LA2A PCB ver 2.0 build thread

[wmb]

[quote author="dripelectronics"]

you might have to do some trouble shooting on that one unit.
this could be a poorly seated tube , to a loose ground etc.

youll have to simplify the chain , so you can make sure it's the
pcb or not.[/quote]

Yeah, I need to just figure out if it's the guitar amp (non la2a related) or one of the two channels with the la2a in line after the pre's. I've been insanely busy with a couple projects and one that is moving between my studio and another. Too much stuff to get done and not enough time to start poking around in the boxes yet.

I think I will set up a project with the all three sources powered up and let it record them during a lunch break. The interval between spikes is about 20-30 minutes so that should be enough to actually catch one and figure out where it's coming from.

Alternatively I could change my metering to hold peaks longer.

Did I mention how great these things sound? The payoff of the experience has been so great that I now want to build all kinds of stuff.

 

[Stagefright13]

I for one am planning on another Drip La And a stereo link cable. I figure if radio stations used this for years back in the day for everything they transmitted... And alot of people 2 buss like this now. (depending on the sound wanted) then there is mojo there. And those older LA's weren't matched component wise like us DIY's can. So a good stereo match is possible. Altho there is a matching procedure to follow... (LA2 manual)

I also have an 1176LN mnats rev D finished with a temp input transformer. When I get the real deal I will probably double up on them 2. And will also use them as a 2 buss thing. But at this point my converters are my weak point...

Many final mixes over the years have been run stereo through each of these classics.

I'm still kinda floored my project studio actually has these now...

 

[wmb]

[quote author="Stagefright13"]I for one am planning on another Drip La And a stereo link cable. I figure if radio stations used this for years back in the day for everything they transmitted... And alot of people 2 buss like this now. (depending on the sound wanted) then there is mojo there. And those older LA's weren't matched component wise like us DIY's can. So a good stereo match is possible. Altho there is a matching procedure to follow... (LA2 manual)

I also have an 1176LN mnats rev D finished with a temp input transformer. When I get the real deal I will probably double up on them 2. And will also use them as a 2 buss thing. But at this point my converters are my weak point...

Many final mixes over the years have been run stereo through each of these classics.

I'm still kinda floored my project studio actually has these now...[/quote]

I started out of the gate with two so another one at the moment would be a bit redundent. I've got a few projects in mind and would prefer another with decent utility and good availability of parts. I'm kind of luke warm on the pultec because it seems like some of the caps are not so easy to come by. I picked up some 1081 boards but it seems the iron is going to be slow in becoming available. I already have enough pre's so eq's and comps are the most attractive tools at the moment.

1176's on the two bus? Seems they might be a little quick for that job, but hey if it works then it's good.

Cheers, wm

 

[chingon]

[quote author="dripelectronics"][quote author="chingon"]I've been putting this project through the paces and noticed that i get quite a bit of hiss from it. Is this normal? Also when i turn it on i can hear the hiss volume slowly ramp up along with a low buzzlike sound and then it stays. Its actually a pretty noisy unit. The buzz sounds like its at the same rate as my cheap alesis monitor power amp so i'm guessing its picking up and amplifying this noise some how. During the build I installed the grids stoppers for safe measure even i'm not sure what its for or what ossilation is.
Another note: When I grounded the 4 pcb points i grounded them all in the same location instead of different areas as indicated in the manual. Could this be a problem?
Has anybody experienced this?[/quote]

the original la2a ground scheme is how it is on the pcb.
the star ground method can work , but with this project
i have found by duplicating the original layout this works
best ,

otherwise i would have just used a solid ground plane on the pcb
to loose the multi ground set up.
i think many revisions ago in my designs and prototypes i did this
only to end up with an expensive noise machine.

you would be amazed at how much the xlr socket pin 1
can effect things.

either ground this to the case next to the socket , like in the manual ,
or ground it to GND#2 on the pcb ,
do not use the pcb pad marked xlr #1.

the 12bh7a seems to cause this ramping noise if its a bad tube or
seated poorly this can happen,

ive noticed this while the unit was on and connected to some speakers,
that pressing it in better ,stopped this .
(dont blow your speakers or fry your self)

if you have the gain dialed hi , it is normal you will have white noise.
try turning your source up higher , and the la2a lower.
this is often understated thing.

hope this helps,

g.[/quote]
turns out that the power in my room was pretty damn noisy at the moment. After a few hours my noise problems went away. I did reground the PCB as stated in the manual though.

I'm curious as to if there are any nicer tubes I could use other than the ones stated on the BOM.

 

[broccoli]

lookee lookee what i found.... new old stock t4b's...

http://studioelectronics.biz/sunshop/index.php?action=item&id=370&prevaction=category&previd=6&prevstart=0

 

[safe as milk]

hi
is'nt mr.kulka a member here?
nice price btw

 

[broccoli]

hmmm... perhaps. i just did a google search for the t4b and his site came up... i hadn't seen this source for t4b's mentioned anywhere on the forum... but i could just be blind and/or out of the loop :wink:

cheers!

