GroupDIY

Project Specific Discussions => Filters/Equalizers => Topic started by: jensenmann on November 25, 2020, 03:40:27 PM

Title: DOA riddle solved
Post by: jensenmann on November 25, 2020, 03:40:27 PM
Here´s some pictures about a mystery DOA riddle which I have solved:

https://ibb.co/4VXXfZG
https://ibb.co/0FPdnf6
https://ibb.co/KKb1Gjv
https://ibb.co/cbbs0C1
https://ibb.co/nB0pZLq

Guess what that is....
 8)
Title: Re: DOA riddle solved
Post by: wlinart on November 25, 2020, 04:19:56 PM
Sontec?
Title: Re: DOA riddle solved
Post by: ruffrecords on November 25, 2020, 05:06:03 PM
15 transistors!!!

Cheers

Ian
Title: Re: DOA riddle solved
Post by: jensenmann on November 26, 2020, 01:39:26 AM
Sontec?

Exactly. That was fast...

Since I repair Sontecs quite often I ran into the problem to repair defective DOAs at some point. Thanks to Corona lockdown early this year I had enough time to reverseengineer a HS2030 DOA. I made a PCB layout and finished my first DIY HS2030  last night. It´s working. Happy camper here :-)
Title: Re: DOA riddle solved
Post by: wlinart on November 26, 2020, 02:09:51 AM
Great job!
Title: Re: DOA riddle solved
Post by: OneRoomStudios on November 26, 2020, 05:08:06 PM
Have you seen Joe Malone's (JLM Audio) work on these?

https://www.jlmaudio.com/shop/hs3030-opamp.html

He's done quite a bit of work on Sontec opamps, including the HS2030, an adaptor for the HS10** opamps, HS2000, and the HS6000, among others.

Title: Re: DOA riddle solved
Post by: jensenmann on November 26, 2020, 05:44:37 PM
Yes, I did. I´m using his DOAs in my Don Classics 250. They are spot on. That combination is as close as you can get to a real 250c. I had them side by side. Joe´s DOAs are available with 2520 pinout, so he´s doing us DIYers a big favor.

Joe´s DOA came out when I was in the middle of reversing the HS2030. I don´t know if I´d done all that work if they were available earlier. Anyway, his DOAs are SMD and my version is all original THT with all those obsolete unobtainum transistors. As I said before I repair Sontec, mostly for mastering studios here in EU, and most clients want it to be as original as possible. That´s what I was trying to accomplish with my PCB. From a commercial POV it doesn´t make sense to do it other than SMD. But paranoid mastering guys love that minute detail ;-)