FEELER: LA-3A - Dual Mono/Stereo 2U Design (AKA The SA-3A) - PAGE 6 TO PRE-ORDER

PLEASE SEE PAGE 6 FOR PREORDERING.

Note: Going through some marketing mumbo jumbo:  Official release name of this design is now the SA-3A.

This was supposed to be a secret, I've been working on it for over a month now, some of you already know about it but most don't.  Just ran it by Peter, and since he just unleashed his 51X version today I thought I'd do the same with my 2U design and make today the day of the LA-3A's.

For you guys that don't have a lunchbox, I present to you my new 2U LA-3A design, aka the SB-3A.





Highlights:

It can be built as a single mono or dual mono with stereo link and share the power supply from the first board (power supply is located on-board).

Plenty of room for polypro caps in the audio chain.

Transistor pair in the audio chain can be either matched 2N5089's like in the original, LM394, MAT02, or MAT12 (which are now in production - I have a couple samples on the way).

Circuits/voltages were kept very faithful to the original for all you audiophiles, with the following minor enhancements:

-True bypass added
-Power supply was changed to modern regulators to allow for use with a standard toroid.  Also more stable this way.
-There original is sort of wiring intensive, with alot of shielded wire, daisy chaining switches/pots, and tacking on resistors on the pot tabs, etc.  For my version - the wiring was very simplified and cut in half with the addition of a couple relays.  All components now mount on-board and all pots/switches wire directly to and only to the board.
-The infamous "mod" was incorporated and is switchable.  
-HF cutoff moved to the front and you can either mount a pot on the front panel, or put the pot on board and put a switch on the front to toggle between "flat" and a HF Boost.
-Output terminated with 600ohm onboard.

Yummy  ;D

When will these be available?


Very nice work!

Dam you ! a race to the finish ?
this ensures i'll be building at least one version
[ like i need more to finish or pay for ]
A kit will go a long way to making it easy for the lazy
or ensuring completion for the busy

Kits will exist mon ami.

okgb said:

Dam you ! a race to the finish ?
this ensures i'll be building at least one version
[ like i need more to finish or pay for ]
A kit will go a long way to making it easy for the lazy
or ensuring completion for the busy

Click to expand...

Haha, nah, no races.  Like I said for the 51X crowd it looks like Peter's well on his way with a wonderful project.

Awesome project! I need a pair of those guys something terrible.

So much to build so little dough ray me....

Mark

hey cudos for putting the compress/limit switch on the front along with the others that normally reside on the back.


now did you plan these with the ed evens/bob clearmountain mods?

pucho812 said:

hey cudos for putting the compress/limit switch on the front along with the others that normally reside on the back.


now did you plan these with the ed evens/bob clearmountain mods?

Click to expand...

Thanks!  Yea, I did alot of researching and tried to address the common gripes people seem to have.

See above - mod included and switcable.

oh geeze.. another amazing project.

does it operate as dual mono and stereo?  Also, does it only use 1 tb4?

dandeurloo said:

oh geeze.. another amazing project.

does it operate as dual mono and stereo?  Also, does it only use 1 tb4?

Click to expand...

The board is mono, so you can build either a mono unit or dual mono with stereo link.  Dual mono would require 2 boards and all the associated components, however I designed it so you can daisy chain the second board off of the first boards power supply, saving you some bucks with having to have a power supply on each board.

Surely two opto's?  

Man, another great compressor to build, you guys are KILLING ME!

ok, That makes sense.  I was thinking it was one board like your SSL comp.  Looks great!

Oh man, you guys are too much! Will this kit be a full enchilada like the SB4000? And is there an ETA? I may as well plan which bank I'm gonna hit, err, withdraw money from now...

when it rains it pours around here

another nice LA3A project.

yes, mexican cooking will be available...eta unknown at the moment.

Good, I'm up for a full burrito.

You know i'm in for a dual with one of those lovely cases

Thanks this is the one thing I have had on my wish list.

I'll have a dual mono with case  ;D

Aaaargh ! I don't need another comp

But of course I'm interrested in this one 

Great work !

I'd prefer to buy just the pcb and then maybe a pack of matched transistors and
some "hard to get parts" (if there are any in this project). But whatever you guys come up with is of interrest.

Holy schmoly!  By the "infamous mod" do you mean one of the various things people have done to lower the noise floor?