LA500A opto comp leveling amp BUILD THREAD 500/51X

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dneilsen
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by dneilsen »

So after doing some more testing I believe that the BIO500V2 pcb may be fine.

If I unscrew the BIO500v2 pcb from the 500 module frame and sit it on a piece of plastic (cd case) the input and output xlr 2 & 3 differences are all 1.23 VAC, as they are supposed to be.
But if I screw it back into the 500 module frame then the output voltage goes higher.

So now I am looking for a short to the 500 module frame from one of the pcbs.

dneilsen
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by dneilsen »

Done some further testing.
I placed a piece of thick paper between the boards and the frame at the front of the unit to test there is no shorts there.
20200717_110816.jpg
As you can see in the photo the only components actually touching the frame are the two pots, the 3 switches and the transformer.

In this configuration output between pins 2 and 3 is 1.23 vac.
If I measure between output xlr pin 3 and the frame it measures approx 1vac. (What the?)

I'm not sure what else to try. Any suggestions?
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dneilsen
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by dneilsen »

So I just came back to my bench to do some more testing and now everything is fine.
I put it back together and all the voltages are correct.
I have absolutely no idea why but I guess as long as its working....

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Joe Malone
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by Joe Malone »

dneilsen wrote:
Fri Jul 17, 2020 1:50 pm
So I just came back to my bench to do some more testing and now everything is fine.
I put it back together and all the voltages are correct.
I have absolutely no idea why but I guess as long as its working....
From your other posts it will be a opto or other component leg under the sidechain pcb touching the back of one of the 2 pot switches boxes.

Good to hear it is going now.
Joe :-)
JLM Audio
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Mattsoniclab
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by Mattsoniclab »

woohoo!
All finished and sounding great. Thanks for the excellent kit and easy to follow instructions Joe. I can see how much work goes into these.
Now to shove some drums through it. ;)

cheers.
Matt
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Joe Malone
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by Joe Malone »

Mattsoniclab wrote:
Fri Jul 31, 2020 8:55 am
woohoo!
All finished and sounding great. Thanks for the excellent kit and easy to follow instructions Joe. I can see how much work goes into these.
Now to shove some drums through it. ;)

cheers.
Matt
HI Matt
Great to hear you liked building the comps :-) Hopefully the drum tracking went well ;)
Joe :-)
JLM Audio
Capturing Audio without Injury

bpark919
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Joined: Wed Dec 16, 2020 10:17 am

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by bpark919 »

Hello All,

Was hoping for some insight for a noob like me. I just put together the comp and the build process went great, but now I’m trying calibrating the unit and I literally don’t understand any of the instructions.

Could someone please post a complete layman’s guide, or somewhere I could get the knowledge? I tried googling “CCW” and all that pops up is stuff about concealed weapons permit, LOL!

Also I don’t really have any equipment like a dbMeter or aVU METER; I found a 100Hz sine wave sound on YouTube but am lost on how I should be setting g levels. Any help would be much appreciated! Thank you so much!

(For reference I was running a shure sm7b to a RND 511 pre, then into this comp.

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Joe Malone
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by Joe Malone »

bpark919 wrote:
Wed Dec 16, 2020 1:22 pm
Hello All,

Was hoping for some insight for a noob like me. I just put together the comp and the build process went great, but now I’m trying calibrating the unit and I literally don’t understand any of the instructions.

Could someone please post a complete layman’s guide, or somewhere I could get the knowledge? I tried googling “CCW” and all that pops up is stuff about concealed weapons permit, LOL!
CCW = Counter clock wise = turn the knob to minimum.
Also I don’t really have any equipment like a dbMeter or aVU METER; I found a 100Hz sine wave sound on YouTube but am lost on how I should be setting g levels. Any help would be much appreciated! Thank you so much!
Your A/D and recording software should have some type of VU PPM meter. If you know the analog clip level of your A/D like +18dBu = 0dBFS you would want to read -14dBFS = +4dBu. or use a cheap multimeter set to AC volts to read the output volts of 1.23vac = +4dBu between pin 2 & 3 of the XLR etc.
(For reference I was running a shure sm7b to a RND 511 pre, then into this comp.
Your recording software should be able to generate a 1khz tone that you can send out of the D/A.

