LA-4 Help Thread!

[djn111]

Hi,

I like to have a go at this project, anyone with four (or more) NSL 6910 LDR spares he wants to sell ?

Or a place I can buy them that have them in stock ?

DJN

 

[ilfungo]

I just finished my third LA4
In this  I used urei 11148 transformer
beautiful sound and 10 dB of extra gain ...
by hairballaudio are reproductions of this transformer, which could perhaps be a good option to OEP ....
I still think the desire to build one with  input transformer, is there a way to baypass entire input section to insert input transformer?
Thanks

???????

 

[Matthew Jacobs]

I just finished my third LA4
In this  I used urei 11148 transformer
beautiful sound and 10 dB of extra gain ...
by hairballaudio are reproductions of this transformer, which could perhaps be a good option to OEP ....
I still think the desire to build one with  input transformer, is there a way to baypass entire input section to insert input transformer?
Thanks

???????

Hi ilfungo.

Yes a transformer on the input is possible. It's something I plan to experiment with. IIRC, I remember reading a post by forum member "strangeandbouncey" where he talked about his modded LA4 with Carnhill input transformer. But I may be wrong. But looking at the schematic it's definitely possible.

Why don't you experiment?

J

 

[regularjohn]

As a drum bus comp I think it's all about what you're looking for exactly. The 1176 is more controlling and keeps the signal in an iron grip while maintaing/adding punch and you can certainly shape the sound in a number of creative ways. The LA-4 just does what it does but what I like about it is that it's a bit more...bouncy. It's strikes me as maintaining a certain musical elasticity. I love that just as much as I love what the 1176 does.

Luny, thanks for the info!  I'm personally not a fan of the 1176 on drum buss, so what you say is good.  My fav's are the Joe Meek/TFPro opto's...some of which even use a little flashlight bulb as the optical element. 

I'll probably end up trying out different opto's, but I'll start with the nsl32, as I can get them here from Newark. 
I'd like to try the nsl6910 also, but I can't find anyone selling LED's that are 150mcd.  Anyone know a supplier for those in the US?
Or if I use a brighter LED and just put it further away from the 6910, say at the far end of an uncut chapstick tube, will that make a difference?

 

[Luny Tune]

Dunno how distance affect it at all...IF at all...

I believe less than 150 mcd will be fine too, or may even be more true to the original than the 150 mcd one.

If you can wait some days I'll be ready to experiment with some softer than 150 mcd LEDs I have...

 

[regularjohn]

If you can wait some days I'll be ready to experiment with some softer than 150 mcd LEDs I have...

Yeah, that would be great!  I'd love to hear what you find out.  Thanks!

 

[Rybow]

I just received my CMOQ 2S today, and I am going to throw it into my current circuit. Just wondering about the wiring of it as I am not sure on a couple things. It looks like I am supposed to wire the primary and secondary in series to get the 1:1, 600:600 spec, but I am not sure where I should take the ground from. Any thoughts?

Thanks!

 

[Luny Tune]

Where it says Chassis on the pcb.

 

[Rybow]

Sorry. I should give more details. I meant where do I connect the ground on the transformer. My oep had a pin to connect it to ground. Is it just a matter of running a wire from the transformers frame to ground? Thanks!

EDIT: Nevermind. I just threw it in there and made the ground connection through the chassis using the transformers frame. No noise or hum. I connected the secondary as primary and primary as secondary as per Luny's advice. Sounds great! I like it more than the OEP. My LA 4 is sounding cleaner. Just used it on a DI bass. Deadly! Ryan Smash!

 

[mac]

Hey everyone,
I have just started looking at this project and cant seem to download the documentation from the link on the first page. Can anyone email me lunytunes pdf doc if you have a copy?

;D

thanks, Mac

all good thanks lunytune!!

 

[Luny Tune]

Just checked both links and they work just fine.

 

[regularjohn]

Hey everyone,
I have just started looking at this project and cant seem to download the documentation from the link on the first page. Can anyone email me lunytunes pdf doc if you have a copy?

