LA-4 Help Thread!

[dirtyhanfri]

Well

I solved the Power supply issues, but new issues are coming, Thanks Insomniaclown.

I connect the compressor with no smoke. The meter was wired backwards, I solved it and I can adjust the zero in the gain reduction position, well.

Then I try to pass audio with no results, I measured the Power Input of the IC´s and found a bad connection, solved it, and then the voltages look ok. Then searched for more shorts or bad solders and found one more betwen the 2 15R resistors, I´ll fix it later and report the results.

 

[dirtyhanfri]

Hi

I solved the short mentioned above, just sucking a bit of solder.

And now I got audio in the output, but not change in the sound when changing ratio,threshold, or Hi/Lo Switch just with the output pot. I have to make some test properly (I was testing with a cheap ipod dock & radio speaker) but I didin´t noticed any change, I tweaked the trimmers with no result.

The needle in the meter chnanged to -3 in GR position when plugged everything ok. and was no measuring any output in +4 or +8 mode (stays in -20db)

I´ve cheked the voltages coming into the IC´s and they look ok, the 139´s & 40 looks ok too, anything gets so hot, and I think it´s hard to short the input and output accidentally, but I´ll recheck again.

Some ideas in what to check specially, some voltages to measure or something?

Too many thanks, It´s great the support in this forum.

 

[Rybow]

Glad you got that issue sorted. Now onto the no compression issue.

What opto's are you using? Did you roll your own with the NSL 6910? Or did you use NSL 32's, or vactrol VTL 5CX series?

The first thing I'd check is your orientation of the LED on the optos. You want the cathode (-) in the hole by the Opto 1 and Opto 2 markings.

The no change in sound on the hi/lo switch is interesting. I would check your switch wiring on that one. We are just flipping a resistor in and out of the circuit, so that should be an easy fix. My guess is that your switch is not opening and closing the circuit like it should.

Interesting about the meters. Probably just a wiring issue. I had similar issues when wiring my meters.

 

[dirtyhanfri]

What opto's are you using? Did you roll your own with the NSL 6910? Or did you use NSL 32's, or vactrol VTL 5CX series?

I´m using NSL 32 , I think I have installed it correctly, looking at the pdf posted in this thread. I´ll rechek later.

The no change in sound on the hi/lo switch is interesting. I would check your switch wiring on that one. We are just flipping a resistor in and out of the circuit, so that should be an easy fix. My guess is that your switch is not opening and closing the circuit like it should.

Ok. I´ll check if the switch wiring is ok , but i think I checked it before, just for be sure.

Interesting about the meters. Probably just a wiring issue. I had similar issues when wiring my meters.

I changed the wiring between the meter and the switch yesterday, it was wrong, I´ll recheck the wiring going to the board.

Also I´ll replace the IC´s, maybe they could suffer some damage during the tests..


Thanks!!

 

[dirtyhanfri]

Sorry, I said I was using a NSL32, actually I´m using a vactrol vtc 5x (I can´t remember the exact numbers, too many thing in my head these days)

I replaced the IC´s and wired correctly the Hi/Lo switch, it works ok now

And then the compression was there, but just on ratios higher than 8:1. 4 & 2:1 didn´t compress anything, the sound is there, but no evident change, and the needle measures no reduction.

Also I noticed a higher volume in 2:1 Ratio, and sometimes in 12:1 and 20:1, randomly the compression appears to go away and the volume goes up again, no reduction in the needle, strange, seems like a bad contact in the pot or something... got to look closer to this...

And again... no output measurement +4 or +8 positions will keep the needle in -20, perfect, with no change tweaking the trimmers. I´ve rechecked the meter wiring, relating to the wiring pdf posted in this thread.

Also, in GR mode, the needle acts a bit crazy, if I get it to 0 with no sound on the compressor changing the trimmers when i put audio on it the needle goes to +3 and then mesures reduction from it (like a 3db offset in the measuring) And in lower ratios, with no audio, the needle goes to -10.

My testing was everything but serious, sh*tty ipod speakers, I had a so busy day, trying it after lunch.  I´d like to get it working propperly before getting it to the studio for real test & calibration.

But, I like what I´ve heared. Much. (my first hardware comp and first "big" & near finalized building)

Now I´m designing the front pannel, I´ll paint it in black and now I´m thinking about get some "transfers" for the labelling (something like vinyl adhesive, i have no experience with this, a friend of mine will do it if finally I´m able to trust him)any suggestions? front pannel ideas/designs to share?

Thanks, today is a great day for me.

 

[dirtyhanfri]

Well, my wiring looks ok now, I used shielded mic wire, being carefull with the lenghts.

I have to test it with the new wiring, but before making it, the meter didn´t show any output, and reading the thread I see people with similar issues. I haven´t installed any germanium diodes before the meter

http://es.farnell.com/jsp/search/productdetail.jsp?SKU=7758227


Would I need them? and exactly what kind and how many? I don´t know anything about this...

