LA-4 Help Thread!

[gary o]

Insomniaclown thankyou for your offer to send resistors ( where else do you find such help these days ....only here) but  I think I have some 5K here now you have given me the info I needed I can match them up.......thanks once again

Gary O.

 

[dirtyhanfri]

Thanks Insomniaclown.

Actually I bought that case. I think it will fit everything (I was afraid of the toroid, but it looks gently big for everything)

Thanks for the answer, I´ ll start my build as soon as I get the boards

 

[gary o]

Well i stuffed my board & added the wiring had it running naked on the bench wow ! did it sound good yes it did! loved it, I very quicky made 2 vactrols with NSL5910s & clear Red leds and some blue tack compressed lovely without adjustments......I was testing meters I had in my junk box , the next time  turned it on I got nasty crackles and not much audio thru........Im not sure what has happened....have looked for loose connections dry joints but cant find the problem.......IC 1 get very hot so have been looking for shorts, cant see any , can it be I had a temporary short & have blown the IC ? have ordered more ICs but am worried I havent solved the problem & may blow the next IC1 I install......

great sounding comp tho sounded great with NSL5910s the short time i had her running.....Im itching to listen more & experiment with LDRs

Any ideas on the crackling sound and hot IC1...it must be cooked tho......

 

[MicDaddy]

Strange question for you guys with finished units.  Would somebody be able to help answer if I could fit a pair into an old Teac reel head? 

edit:  ok I added the pic of the teacs in question

 

[Rybow]

Insomniaclown thankyou for your offer to send resistors ( where else do you find such help these days ....only here) but  I think I have some 5K here now you have given me the info I needed I can match them up.......thanks once again

Gary O.

Your welcome Gary. Just read your other post as well. Hot IC 1 sounds like you do have a short there. I don't recall any of the IC's getting hot in my unit. I would check for shorts on the IC pins to start. The soldering space on those is pretty tight, and it would be easy enough to bridge 2 pads. Could just be a bad IC as well. While your waiting, you could measure the voltages on the pins to see what could be going on.

 

[Rybow]

Thanks Insomniaclown.

Actually I bought that case. I think it will fit everything (I was afraid of the toroid, but it looks gently big for everything)

Thanks for the answer, I´ ll start my build as soon as I get the boards

Looking forward to checking it out!

 

[Rybow]

Strange question for you guys with finished units.  Would somebody be able to help answer if I could fit a pair into an old Teac reel head?

I am not sure. A pair would fit into a 1U rack case with an 8" depth with a good layout. You can stack the boards on top of each other if you have the height. What are the measurements on the teac? I could take some measurements of everything I got to get a better idea of how much space is actually needed.

 

[MicDaddy]

Insomniaclown

Thanks!  Here's a photo to give an idea of the dimensions.  I have yet to gut them so the numbers are a bit conservative.

One day it popped in my head that these scream La4 so I figure worth a shot. 

Dimensions of pcbs for this project would be awesome (sorry if they're posted already and I've overlooked)

Thanks again and regards!

 

[gary o]

Thanks Insomniaclown....Ive checked and checked but cant find a short gone over solder joints too.....I did read somewhere this I can run hot but seems too hot to me....only thing I can think is I had temp short while it was alive on the bench & Ive blown something and now it runs hot as a result....I think the chips & transistors have the correct voltage fed to them.....Im just waiting for mr postman with my ICs....

MicDaddy....I measured my board it is 150 mm X 100 mm my power tran 60 mm its round .....I should think 2 will go in your case.....mine is mono & I have very small case so I may bolt power tran on the back of case

 

[Rybow]

Micdaddy- That should work. The boards might just squeeze in length wise. You have lots of room to work with for mounting all your transformers along the sides and back. I would cut the power supply section off both boards, and then you have more wiggle room. You only need one PS board anyway. Then you can mount the PS anywhere you like. That's what I ended up doing with mine.

Gary o- You can pull IC 2 and pop it into IC 1 to test. Should work as IC 2 is in the sidechain.

Now I need a little assistance. I installed the VTL5C4/2 in place of the 2 VTL5C4's, and I have no compression. I thought I had it right after looking at the manual, but it appears that I have screwed something up. Anyone have an idiots guide to installing the VTL5C4/2 on Gustav's board handy?

 

[gary o]

I think yr LED + is connected to nothing ,it wont light, I think it needs to be in 2nd hole to its left.....there is a pic in the PDF on page 1 of this thread....

Thanks for IC swap idea but silly me didnt socket them .........thats my next job before I PLUG in the new ICs

 

[Rybow]

I think yr LED + is connected to nothing ,it wont light, I think it needs to be in 2nd hole to its left.....there is a pic in the PDF on page 1 of this thread....

