#1894021 - 03/28/24 01:59 AM
Re: Need some tubes
[Re: C Jo Go]
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Popmann
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Registered: 05/23/02
Posts: 33090
Loc: Twangville, TN
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I want you to get it fixed so they can tell you what it is...in case my LA610 has the same weakness!! Ha.
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#1894030 - 03/28/24 03:27 AM
Re: Need some tubes
[Re: Popmann]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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I repaired some UA product for Andy, don't recall the model and I hope it is still working lol. It was a bad Op Amp. Looking at used prices for this UA M610 it would be worth repairing. People who do this type of work are like car mechanics who know how to troubleshoot carburetors. UA wouldn't allow purchase of schematics and profit wise UA hopes you just purchase another UA product. Every electronic gadget nowadays is designed to toss.
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#1894031 - 03/28/24 03:27 AM
Re: Need some tubes
[Re: Popmann]
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C Jo Go
EMERITUS ~ VS Roland
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Registered: 11/05/01
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Loc: carmel valley,ca
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I want you to get it fixed so they can tell you what it is...in case my LA610 has the same weakness!! Ha.
Will do -- really wanted a LA610 MkII
-- but think I am done with tube stuff
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#1894043 - 03/28/24 04:06 AM
Re: Need some tubes
[Re: C Jo Go]
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MadGuitrst
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Registered: 06/10/99
Posts: 20877
Loc: 3rd Stone From The Sun
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Was the opamp socketed, Smelly? Also, was it common and readily available?
Hey CJo, what if it's a transformer? Will you be done with transformer stuff too? And what if a resistor burns up in your next unit? Will you go to surface mount gear after that? You just found out it wasn't a tube, so, why shun all tube gear now? Maybe you just don't want another UA piece.
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#1894046 - 03/28/24 04:12 AM
Re: Need some tubes
[Re: MadGuitrst]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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Was the opamp socketed, Smelly? Also, was it common and readily available?
No, it was a surface mount 14 pin IC and available at Digikey.
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#1894057 - 03/28/24 05:01 AM
Re: Need some tubes
[Re: C Jo Go]
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MadGuitrst
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Registered: 06/10/99
Posts: 20877
Loc: 3rd Stone From The Sun
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Thanks for the explanation, Smelly. But what I meant was, was the opamp socketed or soldered in (or maybe I' misunderstanding you).
CJo, if you need more gain, run out from one channel and into the other. While it's a different type of unit, I sometimes do it with Sebatron (even if I don't need the gain - it allows me to drive one channel a bit if I want, gives gobs of gain if I want for a ribbon, etc.). Just run from the line out of one channel into the line in of the next.
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"Seek first to understand, then to be understood."
- Dr. Stephen R. Covey
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#1894060 - 03/28/24 05:44 AM
Re: Need some tubes
[Re: MadGuitrst]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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Thanks for the explanation, Smelly. But what I meant was, was the opamp socketed or soldered in (or maybe I' misunderstanding you).
It was soldered. The were no socketed components in the unit.
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#1894061 - 03/28/24 05:58 AM
Re: Need some tubes
[Re: Ismellelephant]
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C Jo Go
EMERITUS ~ VS Roland
Loquacious Planeteer
Registered: 11/05/01
Posts: 36568
Loc: carmel valley,ca
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Thanks for the explanation, Smelly. But what I meant was, was the opamp socketed or soldered in (or maybe I' misunderstanding you).
It was soldered. The were no socketed components in the unit. 
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#1894084 - 03/28/24 12:11 PM
Re: Need some tubes
[Re: C Jo Go]
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MadGuitrst
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Registered: 06/10/99
Posts: 20877
Loc: 3rd Stone From The Sun
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Jamie, I hear you about nut width - I'm not a fan of narrow width's either. Of course, we adapt as needed. Still, it's a curious decision on Sire's part, IMHO. Very cool of Cajun to lend you the guitar, though. He's a good guy.
Smelly, it's awesome that you could repair that for Andy. Desoldering ICs/opamps can be a pain and a little bit tedious, especially for larger ones. I saw a video of a guy who had a desoldering pump, that is, a soldering gun that had a large(r) tip that was hollow so that the pump could suck the solder up/out. It was really clean and appeared so much easier than a separate pump and/or a wick.
That said, it's a simple thing for a repair shop. I wonder how much they'd gouge CJo for, though, if that was the problem. It shouldn't cost more than an hour or so of bench time, and the cost of the opamp, but, of course, it will.
Hope the UA can be readily repaired -- just "pop" in and ready to go
Surely they can repair it, but it will cost you. How much? You're about to find out. Who knows? Maybe you'll get lucky. If they'll do a free estimate, it's certainly worth finding out. They might have a minimum price, though, for an estimate. Then, you'll have a decision to make. If that cost is rolled into the repair, it might just be worth doing it, rather than having an expensive door stop for your studio. Only you can say.
