LA-4 Help Thread!

[Matthew Jacobs]

Thanks for all the advise guys... I think I'm gonna finish this build in a couple of months and concentrate on finishing my SSL 9K pre-amps first.

I you can't capture a clear sound in the first place what good is a good compressor, hey? I think a wider selection of pre-amps will help my recording needs more than a comp.

Cheers...

PS I'll probably be back here in a few months when I get some cash to finish my LA4As.

J

 

[helterbelter]

Need cash for building an LA4 ?!? this thing is superinexpensive to build ! (okay, a case for it will eat your budget of course)....

 

[Matthew Jacobs]

Yeah I know, this compressor is probably the cheapest project on my bench and would be easy to complete. I just have a limited budget at the moment and am just wondering where to invest. I need to record some hip hop vocals and need a nice recording chain. I have a G9 and a G-Pultec. I was thinking of using the LA4A but I am now thinking of finishing my SSL 9Ks.

J

 

[Kev]

Nice someone brought the LA 4 back to the board. Seems a much simpler build than many others. I remember Kev built one ages ago and recommended it strongly for diy, I guess he used LED+LDR in a shrink tube...

yes I did
for the projects I put up in the early days
for simplicity and easy and all part of the DIY beginner experiance. Joe of JLM suggested to people the various commercial LED/LDR combos available and people could make their own choice
some even made plug-in modules

My LA4 proto and the Dual Opto Comp ( KDOC ) used the original chip in the sidechain for all the faults and envelope shape of the original and changed the signal chain to SSM in and out and LM833 for unit sections
tants were power supply bypass but I think a simple Bipolar in the signal path

it was all for cheap and simple first time DIY project ... and easy to use

oh
and to smallbutfine
thanks for remembering, Martin
8)

 

[helterbelter]

Yeah I know, this compressor is probably the cheapest project on my bench and would be easy to complete. I just have a limited budget at the moment and am just wondering where to invest. I need to record some hip hop vocals and need a nice recording chain. I have a G9 and a G-Pultec. I was thinking of using the LA4A but I am now thinking of finishing my SSL 9Ks.

J

A G9 and a G-pultec.. Yes, nice, nice, nice !
But if you already have a micpre, wouldn't a compressor be a better choice instead of another micpre ? (even though the SSL9k sounds is great). Especially if you record digital, a compressor would be a better addition... IMHO though.

Sorry if I confuse you more...

 

[gar381]

SOON !!

GARY

 

[MrZpliff]

SOON !!

GARY

Nice one !
Mine's on the way and is going to be something similar.
Anyone knows if the 6,8 uF caps gotta be 63V or if 35V is ok ? 

 

[helterbelter]

35 v should be fine. I think 25 would be just as good for that matter.

 

[MrZpliff]

35 v should be fine. I think 25 would be just as good for that matter.

Thank's !
That's what I thought also, but I thought I'd check.

 

[Matthew Jacobs]

Sorry if I confuse you more...

Nah not at all, good advice.
I think I will do both.

Cheers

J

 

[maxime]

Hello guys,
what transformer ratios are you using for output?
maybe a LA-4  would be a good use for the xformers lying around here..

thanks
Maxime

 

[kazper]

Hello guys,
what transformer ratios are you using for output?
maybe a LA-4  would be a good use for the xformers lying around here..

thanks
Maxime

1:1
600:600

 

[MrZpliff]

Hello guys,
what transformer ratios are you using for output?
maybe a LA-4  would be a good use for the xformers lying around here..

thanks
Maxime

I bought the OEP A262A2E in the BOM. Its 600/2400. If I get it right it should be wired backwards... 2400/600.

 

[Luny Tune]

Wire it so you have 1:1 or 1:2 ratio. That'll give you the best sound.

This circuit is not very sensible to impedance...somehow...and many many trannies will work. Don't be afraid of experimenting and don't be too surprised if even the cheapest trannies sound good in it.

I tried some very cheap Mouser tranies in it and they sounded great in my test. I still have yet to really test them in a mix but in my rough tests they sounded as good as the OEP. Maybe.....MAYBE with a little less sound of "iron" but it WAS there and sounded fine. (And I'll just stress MAYBE one more time... )

You can really drive transformers hard in this circuit.

 

[maxime]

thanks guys for your replies,

I have some sony mxp2000 1:1 output transformers (from a master channel strip), they will of good use..
best regards

Maxime

 

[MrZpliff]

Yep, thank's !
I'll wire the OEP:s primary in series and the secondary in parallell. If I'm right that will give 1:1 (600/600 oooohms).

 

[Matthew Jacobs]

SOON !!

GARY

Hi Gary,

I really like your front panel and would like to use it as an inspiration for my build.

Would you be able to post a illustrator file, close up photo or whatever so that I could take a closer look?

Hope that's ok?

J

 

[gar381]

Hi Matthew

This is a FPE file.  I'll be glad to share. PM me your email
and I'll send it to you.

GARY

 

[briomusic]

Here's my 500 series take on the LA-4 theme  ;D

It ended up being a bit of a squeeze, had to saw off the PSU bit, and cut a few more corners into the PCB as I just HAD to have the sifam retro mini meter. This build has a few 'extended' leads and a few pads that I drilled out too generously (new bosch drill won't take 1mm drill bits, WTF?). Anyway thanks go to NRG for the frontpanel, Lunytune and Gustav for the PCB, silen:arts for the L-bracket.

I will build another one without the 'learning curve' and hope to get it to be a bit less noisy.

 

[helterbelter]

Well, you've built the very first LA4 in 500 format !

When it's inside the rack, it looks very nice and professional.  ;D

but the wiring and the mounting.....  :