Author Topic: universal 610 schematic?  (Read 16405 times)

Learner

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universal 610 schematic?
« Reply #20 on: January 18, 2006, 04:11:33 AM »
Would love a copy too if possible??  :grin:
Never power up your circuit witout a face mask!


SUPERMAGOO

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universal 610 schematic?
« Reply #21 on: January 19, 2006, 07:03:36 AM »
http://groupdiy.twin-x.com/displayimage.php?album=40&pos=0

check this link.i fink it is.... :cool:

Learner

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universal 610 schematic?
« Reply #22 on: January 19, 2006, 08:11:12 AM »
hey thanks SUPERMAGOO!!  :thumb:   :grin:
Never power up your circuit witout a face mask!

Brian Roth

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universal 610 schematic?
« Reply #23 on: September 27, 2006, 09:25:57 PM »
CJ...I'd also like to get a copy of the 610 schematic.  I have a 6176 on the bench and the mic preamp is acting up.  Thanks!

Brian  at  BrianRoth   dot   com
Brian Roth Technical Services
Oklahoma City, OK
http://www.BrianRoth.com

Winston O'Boogie

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universal 610 schematic?
« Reply #24 on: September 27, 2006, 09:40:27 PM »
Quote from: "Brian Roth"
CJ...I'd also like to get a copy of the 610 schematic.  I have a 6176 on the bench and the mic preamp is acting up.  Thanks!



Brian, sorry to say but the schematic that CJ has might not help you that much with a 6176.  He has a schematic I redrew from an original '60's era 610 and the 6176 isn't exactly a clone of that.

Brian Roth

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universal 610 schematic?
« Reply #25 on: September 28, 2006, 03:17:29 AM »
Quote from: "Winston O'Boogie"
Quote from: "Brian Roth"
CJ...I'd also like to get a copy of the 610 schematic.  I have a 6176 on the bench and the mic preamp is acting up.  Thanks!



Brian, sorry to say but the schematic that CJ has might not help you that much with a 6176.  He has a schematic I redrew from an original '60's era 610 and the 6176 isn't exactly a clone of that.


Well,  *anything* is better than nothing, since Universal Audio has a "no schematics" policy! <g>

Bri
Brian Roth Technical Services
Oklahoma City, OK
http://www.BrianRoth.com

Winston O'Boogie

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universal 610 schematic?
« Reply #26 on: September 28, 2006, 05:52:13 AM »
Quote from: "Brian Roth"


Well,  *anything* is better than nothing, since Universal Audio has a "no schematics" policy!i


OK then it's here:

http://www.revolutionrecording.com/images/610A-Schematic.pdf


Basic differences betwixt this and the 6176 are the eq, the output stage and the input transformer.  The 6176 also has a MOS/Zener reg for HT (the 2-610 doesn't however) and, if I recall  (it's been a few years), the heaters are 12V instead of 6V as used on the old 610 and the newer 2-610.  
Good luck fixing it, hopefully nothing major.

buschfsu

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universal 610 schematic?
« Reply #27 on: September 28, 2006, 09:53:24 AM »
any idead if this is the identical circuit as in the mono 610 or the 610 solo tabletop units?
thanks
PRR said...
OHM'S LAW. Not as an abstract thing: you should be able to glance at a small circuit and "instantly" know I and V, the way a soccer player glances at the ball and knows the angle and kick

SSLtech

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universal 610 schematic?
« Reply #28 on: September 28, 2006, 10:03:06 AM »
The detail around the LF switch looks wrong; No difference between '+6' and '0' as drawn...

Keef
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

buschfsu

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universal 610 schematic?
« Reply #29 on: September 28, 2006, 10:08:10 AM »
my next question was, is there enough info on this to be buildable as is.  Obviously for personal/educational use only.
PRR said...
OHM'S LAW. Not as an abstract thing: you should be able to glance at a small circuit and "instantly" know I and V, the way a soccer player glances at the ball and knows the angle and kick


enthalpystudios

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universal 610 schematic?
« Reply #30 on: September 28, 2006, 12:03:50 PM »
if adjusted for inflation, a 610 module, new, would sell today for 1508 USD

Winston O'Boogie

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universal 610 schematic?
« Reply #31 on: September 28, 2006, 01:17:01 PM »
Quote from: "SSLtech"
The detail around the LF switch looks wrong; No difference between '+6' and '0' as drawn...

