UTC o-1 for UA610?

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seavote

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Joined
May 31, 2006
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i've got 2 UTC o-1 ouncers looking for a home. while i was not really planning on adding another tube pre to my "to do" list this looks like a fairly simple, easy to source, build. i have heard the o-1's are not held in high regard,yet her they are in pre that many users like. am i misreading the schematic. 0-1 instead of o-1?
anyone know where i can hear vintage UA610 audio samples?
EDIT:
ok found some samples as well as some video myself. here:
http://www.uaudio.com/media/videos.html?UAVID=Analog_610_Console
more samples.... from the UA web site
"the 610 was used on many classic recordings by
Frank Sinatra and Sarah Vaughan. The Beach Boys Pet Sounds, the Doors LA Woman, and Van Halen’s debut
album were all recorded on the 610.
 
That's it.. UTC O-1. got two of them from a nice fellow here, waiting to be put into the same circuit... Don't know what to do about the output though, would love to get that one remade but no exact winding info on it... Could use any 30K:600 as long as it can handle a bit of DC on the primary (inductance specs on schemo). Winston O'B made a few comments about it in another thread. 

what were you planning on using?

and P2P I assume?
 
to be honest i just saw the thread you were refering to and decided this would be a great circuit to use the ouncers in. so ive only been contemplating this for about 2 hours now. the OT does seem to be a mystery. googled for a 610 console service manual but found nothing.
p2p yes. i wouldnt mind seeing an inside photo of a 610 console channel or even the newer version for lay out ideas .no luck with google image though.
from Winston OBoogie Quoted by mitsos in the other thread:


" Ed Anderson recommended two different output trafos (both Cinemag)
CM-9661A if I use an output cap, and CMO-30/600 if I don't.  Is there an
advantage to either one in this circuit?

If you're building from the schematic I drew rather than trying to build one
like a re-issue, the issue at hand is one of there being about 7mA of
current through the transformer primary.
You need to know the inductance of the primary at the current flowing
through it to determine your low end limit.  Inductance drops when current
flows through the winding.  You figure this low end limit out by knowing the
source impedance coming from the tube plate and knowing the inductance of
the transformer at the standing current.
The 9661 won't explode if you use it to load the plate - in other words,
don't cap couple to it -  but you would want to check what's happening at
the low end.
If you do use a cap to block the DC from the primary (to avoid current
flowing through it and thus not dealing with a lowering of inductance)  then
you will loose headroom if you are then loading the plate before it with a
resistor.  Unless, that is, you raise the H.T. for that tube plate (not the
whole amp) by about a factor of  2.  If you "impedance couple" with a choke
loading the plate then you won't loose headroom.  You just need to, again,
make sure the choke has sufficient inductance for the impedance in hand.
I haven't used the CMO-30/600 but if it has a gap and the inductance is at
least 60 Hy with 7mA, then it will work in the circuit.
"

i will check to see if the CMO-30/600 is gapped and has the specs winston mentions.
any ideas,advice, etc on this build is appreciated. if anyone has any info on the original PSU that powered these moduals please share.

 
Yeah, you don't want a gapped trafo. just needs to have 55mH L with the 7mA on the primary. That would be the most "accurate" reproduction, and not what the new UA repro does, as far as I understand Winston's comments.  My guess is a relatively large, ungapped, 30K/600 trafo would work fine. I ordered some Cinemag stuff recently and forgot to ask them about this. I guess you could test out an edcor and see what happens... cheap test..

About the PSU, all I know is B+ should be 300V. Heaters for these tubes are 12V right? 
 
dont know about the 610 but am i wrong to think the heater voltage was probably 12V AC .
mitsos are you getting that 300V number from tube data sheets or some other source. is the 300V the loaded voltage from the PSU or the plate voltage?
P.S. emailed some OT questions to cinemag tonight .i'll let you know what they write back.
 
ouncers are supposed to be good to 8 db, off 1 db at 20 hz,

probably good on the 610, but the 1176 was a no go according to some people in the netherlands
 
The 300V was what Winston said in that thread. Don't know if heaters are AC, I assume so, but many people use DC with other circuits, assumed it would be OK to try here. 

CJ, The 1176 uses the o-12, no? Did early ones use an o-1? You don't happen to have any winding info on the UTC PA-5946?
 
You should post those! you're on a roll this month!  ;D

OT.. while you're digging into your trafo files, can I put in a re-post request? Should be part of this greatest hits collection: profile  You gave me a bunch of info which I thought would be enough for a guy to make me one, but after paying for two f-ed one-offs I gave up...  Maybe 3rd times the charm, but it'd be good to show him pics. Or wind my own.. Gonna get me a cchina winder. Anyway good job on all the trafos you're tearing up lately!
 
yeah when the bench was at work, i had to drive an hour round trip, make coffee, heat the work space in winter, check mail, hack a transformer, drive home,

having this at home is Way better, 10 times the output,
 
mitsos, was busy reading ,researching,thinking and never relized you were the one who posted the quote i placed in this thread.
yeah,300V is coming off the PSU.
not sure where i saw it but the original console had a multiple pad switch. might be needed to keep the pre from overloading with modern mics as ive read it doesnt have much head room.
cj any info on the PA5946 would be great.
 

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