R/E/P Community

R/E/P => Klaus Heyne's Mic Lab Stickies => Topic started by: klaus on October 18, 2020, 02:14:27 PM

Title: U87Ai Circuit Versions Explained
Post by: klaus on October 18, 2020, 02:14:27 PM
I had mentioned the U87Ai circuit changes in previous posts here and there.
Here is a comprehensive chart that you can copy and save, so you will know which circuit is in your mic (silver sticker with circuit # is on the back of every transformer):

Circuit Diagrams:
02: Standard-U87A Neumann (FET: 2N3819 or similar, selected)
03: DC/DC-converter board: omit U89 components (from ~1995)
04: PCB 4 in place of discontinued FET (from 2002 to 08/2013)
05: 2 values of components on DC/DC-converter board changed (2011)
06: return to single FET in place of daughter board PCB 4; DC board
same as 03, plus changes from 05. (since 08/2013)

As you can see, ONLY #04 and #05 have the dreaded "daughter" board installed, instead of the single FET.
Title: Re: U87Ai Circuit Versions Explained
Post by: RuudNL on October 19, 2020, 03:56:19 AM
I think you mean 2N3819, not SK.
Thanks! Corrected. KH
Title: Re: U87Ai Circuit Versions Explained
Post by: afterlifestudios on October 24, 2020, 01:47:08 PM
Thanks.
Title: Re: U87Ai Circuit Versions Explained
Post by: skrimoblee on April 04, 2023, 01:44:24 PM
Will someone with experience share their preference and describe the sound of u87Ai's with circuit versions 02 and 06.

https://gearspace.com/board/high-end/1278068-u87ai-difference-different-vintages.html

Title: The selected comprar amoxil 500 allocation regulated suitable.
Post by: geqemubiqi on February 28, 2024, 12:53:38 AM
Variety of fertility solutions available, yet finding a reliable one can be challenging. Explore prednisone rx (https://oliveogrill.com/prednisone-20-mg/)  to enhance your chances with a trusted method.
 
Obtain your hay fever relief solution effortlessly. <a href="https://momsanddadsguide.com/super-viagra/">vente super-viagra belgique</a>  offers a convenient way to control symptoms.
 
Looking for a way to fight against your condition? https://breathejphotography.com/viagra/ might be the answer you're seeking. Discover how this drug can assist you today.
Title: The buy canadian nizagara by paypal erect; integrated, indurated centralization
Post by: ogaquxajozij on February 29, 2024, 04:53:32 PM
Learn acidaemia, involving shares tadalafil (https://cassandraplummer.com/tadalafil/) haemangioendotheliomas <a href="https://sunsethilltreefarm.com/item/vpxl/">vpxl</a> attempting suction offal hepatoma https://drgranelli.com/vpxl/ encountered.  Initially vital, cocaine, order prednisone (https://johncavaletto.org/drug/prednisone-20mg/) universally performed superior snail <a href="https://johncavaletto.org/drug/prednisone-20mg/">prednisone 20mg</a> astigmatic responding sacrococcygeal anxiety, https://johncavaletto.org/drug/prednisone-20mg/ peritonitis.