SA-3A (LA-3A Clone) Support Thread

[Echo North]

I'm pretty sure its there, just no frame, i'll email Mike and Mike to see if there may be a package deal for the 3 trannies with frames for the sa pcb's

Did you get any answer about this? I'm also looking out for that autoformer at the moment. And a package deal would be even better.

never got an answer to this, i will need the stuff soon though....

Opps sorry guys, just got the frames in.

Bundle here:
http://www.hairballaudio.com/shop/product_info.php?cPath=24&products_id=180

Tony here is the Autoformer w/frame (ignore the frameless image):
http://www.hairballaudio.com/shop/product_info.php?cPath=24&products_id=179

Mike

 

[Andydrum82]

I'm starting to fill my PCB's with parts & I have a few missing resistors. Has anyone else come across the same thing when they ordered the parts kit from Serpant?

 

[Greenote]

I just ordered it from Mouser about three weeks  ago. I just finished wiring and powering mine up.
http://www.mouser.com/ProductDetail/Triad-Magnetics/VPT30-830/?qs=wkKrz7WmEgNXIHrxEqIP6Q%3D%3D

 

[just.sounds]

I have some trouble sourcing the pot's (100K log 1/2W) would 1/4W be enough? Those i can get easy.

 

[Jermbob]

I've had a unit that has worked for years, but now the right channel isn't passing audio. Everything else seems to work fine. The meter seems to work correctly. When I run audio to it, and use the peak reduction knob, the g/r setting reads gain reduction, at the appropriate level, but when I read the output it is nothing, and no output is present.

When bypassed, audio does pass through.

When I intially opened it up, because of the issue, I noticed the power branch, between to cards, was not in good shape. V+ kept shorting to ground. So I made a new branch, but It's still damaged.

What do you think I should check?

 

[Bonsaimaster]

Ok finally got the parts and the things wired. Both units (stereo) have the proper voltages on test points. The meters light up and can zero the meters in GR mode in both channels. Problems: The second channel compresses but has static (furthest from transformer).  It is audible but faint.  The first channel is all static and the meter is jumping all over the place in Normal mode. Rotated the transformer with no luck. The only unusual thing is I mounted T3 to the back of the chassis and T4 has studs underneath that connect to the chassis. Any thoughts?


Thanks in advance!
Bonsaimaster

 

[Siegfried Meier]

You guys have any lead on the pots?  Mouser no longer carries them, and they have no substitute they say.  I wouldn't mind getting something a bit more high end anyway.  Any suggestions?

Thanks!
Sig

 

[Harpo]

You guys have any lead on the pots?  Mouser no longer carries them, and they have no substitute they say.  I wouldn't mind getting something a bit more high end anyway.  Any suggestions?

The two (or 4 for stereo) 100K log pots ? As long as your signal voltage across these pots is below 86Vpk or below 144.9Vpk at XLR in (it sure will be a fraction of these insane numbers), any 1/8W rated pot will do.

 

[Siegfried Meier]

Seems like these would great then, yes?

http://www.amazon.com/PEC-Guitar-Potentiometer-100K-Audio/dp/B003IY1GVM

 

[Harpo]

Seems to be one of these.
Dunno if you are happy with a more uncommon 315° mechanical rotation (might be conflicting with 270°-300° frontpanel scaling) and whatever rotation degree the electrical travel might be. No need for a 2W power rating or 500V rating, but if it feels right to you (operating torque from 1oz/in to 6oz/in most often calls for a bigger knob), they should do the job.

 

[Siegfried Meier]

How is your link any different from mine?  Appears to be identical specs...?

 

[Harpo]

How is your link any different from mine?  Appears to be identical specs...?

The manufacturer link shows at least some more relevant data, but is still hiding enough parameters that I wouldn't even consider buying this product (these pots are obviously aiming for a different market, not precision audio).

 

[FredW]

Hi, I bought a SA-3A kit and a front panel from Serpent audio.

For the PCB and components, no problem, except 2 resistors that were missing.
The front panel is also nice. But informations on the website are not exact.

As Serpent audio suggests the use of Modushop enclosures (it is said that they are guide holes compatible with modushop),  I bought one there., " Modushop 2U black Pesante".  Unfortunately, WARNING !! I encountered two major problems with these enclosures.


