Build an LA2A DIY compressor
« on: August 28, 2018, 04:03:41 PM »
Hi Everyone,

I am a student at a sound engineering school in Canada and during a soldering class my electronics supervisor told me about the possibility of building DIY gear parts.
I have the opportunity to build modules at my school with the help of my proffesseur and I would like to take the opportunity to build the famous LA-2A compressor.  ::)

I'm looking for assembled kit on internet but I didnt find any, so I started to read a lot of topics on this forum and I could see that some of you have built some by finding parts from different suppliers. :o
I confess that I have a little trouble understanding everything, this is my first time and I do not want to be wrong so I would like to know how and where it is possible to get the different components (Body, knob, vu meter etc.) to assemble the compressor ready to use. ;D

Thank you in advance for your help and please excuse my English I am a Frenchman and I have just arrived in Canada ;D


Re: Build an LA2A DIY compressor
« Reply #1 on: August 28, 2018, 06:29:33 PM »
Hey Mate,

I'd suggest doing something without tubes for your first build. Maybe a guitar pedal or a SSLbus comp if your comfortable soldering. Building gear with tubes requires you to work with potentially lethal votlages.  The parts for something like a pedal will teach you how the hardware works, how to read a scematic and how to source parts.

As far as I know there are no complete kits for the LA2A. But there are excellent Kit offerings from Hairball Audio and PCB Grinder.

Re: Build an LA2A DIY compressor
« Reply #2 on: August 29, 2018, 03:05:21 PM »
Hi and thank you for your reply!
Its precisely why that my teacher offered me his help and his equipment, he himself built a lot of DIY and know how to proceed with these steps.
For the schema, soldering etc. I practice at my school several hours, we began by soldering wires and we also did some effects pedal which allows me to have some good bases to attack the beast.

 I could see some "Vu Meter" and other elements on Hairballaudio and PCBgrinder but from what I understood you can find most of the element on electronic site like "Mouser" while passing by particular lists existing customers, then you must also get a "T4B Attenuator Module", a "vu meter" of "Knob" and its "box".

1 - I would like to know at first if my list is complete or if I miss elements to the complete design of the functional compressor?

2 - Concern the site "Mouser", I could find a list created by "Dripelectronics" but 2 elements of the list are not available, is it possible to find substitutes to replace them? And where can we find already existing lists?

3 - I find a box on the site "Don-Audio" but it is really expensive, I also saw that the site "Diy-racked" to propose, but I did not really understand if he sold only the front panel or the complete box kit.

Re: Build an LA2A DIY compressor
« Reply #3 on: August 29, 2018, 07:04:51 PM »
It seems to be more complicated than expected. I contacted Drip Electronics and they no longer sell opto 6. I made a list of the necessary materials:

1 - Collective Case LA2A
2 - Hairballaudio Vu Meter 8037 Lamp
3 - Knobs
4 - Electronic Drip PCB Opto 6 (with x2 T4B)
5 - Electronic parts on mouser
6 - Tubedepot socket + tube
7 - Output capacitor Mundorf 10uf Supreme
8 - Audio Transformers Sowter: 1090 15k / 600 output transformer + 1449 Input
9 - Lamp, faceted etc.
10 - Additional (cables etc.)

What solutions are available to me in these cases? If I find another PCB for LA2A will the mouser elements selected by drip be compatbile or should I find appropriate ones?


Re: Build an LA2A DIY compressor
« Reply #4 on: August 30, 2018, 03:23:14 PM »
With a PCB use their Bill Of Materials, Dip is very thorough in the BOM for the Opto 7. Im assuming it is the same with the Opto 6. Also people sell Drip Pcbs or kits in the white market once in a while, so maybe take a look there. Not every PCB uses exactly the same parts. Its best to get a PCB and then stick to the BOM.


Re: Build an LA2A DIY compressor
« Reply #5 on: August 31, 2018, 12:57:25 PM »
Yo can try D-LA2A from [silent:arts]. He sells the PCB and custom power toroid on white market. there is a help thread and lots of info there. You can just populate psu and one  of the two channels if you want  it mono...

Re: Build an LA2A DIY compressor
« Reply #6 on: August 31, 2018, 07:30:54 PM »
Thank for ure help !
After a lot of research and advice I think I finally made a decision.
I am going to build a ptp model with the help and the scema available on Recaudiopro.
I can get a ptp box easily, however the available "part list" is getting old and unfortunately most of the elements can't be found or have become obsolete. The only information available on the list is the value of the resistance in question (example 68k) without more details.
How canI find substitutes without making mistakes?
How can I be sure that I will do the right choice and find the perfect parts for replace the overs?


Re: Build an LA2A DIY compressor
« Reply #7 on: September 01, 2018, 07:20:42 AM »
I can only recomend the P2P route. To me it is a lot more fun than just stuffing a PCB.
You should read Raintons threads. He also has a site dedicated to building classic gear.


Re: Build an LA2A DIY compressor
« Reply #8 on: September 01, 2018, 02:26:29 PM »
I second Rainton for P2P.


Re: Build an LA2A DIY compressor
« Reply #9 on: September 01, 2018, 06:00:11 PM »
I built a point-to-point LA2A. It takes more time than a PCB, especially in sourcing parts, but it's way cooler!


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