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

[ruckus328]

a dual mono unit is going to be surprisingly affordable.

oh.. it's not your box that's gonna put me over the top, its the 96! other pieces of gear that are sitting in the shop right now  

Haha, I'm right there with you.  I have like 10 other projects laying around I haven't even started yet, and 4 SB4000 units lying around now from prototyping (I don't even know what I'm gonna do with all them)

Changed the topic title (old title didn't really make sense anymore)

 

[snipsnip]

gah, this looks nice.

i have to stop spending money... but its soooo hard.

 

[jandoste]

gah, this looks nice.

i have to stop spending money... but its soooo hard.

Same here
But, I'm in !

 

[ruckus328]

Awe.....look at the little babies....Soon they'll be all grown up

 

[Ringwraith]

Sweet!
Love the colour.  ;D

Sean

 

[rrs]

Well as impatient as i am I have just purchased 2 T4b's from Bill at Kenetek. I here there great quality and can do matching pairs which will be of benefit for a stereo unit.

I also need to place an order for another project at mouser so I want to save on international shipping and order parts for this also. So does it differ much from the original schematic and is there a parts list organized. You can PM me if you like.

Thinking of using Carbon composite resistors and Orange Drops as I did in my Blue Stripe 1176 which sounds awesome.

 

[Ptownkid]

not stereo, dual mono. It's probably worth your while to wait for the kit pricing to come out, it may even be cheaper than self sourcing.

 

[ruckus328]

not stereo, dual mono.

Incorrect.  Stereo link switch is right in the middle.  When disabled - unit works in dual mono.  This is assuming your using 2 pcb's.  You can also chooose to build just one pcb and have a single mono unit.

As far as components, honestly it's a little early for that.  The power supply section is totally different and there are some other random adds.  Audio/sidechain sections are almost exactly as original, but few tweaks here and there.  Let me fire it up first.

 

[rrs]

It's probably worth your while to wait for the kit pricing to come out, it may even be cheaper than self sourcing.

But that's taking half the fun out of it.

 

[audiophreak]

  Hi  ....... My name is Chip .......  I'm a DIYaholic .....  ;D

 

[ruckus328]

  Hi  ....... My name is Chip .......  I'm a DIYaholic .....  ;D

[Everybody]: "HI CHIP!!"

 

[rrs]

Hey ... I don't have a problem.
I can stop any time I want.

 

[diyfanatic]

Hey ... I don't have a problem.
I can stop any time I want.

that's what a famous french televison star says whe the police cought him taking 10gr of coke a day... 8) I've no probleme with drugs... ;D

 

[Ptownkid]

not stereo, dual mono.

Incorrect.  Stereo link switch is right in the middle.  When disabled - unit works in dual mono.  This is assuming your using 2 pcb's.  You can also chooose to build just one pcb and have a single mono unit.

No more late night posting for me...stereo/dual mono

 

[ruckus328]

Hey ... I don't have a problem.
I can stop any time I want.

I used to do DIY to feel good............

Now I have to do DIY so I don't feel bad..............

 

[grantlack]

I used to do DIY to feel good............

Now I have to do DIY so I don't feel bad..............

i used to lurk the forum while drinking...
now i participate to replace drinking.

the ball and chain prefers ignoring my geek speak to ignoring my drunk speak, can't figure why  ???

dying to get some solder to a couple of these pretties.

 

[ruckus328]

Awe look........the little baby's all grown up

First board worked on the first try.  I'm waiting for a couple of parts to come in tuesday to finish the other channel for stereo linkage.  It was really easy to build.  Board only took a few hours to stuff (with no BOM mind you haha).  I don't have an original to compare to, but first impressions:  sounds sooooo good it's just silly.  Threw a mono lead guitar track on, hit it with about 10db compression - sounded like butter (I couldn't believe it wasn't margarine???).  I used all polypro film & mica caps, and an elna silmic cap for the single electrolytic in the audio path.  Initial tests were done with two 2N5089's in the audio path (hfe matched), but I'm going to drop in a LM394, MAT02, & MAT12 and do some comparison tests to see if/what the sonic differences are.

Checked against original power transformer, results on sidechain voltage were within 1V with a standard off the shelf toroid.  Which means it eliminates the need for the custom power xfmr used on the original.

If anyone wants to play - I could really use some mono vocal/guitar tracks to do some tests with (something that's ok to post on the board).  I'll run them through and post the original/compressed versions so we can all critique.

Still have to start the whole RMAA process, but unit is ultra quiet, no hum, etc.

On a somewhat sidenote - today I was reminded the importance of practicing safety when working on electronics, even lower voltage units like this - reality is, it can still kill you.  I had the unit powered down, and was cleaning up some wire runs around the toroid/IEC outlet.  Although it was powered down, I wasn't thinking about the fact that the IEC outlet still had line voltage on it, because the unit was still plugged in.  Well, I was quickly reminded.  And so I'll remind all of you so nobody makes the same stupid mistake.  Please be safe!

Now, without further ado...here is your porn for the day

 

[snipsnip]

very very nice.

Amazing work

 

[TheGuitarist]

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!!!

 

[haima]

On a somewhat sidenote - today I was reminded the importance of practicing safety when working on electronics, even lower voltage units like this - reality is, it can still kill you.  I had the unit powered down, and was cleaning up some wire runs around the toroid/IEC outlet.  Although it was powered down, I wasn't thinking about the fact that the IEC outlet still had line voltage on it, because the unit was still plugged in.  Well, I was quickly reminded.  And so I'll remind all of you so nobody makes the same stupid mistake.  Please be safe!

that's why it's always good practice (and LAW in many countries i believe) to insulate all mains connections - i would suggest ALWAYS using insulated crimp boots or heatshrink on every exposed mains connection. still doesn't make it 100% safe, but it's a lot better.

it's also very good habit to keep your workbench mains power outlet visible at all times - so you can double check the unit is unplugged before/during working on it.

if you do need to do adjustments on a unit while it's powered up, practice the "one hand in your pocket" rule - you want any shocks to go from hand to foot, not hand to hand (via your HEART!).

just some safety tips we can all be reminded of!

despite practicing these mantras, i've still had my fair share of zaps - the most recent was when i was working on a EMT 140 plate reverb in cramped quarters, i had reversed the power and i/o connectors (which are the same, and aren't "keyed" to prevent miswiring...), placing the case at mains potential - i picked up the unit with both hands (idiot move!) and copped 240v across my chest, loud BANG! OUCH. i'm lucky to be alive....