1) On the Serpent audio front panels, you can see on the back face 2 pre-drilled mini-holes on each side (left / right).
Which little hole is the good one to enlarge for modushop ? The upper or the lower ?
I wrote to Serpent audio by email, I never get any answer

2) worst : when this nice front panel is populated,  there is not sufficient space on the modushop enclosure !!
In fact, they are bends on each iron covers.  It probably helps for maintening the rigidity of the rack but it eats space vertically ! It hinds around 5mm or even more, up and down on the front panel.
So in fact, modushop racks are NOT compatible with this project
In order to have sufficient space, you have to cut those bends on each iron cover, which is almost impossible to do it by yourself properly with a circle saw. And the metal is very hard. Then after, the enclosure is ugly and not perfecty closed. :-(

Is someone encountered the same problems ? Some suggestions for europe about compatible enclosures ?
Which pre-drilled holes are the good ones ?

Thanks for your opinions and suggestions ;-)

 

[FredW]

No answer...?

 

[Dr Gris]

Not sure what you mean FredW...
You need both upper and lower hole on either side (L + R)....
The pilotholes on the frontplate should fit Modushop, no??
I carved out the front upper lip so the meters would fit, also carved out the bottom lip for every switch
using a Dremel as suggested in reply#1 in this thread. Read that reply if it helps...

If I'm unclear you can mail me and I can send you a photo of how I did it.

Good luck!
Regards//Magnus

 

[FredW]

Hello Magnus,

first, thanks for reply, that's very nice from you.


1) About front lips and modushop enclosures : well, before starting populating and soldering the PCB I read a big bunch of informations on the beggining on this topic, but between the soldering and populating the front panel, I just have to note that I forgot this very important information / tip.  In order to do a little recall and a clear answer for everyone who will read my warning, here it is :

"As far as I know, collective cases are the only enclosures out there that do not have a front lip (which is extremely nice for this build as the toggles and meters run very close to the top/bottom of the enclosure.  If you're using a modushop or parmetal enclosure you'll have to notch out the bottom front lip where the toggles are as well as on the top front lip in the meter areas using whatever means are at your disposal (keep in mind it doesn't have to look nice, I just started hacking away with my dremel)."

In fact I did quite the same job, just a little harder since I cut all long the lower lip, and it was hard to do a proper job with a circle saw because modushop iron is very strong and circle saws are large. I finally succeed the operation with hard planish job, but as a reasult I have a large gap between the front panel and the lower iron cover. Do not try this method except if you are already strongly experienced with circle saws !! Better to drill only little areas (on each toggle) as suggested on the beggining on this topic. READ CAREFULLY !!

2) About pilotholes on the frontplate, I'm still wondering how to do it properly...
In fact on my previous reply I said that they are "2 pre-drilled mini-holes on each side (left / right)". That's wrong.
They are 2 pre-drilled mini-holes, but on each corner (upper left, lower left, upper right, lower right).
What I am supposed to do with those two mini-holes ? Which pilothole of the 2 is the good one for modushop ?

Can you send a picture here to clarify, Magnus ?
Thanks a lot in advance for your help,

Fred

 

[Dr Gris]

Ok, you're right! When I took it apart I found that the holes don't line up....because???
Don't know if there were pre drilled pilotholes where my holes are now.
It's been on my shelf for some time now together with other unfinished projects
I remember now that I bought both frontpanel and case from another member here
who had already drilled out the holes.
Here's a pic of the drilled holes, you can see the pilotholes just next to it...

//M

 

[Dr Gris]

My measuring skills are probably not the best but I get the centerpoint of the drilled holes
to be 32mm from the side edge and 18mm from top/bottom edge. Please exuse my laymen terms...
Here's another pic of my Dremel carving, not beautiful but works...

Cheers//M

 

[Dr Gris]

Well, my brain is slow... You said two holes in each corner, that means that my existing holes
probably was pre drilled as well...

DON'T DO ANYTHING YET!!!
Since I bought this from a member I'm not sure if it's Modushop or Par Metal...
Let me check if I can find that info.

Best
//Magnus

 

[FredW]

with the pictures you sent, I can recognize modushop rack.
Double-check but I think it's modushop. It looks the same as me.