D-LA2A Support Thread

[rock soderstrom]

Hi, C8 is after the 7805 regulator, so this cap will see 5Volt maximum.  Your capacitor is ok!

 

[elpapadelcrio]

Great, thanks

 

[troubleous]

Hi guys!

After having a little unvoluntary break from DIYing, I got back to fiddling with my D-La2a. Still trying to figure out why the heck I can't zero my meters. I tried the suggestion below, but the result is the same (with 2m trimpot installed).

There is probably a simple solution to this, but I just can't figure it out, darn.

Otherwise the unit works fine and has no noise. I haven't been able to test/measure it with DAW but just running audio through it seems to work exactly like it was supposed to.

Frustrating to say the least

Cheers!

can you get a larger trim pot so it swings further (down or up) away and see if you can get it to zero out and then compress and see if the meter is somewhat close to the actual compression on the signal out of your daw and back into your daw?

 

[j.frad]

Hi everyone,
Did anyone ever measure the max AC voltage the EL panel in a T4B can take?

I built one using kenetek T4Bs, and it has died on me.
Putting it in a working LA2A kills the compression,
All voltages are OK, and the 6aq5 tube is good...

Sending a sinewave in the compressor and measuring AC voltage on pin3 I can get up to 30v...

 

[maq3396]

Hi

I see that the pcbs are out of stock.

Can you please tell me if there will be  another run?

Thanks
Mac

 

[elpapadelcrio]

Hi everyone:

I just finished the build of my D-LA2A and I happy to say it did worked like a charm, no incident or issues so far, after the calibration I started using it right away, sounding great... Thanks Volker!!!

I built a few months ago a point to point LA2A replica using carbon resistors, NOS pots and caps, Sowter trafos, etc (pretty expensive). I compared (sonically) the unit with some old LA2As at Sonic Ranch studios and the P2P replica sounded real good/close, as good as the olds LA2As.

Now, I just compared the P2P with the D-LA2A and there are audible differences (to me, I'm blaming the Edcors vs. the Sowter and maybe the 1% film resistors vs carbon), the P2P sounds a little more open and clear but there is not that much that is a deal breaker to me, on the other hand the D-LA2A is more focused and sharp than the P2P, the "Color" is pretty similar between the two units being the P2P a little more "full" (again, blaming the trafos).
(Note about the P2P: I used 100K a pot at Gain having a lot of output volume which I solved doing a pre-attenuation circuit on it)

I also did a comparison of the D-LA2A with the UA Teletronix LA2A  Grey plug in, huge diference here, analog rules !!!, for the money, my D-LA2A with the Edcor transformers sound's more than good.

The D-LA2A stereo program is so far great, I did not had problems to match the sides neither the meters.

Here some D-LA2A notes:
My intention in this built was to buy the less expensive components possible to "hear" how much of audible differences may be there by doing so.
I used a matched pair of slow Kenetek's T4Bs (Bill Jones went the extra mile to match the two units).
The case is from Dan Deurloo at Collective Cases (I loved it).
The BOM was Azone's.
I got the guys at Tube Depot to match the tubes.
Spent some time choosing the resistors and caps with closest readings (where possible), worth it!!!
Used 25K pots and 75K resistors at Gain. (this modification made the unit a little to quiet to me, I'll "fix" this at latter time).

I'm planning to change the pots for Gold Point Stepped Attenuators and will get the Sowter trafos cahnged to use this units in my mastering rig, I'll let you guys know how it went...( It may take a little long since I'm about to start a build of a Drip 670, wish me luck).

Here a picture of the built, the soonest find out how to upload more I'll do so.

 

[maq3396]

Hi Volker

So.....another run of pcb's?

Please?

Cheers
Mac

 

[[silent:arts]]

So.....another run of pcb's?

PCBs are back in stock

 

[saxmonster]

Hi Guys,
Having an issue with my D-LA2A now.  The left channel seems to have this high pass filter that comes on when no signal is going through the channel.  I have included an audio file of it.  Sorry for the TV in the background and the clicking clock, the wife was home hahahah.  What should I start looking at to get rid of this issue.  It doesn't seem to do it when I first turn on the unit.

I am running a elam251 clone into a 1073 clone which work just fine.  I have narrowed the signal channel issue down to the left channel on my la2a.  the right channel seems ok for now.  Thanks so much.

http://www.ehornstudios.com/media/LA2A.aif

anyone?  I got a visual on all the caps and everything looks great.

Gonna swap tubes and see if the sound goes to the other side

 

[Barton]

So I have my DLA-2A up and running.  However, I'm still confused about the meter lamps.  I have the 12V Hairball meter.  From what I gathered you can replace them with 5V leds.  For power, do I just jump 2 wires off of the 5V relay power to run to the + of the LEDs, then return one wire from each LED to the relay 0V?  It seems like it would be a sloppy way of doing it.  Any better suggestions?  Thanks.

 

[Barton]

Disregard my last post.  Figured it out.  I do have a more significant problem though.  The right and left channels are bleeding into each other slightly when compressor is engaged, but doesn't do so in bypass mode.  Any thoughts on where the bleed is occurring?  It happens in both link and dual modes as well.

 

[weiss]

hey guys, finally i finished wiring this beast  8)



but i have a weird problem: channel 1 is only passing high frequencies above 1k with the same volume as in bypass (pictures attached) and when i enable VU output instead of GR the overall volume changes.

any help would be highly appreciated as i don't now how to solve this problem!

here are some pics:
http://s300.photobucket.com/user/dafuqwhocares/media/IMG_3230_zps0nsqdz2x.jpg.html
http://s300.photobucket.com/user/dafuqwhocares/media/IMG_3228_zpsjdallwfh.jpg.html
http://s300.photobucket.com/user/dafuqwhocares/media/IMG_3226_zpshoduogwj.jpg.html


thanks
weiss

 

[peterc]

Hi all

Off the wall question......

What is the minimum HT that I can use for this unit?  Will +300v be OK?

Thx, Peter

 

[Spencerleehorton]

Just thought I'd ask a quick question, I've made a couple of point to point LA-2A and one works perfectly, the other seems to work exactly the same but the top end is much duller.
I was going o swap out V1 to see if it is the valve which is the problem, if it's not what would be the components to check which effect the top end?

Regards

Spence.

 

[rock soderstrom]

Hi Spence, follow this link for some information about that topic.

http://groupdiy.com/index.php?topic=32677.msg535420#msg535420

 

[Spencerleehorton]

Look at C4 and change 12AX7 to 12AY7 it is then!!!
Im pretty sure i've put a adjustable capacitor on C4 and on my other one with good top end i've got mica 150pf.

regards

Spence.

 

[maq3396]

The White Market thread for this pcb/project has disappered!

 

[Matt55]

Also interested where the white market thread went was looking to order some pcbs for a dual LA2A build. Thanks, Matt

 

[[silent:arts]]

White marked link is working again  8)

 

[schrobbelbop]

Got my first D-La2a build up and running

the overall thing i notice is that i have to fully counter clockwise turn the stereo adj. trimmers
to get te compression working. (trimpot wrong way?)

The overall sound of the unit is a bit harsh and to much hi-end. (try to do a sweep later on and post)

I use the edcors and the standard BOM, do i need to adjust something ? can i change hi freq response of the unit? (not the compressing)