capsule is of course already soldered to the board.

Ricardus

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3244 on: March 27, 2021, 11:48:40 AM »
Hi! One of my DIY U87 built with DanyB pcbs have a multipattern capsule (RK87). I skipped the switch pcb but would like to insert a jumper installation to change to figure 8 and omni when needed. I tried to jumper the pads on the board ”CRD” and ”8”. Could not get it to work, is there anything more I need to do? Both sides of the capsule is of course already soldered to the board.

 Jumpering CRD and 8 should give you figure eight. At least according to what I'm seeing.
Audio mastering for hire..

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3245 on: March 28, 2021, 07:55:54 PM »
Snow and noise -

Hello everyone - I have built a Dany B U87i. The polar Patterns 'Cardioid and Omni' have low level white noise- like that of snowy hiss yet the figure 8 pattern is very quiet. My first thought was that the pcb has flux that was making a connection between points at the high impedance input or at the switch connections. I have re- cleaned the board with isopropyl and it persists. Perhaps this is a capacitor issue? Has anyone else had this issue? Looking for advice for where to pursue this issue. Everything else works as intended.

Thanks!


zaraxisof

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3246 on: April 05, 2021, 11:32:12 AM »
Hello everyone. Found a used B2 Pro for almost nothing. Early version detachable head 797 K67 capsule.
I have already poctop's U87 finished and biased build, waiting for a body and K87 style capsule.

Could i use the B2's K67 capsule in "vintage U87" design for both Cardioid and Omni ?
I guess i just connect front/rear diaphragm to FD and body(backplate) to FBKT, but for Omni?
« Last Edit: April 06, 2021, 12:07:31 AM by zaraxisof »

joakimkarlthomas

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3247 on: April 06, 2021, 03:42:34 AM »
Jumpering CRD and 8 should give you figure eight. At least according to what I'm seeing.

Thanks! It does, found out I had the backplates wired wrong. 🤦‍♂️

zaraxisof

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3248 on: April 06, 2021, 12:17:29 PM »
Hello everyone. Found a used B2 Pro for almost nothing. Early version detachable head 797 K67 capsule.
I have already poctop's U87 finished and biased build, waiting for a body and K87 style capsule.

Could i use the B2's K67 capsule in "vintage U87" design for both Cardioid and Omni ?
I guess i just connect front/rear diaphragm to FD and body(backplate) to FBKT, but for Omni?

Anyone?

 

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