I had a similar problem.  It seemed like I was just loading a blank page and thought there was something wrong.
If you wait a couple minutes it will eventually load.

 

[bigswole]

Just finishing up my la4a, i cant get my vu meter to sit at 0db.  The highest it goes is -1db in gain reduction mode.  It's a sifam al-29, but i dont think its the true vu type because it only works in gr mode.  However thats fine with me,  I just want to be able to get it to track correctly in gr mode.  any help is truly appreciated.

 

[helterbelter]

(kinda) Finished my dual LA4 today. I still have to tidy the powerdistribution , and I have to calibrate the whole. I tested the compressors earlier, I used these as SSL compressor modules before I decided to put them in a 19" enclosure.

I'm really satisfied with the frontpanel. It's CNC'ed by Frank (NRG), he did a really nice job. With designing it I started with Ilfungo's design, but when I was adjusting it to taste, I kinda realised it could be put in a 1R unit as well, so, I ended up with a different design. The lettering remained the same, but I changed the scales and overall layout in the end.

Frank, Luny, and Ilfungo : Thank you all !





The cutouts for the meters worked out really good. 3 blue leds form the  backlight. The VU's are taken from an old Sony Umatic recorder btw. It was a bit tricky to get the meters fitting, in regards to the case. Height of the meters is 40mm....


When the unit's off :


round corners :


The guts :


The meterswitch, with a bypass added. The rotaryswitch is a Seuffer with a 4mm shaft. Knobs are Sifam.

 

[Matthew Jacobs]

Helterbelter! Nice build!!!

I'm jealous....  ;D

Simply awesome... a real inspiration...

I'm digging the blue LEDs on the meters...

J

 

[SIXTYNINER]

i agreeeeee
8)

Helterbelter! Nice build!!!

I'm jealous....  ;D

Simply awesome... a real inspiration...

I'm digging the blue LEDs on the meters...

J

 

[ilfungo]

ciao helterbelter
BRAVO!!!
can you help my about the relay bypass?
how i can add on my dual LA 4?
Thanks

 

[helterbelter]

Thanks guys, !

Ilfungo, yeah, sure, but I'm currently having serious PC problems, I'll be offline a couple of days.

in a nutshell : For the meterrotary switch you'll need a 3P4T, instead of a 2P3T (The BOM of luny says a 2P6T, with the ring set to 3T). Simply connect the voltageline for the relays to the 4th pole, and use the corresponding outputpins for relays on and off. I have built mine so that when the relays are switched in, the LA4 is bypassed. In other words, I have connected only the 1st throw to the relays.

When I've solved my PC trouble, I'll draw it for you.

Now I've to log off, the PSU of the PC could die any minute (the motherboard draws way too much current).

Cheers,

Paul.

 

[kazper]

Sorry for the blurry pics...

Inside are not complete yet.

I have LED's still to mount inside the O in the OL, Stereo Link  ON and Power ON

Knobs are the small 1176 and LA3 Knobs from Hairball Audio , Sifam AL-19B meters, Par metal case and FPE for the $65 front panel engraving with no infill.

 

[Rybow]

Helterbelter, that is one beautiful unit you got there. Classy to the max! Big change from your console module all those posts ago. I see you still didn't put those tantalums in. Blue backlit meters have to be the sweetest looking things in the world.

Kazper, also very cool looking unit! Nice choice on the front panel design too. Kind of has a vintage look to it. Nice choice on the knobs as well. Have you been able to fire it up yet?

I have tried out a couple of things with LED's for the 6910's. First was diffusing a standard LED to reduce its brightness. That didn't work. At the moment I have an LED that was rated 10-82mcd, 1.7V, and 10mA. Seems to be working. Compression is much more controlled with less artifacts. I seem to have lost my 8:1, 12:1, and 20:1 ratios though. Weird. Not sure if its related to the LED's. This one channel is cursed. Cursed I tell you!

I have a couple more small issues to work out, or demons to expel, but its nearly there. Just have to find the time.