D-LA2A Support Thread

[youngsinsei]

How does one purchase this build kit?

 

[The_Nimaj]

How does one purchase this build kit?

It's not a kit, but [silent:arts] sells the PCB (send him an email). You'll need to source the parts yourself but there's a BOM linked in the first post and plenty of info in this thread.

 

[Schatzi]

Just to follow up on this, I ended up using an Antek AS-05TC250 . I cut the lead of the 5v on the transformer and jumpered the second 6.3v to the 5v Relay rail at the terminal blocks ( The 5v tap would've been a little too close for comfort to the drop out voltage on the regulator I used). This works well and is inexpensive (currently $32 + 8.5 shipping) for US buyers.

Do you have any photos to share of this setup? I'm interested in seeing how this looks!

 

[The_Nimaj]

Do you have any photos to share of this setup? I'm interested in seeing how this looks!

Sure. It's not a great photo but you should be able to see the jumper between the Channel 2 heater and the relay input. Later on I connected wire from that same terminal block to power the vu lamps. They're pretty bright even at the heater voltage.View attachment IMG_0148.jpeg

 

[thelivingroom]

I’m late to the party, but here’s another successful D-LA2A build! I read every post before starting, and all went smoothly. I decided to try something new to me and get a little fancier with PRP resistors, Mundorf MCap EVO Oil for C2, C3, and C5, Auricap XO for C1, and Charcroft Audio for all the Micas. I also opted for the Zener over the neon bulb for longevity and less noise. V1 12AX7’s and the 12BH7’s are NOS black plate RCA’s. I don’t know if any of that mattered much, but it sounds beautiful and it’s really quiet.

I originally had the SC HPF switch set up linearly with three 240k resistors (for 240k, 480k, and 720k) but it didn’t feel right, and I changed them to more of a log with 82k, 240k, and 330k resistors (82k, 322k, and 652k) and it feels like a much more natural progression now.

Calibration was easy thanks to all the info in here, so thank you to anyone who has contributed to this project over the years. I did a quick base cal first, then after letting it warm up for a few hours I took my time and let the needle on the VU settle for a couple of minutes between adjustments, and it’s remained dead-on each time I’ve fired it up for the past few days.

On the initial sweep Channel 1 was up .8 dB at 20k, and 2 was only up .1 dB. I lowered C104 to 100pF (it was 150pF) on Channel 1 and it’s now only up .2 dB. I didn’t order any values lower than that, or else I’d have probably tweaked obsessively (and unnecessarily) until both were totally flat. I appreciate every connection on the PCB having a connector footprint, as it took under 10 minutes to remove it, make the change, and reinstall it. Thank you for that Volker, and for this project! It sounds wonderful!

 

[[silent:arts]]

Congrats! Nice built. I like the clean wiring.

 

[shoetique]

Beautifully done @thelivingroom !! Great write up and fantastic wiring job!

 

[r2d2]

I’m late to the party, but here’s another successful D-LA2A build! I read every post before starting, and all went smoothly. I decided to try something new to me and get a little fancier with PRP resistors, Mundorf MCap EVO Oil for C2, C3, and C5, Auricap XO for C1, and Charcroft Audio for all the Micas. I also opted for the Zener over the neon bulb for longevity and less noise. V1 12AX7’s and the 12BH7’s are NOS black plate RCA’s. I don’t know if any of that mattered much, but it sounds beautiful and it’s really quiet.

So nice job !!!
Very clean and tidy inside,
any audio sample as well for the diy fans here ?
cheers

 

[Trent _L]

Hey everyone! Just about in the middle of my build and about to order the in/out transformers. After a lot of research and reading through this thread and the Sowter website I've settled on their 4383 for the input, and their 1290 for the output, does anyone have any input on this transformer selection? Will the lead colours still match those marked on the PCB? Also is it better for shielding/hum reduction to mount the threaded grommit transformers inside or outside the chassis? I've seen them mounted both ways in peoples' builds.

 

[thelivingroom]

Hey everyone! Just about in the middle of my build and about to order the in/out transformers. After a lot of research and reading through this thread and the Sowter website I've settled on their 4383 for the input, and their 1290 for the output, does anyone have any input on this transformer selection? Will the lead colours still match those marked on the PCB? Also is it better for shielding/hum reduction to mount the threaded grommit transformers inside or outside the chassis? I've seen them mounted both ways in peoples' builds.

I used the 4383/1290 combo in my build a few posts above, and it sounds fantastic. The 4383 lead colors match the PCB, but the 1290 should connect as follows:

Red 1290 to PCB Yellow
Yellow 1290 to PCB Green
PCB Black NC
White 1290 to PCB Pink
Grey 1290 to PCB Grey

Inside or outside mounting with the Mu-metal cans doesn’t matter. I mounted mine on the outside to save real estate and keep the inside cleaner, to eliminate having to make mounting brackets, and to be able to arrange them so the wires had a short and straight shot to their locations on the PCB.

Good luck with your build!

 

[schrobbelbop]

I have a drip opto7 running perfect for years but now 2nd channel has dropping its meter readout.
i see the meter bumping around a bit. and it's 0 point lowerd 5db's.

Voltages at NE-2 20v instead of the 56v compared to left channel. Reading higher resistor value accross R28/C16(28meg)

It's just something in the meter circuit. audio is doing fine, swapped all tubes and t4b makes no diffrence.
What to replace?