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MadGuitrst has left the building....but not before committing acts designed to offend the senses....
"Seek first to understand, then to be understood."
- Dr. Stephen R. Covey
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#1894111 - 03/28/24 01:33 PM
Re: Need some tubes
[Re: MadGuitrst]
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Popmann
Loquacious Planeteer
Registered: 05/23/02
Posts: 33090
Loc: Twangville, TN
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I think the thing you repaired for Andy was a 710 Twinfinity thing….shall we call that “a new school UA design”. These are Putnam preamps from the 60s….mine taking the front of the Putnam preamp and replacing the whole output stage with that of an LA2A-similar era of design.
I dont think theres a surface mount component in mine. CJo’s is even an older version of the preamp. I remember thinking (after exam) that mine is probably a cold solder joint somewhere. I think that determination was made because wiggling some wires produced some noise. Super electro scientific, I know! Hats where my electronic troubleshooting skills end-does shit power up? Do tubes light? Anything look burned or melted? Caps bulging? Yes, yes, no, no.
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#1894144 - 03/28/24 03:33 PM
Re: Need some tubes
[Re: Popmann]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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Yes it was a 4-710d 4-channel Microphone Preamp & Compressor. And only 1 ch was not working, So without a schematic what you do have is 3 working channels, so compare signals against the bad channels.
Cjo says his is "not working" Yours is "dead".
Not working doesn't say much, and dead to me is no lights, no power like it isn't plugged in at all. Or is yours not working?
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#1894152 - 03/28/24 04:10 PM
Re: Need some tubes
[Re: Ismellelephant]
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Popmann
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Registered: 05/23/02
Posts: 33090
Loc: Twangville, TN
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It’s not passing audio from any input to the only outputs. Lights. Tubes light. Nothing even makes hiss increase, so I I feel like it the signal was stopping early, it would still amplify the self noise some going from off to full output level-doesn’t. DI, line, or mic input. I feel like also never registers any level on VU.
The compressor stopped reducing gain years ago. So I kept it in bypass, because I always hated the sound anyway—but the output stage IS the la2a output circuit…variable pot on the big “knob” to the far right.
I feel like in internal exam with wooden skewer while on, I could get some crackle noise on the output by wiggling some wire molex like connectors…but, was passing the test signal that I was feeding into it during the crackles….so….eh….it didn’t seem like those wires being sketch was THE issue….
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#1894160 - 03/28/24 04:34 PM
Re: Need some tubes
[Re: Popmann]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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Looking at the UA M610 it is a one channel device? I would use a signal generator and a audio tracer and follow the signals path, based on a schematic, and see where the signal drops off. As well as checking all supply voltages. And UA doesn't do schematics so that would make it tricky.
I am always willing to try repair for free when there is nothing to lose.
Is this your device?
https://www.uaudio.com/hardware/la-2a.html
If so this site has schematics possibly
http://www.recproaudio.com/diy_pro_audio/teletronix_la2a.htm
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#1894170 - 03/28/24 05:05 PM
Re: Need some tubes
[Re: Ismellelephant]
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Dot
Planeteer
Registered: 12/13/00
Posts: 9013
Loc: New York
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C Jo, I'd stay away from anything heavy like a 1073-based preamp. It's too colored and the resolution is slow.
I'd recommend a Focusrite ISA Two. This is Rupert Neve designed with a Lundahl input transformer. IMO, ISA is the best general mic pre on the market. When I had stacks of preamps available, I used ISA for an entire album with multiple instruments and voices. It just does the job perfectly.
For heavier music, sure we can get into Neve and API stuff, and for critical and classical in great acoustic spaces with high resolution there's Millennia, and even Mad's John Hardy and Jensen-transformer based SCA J99 recommendation is more in the range you want.
I wouldn't bother with EQ either. The ISA has enough sound shaping tools and 80dB of gain.
Here's one on Reverb for $679. Even brand new the price is only $899. You could also look at an ISA 428 for $1000. One in CA for $1099.
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#1894176 - 03/28/24 05:27 PM
Re: Need some tubes
[Re: Dot]
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Popmann
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Registered: 05/23/02
Posts: 33090
Loc: Twangville, TN
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No, that's the original 60s compressor they used for the output section.
https://www.soundonsound.com/reviews/universal-audio-la610
My understanding is that they took a 610 preamp circuit...without it's output amp and put a La2a's optical circuit and output amp. Later revisions they had to rework because people wanted a break--so, they modified it to have a preamp output line amp and compressor line input--thus the blackface "mk2"...then, I think they stopped making it because it can't be ROHS compliant due to requiring the old stock only tube for the compressor part of the circuit. They decided to discontinue it rather than try to redesign it to use a modern production compressor tube.