Keef


Looks fine to me:
Two poles for the low switch.   No difference on the bottom (as drawn) pole for the +6 and zero position.  This one's for the bass 'cut' or 'roll' and opens up C13 and R25 which are then in series with the C14 coupling cap and, together with the 250K level pot, are a simple hi-pass.  
The other pole (top one as drawn) does nothing in the -6 and zero position but, at +6, opens up C9 and R21 in the feedback loop and causes less L.F. feedback.  You then gets mo' bass mo' fo'.   :wink:

Quote from: "buschfsu"
any idead if this is the identical circuit as in the mono 610 or the 610 solo tabletop units?
thanks


It isn't.

Quote from: "buschfsu"
is there enough info on this to be buildable as is.  Obviously for personal/educational use only.


The only thing missing on this schematic from the original 610 channel amp is the wiring to the back connector and the stuff for the buss selection.   Unless you're building a desk you don't need that info.  


For the input transformer, use your favourite valve-mic-amp step up or look for a UTC 0-1 if you want original.  

You aren't going to find an original transformer for the output so you'll have to improvise.  You'll need to source a good 7:1 candidate that will take a bit of mA and still have sufficient L for good low end.  There aren't too many of those 'off the shelf' but a quick peek at the usual suspects and I come up with a Lundahl.  I do have all the winding info for the original output, which was also used on the 175, 176 and 177 compressors and a couple of other old UA things, but don't count on me giving it out  any time soon as the paperwork for this, as well as some other blueprints, cost me dearly and I also sacrified an original to verify matters.  
The output transformer used in the current UA 610 derivatives will NOT work in this circuit so buying a 'replacement' part from them won't help.  I'd say Lundahl for clean or some vintage UTC from the junk drawer for more of a vibe... or whatever takes your fancy really?
Other than that, it's good to go.

Edit:  
1. Feed it 300V HT.  
2. Plan on implementing an input pad of some sort unless you like your hotter input signals rather less clean than a fuzz-face.
3. The posted schem is for the 610A which was the unit that was available  for purchase from the old Universal Audio company.   The 610 units as used in the United Western Studio desks where a bit different in the front end (biasing and FB) and also the EQ.  I've also taken a peek at Neil Young's 'Green' board and it too has a few differences in the 610 amp channels.

enthalpystudios

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universal 610 schematic?
« Reply #32 on: September 28, 2006, 02:49:14 PM »
a UTC A-25 is a bit different, but possibly it could bu used at 15K:250 or 15K:333 for a close ratio to the one in the schem....  it'll do 8mA unbalanced dc.

would it have enough L for the app?

A26 would probably be better, but doesnt take any dc....  

also, is the 8mA in an A25 enough headroom for this output?

SSLtech

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universal 610 schematic?
« Reply #33 on: September 28, 2006, 02:54:04 PM »
Quote from: "Winston O'Boogie"

Looks fine to me:
...
The other pole (top one as drawn) ... opens up C9 and R21 in the feedback loop and causes less L.F. feedback.  You then gets mo' bass mo' fo'.   :wink:

Not as drawn... you'd have to lose the connection to the common middle terminal to do what you describe... unless I'm reading the actuation of the switch wrongly...

Keith
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

Winston O'Boogie

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universal 610 schematic?
« Reply #34 on: September 28, 2006, 03:07:54 PM »
Quote from: "SSLtech"

Not as drawn... you'd have to lose the connection to the common middle terminal to do what you describe... unless I'm reading the actuation of the switch wrongly...

Keith


Ah!  Now I see what you think you're seeing...I think? -  This isn't an 'on-off-on' toggle, it's a rotary switch.  The grey rectangle to the left is the wiper and there are three discrete positions.

SSLtech

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universal 610 schematic?
« Reply #35 on: September 28, 2006, 03:23:19 PM »
AH. -Right. I read it as a 'slide' switch (that's the symbol that I use for a slide) -It looks a lot more like a DPDT center-off slide switch as drawn, So I expected the grey 'slide' part to 'bridge' with its neighbours.

Okay, as a rotary, with the common as the grey rectangle, contacting each of the three circles individually in sequence, then it will indeed work as described.

Phew! -I thought I was mad for a minute.