 

[Greg Dixon]

I paid $90 from the JBL tent sale!

 

[Stagefright13]

According to stuff I read on the net somewhere Tom Petty and others 2 bussed with 1176's at some point on the main mix. The release and attack is actually pretty slow depending on setting.

I got my t4b nos from Studio electronics. They are very reputable and sell on ebay as well. You will get the original Urie in a sealed box. But however I think Drip has a MUCH better price. And the choice of fast and slow. Slow I imagine is the original. Correct me if I am wrong. And fast would be really interesting to try!

The Urie one is nothing to write home about. It looks like someone made it diy and has globby black silicone dripping out of it...

 

[idylldon]

[quote author="Stagefright13"]Slow I imagine is the original.[/quote]

That's correct.

And fast would be really interesting to try!

Sure would. :razz:

Heh.

Cheers,
--
Don

 

[wmb]

How would one go about determining the performance of an LA2A. I'm trying to get some understanding of how my two new drip v2 units perform. There is lots of goodness in the way they sound but I would like to understand what I'm hearing a little more.

How can I go about testing them? I would like to have a concept of attack time and ratio. I would appreciate any suggestions.

Cheers, wmb

 

[bluesman714]

Is Parusha's La2a type case ventilated well enough? Or should I punch some holes in the bottom to get that convection thing going on?

 

[Stagefright13]

You'll have no problem. Mine barley gets warm even after 10 hours of use. My hardware reverbs are another story lol...

John

 

[chingon]

I bought the tubes recommended in the BOM. Are there any tubes that would be an upgrade from them?

 

[wmb]

In one of the other threads I think it was mentioned that one of the 12ax7's and the BH7 are the ones that matter. I think they are V1 and V2 respectively. I'm sure someone here will have more accurate information but that's a start.

 

[Stagefright13]

Yeah v1 and v2 are in the audio path. The BH7A and the 12AX7 #1. I can't tell you the difference in sound between the stock tubes and the ones I used. I built mine with NOS from the beginning. I put a 12AT7 in the 12AX7 spot because I already had some. Vintage NOS 12Ax7's can be pricey... But if ya go to tubeworld.com they have a pretty good explanation of the difference in sound between the various tube manufacturers. And in all my other tube equipment I have replaced the tubes and gotten better sound. Not usually night and day but with a good set of monitors you will notice the difference right away. Especially in the bottom end and highs.

 

[Stagefright13]

Ebay has some great deals on tubes. Such as Mullard Telefunken RCA GE etc. I've gotten some great tubes in a multi-tube purchase. I match them with my tester if I need a matched pair. None of the current production tubes sound as good as the older ones. Period...
Also used tubes are a great deal. For example a ribbed plate tele 12at7 has a reported 10,000 hour lifespan. And some other versions can last 50,000 hours. Wich the JJ tesla ecc83s is modeled after. But a tester is necessary to see what ya got.
I would be happy to test and match up anyones tubes if they go that route free of charge just email me.
I've gotten really expensive tubes off of Ebay that tested just about new! And were super cheap in comparison because they were used. Also some tubes labeled "Phillips" are actually telefunken. Ask for a pic of the bottom with the diamond stamp.

 

[moogfrotee]

Just wanted to share that i´m busy building the drip/OPTO. I received the arco´s from Nebrasca today.
The board is almost complete, only 4 parts missing and i´m still waiting for the Sowter transformers.
I´m having the best time. Its a bit like building a model aircraft when i was a kid.
I also did two SSL comps, that was my first experience with the world of DIY.
I used to do the electrical installation myself in my studios, so i´m used to high voltage.

This board is so good!!! The size and the whole feel is perfect. can´t wait to hear how it sounds!

 

[wmb]

It's a great sounding board! The sowter iron sounds really nice. Very thick. Haven't done a side by side comparison but I am working with some vocals tracked through a reissue. It's really in the same family in a big way.

I tracked an acoustic guitar two nights ago with a huge amount of GR. It sounded like that bracing inside the guitar was about to explode through the speakers. It really made the tone stand up to some pretty heavy egt at the end of a song. The pre was a brent averill 312 with the avedis DOA. Very interesting sound.

Cheers, wm

 

[moogfrotee]

Thats exciting! The sound of exploding guitars!

The sowter package arrived yesterday! nice and heavy. :grin:


Now theres only very small parts missing, ordered them today.
and i´m still thinking about what case would be best.
Just sent a mail to purusha.


QUESTION:
I have a VU meter that i disassembled from an old Sony tape-recorder.
Does anybody know if that would work with the drip/OPTO?
It´s quit big and has an extra metal frame for on to the front and a light too.


Cheers