I looked--I was wrong--there is a single IC.
I've seen someone did a schematic for the mk2, with various mods to make it perform more linearly....but like I said--very redesigned circuit. I've never touched a mk2.
I could probably get more scientific. The PCB is well labeled...connectors for "preamp out"....to a daughterboard...to "limiter in"...I've got continuity from the input to limiter in...nothing on the limiter out or output--no matter whether I put it in comp, limit, or bypass. Note that "bypass", doesn't take the compressor out of the circuit-it takes the gain reduction out--it's "gain" is still the output amp of the unit since again--it was an attempt to sort of split the units. Unlike the 6176, which has always BEEN a mini version of an 1176 internally normalled to a 610 preamp. Both usable individually. This was a FrankenUnit...
I need to hook a test signal back up...I did that initially, but I was really expecting to just find a bad switch connection or open pot or something...bad tube....
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#1894185 - 03/28/24 05:49 PM
Re: Need some tubes
[Re: Popmann]
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Popmann
Loquacious Planeteer
Registered: 05/23/02
Posts: 33090
Loc: Twangville, TN
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Check it...I DO have a burned spot. Sort of...I'd have never noticed it, were it not for the pic in this thread....
https://recording.org/forum/pro-audio-re...-voltage-points
R71 resistor. Mine doesn't look NEARLY that burned up, but on bright light inspection, it's definitely a little bit burnt on the PCB. Both sides of the resistor on the board it's discolored. Resistor itself seems clean/fine.
That DOES seem to be about "compressor not working"...rather than signal not passing, but still...better than the nada I came up with on first inspection years ago! Ha.
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#1894188 - 03/28/24 05:53 PM
Re: Need some tubes
[Re: Ismellelephant]
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C Jo Go
EMERITUS ~ VS Roland
Loquacious Planeteer
Registered: 11/05/01
Posts: 36568
Loc: carmel valley,ca
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Cjo says his is "not working" Yours is "dead".
Not working doesn't say much, and dead to me is no lights, no power like it isn't plugged in at all. Or is yours not working?
Yes, lights come on -- no sound -- new (tested) tubes placed in yesterday -- no output
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#1894189 - 03/28/24 05:54 PM
Re: Need some tubes
[Re: Popmann]
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Popmann
Loquacious Planeteer
Registered: 05/23/02
Posts: 33090
Loc: Twangville, TN
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Thanks to Bing AI, here's replacement T4 cells, tested to be slow (ala the vintage units) if that ends up being the problem:
https://sites.google.com/view/curiousaudio/catalog/new-t4b-opto-el-panels
I seem to remember when I talked to UA, it was a pretty expensive OEM part "if that turns out to be the problem". Because unlike the little cans they make for the actual 2a repros, this is in a little black box on the PCB. I don't think they ever used that again. But, those cells, I think are the raw stuff IN the box, which screws apart...
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#1894192 - 03/28/24 06:02 PM
Re: Need some tubes
[Re: Ismellelephant]
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C Jo Go
EMERITUS ~ VS Roland
Loquacious Planeteer
Registered: 11/05/01
Posts: 36568
Loc: carmel valley,ca
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Looking at the UA M610 it is a one channel device? I would use a signal generator and a audio tracer and follow the signals path, based on a schematic, and see where the signal drops off. As well as checking all supply voltages. And UA doesn't do schematics so that would make it tricky. I am always willing to try repair for free when there is nothing to lose. Is this your device? https://www.uaudio.com/hardware/la-2a.htmlIf so this site has schematics possibly http://www.recproaudio.com/diy_pro_audio/teletronix_la2a.htm
Wish I owned such " fancy" tech gear > this is the extent at our studios 
Edited by C Jo Go (03/28/24 06:03 PM)
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#1894193 - 03/28/24 06:09 PM
Re: Need some tubes
[Re: C Jo Go]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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Looking at the UA M610 it is a one channel device? I would use a signal generator and a audio tracer and follow the signals path, based on a schematic, and see where the signal drops off. As well as checking all supply voltages. And UA doesn't do schematics so that would make it tricky. I am always willing to try repair for free when there is nothing to lose. Is this your device? https://www.uaudio.com/hardware/la-2a.htmlIf so this site has schematics possibly http://www.recproaudio.com/diy_pro_audio/teletronix_la2a.htm Wish I owned such " fancy" tech gear > this is the extent at our studios
I used to have "fancy gear" access when working. A signal generator and signal tracer can be built cheaply though but with limited functions. Usually good enough most of the time for me.
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#1894194 - 03/28/24 06:12 PM
Re: Need some tubes
[Re: C Jo Go]
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bear
Planeteer
Registered: 10/25/99
Posts: 6539
Loc: abq,nm,usa
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Some confusion going on here I think - Pop is talking about HIS unit and CJo is talking about his??
