LA2A PCB ver 2.0 build thread

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Thanks David :thumb:

I am using Drips 2.0 boards. Can you point mo to the right trimmer cap of the two on the board so I can try this with the scope?

Maybe this will solve the subtle ringing on the top when doing a lot of GR.
 
[quote author="wmb"][quote author="wmb"]Do you have a volt meter? This can be pretty simple if you are as careful as one should be when dealing with high voltages found in tube circuits.

What is your mains voltage? 240?

from the documentation...
"* FOR PRIMARY WINDING WITH SOLID CORE WIRE AND SLEEVING
You will note that the Primary is built up in sections and the two wires in the Blue,
White and Red sleeves must always be individually joined to make the primary circuit
complete. Spare connections not required can be cut short, each colour joined
separately and isolated. The solid wire inside the sleeving is coated with
polyurethane and needs to be stripped away and tinned if the leads are shortened. For
secondary windings with solid core leads please follow the same process.
FOR FLEXIBLE LEADS PRIMARY
Just cut short and isolate any spare connections "
Click to expand...

Looks like you have the flexible leads primary from the photos.

EDITED
The BLUE and BROWN are the mains for the primary for a 240 volt mains line. This will connect to the PCB at the X-BLACK solder pads. You might trace the lines on the bottom of the board to assure the BLUE wire will connect eventually to the solder pad marked AC WHITE and the BROWN wire to the AC BLACK position.

The ORANGE wires on the secondary side connect on the points marked RED. The YELLOW wires are for the heaters marked GREEN on the PCB.

The YELLOW/GREEN, GREEN and GREY wires should be connected to the chassis.

I am fairly certain about all of the connections above and they satisfy all the PCB connections and earthing specified in the drip documentation.

From the sowter document it looks like you can cut all the unused wires on the primary side. I would do something to make sure they are completely unable to short circuit with anything as this could cause some serious problems.

Furthermore, I would confirm all the voltages with a volt meter before inserting tubes or t4b.

Post back here if you have a different mains voltage than 240.

Hope this helps.[/quote]

I edited this post because I had indicated an incorrect position for connecting the primary of the power transformer. I was going from memory. As I was thinking of taking a nap I was mentally reviewing my original post. I remembered how I suggested connecting the primary and realized it was not correct. Hopefully this did not cause any problems.[/quote]


hi wmb

thanks for the help, it was realy simple in the end!
now my la2a is finished and worked from the first moment i switched it on!
it´s fantastic!

by the way : does anyone know how to get hold on drip ?
greg do you read this?
 
I've gotten in touch with him before using the drip email:
dripelectronics at hotmail dot com
He usually responds quickly. I just emailed him about ordering some boards and what not. No response yet but he's usually pretty prompt.
 
[quote author="Purusha"]Thanks David :thumb:

I am using Drips 2.0 boards. Can you point mo to the right trimmer cap of the two on the board so I can try this with the scope?

Maybe this will solve the subtle ringing on the top when doing a lot of GR.[/quote]

I'm not familiar with the Drip board but in the original design C4 (the trimmer capacitor that adjusts frequency response) is in parallel with R22, a 33k resistor. One side of C4 goes to ground and the other side connects to R11, a 68k resistor. The other side of R11 goes to pin 3 (cathode) of the 12AX7A input tube.

Adjusting C4 will probably reduce ringing, but the amount of ringing would not change with the amount of GR, so maybe there is some misunderstanding? ("Ringing" does not sound like ringing, so the term is a little misleading. It generally translates to a high frequency bump at 20k or 25k. I can't even hear that high any more, but maybe you can!)
 
I've been using my two drip optos for several months but finally got around to installing a stereo link connector on the back. Setting it up was pretty simple and it took longer to get them out of the rack and back in than it did to drill the holes and do the wiring.

It works fine. There is one thing I have not noticed before, the two units are out of phase with each other. I've checked all the cables to see if pin two is the tip on the TRS going to the patchbay. I've looked inside the units and the XLR's are correctly and similarly connected. I'm using a portico 5012 and they are correctly phased.

Is there somewhere on the boards where I could get the phase reversed? I used the board mounted sowter I/O iron. Where else could things get turned around? I need to check all my patch cables again. I am able to get around this problem in the DAW pretty easily but I would like to know what's going on and fix it.

Thanks, William
 
Just got my PCB & it looks GREAT:!: :thumb:

I have a question though...
What DIRECTION was the board designed to go in the chassis?

The reason I'm asking is - 99% of ALL my gear has the Power Trannys on the LEFT Back (when looking at it from the BACK)
I like this because it keeps the AC away from the signal, even on equipment that is on top or bottom.

Looking at the PCB it looks like it would be backwards... with the Power Tranny on the right back instead. :?

I'm just trying to save myself a headache (crossing the AC or 6.3v AC with the signal too much or at ALL.)

