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

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TheGuitarist said:
ptownkid: what are the chances of getting a stripped down parts kit, like transformers, t4b, mat-12s, etc so people can choose their own caps and resistors?

ruckus: that looks incredible!!!

Actually, I'm working (and have been for quite a while) on the transformer end of things as well as the matched pair, whether that will be the 2N5089's or mat12's is indetermined at the moment.  The critical stuff's likley going to be bundled with the boards (at the very least the input and and absolutley the step up transformer), and the matched pair.  Info will be available as soon as it's all worked out.
 
Alright! Riken and Muldorf supreme's here i come!!!

haha. If i decide to pay 10 bucks a cap, 1.70 a resistor and do some funny mounting scheme for the overly large capacitors that is.
 
.... really looking forward to this project  :)


EDIT :  ... and how rude of me !    Thank You ruckus328 , for creating and making this project available  ;D    Excellent Work !
 
mikefatom said:
Very well done Mike!

I see you like the 0.1" Molex friction fit connections like I do.  ;D :D

Cheers,

Mike

Yes, for this - the bolt type really aren't the logical choice, it would be very difficult to wire (especially in the 8" parmetal chassis - it's tiiiiiiight!), and alot of the wires are shielded and trying to stuff the shield into the bolt type - not so easy.

That and I'll never prototype with the bolt type again except where I need to be able to quickly try out different things (like the mains xfmr).  For my SB4K I needed to remove that board like 100 x's for various testing purposes and it takes foreeeeeeeever with the bolt style.  Lesson learned.

Now, for a 1 time production build where the chances are likely it'll be wire it in once and never touch it again - the bolt type are much better choice as they're quicker and cheaper.
 
Well...I may offer a stripped down kit, but that makes stocking parts very complicated so I may not be able to. Too early to say, need to do some looking into first.

Excellent work Mike!
 
I would think the transformers ,case and boards would be the most important to get as a kit. maybe matched transistors.
I am guessing the knobs are available at hairball and Kenetek @ Drip both have T4b's cheep.
The other parts I am sure builders may have preferences to certain brands.
 
I'd plus one on a stripped down kit ala hairballs 1176, case, knobs, xformers, matched transistors etc. Everything but things people might go i want a specific type.
 
Ha, funny you bump this when you did.  Beat me to it.  Dual unit is completed, tested, and 100% operational.  Info/pricing/pics/soundclips/RMAA results will be up soon.  Will have more details later but all the original iron (input, interstage, & output) will be available with the boards.
 
OK, it's time.  I've added the word feeler to the topic.  I don't have exact pricing figure out yet so final price might be a few bucks more or less so, but I have some very close ballparks for feeler purposes (see below).  I'm going to need some preorders for this to make it happen, at least 20-25 channels.  There's alot involved with this one and I'm dealing with very large quantities to get the prices down to where I have them, so I need to make sure the interest is there.

Pics/RMAA results/sound clip are below.  Dual unit has been thoroughly tested.  I'm giving it my final seal of approval.  Stereo functionality has been verified and kicks butt.  According to RMAA, unit exceeds the original's noise floor and freq response.  Some 60Hz bump and harmonics (I believe no different than the original though) but peaks still well below -80dbu (published noisefloor of the reissue).

Just a recap, all rail voltages/components/values are identical to the original.  The only changes I've made are some relay additions (to ease with assembly), and to the power supply section (to reduce costs on a dual unit, increase stability, and eliminate the need for the custom power transformer used on the original).  It'll work with any 30V toroid now, 25VA or larger.  I've modified the PS rails so the sidechain rail is now regulated (shared with the LED's/relays).  What does this mean - it means you'll get consistant voltages whether you have a single or dual unit.  It's no longer running directly off the transformer like the original, which I never liked from the beginning.  Everything checks out with the single power supply, which saves some bucks since you don't have to populate the PS section on your second board, it just piggy backs off of the first board.  I've increased spacing on the resistors so you can fit 1/2W carbon comps like the original if you'd like (although I used 1/4W metal film in my build).  Two boards will fit into an 8" deep 2U chassis.  It's tighter than a (fill in the blank), but it fits.

All 3 custom transformers will be available through me and bundled/shipped with the board.  A big thanks to Ed Anderson and Mike at hairball for helping to make this possible.

Input - custom cinemags (same as the UA reissues).  They'll be the PC Pin version for the production run.
Interstage - Ed is working on a recreation of the original for me.
Output (original is same used on the 1176 Rev F/G).

Board/Transformers Bundle (all 3 transformers included) will be around $150USD plus shipping (Broken down that's $115 for the xfrm's + $35 for the board).  Keep in consideration just the existing input alone from studioelectronics is priced at $125, so this is a very fair price.  I've gone to great lengths to make it possible to include them all with, and to make this happen will need to really sell them as a bundle, but I can sell just boards if anyone deosn't want the original transformers for some reason?  Although wouldn't see why you would want to do this, but who knows.

Front panels - around $50 + shipping.  Now, this is where it's a little complicated.  I'll do whatever the majority wants.  If you guys mostly want single units, I'll do single front panels - dual, I'll do dual panels.  If it's split, I could do both as long as there's enough of each.  I suspect most of you guys are going to want dual units, so at the moment, that's what I'm planning.

Matched Transistor Pair - somewhere around $10

I've had alot of requests for finished units already, so I'll be bringing in alot of PCB component inventory for those builds.  If you guys are interested, I can do PCB component kits as well, if the interest is there.  If I do they'll be top notch - silver mica caps, wima polypro's in the audio chain, Panasonic FC lytics, bourns pots, etc.  I still haven't finished exactly what the total for it would be, but best guess right now is somewhere around $75-$85, and would include the matched pair.  

What I won't be providing:
T4B Cells (Lot's of good sources for these - Kenetek, Drip, etc.)
Cases
Meters
Knobs
Power xfmr

I'm in the process of running some bass, guitar, and vocal tracks through for posting and will also be doing some side by sides with the waves cla-3a.

In the meantime, here is a clip of a stereo lead guitar and the same track ran through the unit at 10dB gain reduction (Drip t4b cells used).  It's already a heavily distorted track, and therefore not too dynamic, so the effects are somewhat transparent, yet it definately adds some grit and fullness (especially to the little palm mutes.)  Even still, transparent at 10dB is saying something.

Original (Uncompressed):
http://dl.dropbox.com/u/4740474/SB-3A/Tests/CC_Stereo_Lead_Original.mp3

Compressed 10dB gain reduction
http://dl.dropbox.com/u/4740474/SB-3A/Tests/CC_Stereo_Lead_Limit_10db-3.mp3

Test results - (0dbfs with my soundcard is equivalent to about +15dbu, so minus 15db from all of the graph numbers for the dbu equivalent).

RMAA Noise Floor:
SB3A_Noise_Floor.JPG


Freq Response
SB3A_Freq_Response.JPG


Overall scores
SB3A_RMAA.JPG


Dual Unit Guts
SB-3A_Dual.jpg
 
Dual kit for me, boards and transformers, front panel, transistors. I think i'll source my own components.

FWIW if anything does get offered extra, i'd take everything BUT resistors (bar the trimmers, i'd take them) and caps. Just so we can choose our flavours (carbon comp, polypro/polyeester/whatever)
 
2x board+transformers+front panel+matched transistors kit. I vote for a stereo front panel. If you'll be offering VUs to go with the front panels, I'll take those too.
 

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