Thanks for IC swap idea but silly me didnt socket them .........thats my next job before I PLUG in the new ICs

Haha! Booyah. Man I can be dumb. Well, down into the shop again to get that fixed up.

Yeah. Socketing can save a lot of pain.

 

[Rybow]

And it works! Sounds good too. Just ran some vocals through it using it after running the vocal through stillwell's rocket comp to catch the peaks. Buttah. Ran that along with a back up vocal going through the NSL 32 equipped channel. Very cool sound. Very cool indeed. So cool. Did I say it was cool? Ok good. It's so nice to have this thing back in commission. For the first time since I started this project so long ago, I get to put the top on!

I originally had Luny's mod in place on my vtl5c4 channel. Replacing r13 with a 150k resistor, but I had a lot of issues getting it calibrated. Changed back to 82k, and calibration is better. I am missing 12:1 for some reason, but that's OK. I usually just use 4:1 and 8:1. Still need to do more with 2:1 as it's soft knee and steep slope would be very useful. My other channel is much more dialed in. Both sound great. Initial thoughts are my Slow channel has a softer, smoother sound with the VTL5C4/2 and OEPA262A2C. little more saturated as well. The NSL32 with Cinemag CMOQ 2S is more aggressive and bright. I could tell right away because the back up vocal I fed through it, even at a lower output level, was more pronounced than the lead. It's also a little cleaner sounding.

I like em both. Can you tell? So excited! Now, where did I put those screws for the lid? It's been over a year since I put them somewhere for safe keeping. Where was that?

 

[gary o]

brilliant Insomniaclown dare I say COOL 8) now you have 2 tasty flavours .....Speaking of COOL my new IC1 is cool too in its new socket that I should have instaled in the first place.... old IC must have been shorted or just a dud.....Its sounds good Im gonna try n cram it in a small case I have, cant wait to mess with LDRs & LEDs & vactrols, il probly end up with a switch as I wont be able to decide which combo is best sound....more flavours .....oep OP tran flavour tho due to lack of anything .....tho I may try a Sowter....

 

[Rybow]

Thanks Gary! I love having 2 different flavours to choose from. There are times I wish I had 2 identical channels for stereo processing, but I much prefer choice. They are a little quirky, but I love them! Just have to figure out my meter lamps. I have to keep the current draw low to avoid over heating the regulators, so the light is really low. I am using hairball 8037 meters, and I am wondering if I have the option to convert them to a couple of LED's.

Good to hear everything is working! Can't wait to see the finished project. I was thinking about doing different LDR's at one point. You may need to put a resistor somewhere in there to bias the different opto's. Never tried it though. I don't mind the OEP's at all. Compared to a cinemag, the OEP has a stronger colour to my ears. A sowter would probably sound great too!

 

[MicDaddy]

and I am wondering if I have the option to convert them to a couple of LED's

I did just this with my Rev A meters...  I used UV blue LEDS and suspended them above (hot glue) the VU housing facing down, used a total of 6 LEDS but could use 10 and really light it up.

I'll look for a photo....ok I found one that had only 2 LED still.  I did end up adding 4 more LED for a total of 6 and in hind sight wish I had done 10.  But I was going for a very very bright UV glow.  The 2 LED really doesn't light the VU faceplate very well.  How the LED are positioned had a HUGE impact on the look, as the ones I used were very directional.

 

[Rybow]

Hey Micdaddy! Those look good. I have a few 10mm super bright LED's that I might be able to try out. They are red, but could work for the experiment. Thanks for the info!

 

[dirtyhanfri]

Finally I got my board yesterday

I`ve started populating it, everything is ok. But in the pdf I see a 2.2k and a 5.6K Resistor wich I don`t find in the PCB, where should I solder them? and in the 3.6K value I just Find 2 resistors, the PDF says 3, an errata maybe?

Just for be sure, in the power supply part of the PCB, the 18C dc Supply is wired to the self pcb where it says 2x18 V DC?

Looks like a really funny project.

 

[gary o]

Hi dirtyhanfri theres a few off board resistors 2k2 between op pot 7 threshold ....a 3k6 & 5k6 on ratio switch..... & a 4k7 on meter switch......you better check this tho.....

from this thread a member did this handy drawing
http://www.bitterend.se/LA4-Offboard-Wiring.pdf

I think I understand your last question.........you need to connect PSU part of the board to the rest of it ( like I didnt & wondered why it did nothing)

 

[dirtyhanfri]

Great!

Thanks for the schem, I´ve found the info on the pdf attached in the first post too.

I ordered the components from Farnell some time ago and yesterday I found that one of the 6.8uF Electrolitic Caps is 50v not 63v as the BOM says. I just left it out by the moment,  but, could I use it or should i get a 63v Cap?

Thanks