DOA riddle solved

[jensenmann]

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)

 

[wlinart]

Sontec?

 

[ruffrecords]

15 transistors!!!

Cheers

Ian

 

[jensenmann]

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

 

[wlinart]

Great job!

 

[OneRoomStudio]

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.

 

[jensenmann]

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 ;-)

 

[aurt]

jensenmann,

Sorry to revive an old thread, but is there any chance you'd have docs/prints on those? Info on what sort of unobtanium transistors they are? I just put one up on the bench, and the darned things have the numbers filed off. Lovely. While doing a deep dive on it might be fun, I doubt the owner wants to fund that many hours.

Any help would be appreciated. Thanks.

 

[jensenmann]

pm sent...

Just for the record I won´t give away my complete docs, but I will help if I can.

 

[thegrobinson]

jensenmann,

My mastering studio is starting down the road to overhaul a well loved, but very sick, MES-462C9. I wanted to get your opinion on rebuilding / replacing the DOAs. We're considering getting a full set of replacement DOAs so there's a baseline to work on the rest of the unit. The JLM HS3030s look like a easy drop in option, but the chief and I are curious if you have any info or services that could help us get this EQ back in service and as close to original as possible.

There's obvious heat damage and damage to the edge contacts. Is something like this even workable?

I would PM you, but I'm too new to the forum to have that permission yet.

 

[jensenmann]

pm´d