All things LA2a related

[emrr]

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?

 

[emrr]

[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.

 

[dripelectronics]

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,

 

[emrr]

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.

 

[CJ]

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?

 

[emrr]

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.

 

[CJ]

Hmmm Langevin Leveline?

The 670 is correct.

UTC A 26 in reverse.

 

[Jazz]

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.

 

[emrr]

[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.

 

[babyhead]

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.

 

[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...

 

[matta]

[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... [/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

 

[Stagefright13]

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.

 

[Purusha]

I wonder what are my alternative solutions for the Mallory TC72 if I don't find one. Will this expensive solen work just as good or will it effect the sound in a different way?

 

[Stagefright13]

Alliedelec.com has the TC-72's for 11 usd. 483 in stock right now. Plus shipping to Slovenia of course...

 

[Purusha]

Thanks! But what would I gain or loose if I put in the Solen cap instead?

 

[matta]

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

 

[Purusha]

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

 

[guavatone]

What is A11 and A14 and where are they. Turret points?

I've been trying my best to search this monster :twisted:

 

[mcfarlane_audio]

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