 :twisted:

Keef
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

Gus

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universal 610 schematic?
« Reply #36 on: September 28, 2006, 03:24:33 PM »
output section kind of looks a little like

http://www.larryseyer.com/content/view/59/39/

Winston O'Boogie

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universal 610 schematic?
« Reply #37 on: September 28, 2006, 03:31:34 PM »
Quote from: "SSLtech"


Phew! -I thought I was mad for a minute.

 :twisted:

Keef


You had me going for a minute too  :thumb:

Quote from: "Gus"
output section kind of looks a little like...



Yes a little.  I seem to remember Paul Stamler saying the input stage is very similar to a Dynaco pre amp as well.

A lot of these older circuits seem to have elements that look to have been lifted straight from valve data manuals.   I have a UK Mullard one from 1959 (same year as the REDD47 was designed) and it contains pretty much the exact EF86 input stage for the REDD.  Maybe this and the Dynaco and the BA-2A is just an RCA tube manual circuit?  Then there's the 'White' output stage for the LA-2A which is in Howard Tremaine's  book...

Quote from: "enthalpystudios"

...also, is the 8mA in an A25 enough headroom for this output?



Don't know the max signal of the A25 but the amount of standing DC it'll take without keeling over really just affects the low end distortion, unless you push it way too much.  I recall about 5-6mA in the last 6072 half so it's probably fine.  Worth a shot anyway.
15K:333 is a fine ratio if you load the 2ndary with no less than 600R but you should check frequency response as you're more than 15% (my rule of thumb) out of specified Z.

pstamler

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universal 610 schematic?
« Reply #38 on: September 28, 2006, 03:51:51 PM »
Quote from: "Winston O'Boogie"
Yes a little.  I seem to remember Paul Stamler saying the input stage is very similar to a Dynaco pre amp as well.

A lot of these older circuits seem to have elements that look to have been lifted straight from valve data manuals.   I have a UK Mullard one from 1959 (same year as the REDD47 was designed) and it contains pretty much the exact EF86 input stage for the REDD.  Maybe this and the Dynaco and the BA-2A is just an RCA tube manual circuit?  Then there's the 'White' output stage for the LA-2A which is in Howard Tremaine's  book...


It's essentially the output stage from the Dynaco PAS preamp, with a few minor changes. I've seen essentially the same design elsewhere -- Marantz Model 7 high-level stage? -- but I think it originated with the Dynaco. I haven't found it in any of the RCA tube manuals disintegrating around the house.

Peace,
Paul

CJ

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universal 610 schematic?
« Reply #39 on: September 28, 2006, 10:47:11 PM »
UTC A -25?


hmmmmm, lets see....

cj constants say B max = 2.42 * 10^8 E/(Area in^2)(Turns Squared)

Now all we need is the cross area of the core in inches, the turns, and the applied rms....I guess you would need a blueprint, unless somebody has been inside one of those things....
.
.
.
Wait, I have!  Thats a twice stack 50 FG lam, half nickel, and 5000 turns on ther primary.
FG lam has 1/2 inch tongue, so twice stack = 1/2 time 1 = 1/2 square inch.
Turns squared is 25,000,000, so

B max = 2.42 * 10^8 E/(0.5)(25,000,000) = 2.42 * 10^8/12,500,000

B max = 0.01936 times your rms volts on the plate of the ay7.

Lets say you are close micing Pavarotti for the full swing of say 300 volts RMS, that ought to give us some leeway...

300 time 0.01936 = 5.808 kilo gausses, just perfect for 50/50, which has a flux pain load of 10 K gausses.

But wait, you know what that dc does to an SE xfmr, so derate it by at least least 50% and we should have a nice, "warm" transformer sound at full wada.

Whats with the 8 ma? My manual says 3 ma for an ay7?

Lets see if the turns on the A 25 match the chart:

I saw 900 t of sec, and 5000 t of pri.

If the 900 t is supposed to be 500 ohms out, 5000/900 = 5.55 turns.
Turns squared is impedance, so 5.55^2 = 30.86.

30.86 time 500 is your plate load, thats 15,430 ohms pri imp.

What does the book say? My site's down rt now.
If I can't fix it, I can fix it so nobody else can!
Frank's- www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar- http://tdsl.duncanamps.com/schematics.php


 

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