Also I saw at 4:1 ratio and mid threshold pot position the needle looked like measuring output and no GR, strange....

I´ll continue cheking...

 

[Rybow]

Good to hear you have some compression happening! One step forward.

Your meter states that it is a VU meter with rectification, so that shouldn't be the issue. What level are you sending your audio in at? Are you using a test tone from a DAW?

Gain reduction. Have you adjusted the ratio trimmer? Also, have you setup your VU meter tracking? The 2:1 ratio should bring on massive GR. I would double check how you have connected the poles on your ratio switch. On a 2 x 6 lorlin, pin 7 is not connected to anything in 2:1 IIRC.

I don't have the schematic in front of me, but the VU meter is strapped across the output for measuring the output level. If it's not showing level, than it is not connected properly, the meter measurement is outside the usable range, or the meter is not actually rectified in which case the datasheet is a big fat liar.

If you are using a DAW to do your testing, I would send in a sine wave of 1khz or 2khz @ -20dbfs. then lower the threshold while watching a DAW meter (sonalksis freeG is quite detalied) to see how much gain reduction is taking place. We need to see if the issue is just the meter, or possibly the optos themselves. If you have a scope, that's even better.

 

[Davo]

Hi Guys,

I thought I'd upload my wiring diagram... MrZpliff's was incredibly helpful, although tough to read.
I didn't bother putting the power connex on here and I used a dpdt for the meter (GR and +4), but most of it's there.  Please let me know if
you spot any errors.

Cheers,
Dave

 

[Davo]

and a couple pics of my quad la4......

 

[kepeb]

VERY nice
is that two different pairs of op transformers? what did you use?

 

[dirtyhanfri]

Nice build Davo, and thanks for the wiring diagram.

Well, I had a bit of time this morning to mess around with it, new shorter and shielded wire, and it´s all the same.

I noticed the meter was wired wrong, changed it and works bad, so it could be a way to follow, maybe all the meter switch is bad wired. The Needle go backwards in GR Mode, and no output measured, also, when it "worked" (wired theorycally bad) I noticed that in 4:1 ratio, at mid Threshold positions the needle goes up with the level, no compression at all, and the needle looks like measuring output.... crazy for me

The Ic2 gets a bit hot with 2:1 Ratio, but not burning or smelling, I´ll buy one new this afternoon, maybe it´s damaged...

And, one (maybe) silly question... I just installed one vactrol, relating to the pdf by lunytune, is it ok or totally wrong?

Your meter states that it is a VU meter with rectification, so that shouldn't be the issue. What level are you sending your audio in at? Are you using a test tone from a DAW?

Well, right now I´m feeding it with an ipod, waiting for medium functionallity before bringing it t the studio for making formal test.

Gain reduction. Have you adjusted the ratio trimmer? Also, have you setup your VU meter tracking? The 2:1 ratio should bring on massive GR. I would double check how you have connected the poles on your ratio switch. On a 2 x 6 lorlin, pin 7 is not connected to anything in 2:1 IIRC.

I adjust it to get the needle in zero with no audio, but as soon as I move the ratio switch it goes to -10 (in lower ratios), and when the audio is passing, it goes to +3 and then it goes down from there.

I don't have the schematic in front of me, but the VU meter is strapped across the output for measuring the output level. If it's not showing level, than it is not connected properly, the meter measurement is outside the usable range, or the meter is not actually rectified in which case the datasheet is a big fat liar.

Well, I´ll look deeply at the schematics today, but more I check the schematics, more I think it´s ok.

I can hear clearly how the volume goes up whith 2:1 ratio, just the opposite of expected... great!

This was a hard weekend for me, and now I´m a bit dicouraged with this, so I think I wil wait a few days before going back to it, for refresh my mind a bit, I got some other projects ready for work on them, maybe it´s time to start them....

Ideas, suggestions?

And, lot of thanks for your time, guys. I´m pleased.

 

[Davo]

Thanks guys!  Bit more work than expected , but works great... dead quiet on all channels and compresses like a champ!

Kepab, yes, 2 sets of op xformers.... oep A262A2E's and EA-11148 from Hairball.... both work very nicely, although I prefer the 11148's. 

There was some talk earlier in the thread about using a blocking cap with the 11148's... I measured milliamps on the outputs and it turned out to be
somewhat significant, but only at really high output levels... I can't remember exactly what the measurements were.  Anyway, I decided to just drop in the blocking
caps for drill.

dirtyhanfri, a couple of thoughts.... in GR mode the needle is supposed to go backwards (am I misreading you?)  Also, what kind of vactrol are you using?  Is is a dual
vactrol and is it wired correctly?  If it's a single (and you're only using one).... your problem lies there, I had a bad connection on one of my vactrols and got all kinds of
interesting behavior until I tracked it down. 