Also check out this link to free software etc http://www.jlmaudio.com/forum/viewtopic.php?f=2&t=137
Joe :-)
JLM Audio
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bpark919
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by bpark919 »

Joe Malone wrote:
Wed Dec 16, 2020 1:30 pm

Hi Joe,

Thanks so much for the reply. I am so sorry that I'm such a noob. I think a lot of this is probably expected for me to know, but I'm jsut getting into voiceover and approached it from the hardware side after not being happy with the tone I was getting from plugins. And please let me know if there's a different place I can go to get this info! But still having a bit of trouble following.
Your A/D and recording software should have some type of VU PPM meter. If you know the analog clip level of your A/D like +18dBu = 0dBFS you would want to read -14dBFS = +4dBu. or use a cheap multimeter set to AC volts to read the output volts of 1.23vac = +4dBu between pin 2 & 3 of the XLR etc.
when you mean +4 dB, are yo utalking about the VU meter on the compressor unit itself?
Your recording software should be able to generate a 1khz tone that you can send out of the D/A.
I downloaded the audio test software that was linked, and I've figured out how to do the 1khz tone. However, I'm a bit confused because it is playing through my monitoring headphones. I don't have studio monitors; am I correct in thinking that the 1khz tone needs to be playing into my microphone input?

I'm going to keep trying to figure out how to do this in the meantime, but any help/direction is much appreciated! Thanks so much!

bpark919
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by bpark919 »

Hello Joe,

So I didn't get a response to my last query but I think I figured out a lot of the stuff. My DAW has the ability to play a 1KHz tone like you said. I'm playing that on repeat while I plug the output of my audio interface (Audient evo 4) to the DI of my preamp (a Hairball audio Lola). Then it's feeding into the compressor. I measured 1.23 VAC on pins 2 and 3 of the compressor, and adjusted the gain and output level on my preamp until it hit 1.23 VAC. Here's the issue I've run into:

When I adjust the "Meter 0VU" pot using a small flathead screwdriver, while the tone is running and steps have been followed (HPF toggle set to flat, VU toggle set to VU, ratio to 3:1, both knobs fully CCW) the pot does absolutely nothing. I tried setting my "ZERO GR" pot to display as 0, and that one works fine. Then when I try rotating the balance pot, nothing happens once again. I've checked the soldering job and they all look fine. Really confused how to move forward with this.

thanks, and merry christmas!

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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by Joe Malone »

bpark919 wrote:
Sat Dec 26, 2020 7:28 am
Hello Joe,

So I didn't get a response to my last query but I think I figured out a lot of the stuff. My DAW has the ability to play a 1KHz tone like you said. I'm playing that on repeat while I plug the output of my audio interface (Audient evo 4) to the DI of my preamp (a Hairball audio Lola). Then it's feeding into the compressor. I measured 1.23 VAC on pins 2 and 3 of the compressor, and adjusted the gain and output level on my preamp until it hit 1.23 VAC. Here's the issue I've run into:

When I adjust the "Meter 0VU" pot using a small flathead screwdriver, while the tone is running and steps have been followed (HPF toggle set to flat, VU toggle set to VU, ratio to 3:1, both knobs fully CCW) the pot does absolutely nothing. I tried setting my "ZERO GR" pot to display as 0, and that one works fine. Then when I try rotating the balance pot, nothing happens once again. I've checked the soldering job and they all look fine. Really confused how to move forward with this.

thanks, and merry christmas!
The pots are 25 full turns from end to end and come set to the centre position. So you have to turn a few turns usually to get 0VU (power up the VU meter first time will usually be about -2dB)

The GR meter it will be higher than +4VU and need to be turned back a lot of turns to get to 0VU.

