Help With Original UA610

Hi All,
      I have a small recording studio and am trying to build a single channel UA610 for personal use of course. I have always loved the sound of those old chips moman recordings from the late 60s. I have managed to gather some of the parts but I can't seem to find a verified schematic. I found one online that I think originally came from someone here at group diy but I am not sure. I also read that the input stage varied a little on some of the very first 610s. If anyone could help me with a schematic that is faithful to the original I would really appreciate it .....Thanks to all in advance.

Don't want to make it too easy, but here are my saved bookmarks on the topic.

http://groupdiy.com/index.php?topic=45039.0
http://groupdiy.com/index.php?topic=38943.0
http://groupdiy.com/index.php?topic=13038.0
http://groupdiy.com/index.php?topic=47543.msg598417#msg598417
http://groupdiy.com/index.php?topic=37944.0
http://groupdiy.com/index.php?topic=7707.0

You'll have to go through and read, but my (very possibly faulty) recollection is that the PDF schematic in the 1st and 2nd links was drawn by Winston O'Boogie, who helped with the reissues for UA, which by the way aren't faithful to that original schematic.

Use UTC O1 or similar for input. Cinemag CMO-30/600 looks ok for the output.

Thank you Dylan, I really do appreciate it. From the links it seems that the output trans is going to be kind of a try it and see proposition. Has anyone here at group diy completed a 610 build with a cinemag or sowter output transformer?

If you're in the US, you might just give Cinemag a call. They're really helpful.

Yeah, that sounds like a good idea. At this point I can't even locate a UTC 01 for the input...so I might have to go with Cinemag for both. It kind of sucks because I was shooting for an authentic as possible build and don't know how much the cinemags are going to change the sound.  I read in one of the other posts that someone here at group diy actually did get a unit built but could not source the original transformers and had to use cinemags .  He was saying that the sound was kind of dull or flat. Do you have any experience with Magnetiks ?....I could be mistaken but I believe they used to be UTC ....I don't know how faithful their current transformers are to the old but it may be an option.

UTC O-1's are super common.  Just because you don't see one on ebay this week doesn't mean it'll be hard; in fact you'll own several within weeks pretty easily.    The input will define the sound more than the output.

Output; the Cinemag is probably the best bet.  You won't find an original or any off the shelf vintage part that's overall as close. 

You can look for UTC O-2 also. It is the same as a O-1 with an addition of a center tap. Cheaper since the UA use brings up the cost of the O-1s.
I made four 1108s, one with an O-1 and three with O-2s.
Also search both O 1 (oh) and 0 1 (zero) on ebay. Commonly mislabeled.
And you probably want the O-17 shield on it if you can find one.

You might also look at the pair that EMRR has in the Black Market (if they're still available... EMRR?).

http://groupdiy.com/index.php?topic=58434.0

dmp said:

You can look for UTC O-2 also. It is the same as a O-1 with an addition of a center tap. Cheaper since the UA use brings up the cost of the O-1s.
I made four 1108s, one with an O-1 and three with O-2s.
Also search both O 1 (oh) and 0 1 (zero) on ebay. Commonly mislabeled.
And you probably want the O-17 shield on it if you can find one.

Click to expand...

Utc P-1 and P-2 should also work (just buy octal sockets)

M.

Just knowing that they are fairly common helps a lot...I was beginning to think I was looking for something that didn't exist. I'll keep looking  . The tip about the utc 0-2 ,p-1 and p-2 is very interesting ...thanks.  Dylan, I checked out the link but didn't see any 01s , so he must have sold them. All is good though ...I'll just have to be a little more patient and I'm sure one will turn up somewhere. I can go ahead and at least gather the cinemag output transformer and all of the other parts in the meantime. I just joined this group a couple days ago and I have to say you all are really cool people. Your help is very much appreciated.