BTW... I'm not NEW to building LA2A's. I built 2 & wired them by hand YEARS ago. :green:

dripoptoboard_web.jpg
 
I put my ver 2.0 PCB in backwards from what the photo is (PT on the "usual" side. I had to extend a few of the wire from the PT, but I twisted them all really good and crammed them down in the corner of the box.

My DRIP LA2A has no real noticable hum...just the usual electrical noise, and of course the trademark bouncing noise floor.
 
Thanks :thumb:

From Drips Manual:
The ver 2 circuit board has more similarities with an actual
point to point unit
Click to expand...

This would make sense... the originals have the Power supply Filter caps & Diodes on the RIGHT FRONT side - also next to the power switch.
:green:
 
[quote author="Stagefright13"]The AC section goes toward the back. The power tranny will be on "Stage Left" Such as this pic:

http://www.stagefrightonline.com/latop[/quote]

Well... that's were you put it & this is my point.
I don't like it on that side. Those "Types" of trannys have a pretty strong field
& being on THAT side COULD affect my other gear & I'd rather stick to the "Norm" which is on the other side.

For most, even myself, I do realize this may not be a big deal.

I REALLY asked in this thread so that DRIP could tell us/me what direction HE had in mind when designing the PCB.

Please don't be offended... I do appreciate you guys sharing your successful layouts. :thumb:
 
[quote author="khstudio"]Well... that's were you put it & this is my point.
I don't like it on that side. Those "Types" of trannys have a pretty strong field
& being on THAT side COULD affect my other gear & I'd rather stick to the "Norm" which is on the other side.

For most, even myself, I do realize this may not be a big deal.

I REALLY asked in this thread so that DRIP could tell us/me what direction HE had in mind when designing the PCB.

Please don't be offended... I do appreciate you guys sharing your successful layouts. :thumb:[/quote]

Kevin,

You already have the answer you are looking for... take a look at the PCB guide that Greg's did called "Building the case"... where do you THINK he put the power transformer?

Dig a bit deeper... and try not to blow off other people and BOLD and CAPITALIZE your statements as if to say 'Screw you, I'll wait for Greg to answer'...

There have been alot of these Drips LA-2A's built and pics shared if you do a search (including mine), where does the power tranies goes?

I even designed the rack case layout that Purusha now sells, to Greg's specs as HE outlined... it wasn't some random accident...

Do with that what you will :thumb:

[quote author="khstudio"]This would make sense... the originals have the Power supply Filter caps & Diodes on the RIGHT FRONT side - also next to the power switch.[/quote]

Yes, but this isn't an original. compare the REV1 and 2 boards and see the differences, even someone with a limited knowledge of electronics can see them... orientation is not one of them...

Matt
 
If you want the IEC to be on the left (looking at back), then mount the PCB to "top" of the chassis, and then take off the bottom for servicing. However, the unit would then have very poor ventilation.

I'd opt for putting the power transformer on the right (looking at back) as designed... otherwise AC will be criss-crossing.

My name is Greg... though not Drip Greg. :grin:
 
[quote author="matta"][quote author="khstudio"]Well... that's were you put it & this is my point.
I don't like it on that side. Those "Types" of trannys have a pretty strong field
& being on THAT side COULD affect my other gear & I'd rather stick to the "Norm" which is on the other side.

For most, even myself, I do realize this may not be a big deal.

I REALLY asked in this thread so that DRIP could tell us/me what direction HE had in mind when designing the PCB.

Please don't be offended... I do appreciate you guys sharing your successful layouts. :thumb:[/quote]

Kevin,

You already have the answer you are looking for... take a look at the PCB guide that Greg's did called "Building the case"... where do you THINK he put the power transformer?

Dig a bit deeper... and try not to blow off other people and BOLD and CAPITALIZE your statements as if to say 'Screw you, I'll wait for Greg to answer'...

There have been alot of these Drips LA-2A's built and pics shared if you do a search (including mine), where does the power tranies goes?

I even designed the rack case layout that Purusha now sells, to Greg's specs as HE outlined... it wasn't some random accident...

Do with that what you will :thumb:

[quote author="khstudio"]This would make sense... the originals have the Power supply Filter caps & Diodes on the RIGHT FRONT side - also next to the power switch.[/quote]

Yes, but this isn't an original. compare the REV1 and 2 boards and see the differences, even someone with a limited knowledge of electronics can see them... orientation is not one of them...

Matt[/quote]

Sorry MATT... everyone.,
I DID NOT mean
'Screw you, I'll wait for Greg to answer'...
Click to expand...

Read the sentence before & after the BOLD one. :wink:

I did not realize that Greg/Drip, you & Tat worked all this out. :oops:

Am I the only one who likes their Power Trannys on the left (looking at back)???
 
The Allied power transformer does NOT have a strong field. I have the can grounded to the case with a star washer. I frequently run cables right on top of it with no problem. Altho it seemed disturbing to me at first.

If I knew this when I was building it I would have put it on the inside. I still may at some point.
 

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