la-3a reissue

[soundguy]

its up on the Ua page right now. It says it has a class a amplifier, wtf? didnt the originals use an 1109 output amplifier? I would love to see the back, if they left that comp/limit switch back there, Im gonna laugh. I think the mod they talk about in the copy is the clearmountain thing.

AES this fall is going to rule.

dave

 

[Bryson]

I wonder if the value of the originals will go down, like with the 1176 and LA2a.

 

[soundguy]

if the new la3's sound decent and dont have a bunch of stupid mistakes like the reissue 1176, I cant imagine half a reason to own an old la3, they really werent made particularly well. If its really class A, I think its different, Im nearly positive the old la3's used the 1109 output circuit which was a/b. Im hearing the retail on these is over $2k for a pair, so its not a bargain compared to an old one by any stretch, thats what I see old ones sell for.

dave

 

[Lindell]

[quote author="soundguy"] Im hearing the retail on these is over $2k for a pair, [/quote]
It's $3k for a pair... $1495 each

 

[Bryson]

[quote author="soundguy"] Im nearly positive the old la3's used the 1109 output circuit which was a/b.
dave[/quote]

Yes....like the later 1176.
The early 1176 class A output was like an 1108.

 

[pucho812]

I am waiting for the new 176 compressor. if they ever make that and make it well i am there.[/quote]

 

[Tekay]

Does anyone know why the positive voltage is feeded to a separate winding on the output transformer?
V+ is feeding the winding through a 24K resistor, winding in revers!

 

[tardishead]

hey Soundguy - what were the mistakes in the reissue 1176 out of interest.

I think its a joke how they can charge more for a reissue LA3A. still it would probably be pretty cool with the class A output stage. its because they have a **** load of parts and transformers for class A stage in the 1176.
I wonder what they did for the interstage transformer. I think that a few people looked into DIY LA-3A but nobody could get the info for the interstage transformer. Maybe we should try and ressurect this. did anyone get any further?

 

[wilebee]

I'm suprised that Sceneria hasn't come up with a Bloo la3 Wil

Wilebee

 

[soundguy]

there were biasing errors which were discussed here, the front end is also redesigned for the newer units. probably totally right about tthe use of the class a stage because they had parts. I wonder if they even bothered with the interstage transformer at all? Seems kinda lame to redesign a box for convenience circuit wise and then do something stupid like putting switches on the rear panel just so it looks like an old one so you can take advantage of your customers. I dont want to jump to any conclusions, but its not like it DOESNT look like that, right? Why bother making it troublesome to use like an old one if you've already gutted it and put a totally different circuit in there? That is totally illogical to me. Im looking forward to checking one out though. It actually might be cool with a different output stage. Makes you wonder why youd need that clearmountain mod though...

dave

 

[SonsOfThunder]

Dave,

According to the schems on the JBL site, the La3a had the same (or a very similar) o/p arrangement as the 1109, which appears to be push-pull, class AB. The "transformer" labelled as T4 (this is confusing to label it this way!!) appears to be a tapped inductor that is driven by a very similar circuit as the output and drives the EL panel. That shouldn't be difficult to mimic if you had a vintage unit to measure the inductances.

Who knows what the reissue REALLY is?

HTH!
Charlie

 

[pucho812]

Bob says it's not his mod it is the ed evans who I dunno who that is.

 

[Rogy]

Here's a link to the Ed Evans mod.

http://users.pandora.be/Rogy/LA3A%20Mods.pdf


Anyone has info to share about the Bob Clearmountain mod? I would love to know more about it...


Regards,


Rogy

 

[Guest]

inside the new ones......

http://www.uaudio.com/webzine/2005/April/index.html

 

[smilinfu]

Jhaible and Gyraf had some wisdom about the sidechain transformer over at this thread.
http://www.groupdiy.com/index.php?topic=692&postdays=0&postorder=asc&highlight=la3&start=0

 

[soundguy]

oh, everyone check that link to the article.

my only quesiton is why is UA advertising this box as class A? Is that phrase so desirable from a marketing standpoint that you'll use it even if your box is not class A? That just doesnt seem honest at all. And their speak in that article of the 1176 being a faithful reissue is hogwash if you happen to buy one say after 2002 or something, the front end is totally different, not re-issued but cre-ated.

dave

 

[Guest]

Anyone has info to share about the Bob Clearmountain mod?

The Ed Evans mod is what is being referred to when people say 'the Clearmountain LA-3A mod'. It has been mistakenly credited to him for quite some time.

I dunno who that is.

Ed Evans was the chief tech at Power Station who came up with the mod.

Am I the only one who finds it irritating that they obviously left the comp/limit switch on the back of the unit?

Zach

 

[soundguy]

no you are not, also, its not annoying, its ******* retarded. why would anyone design anything at any point with switches that get used on the back of the box?

I swear sometimes this stuff is designed by people who have never done a session in their life. "oh, it will look cluttered with all those switches on the front".

it woudl be really horrifying if they chose to use one of those slide switches too, anyone taking bets on that?

dave

 

[chriss]

Tardishead, Smilinfu,

I tried a few times to get info on this transformer on the forum, but didn't get too much feedback. But I now have a fully working sidechain-section of the LA3A.
What you refer to as an interstage-transformer is an output-transformer rellay. The sidechain-path is a little power-amp (5W or so) followed by a 100V-transformer, wich is strangely wired (the secondary side left open). I wrote about it here:
http://www.groupdiy.com/index.php?topic=6829
but noone seemed to notice...

Chris

 

[Helsing]

The EL driver transformer in the Urei BL-40 is 1:10 ratio. I believe it is the same part used in the LA-3a.

Helsing