I do not believe CJo's unit has a compressor does it? I might be wrong, I thought it was just a preamp.
The electroluminescent panel would be used in a compressor circuit.
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#1894195 - 03/28/24 06:12 PM
Re: Need some tubes
[Re: Popmann]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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Thanks to Bing AI, here's replacement T4 cells, tested to be slow (ala the vintage units) if that ends up being the problem: https://sites.google.com/view/curiousaudio/catalog/new-t4b-opto-el-panelsI seem to remember when I talked to UA, it was a pretty expensive OEM part "if that turns out to be the problem". Because unlike the little cans they make for the actual 2a repros, this is in a little black box on the PCB. I don't think they ever used that again. But, those cells, I think are the raw stuff IN the box, which screws apart...
Funny thing about the older units, when compression stopped working, usually the Opto Cell T4, was the culprit. You should be glad you don't have the vintage unit, although the Opto parts are
available at times. Yikes
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#1894196 - 03/28/24 06:13 PM
Re: Need some tubes
[Re: bear]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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Some confusion going on here I think - Pop is talking about HIS unit and CJo is talking about his??
I do not believe CJo's unit has a compressor does it? I might be wrong, I thought it was just a preamp.
The electroluminescent panel would be used in a compressor circuit.
Yes it gets confusing.
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#1894200 - 03/28/24 06:18 PM
Re: Need some tubes
[Re: bear]
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C Jo Go
EMERITUS ~ VS Roland
Loquacious Planeteer
Registered: 11/05/01
Posts: 36568
Loc: carmel valley,ca
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Some confusion going on here I think - Pop is talking about HIS unit and CJo is talking about his??
I do not believe CJo's unit has a compressor does it? I might be wrong, I thought it was just a preamp.
The electroluminescent panel would be used in a compressor circuit.
Yes, our is the straight single pre amp -- we use a Manley limiter in line
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#1894206 - 03/28/24 06:36 PM
Re: Need some tubes
[Re: Popmann]
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Ismellelephant
Loquacious Planeteer
Registered: 07/10/01
Posts: 56076
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Check it...I DO have a burned spot. Sort of...I'd have never noticed it, were it not for the pic in this thread.... https://recording.org/forum/pro-audio-re...-voltage-pointsR71 resistor. Mine doesn't look NEARLY that burned up, but on bright light inspection, it's definitely a little bit burnt on the PCB. Both sides of the resistor on the board it's discolored. Resistor itself seems clean/fine. That DOES seem to be about "compressor not working"...rather than signal not passing, but still...better than the nada I came up with on first inspection years ago! Ha.
Some large resistors do get warm, but it wouldn't hurt to lift a lead to check it out. One plus, this unit seems to have a lot of admirers so a lot of online content. Also, the used market is around $1000, so if taken to a shop in Nashville and even if it cost $200-300 it might be worth it.
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#1894227 - 03/28/24 07:20 PM
Re: Need some tubes
[Re: Ismellelephant]
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Popmann
Loquacious Planeteer
Registered: 05/23/02
Posts: 33090
Loc: Twangville, TN
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Sorry--I can bow out. You guys talk about Cjo's.
Correct, same preamp section...different units.
Re:used prices...it's funny...I've seen them SIT here locally for sale for $600 fully working and not moving. I never asked what Herr Doktor sold his for years back in his big selloff--but, I know he was SUPER disappointed in what it went for--and he loved it SO much...BUT...that era of gear has probably gone up in value. Unlike the axe, this really was always intended for me to fix when the opportunity or need arose...
I DO think whatever they did to make it "brighter" than the original 610 (to better match the dark opto) made it more useful. It was actually more transparent sounding to my ear than the Neve and API "vintage iron" preamps I have had around here.
Sorry for derailing, Cjo.
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#1894240 - 03/28/24 08:33 PM
Re: Need some tubes
[Re: FalconEddy]
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C Jo Go
EMERITUS ~ VS Roland
Loquacious Planeteer
Registered: 11/05/01
Posts: 36568
Loc: carmel valley,ca
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Not great customer support these days -- answering no calls -- so will continue to email them >>
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#1894248 - 03/28/24 09:02 PM
Re: Need some tubes
[Re: Popmann]
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C Jo Go
EMERITUS ~ VS Roland
Loquacious Planeteer
Registered: 11/05/01
Posts: 36568
Loc: carmel valley,ca
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.
I DO think whatever they did to make it "brighter" than the original 610 (to better match the dark opto) made it more useful. It was actually more transparent sounding to my ear than the Neve and API "vintage iron" preamps I have had around here.
Sorry for derailing, Cjo.
Stay on board POP -- the more related info :: the better --thanks
I do like the UA "sound" - wonderful not just on vocals ++ but DI ---totally different than out Manley
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-- checking into a estimate >> might cost more to fix /\ than its worth 
