All things LA2a related

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
no, not audio directly into the case from tube through cap to ground; swapping the relative positions of the output cap and the output transformer with one another. Same end result; no DC flowing through transformer, but audio seeing transformer before seeing cap. Biggest difference, and I'm talking about the UTC or similar hi-voltage rated iron, is transformer having DC potential. The UTC is rated to handle the potential. I'm certain the Edcor isn't.

I'm a little amazed in 108 pages that no one's tried to get a better deal on an LS-10 or LS-50 and used them instead. They're sometimes cheaper these days, and certainly better sounding AND more level appropriate. I can't begin to imagine why someone would pay over $150 for an HA-100X over an LS-10. I've won LS-50's as cheaply as $50 in the last six months. Why would I want to pay for an A-24 in this situation?
 
[quote author="raysolinski"]I built Drip's unit with edcor's on the input and output....just for giggles I put a UTC A25 on the output last night...REALLY different...the UTC was way more thick and vintage sounding..I prefer the Edcors hands down ..I could see a place for the UTC but the Edcor is much cleaner..I was suprised how different the two tranny's sounded..I was expecting subtle differences...

Cheers,
Ray[/quote]


I'd never expect an A-25 to compete with an A-24 here. I'd only consider it to be a purposeful sonic downgrade.
 
hmmm that sounds like it's worth exploring ,
im kinda bored now that im done with the v2 pcb.

havent tried the LS series , it's probably one of those secrets
people keep.

best

g,
 
LS only seems to be a secret among recording types; I have no idea why. Too big? The taint of the hi-fi people liking them? They got something right. They used to cost way more, but the recording people have pushed the A and HA stuff over the top (since it used to be cheap) while totally ignoring the LS stuff.


Somewhere in this thread, use of backwards A-24 as input with lower step-up gain is mentioned by someone and not reported on further. I've got 1970's RCA preamps using A-24's as inputs in an API 2520 based circuit, so it's been done before.
 
LS 10, Gibson Hummingbird, same deal across the pond.
No listen, just stare.
Thats why. Check evilbay.

A 10, HA 100 twin sec is art work.
4 Pies = 16 times less stray C.
New UTC has 2 Pies = 4 times less.
Somone wanted 3 pole, ended up with Bessel vacuum cleaner, vacuums up the highs, that is!



LS much easier to wind.

Can you name a compressor that uses backwards UTC?
 
Nice riddle/poem CJ!


Compressor using backwards UTC? Hmm...
guesses:

UA 175/176 family interstage? don't have the data in front of me

Fairchild 660/670 sidechain amp section? don't have the data in front of me; think not right.


And a question for you: Guess the mono limiter using (3) LS-10X's and an LS-63.

Hint: Uses a pair of #46 bulbs as variable resistors in a bridge shunt circuit (in between two separate amp sections), along with a feedback based variable-mu front end. Actually, that gives it away if you've ever seen it.
 
I have some sprague oil filled caps 0.1uf 400v I wanted to try these has anyone done it yet? any feedback?

Also the important cap 10uf/450v I have a sexy looking Angela cap that I am tempted to try, but it is not electrolytic it is Metalized Polypropylene. It can be seen here. Wondering if this would work?

http://www.angela.com/

Did not mean to pop in in the middle of things. I just noticed the posting of all La2a things should be posted here.
 
[quote author="CJ"]Hmmm Langevin Leveline?

The 670 is correct.

UTC A 26 in reverse.[/quote]

Ah! didn't realize there was an A-26 in the 670.

Correct answer is Gates 28-CO. Most versions instead use two HA-100 and an A-11 instead of the three LS-10.
 
Hey All.

Having just finished a drip LA-2a, I thought I had a problem with the threshold. It seemed that I had to hit it pretty hard to make it work. Being a tweaker, I thought of picking up the side chain before the 68k R6 and adding a 33.1k (R6.5?) to the GR pot. It acted like a nuke, almost worthy of a switch... The scheme didn't seem as useful as the normal configuration so I left it. I have a vintage looking panel that I dont want to muck up. I might do this on #'s 3 & 4 LA-2as, though. The next one on the bench is with the Jensen output. I will compare the two and then attempt two in one box... joy.

You all Rock.
 
I have finished my LA-2A with Sowter iron and ver. 10 PCB and just read a thread at Gearslutz
where Fletcher mentioned that todays UA version doesn't sound as the real Teletronix or Babcock
LA2A which are the best sounding LA-2As you can get in his opinion. Anyway I wonder, does
anyone know what transformers are in UA version, Sowter maybe?

I wish someone could compare the Drip version with Sowter iron to the real Teletronix or Babcock LA2A... :cool:
 
[quote author="Purusha"]I have finished my LA-2A with Sowter iron and ver. 10 PCB and just read a thread at Gearslutz
where Fletcher mentioned that todays UA version doesn't sound as the real Teletronix or Babcock
LA2A which are the best sounding LA-2As you can get in his opinion. Anyway I wonder, does
anyone know what transformers are in UA version, Sowter maybe?

I wish someone could compare the Drip version with Sowter iron to the real Teletronix or Babcock LA2A... :cool:[/quote]

UTC Reissues, ALOT more expensive than the Sowters, you can buy them from UA as spares, about $300-$400 a set I think.

And Greg HAS compared them, if you read his notes over the various threads when he deisgend the board he bought an ORGINAL Tele unit and a Reissue to compare them and make tests, he will tell you how different they sound.

Cheers

Matt
 
Studio.electronics on ebay sells the reissue transformers. They are also the ones that sucked up all the last Urie t4b's. Of wich I purchased 1. Think the output was like $200 and the input $150. But they have a cheaper input solution I believe. They ARE reputable and I did get a sealed NOS Urie t4b.
 
Thanks! But what would I gain or loose if I put in the Solen cap instead?

A different sound....

If you read Greg's (Drips) thread he used a Sprague and found it didn't sound like his LA-2A reissue, tonally it was different, he then added the Mallory... BINGO!

It didn't sound BAD, just not the same...

I suspect sonically the Solen would be a smoother sound, poly caps normally are, just around the time the LA-2A was built/designed there were not caps of that size that would easily fit the unit, and also would have cost alot more.

Since you already have a working LA-2A with a TC72 why not get a Solen and A/B it?

Seems easy enough to do, then you can let us know what you think.

Cheers

Matt
 
Thanks Matt. I might do that but it will be a test with my first unit as the second won't have the same PCB, T4B and neither the same tubes.

BTW, what tubes do you guys prefer in this project? I plan to go with JJ this time.

It's sooooo long thread so I don't feel inspired right now to go through all the way :oops:
 
What is A11 and A14 and where are they. Turret points?

I've been trying my best to search this monster :twisted:
 
ok so after paroozing all 110 pages of this thread, i have a question, my la2a is working great, save for one problem, its quiet, that is to say, im loosing alot of signal somewhere, at max it pushes about -7 db output (with a 0db input), with no reduction, any bright ideas seeing as ive checked all my voltages to be correct..?? thanks eveyone
 
Back
Top