D-LA2A Support Thread

[groselicain]

What's the voltage on the working channel at ?? TP 10 out of curiosity.... bulb??

All the tubes  in right places???

[list type=decimal]
[*]97.9
[*]1.052
[*]202.1
[*]107.9
[*]1.130
[*]215
[*]99.1
[*]262.9
[*]17.34
[*]51.85
[*]75.4
[*].834
[*]6.67
[*]127.5
[*]117.1
[*]364.7
[/list]

All tubes in their right places, and as I said before, I've tried them in both channels—along with the T4Bs.

 

[scott2000]

Possible wiring goof  in the problem areas somewhere?...
Never hurts to take a magnifier , ...even strong readers up close helps....to things  if you haven't already....?
Maybe try chop sticking some wires around too to see if there are any changes just to rule out bad contact..etc if you haven't?

Hopefully someone familiar with similar issues can chime in....

Good luck!

All tubes in their right places, and as I said before, I've tried them in both channels—along with the T4Bs.

 

[groselicain]

So the issue is actually on the PCB. Somehow the two VU pads for Channel 2 have continuity, even unwired and cleaned of solder and flux residue. Going to use a razor blade between the pads and see what happens. I hate that I just unwired everything on that side of the board, but at least now I know it wasn't me.

Update: I've cut between the pads and there's no change. I cut between the transformer pink and grey pads and my VU started working in output mode and gain reduction mode. That said, there are discrepancies between the two channels. Channel 2 has more gain, is noisier, and by the time the meter reads zero in output mode, there's some distortion. However, it's output pot operates as I would expect with the 75k resistor in series with the 25k potentiometer. Channel 1 has almost no noise, lower gain, and the VU seems to operate correctly, but it's still as if I never removed the original 100k potentiometer, even though I did. Please tell me any of this sounds familiar.

 

[groselicain]

https://www.dropbox.com/s/gi6kada7tv2oy9u/Video%20Sep%2006%2C%203%2050%2031%20PM.mov?dl=0

Here’s a link to a video demonstration of the behavior, of that helps.

 

[[silent:arts]]

Don't waste your time searching for PCB errors.
Swap your left / right gain potentiometers.
And change your wiring to shielded cables!

 

[curranm]

OK,  I have had a D-LA2A sitting in my shop collecting dust for about 5 years. I stopped ******* with it because of the molex nightmare. SO I have decided to try and finish it so I can actually use the damn thing in my recording studio, so I am going to strip out the wiring with the old molex **** RE-BUY new molex connectors, I have a molex crimper, and re-do this. SO I would like recommendations for wire, wire gauge, and and where to buy the wire, I usually use markertek , but I do not care. ALSO! I would like to know  if I should bother using XLR style cable or shielded cable any where in the project. I would think I should use it going from the XLR to the board for the ins/outs of the kit. again recommendations for wire, and wire gauge would be very very welcome, as I already sat down with this for 10 minutes trying to do ONE molex connector and just about want to put the entire thing in the garbage. Does everyone else hate this molex **** as much as I do or am I just doing something wrong with it having never used it before. it seems cheap/shody and a very poor way to connect important things like audio signal to other things..........

HOWEVER I do appreciate any help you guys are willing to offer so I can actually utilize this thing.

 

[ron_swanson]

OK,  I have had a D-LA2A sitting in my shop collecting dust for about 5 years. I stopped f**king with it because of the molex nightmare. SO I have decided to try and finish it so I can actually use the damn thing in my recording studio, so I am going to strip out the wiring with the old molex sh*t RE-BUY new molex connectors, I have a molex crimper, and re-do this. SO I would like recommendations for wire, wire gauge, and and where to buy the wire, I usually use markertek , but I do not care. ALSO! I would like to know  if I should bother using XLR style cable or shielded cable any where in the project. I would think I should use it going from the XLR to the board for the ins/outs of the kit. again recommendations for wire, and wire gauge would be very very welcome, as I already sat down with this for 10 minutes trying to do ONE molex connector and just about want to put the entire thing in the garbage. Does everyone else hate this molex sh*t as much as I do or am I just doing something wrong with it having never used it before. it seems cheap/shody and a very poor way to connect important things like audio signal to other things..........

HOWEVER I do appreciate any help you guys are willing to offer so I can actually utilize this thing.

I built mine using Belden Brilliance 8451 22 AWG 2C Mic Line Instrument Cable Beldfoil Shield.

https://smile.amazon.com/gp/product/B00CWENGV2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[ron_swanson]

OK,  I have had a D-LA2A sitting in my shop collecting dust for about 5 years. I stopped f**king with it because of the molex nightmare. SO I have decided to try and finish it so I can actually use the damn thing in my recording studio, so I am going to strip out the wiring with the old molex sh*t RE-BUY new molex connectors, I have a molex crimper, and re-do this. SO I would like recommendations for wire, wire gauge, and and where to buy the wire, I usually use markertek , but I do not care. ALSO! I would like to know  if I should bother using XLR style cable or shielded cable any where in the project. I would think I should use it going from the XLR to the board for the ins/outs of the kit. again recommendations for wire, and wire gauge would be very very welcome, as I already sat down with this for 10 minutes trying to do ONE molex connector and just about want to put the entire thing in the garbage. Does everyone else hate this molex sh*t as much as I do or am I just doing something wrong with it having never used it before. it seems cheap/shody and a very poor way to connect important things like audio signal to other things..........