But you must set 0VU first before going on to any other trimpot like GR.

If you cannot get to 0VU with 1.23vac on the output then something is built incorrectly. Usually one or more solder pads not soldered or solder short between pads etc
Joe :-)
JLM Audio
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flyingcloud
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Joined: Mon Jan 11, 2021 6:48 am

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by flyingcloud »

Hi Joe,

I just completed this build. everything seemed to go smoothly- but when I powered the unit up I heard a crackle, saw smoke and immediately cut power.

turns out R15, R16 (10R) on board SCv3 both completely fried.

here are some photos of the boards: https://www.dropbox.com/sh/yo4ow2i66yt7 ... VH4_a?dl=0

wondering if you have any ideas of what this could be?

thanks!

flyingcloud
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by flyingcloud »

Ok so I replaced the resistors and went through and hit every solder point..it fires up without exploding!

it will pass audio, but the meter is pinned and the when turning the threshold pot cw audio stops completely. makeup gain seems to be working... any tips for troubleshooting this? thank you!

flyingcloud wrote:
Mon Jan 11, 2021 4:42 pm
Hi Joe,

I just completed this build. everything seemed to go smoothly- but when I powered the unit up I heard a crackle, saw smoke and immediately cut power.

turns out R15, R16 (10R) on board SCv3 both completely fried.

here are some photos of the boards: https://www.dropbox.com/sh/yo4ow2i66yt7 ... VH4_a?dl=0

wondering if you have any ideas of what this could be?

thanks!

flyingcloud
Posts: 3
Joined: Mon Jan 11, 2021 6:48 am

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by flyingcloud »

ok sorry for taking you along for this ride- looks like the problem could be that the ne5532p opamp on the sc board was installed in the wrong orientation. I noticed that someone here had a similar issue a few years back. I removed the opamp and the needle was no longer pinned with power on. flipped opamps with the la500 board and voila- no audio- so I'm lead to believe that the sc opamp went out along with the two original resistors.

ordered new opamp - hopefully that'll do the trick!



flyingcloud wrote:
Tue Jan 12, 2021 10:33 am
Ok so I replaced the resistors and went through and hit every solder point..it fires up without exploding!

it will pass audio, but the meter is pinned and the when turning the threshold pot cw audio stops completely. makeup gain seems to be working... any tips for troubleshooting this? thank you!

flyingcloud wrote:
Mon Jan 11, 2021 4:42 pm
Hi Joe,

I just completed this build. everything seemed to go smoothly- but when I powered the unit up I heard a crackle, saw smoke and immediately cut power.

turns out R15, R16 (10R) on board SCv3 both completely fried.

here are some photos of the boards: https://www.dropbox.com/sh/yo4ow2i66yt7 ... VH4_a?dl=0

wondering if you have any ideas of what this could be?

thanks!

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Joe Malone
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Post by Joe Malone »

flyingcloud wrote:
Tue Jan 12, 2021 5:15 pm
ok sorry for taking you along for this ride- looks like the problem could be that the ne5532p opamp on the sc board was installed in the wrong orientation. I noticed that someone here had a similar issue a few years back. I removed the opamp and the needle was no longer pinned with power on. flipped opamps with the la500 board and voila- no audio- so I'm lead to believe that the sc opamp went out along with the two original resistors.

ordered new opamp - hopefully that'll do the trick!



flyingcloud wrote:
Tue Jan 12, 2021 10:33 am
Ok so I replaced the resistors and went through and hit every solder point..it fires up without exploding!

it will pass audio, but the meter is pinned and the when turning the threshold pot cw audio stops completely. makeup gain seems to be working... any tips for troubleshooting this? thank you!


Just got to check your post and photos and the opamp is backwards so will short the power rails together. Do not plug that opamp in again. Put it in the bin. Changing the 2 x 10R and NE5532A plugged in the correct way should fix your problems.
Joe :-)
JLM Audio
Capturing Audio without Injury

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