D-LA2A Support Thread

[daveode]

Anyone?

Can someone at least tell me if it's normal for the gain reduction part of the meter to move real slow on this thing? All the other la2a's I seen on you tube move way faster.

 

[bernbrue]

Anyone?

Can someone at least tell me if it's normal for the gain reduction part of the meter to move real slow on this thing? All the other la2a's I seen on you tube move way faster.

http://www.groupdiy.com/index.php?topic=22288.0;topicseen

this thread answers at least your distortion problem. Search further threads about modern soundcard levels and analog gear level. Meter movement in gain reduction mode depends of course on the audio material you send through the compressor. Try to regard the meter movement as a kind of envelope follower and you´ll see that the LA2a does wonders to vocals and bass guitars
regards
Bernd

 

[daveode]

Thanks for the reply! But I do understand the difference between digital meters and analog. and I got the opposite problem for the distortion, he explains he has to "hit it light" or he gets distortion. On mine I have to crank the output hard to match the incoming signal or hit it hard with signal to get the reduction to work. and when I mean hard, I mean like turning my access 312 half way up or more with a condenser mic to get it to compress!! And when I mean the meter moves slow I mean a singer holding a loud note out the meter goes to +1Vu before it swings to  negitive Vu which takes a full second or more?? I don't think its working right at all (meter, reduction or gain).

I take it I got a problem somewhere on the input which is probably why everything else isn't working? I used my Phonic PAA2 to send a 1K signal through the la2a and back into the PAA2. The PAA2 is outputing a 1k tone at -10dbu. When the la2a is in bypass, the PAA2 reads (you guessed it) -10dbu. With the la2a on (bypass off) and the gain reduction knob is all the way down, I have to crank the gain Half way up to match the -10dbu?? I just wanted to know if this is normal for the gain? I have the 25K pot/75k resistor installed. And the meter on the la2a is reading -18VU??

As for the reduction, with the Phonic reading the -10dbu, turning the reduction knob up half way only yields .1dbu of reduction?? turning 3/4 way up gets only 1.7dbu reduction? and all the way up gets 6dbu reduction? This is on both channels. :-\

 

[bernbrue]

Ok,
a few recommendation for checking the LA2a:

- Input/output transformer wiring: maybe you turned around the sowter input tx (has it the 1:4 ratio?), molex connectors connected wrong or may have bad contacts.
- check the relays, if these are suitable for this project (infos are here as well, check first thread)
- check the voltages and grounding for each channel. (heater, B+ and relay psu), measure also directly at the tube sockets
- verify that the heater wiring is correct
- double check meter wiring (polarity and trimpot)
- T4b (Drip?): sometimes the EL panel gets loose or is not in correct position caused by shipping, transport etc., open it up and check
- tubes: try another set if available or swap tubes from one channel to another
- verify that limiter response and stereo link potentiometer are trimmed correctly (there is a pdf with very good instructions)
- check for faulty contacts, cold solder points, etc.

I´m quite shure that there is some basic wiring problem that causes your "low gain" and "distortion problem". I would check the T4B first, since your "meter strangeness" is directly related to it. A few picture would help a lot.
regards
Bernd

 

[daveode]

Cool! Thanks Bernd!! I'll check these things in a bit. My priorities changed (FF800 broke so I'm transfering projects from Logic to Radar). I'll report back soon.

Thanks, Dave

 

[sonicwarrior]

I finished the PCB today. Would be nice if someone could look over the pics to see if I made any obvious errors:

I used 0.5 mm² dual cable for the heater wiring (doesn't look good, I know):

 

[bernbrue]

Hi,
since we have AC for the heater it might be better to twist the heater wiring in order to avoid hum. Other wise it looks fine. What I always do before firing up a new built is to measure for shorts. Just take your multimeter and check, whether there is any resistance between -/+ of each, heater, B+ and relay psu. Do the same for the audio path.
regards
Bernd

 

[sonicwarrior]

OK, thanks. If I'll experience hum I'll redo the heater wiring. Didn't thought about that.  :-[

Checked for shorts and it looked OK.

 

[desol]

Just wanted to give a few observations as per my DLA2A, now that i've had it for a while. I did both the gain pot modification and the 12AY7 input gain substitution. I never used an LA2A before so it was a bit of a learning curve. (actually, every compressor seems a new learning curve, in use) This unit needs a good deal of input gain to drive the gain reduction circuit. My 1290 pre is probably on 45-55 db of gain to get the needle moving well. I'm assuming this is because of the 12ay7 substitute. Gain knob seems to make no difference over how much gain is applied to peak reduction...only external preamp gain(output). I didn't realize this before. I assumed gain was connected to peak reduction...it isn't. Anyway, the single biggest improvement in sound(and usability), was moving to a better optical attenuator. 