HOWEVER I do appreciate any help you guys are willing to offer so I can actually utilize this thing.

As for making the Molex connections, assuming you have the correct crimpers and appropriate sized connectors this works for me...

1. Strip each wire to about 1/16" to 1/8" and twist the strands tightly.
2. Insert the connector in your crimper just tight enough to hold the connector, but not too tight - almost loose.
3. Using a table top magnifying glass so I can see how far the wire has been inserted, I push the wire far enough into the connector crimp area so the tips of the bare wire is just touching the tiny bump on the bottom of the connector crimp area.
4. This is a visual / feel operation that takes some practice.
5. Assuming your wire was stripped appropriately and you've pushed the wire to touch the 'bump' , crimp!
6. Remove the connector / wire assembly from the crimper and check that the outside crimp area is firmly holding the wire covering and the inner crimp area is firmly connected to the bare wires.
7.  Give a slight, but firm tug on the connector after removing form the crimper to ensure you've made a solid connection.
8.  Check continuity & repeat...

Hope this helps...

Greg

 

[Icegoldnixon]

Apologies if this exists somewhere, but I can't seem to find it. What are the specs for the power transformer? I'm in the US and would like to order one from Heyboer. Thanks!

 

[[silent:arts]]

The specs of the transformer I sell:

- Primaries: 115V + 115V
- Secondary 1: 2x 250V / 2x0,05A
- Secondary 2: 2x  6,3V / 2x2,00A
- Secondary 3: 1x 9V / 1,00A
- Cu-Foil Screened
- ta 40/E  50/60Hz  n. EN 61558

 

[Rlucas41]

It IS ALIVE! Finally got it finished...
Sowter transformers
Kenetech “Classic” T4B’s (matched)
Solen and Orange Drop caps
RCA 12BH7A’s
Mullard 12AX7’s
Alps Detented pots
Collective Cases (Thanks Dan!)

calibrated perfectly

It sounds AMAZING!

Thanks Volker for this project and  your optimistic encouragement when I screwed up the first PCB!

PS... I found my mistakes on the first build too which is growth I believe! LOL

 

[Rlucas41]

What is the definition /qualification of a “mastering compressor”?

Asking for a friend :

 

[scott2000]

What is the definition /qualification of a “mastering compressor”?

Asking for a friend :

Maybe start a thread asking this in Studio A section....

Sometimes not everyone visits the build specific threads although it does seem everyone has  these..

 

[Rlucas41]

Scott that is probably a good idea!

On another note... FOLKS WHATS YOUR FAVORITE 12AX7 FOR THE LA-2A input?!

Okay for what its worth... for just noise floor in my D-LA2A, using the BlueCat Freqanalyst plugin in my DAW...
from Best (least noise) to worst from what Ive tried are:

1. Some old RCA 7025’s I had laying around... again least noise
2.NEW Telefunken ECC83’s
3.New Mullard ECC83’s
4. NEW Mullard CV004 ECC83 12AX7’s

And I think the RCA’s have the warmest tone, Telefunkens have a little more top end “air”.... Mullard are nice too just noisier.
Just wanted to share... all tubes I was able to balance perfectly with the stereo adjust

 

[desol]

Here's mine on drums. It has 12AY7's in the first stage. 
https://www.youtube.com/watch?v=cwY0pluE-tc

 

[curranm]

Victory! After having this D-LA2A at the 99% point of completion for about 5 years,  I finally sat down and learned how to Molex. I ended up redoing 100% of the molex connectors and now have signal passing through in bypass, AND with both sides engaged!  It was actually a good thing I took the entire board apart because I realized I had mis-wired the heaters for the 6AO5A tubes!!!!!! I have everything wired up and I am getting gain reduction in both the compressor setting and in the limiter setting. I cannot find a clear thread or answer on calibrating the meters. I have them set to 0VU in G.R.( I see some needle movement when I really scream into the mic) setting and the meter SEEMS to function in OUTPUT mode.

So my question since I really haven't put any program sounds into the unit( my signal generator is on the fritz and I am waiting for the replacement) IS this unit actually Compressing and Limiting EVEN if the meter's are not calibrated? AND I am looking for the best way to calibrate this, with the clearest information( I cannot find it here vary well at all, I AM using the search windows though) i have a digital scope and I have a signal generator on the way. let me know if you guys can!

 

[curranm]

OK Fella's!!!!! I am completely DONE and Happy with this compressor!!!! I "calibrated" with my guitar(Because I understand what that should do) I just smashed heavy power chords into it and set the peak reduction to "3" and the G.R. VU to show 3db of reduction at the same time, and the same for the limiter. I don't care of that is accurate...this thing is INCREDIBLE. I think I need to build another one ;D 8) : :-X :-\

 

[andow]

I accidentaly ordered the wrong Zener diode (as substitution of DS101/DS201) which has only 1,3W power rating. Is this sufficient or do I really need 3W or more?  ???

 

[BerndVP]

So, simple question...

For the VU metering.
Do I need to go with the Molex labeled VU and the Molex labeled GAIN RED to a DPDT ON-ON switch and then to the VU?

 

[[silent:arts]]

Yes  8)