I'd really go through with a sharp eye and make sure that all my onboard components are correct... then go through with my wiring diagram and check all your connections...
I have four channels working flawlessly with this setup (all that I omitted was the +8 on the meter switch)  Thankfully, this is a relatively easy build, so I'm sure you'll get there.

Cheers,
Dave

 

[chrispbass]

Nice build Dave, beat me to the quad! 

 

[dirtyhanfri]

dirtyhanfri, a couple of thoughts.... in GR mode the needle is supposed to go backwards (am I misreading you?)  Also, what kind of vactrol are you using?  Is is a dual
vactrol and is it wired correctly?  If it's a single (and you're only using one).... your problem lies there, I had a bad connection on one of my vactrols and got all kinds of
interesting behavior until I tracked it down. 

You´re great man, my opto is just one channel, thanks for opening my eyes:
http://es.farnell.com/jsp/search/productdetail.jsp?SKU=1652521

Ok, I got two of these, and also a pair of NSL32´s, wich I think I will use...

Anyway, the vactrols have 5 pins. How should I wire them?

Thanks for the tip Davo.

I was thinking in letting it apart for some days, and feeling really bad about it. I will give it a try tomorrow (1 a.m. here) and see what happens with NSL32´s....I don´t know if I can wait....

Thanks, I was really stucked, now, let´s look for the next issue!

 

[Rybow]

Nice build Dave! Very very nice.

dirtyhanfri- Don't give up! You're almost there. This comp is worth it.

The Vactrol VTL5c4/2 has wiring info in the manual. There is a link on the first page. I also posted a little diagram a page or 2 back when I was trying to figure out what was wrong with mine. The only thing I forgot to do was jumper the LED pads on Opto 1, and now it works just fine.

NSL 32's work great, and sound really nice too. Give them a try for sure. You may have to increase your ratio trimmer value for these. I seem to remember putting in a 1k trimmer.

 

[gary o]

Yeah I agree with insonia dont give up nearly there & worth it.......sounds like the meter tracking needs to be adjusted I just had to fiddle with mine but I would get the compression sorted out before that.....

Have you got any leds & ldrs laying around.......if you connect a LED to board (check with schematic) its not marked on the board which holes are LED but you can work it out & also LED polarity must be correct.....when you play yr pod with another level & yr threshold is down you should see the LED lighting if it does it confirms the side chain is working......chip 2 I think ?

Then you could connect  LDRs to the board (check with schematic).....the level shoul go down coz they with be seeing daylight your meter may register compression also......put blob of gum over LDRs to hear louder level & make meter move back... this will confirm that it will work if vactrol is wired correct......the sort your meter tracking out

Im not a real tech so clever guys with better ideas please chime in here...

I would study & get to know the schematic its easy to froget its there when we do paint by numbers projects.

good luck

 

[dirtyhanfri]

I won´t give up, don´t worry, just thinking in take some days and refresh my mind (now, this is personal...), but my other projects are waiting for some comps to arrive so I´ll keep on this.

I´ll install NSL 32´s today, then I´ll post the results.

Thanks for the help to everyone.

 

[Davo]

Thanks for the compliments guys, much appreciated! ;D

dirtyhanfri, you're almost there man, keep plugging

cheers
dave

 

[dirtyhanfri]

Hi, I`m right now with this...

I just installed the NSL 32s, changed R13 for a 82K (was 150K for the Vactrol as I read in the pdf) and the 10k trimmer for 500 Ohm.

Ok, I oriented the dot (- led as I read in the datasheet www.silonex.com/datasheets/specs/images/pdf/103708.pdf) to the outter side of the pcb (the dot stays next to Opto 1 & Opto 2 lettering) And the upper legs as seen in some pictures around here (Davo`s build some posts ago as example)

Then I plug it, no audio, and the needle in GR goes below -20, no moving (actually looks like stucked trying to get lower), passing audio doesnt measure any output. I`ve rechecked the wiring and I could bet my right hand it`s ok. When I wire it to the switch opposite as indicated in the wiring driagram from MrZpliff (A from the switch to +, C to -) and plg the unit on, the needle goes to 0 in 20:1 and 2:1 the rest of the ratios it stays in -5, no audio passing.

Passing audio with the threshold down in the pot, so louder in 2:1 and 20:1 ratios (again), almost silent in the rest of the ratios

Getting the threshold pot up I notice strange actings... in 2:1 & 20:1 there`s no compression, and in the rest of the ratios there`s something wrong, the volume goes down in the softer parts, like the opposite of I expected (expander?)

All this was in the Low position in the input range switch (30K resistor is out)

IC2 is getting so hot, changed it and the new is so hot too...

SO I think IC2 is acting bad, measuring with a multimeter gives me some light, between pin 8 and ground I got -16v. dc, and 0 in the other ICs, no shorts around. The voltage in Vcc+ and Vcc- pins looks ok, I`m a bit lost right now, any ideas of what could I do?

 

[dirtyhanfri]

A few pics...