 

[MicDaddy]

desol, what Opto did you go to, from what looks like V1 Drips?

 

[desol]

No comment...although i will say...a normal one.

I'm officially against inflating prices any higher than they already are.

 

[daveode]

Just wanted to give a few observations as per my DLA2A, now that i've had it for a while. I did both the gain pot modification and the 12AY7 input gain substitution. I never used an LA2A before so it was a bit of a learning curve. (actually, every compressor seems a new learning curve, in use) This unit needs a good deal of input gain to drive the gain reduction circuit. My 1290 pre is probably on 45-55 db of gain to get the needle moving well. I'm assuming this is because of the 12ay7 substitute. Gain knob seems to make no difference over how much gain is applied to peak reduction...only external preamp gain(output). I didn't realize this before. I assumed gain was connected to peak reduction...it isn't. Anyway, the single biggest improvement in sound(and usability), was moving to a better optical attenuator.

This is exactly what mine is like. Except mine has the 12AX7's in it. If I use a preamp and crank it, I can get it to reduce, but if it's a line level signal from my DAW, it's not enough to get the thing to go to reduction.

I will try the things tonight I was asked a few post up to see if I have a problem somewhere. I'll report back soon.

 

[[silent:arts]]

I will report how mine behaves:
Gain: I have unity gain @ 12 o'clock
Peak reduction: with normal line Level (+6 dBu) my "standard" peak reduction setting is around 12 0'clock, giving me 2 to 6 dB gain reduction (signal dependent, of course).

I guess your "line level signal from my DAW" is -10dBV ?

 

[electrisizer]

i have 1:1 input trannys and Rx05 set to 10k -> tons of gain reduction with soundcard line level signals. its called the "jensen mod" a more modern behavior of the compressor...

the only issue i have: one of my drip T4 catches oscillation. its a grounding problem in the cell. got to order a new one.

when i make a THD picture with 1k sinus of the working channel i see some light harmonics in GR mode. is that ok?
(however the sound is very nice on vocals and analog synthis)

 

[audiophreak]

Hello ,
          I received my Sowter order and went to wire them in , printed the spec sheets from  the 1010 and 1009 , then for the 4383 and 8940 listed on the PCB - so I just want to make sure I have the connections right ,
so from edge of PCB down

for input :  On Trans  /  On PCB
                      RED      =  BROWN
                    WHITE    =  PINK
                    BLUE      =  GREEN
              ( NO BLACK )  =  BLACK
                    GREY      =  GREY
                    GREEN    =  BLUE

for Output :  On Trans  /  On PCB
                        RED      =  YELLOW
                    YELLOW    =  GREEN
                      BLACK      =  BLACK
                      WHITE    =  PINK
                      GREY      =  GREY


  ... is this right ??    I did a search , but didn't  find anything - also - I got the 1009's with the threaded mount , and it has no BLACK lead ... so should I mount these to the case to ground/ shield the housing ?

  Thanks in advance 
             

 

[andia]

can I ask you how long it took till you got your xformers from sowter?

 

[audiophreak]

I emailed Sowter first - very quick reply, said about two weeks to the U.S.,  ... I placed the order March 7 ,  New York USPS  received on March 12 , but I didn't receive them in CT till March 22,  ( probably Customs ? )  ... so , 16 days but most of the time was customs . 

  .. only 6 days from order to New York 

 

[andia]

thanks, sounds nice! so, i might get them even faster because I'm in europe

 

[sonicwarrior]

I got my xformers 8 days after I placed the order (in the evening I have to say). They have been shipped 3 days after the order. UK to Germany.

 

[Lowfreq]

The VU meter on the right side of my D-LA2A has suddenly decided to stop showing me Gain Reduction. 
I can hear the compressor working, so i know it is compressing, but the needle just sits at 0. The zero adjust pot still works, the NE2 still lights up, and I've tested all the connections  according to the schematic with a multimeter. All good here, so I'm a bit stumped as to where I should be looking with this issue.

It's been working fine for over a year, and only decided to stop in the last week. The problem is on the pcb somewhere, because when I swap the VU meters over, the same thing happens. It dosen't follow the meter. Connections are good too, and when I switch to VU instead of GR its all fine and dandy.

Any ideas for my next move? I can live with it for now, coz at least the compressor still works.