Ask about U87 Components
« on: March 18, 2020, 09:33:18 AM »
I'm now making EVM for U87.

Already complete of the Resistor and Ceramic Capacitor to SMD type for easy assembly by SMT process.


Anyway, I don't have any information about T1-8280800006 and LP-PCB #984908.
I saw that T1 is can replace 2N3819 but I wanna know original JFET model number.


Also, I saw that LP-PCB #984908 that on U87A schematic.


In conclusion, is this.
Q1. T1-8280800006 is can replace to 2N3819?
Q2. Can I get schematic of LP-PCB #984908?

Thanks to reading my question?


RuudNL

Re: Ask about U87 Components
« Reply #1 on: March 18, 2020, 12:49:33 PM »
Is it your intention to commercially reproduce the U87 design?
(I get this impression because you write "SMD type for easy assembly by SMT process")
There is a solution for every problem!

http://www.vansteenisaudio.nl

OneRoomStudios

Re: Ask about U87 Components
« Reply #2 on: March 18, 2020, 01:22:34 PM »
Is it your intention to commercially reproduce the U87 design?

Hopefully not. Commercially producing (another) U87 via SMD would be pretty dumb at this point. There are so many other clones out there, and little or no differentiation between the cheap ones. Cheap U87 clones are a dime a dozen these days. Hopefully that's not the goal.

To answer your questions, in case others might have similar ones, the original JFET was the 2436, which is long gone, but Neumann also used the 2N3819 in production models. There's no direct SMD equivalent, but MMBF5484 should work. As always when substituting a transistor, you'll likely have to adjust the bias.

As for the "LP-PCB #984908," I'm pretty sure that's just the PCB itself.

Ricardus

Re: Ask about U87 Components
« Reply #3 on: March 18, 2020, 06:14:27 PM »
2N5457 is a good 3819 replacement. There is an SMD version apparently.

https://www.taydaelectronics.com/mmbf5457-jfet-n-channel-amplifier-transistor-sot-23.html

Audio mastering for hire..


 

Related Topics

  Subject / Started by Replies Last post
3 Replies
2452 Views
Last post June 04, 2005, 02:34:11 PM
by NewYorkDave
3 Replies
1225 Views
Last post March 02, 2008, 10:02:27 AM
by matta
6 Replies
1043 Views
Last post May 11, 2009, 11:52:41 AM
by Deyo
5 Replies
455 Views
Last post February 05, 2020, 08:59:23 AM
by JohnRoberts