LA500A opto comp leveling amp BUILD THREAD 500/51X

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

Postby greenote » Wed Aug 10, 2016 2:37 am

Thanks Joe. GR meter still isn't right, but easy enough to use my ears and the VU meter.
I've got two older LA 500s, one has a meter issue and one doesn't pass audio. I'm glad I got a handle on this one as it should make troubleshooting the others easier. I love the smooth sound of these guys and the output has a nice girth!

Great kit, thank you!

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

Postby Joe Malone » Thu Aug 11, 2016 8:19 am

greenote wrote:Thanks Joe. GR meter still isn't right, but easy enough to use my ears and the VU meter.
I've got two older LA 500s, one has a meter issue and one doesn't pass audio. I'm glad I got a handle on this one as it should make troubleshooting the others easier. I love the smooth sound of these guys and the output has a nice girth!

Great kit, thank you!


What problem are you having aligning the GR meter?

Which step in the alignment do you get to?
Joe :-)
JLM Audio
Capturing Audio without Injury

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

Postby rbkonline » Sun Oct 02, 2016 4:19 pm

Hi

I have a pair of LA500As. Both of them pass audio with their threshold and makeup knobs turned fully counter clockwise and even when the 500 series chassis in which they are mounted is switched off. Is this normal?

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

Postby Joe Malone » Mon Oct 03, 2016 9:21 am

rbkonline wrote:Hi

I have a pair of LA500As. Both of them pass audio with their threshold and makeup knobs turned fully counter clockwise and even when the 500 series chassis in which they are mounted is switched off. Is this normal?


Yes. The LA500A comp has a relay hard bypass so when they have no power or are switched to off audio bypass will connect the audio in and out. When you switch to GR or VU the meter should light and the bypass relay will switch to the comp output. You can prove you are listening to the comp output by turning up the makeup pot which should turn up the audio level when in GR/VU but not in off position.
Joe :-)

JLM Audio

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kante1603
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Postby kante1603 » Fri Dec 02, 2016 3:14 am

Hello Joe,

long time no hear,hope you´re fine,hahaha…..
You know I have a bunch of both the old and new versions,and they´re still my favorite compressors.
Now I have an issue with a LA500A at my work.
It worked perfect for a year or so in an exclusive tracking chain,at least 4 to 5 days a week,and I absolutely do not want to miss it in any of my vocalese sessions.
Yesterday I recorded with it for a couple of hours,then all of a sudden a noise floor appeared,sounding like pink noise.I thought I only heard it in the breaks,but it´s there,loud enough to hear.After a long break I quickly checked back and have results as follows:

1.The noise is introduced when in active mode,not in bypass as expected.
2.The level is around -50 to-45dBFS in my PT system.
3.It is steady,not coming and going.
4.The noise floor follows the makeup pot.
5.Functionality seemed to be normal,it compressed,though I´m not sure if I might have heard some kind of unwanted distortion from time to time,my ears were tired,it was a long session.

My goal is to get it back up and running quickly,otherwise I must tear out a module from my studio at home because I need one for recordings by tuesday.
Does my description contain any hint for you where to look at first?
I don´t have too much of time for a long repair atm.
For me it looks like an opamp issue on the i/o board,but I´m not sure about it.
The only thing I can do quick by tomorrow is swap out the 2604 because I have some here.
Is that the way to go or do I have to go in deeper?

Thank you in advance,

best regards,

Udo.

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

Postby Joe Malone » Fri Dec 02, 2016 8:05 am

kante1603 wrote:Hello Joe,

long time no hear,hope you´re fine,hahaha…..
You know I have a bunch of both the old and new versions,and they´re still my favorite compressors.
Now I have an issue with a LA500A at my work.
It worked perfect for a year or so in an exclusive tracking chain,at least 4 to 5 days a week,and I absolutely do not want to miss it in any of my vocalese sessions.
Yesterday I recorded with it for a couple of hours,then all of a sudden a noise floor appeared,sounding like pink noise.I thought I only heard it in the breaks,but it´s there,loud enough to hear.After a long break I quickly checked back and have results as follows:

1.The noise is introduced when in active mode,not in bypass as expected.
2.The level is around -50 to-45dBFS in my PT system.
3.It is steady,not coming and going.
4.The noise floor follows the makeup pot.
5.Functionality seemed to be normal,it compressed,though I´m not sure if I might have heard some kind of unwanted distortion from time to time,my ears were tired,it was a long session.

