LA2A vs DAOC.........compression characteristics???

Here's the link to my build of the Dual LA2A style box using Silent:Arts pcb

http://www.groupdiy.com/index.php?topic=32677.400

which is available in the White Market

http://www.groupdiy.com/index.php?topic=39570.0

The Drip v1 and v2 which I have also built are very good, but I think the Silent:Arts pcb is as least as good as either of them
and actually performed better in terms of noise floor for me.

It is very, very quiet.

As far as sound goes, the dual is very nice - it depends a lot on your parts choices.

The Dual LA2A cost about the same as the single channel Drips. You can't go wrong.

Let me know if you want more detail - I'll post in the other thread.

click on the banner ;D ;D ;D

alexc said:

It is very, very quiet.

Click to expand...

My DAOC is the quietest piece in my studio, and the LA2A not far behind.
Listening through headphones, they both had less "thermal noise"/hiss than either of my 1176s and GSSLs.

So whatever Volker is doing with his [silent:arts] pcbs, it's awesome for low noise!!

Thanks Volker !

If my 1176 or gssl builds were this quiet I'd be 10-15dBu happier with them 

And that first tube postion is a perfect 12AX7 tester.
Noisy tube shows up real good there. I used common Sovtek 12AX7LP.

I'm about 1/2way thru my DOAC with jensen 1:4 inputs, edcor 4:1 outputs,
musikding toroid and eh tubes. 4 meters again, of course.
I'm hooked on that.

Looking forward to comparing with the DLA2A. I expect the compression
characteristic of the vactrols will be more aggressive than the EL opto.

My other vactrol unit certainly is. In a good way - just more noticable.
It's the JLM MAC kit (micro compressor) - sidechain of opamp ->  bridge rectifier ->single GR vactrol
with the ldr shunting the input of a buffer opamp to ground.

The smoothest of all is the poorman vari mu.
Need to set it to quite fast settings to even hear the compression at all.
Otherwise it's just plain ol  "gain reduction" 

Randyman... said:

alexc said:

I've just finished the dual LA2A style box.

The easiest, best value and most useful build I've done.

Highly recommend it.

Click to expand...

Which one is that, exactly? 

Where would the Drip LA2A fall in your opinion?

I have lots on my plate - but I'm itching to tackle a 2-LA2A or even a mono LA2A early in 2011 (might even use NOS or OEM T4B's)

Thanks for your feedback  8)

Click to expand...

The 2LA2A or D-LA2A is a board designed by silent arts and available in the white market.

Drips one is expensive in my opinion.

I just bought 1 of silent arts DLA2A boards and cut it in two to get 2 mono boards for my 2 mono LA2As. A lot cheaper than drips PCB for a similar design.

Drips boards are super solid. I have a 175b and it's cool. Drips LA2A board currently offers you the option to switch between a fast cell and a slow cell which is a advantage.

In a nutshell Silent Arts boards are cost effective and are faithful to the original design and Drips boards are solid and have some extra features.

Regards
JD

Doing the LA-2A point to point's quite inexpensive, in the $ domain.  You make up for it in the time domain, if you're slow as hell at metalwork, like me, but it's a lot of fun, and allows you to put your own spin on things.  Just thought I'd throw it out there, as I feel that I learned alot that I wouldn't have by going that route as opposed to the pcb-way.  Definitely do the la-2a in one form or another, though, as it's a winner.  Kenetek's t4B is very nice sounding, FWIW. 

I'll investigate further.  Who sells slow and fast T4B's?  Is this a "binned" type thing based on tolerance and measurement - or are the fast and slow T4B's actually different designs?  I recall UA was supposed to have their 2-LA2A with the fast/slow switch and even had the switch on the pre-production run and marketing documentation - but they had to back out on the actual production version and just had the single T4B (due to availability IIRC) - and ticked lots of people off.

From the comments so far, it seems like the Silent Arts version will be calling my name next month!  I would prefer a 2-LA2A in one chassis.  I'll start scouring the various support threads and see what I can come up with as far as build documentation, BOM's with part #'s, and wiring guides goes.  The one with the most complete documentation and complete BOM will likely win my dollars regardless of cost.  I'm not quite to the point where I can pick and choose components based on what I'm looking for in the sound (I just know I like the original LA2A sound!  Especially on rock vox with the needle buried  ).  I'll pay to have lots of guesswork removed from the equation and save a few headaches on my side.  I'm learning little by little with each new build - and I do hope to be at that level a few years down the road.  But I can't wait that long to have a LA2A in my rack   Maybe DIY LA2A #2 in a few years will be one that I can experiment with component selection, etc.

Thanks for the input - and Rock on!  8)

Who sells slow and fast T4B's?

Click to expand...

http://www.dripelectronics.com/index.php?option=com_content&view=article&id=9&Itemid=30

Im thinking about adding a switchable T4 option for the D-L2A boards. Should be not so difficult. Still unsure if i just should switch the LDR part of the T4B or also the light foil part.

I don't know how I missed that Drip sells both fast/slow T4B's!!!  :-[  Sorry about the noob-ness over here...

I'm leaning towards the Silent Arts D-LA2A as well - but I do find the switchable opto cells on the Drip version to be an intriguing option.  What is involved with adding a second set of T4B's and switching facilities to the D-LA2A?  Is it simply a matter of cutting traces and "inserting" a Double Throw switch with enough poles to swap one T4B for the other?  And of course finding a place to put & mount the extra T4B's!

Also - Can anyone speak on the sonic differences from the Drip T4B's vs a used OEM or even NOS OEM T4B?  The used OEM's are 2x the price of the Drips - and the NOS are even more ($250/ea!)!

Who makes 3RU Stereo LA2A front panels?  I see a few 2RU, but Silent Arts specifically recommended the 3RU chassis to keep things cool and to avoid the clearance issues with the tubes.  If the 2RU version will require a free rackspace above it for ventilation - then why not just go 3RU from the get-go?

Lastly - I saw azone posted a fairly current BOM here (09/2010):

http://www.groupdiy.com/index.php?topic=32677.msg507646#msg507646

Can anyone comment on the completeness and appropriateness of this BOM for a D-LA2A build?  It looks very well put together!

Thanks for getting me going.  This will (eventually) be my first high-tension/tube project!  I'll be sure to be safe and discharge all of the HV caps when troubleshooting (I'm sure I'll have my fair share of troubleshooting on this one  )

Have a great evening  8)

Randyman... said:

...I'm leaning towards the Silent Arts D-LA2A as well - but I do find the switchable opto cells on the Drip version to be an intriguing option.  What is involved with adding a second set of T4B's and switching facilities to the D-LA2A?  Is it simply a matter of cutting traces and "inserting" a Double Throw switch with enough poles to swap one T4B for the other?  And of course finding a place to put & mount the extra T4B's!

Click to expand...

if you mount all 4 T4Bs externally no need to cut any traces.
wires from the PCB octal socket to the switch to the T4Bs should work fine.

Interesting!  I'll ponder that.  I'll probably just stick with the slow ones - they were good enough for the real McCoy.

PS - Payment sent for a PCB & Mains Transformer...

Merry X-Mas  

Hey Guys, I am doing a few Dual LA 2A cases for a few guys and it got me thinking if I should consider doing one as well or the D-AOC.  I have a drip LA 2A which I love love love!

But I wonder which would be better for buss kind of stuff.  Anyone have any ideas?  Or for drum overheads and things like that?

There is another a AOC one I designed exclusively for the two buss, it came right after the AOC improving on the original design

analag said:

There is another a AOC one I designed exclusively for the two buss, it came right after the AOC improving on the original design

Click to expand...

Hi Analag, I am great fan of your AOC and really interested in the updated "two bus" version.