My goal is to get it back up and running quickly,otherwise I must tear out a module from my studio at home because I need one for recordings by tuesday.
Does my description contain any hint for you where to look at first?
I don´t have too much of time for a long repair atm.
For me it looks like an opamp issue on the i/o board,but I´m not sure about it.
The only thing I can do quick by tomorrow is swap out the 2604 because I have some here.
Is that the way to go or do I have to go in deeper?

Thank you in advance,

best regards,

Udo.


HI Udo Great to hear from you. Sorry to hear about the LA500A playing up

First unplug what ever is plugged into the input of the LA500A to make sure the noise is not coming from further up the chain. But since bypass removes the noise this should be not be the case but always best to double check with no input plugged in.

Does the noise reduce with compression? (You can hear this by putting a 20Khz tone in to compress)

If the noise reduces with compression then it should be the OPA2604AP

It is doesn't reduce with compression it should be the JLM99v

Unplug and reseat the 99v opamp just to make sure the 6 pins have good connection. I have often seen noise floor raise very high due to the JLM99v become half unplugged.

If the noise remains best to swap the JLM99v with one of your other comps to see if the noise follows the JLM99v.

If you take 2 x OPA2604AP and 1 x JLM99v with you maybe stolen from one of your other LA500 you should have it going again in a minute or two.
If not let me know what you find so I can help some more.
Joe :-)

JLM Audio

Capturing Audio without Injury

kante1603
Posts: 85
Joined: Wed Jan 20, 2010 6:12 pm

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

Postby kante1603 » Fri Dec 02, 2016 9:38 pm

Joe Malone wrote:
HI Udo Great to hear from you. Sorry to hear about the LA500A playing up

First unplug what ever is plugged into the input of the LA500A to make sure the noise is not coming from further up the chain. But since bypass removes the noise this should be not be the case but always best to double check with no input plugged in.

Does the noise reduce with compression? (You can hear this by putting a 20Khz tone in to compress)

If the noise reduces with compression then it should be the OPA2604AP

It is doesn't reduce with compression it should be the JLM99v

Unplug and reseat the 99v opamp just to make sure the 6 pins have good connection. I have often seen noise floor raise very high due to the JLM99v become half unplugged.

If the noise remains best to swap the JLM99v with one of your other comps to see if the noise follows the JLM99v.

If you take 2 x OPA2604AP and 1 x JLM99v with you maybe stolen from one of your other LA500 you should have it going again in a minute or two.
If not let me know what you find so I can help some more.


Dear Joe,

thank you very much for the fast reply indeed!

Noise reduced with compression when putting in 20kHz sine,so the 2604 had to be inspected.
It turned out that it became really hot after seconds,at least so hot that I wasn´t able to touch it.Still working but introducing the mentioned noise floor.
So I swapped it out to a new one from my shelf,all seems to be o.k. now.
For reference I pulled out our second LA500A and have them now side by side,attached via extender cables and heavily feeding them with music program for about 3 hours now,no breaks.
Both OPA2604APs now feel the same temperature-wise,and both seem to have a "healthy and identical" noise floor when totally "mistreated" (meaning makeup gain fully cw…..not a usual setting of course….but the only way to get the noise visible on a meter now,giving me a -70dBFS or so).
Noise goes to invisible by turning back makeup to 3 o´clock position latest.
Perfect I´d say.And completely inaudible.

So the 2604 must have been on the edge I think.

Thank you very much again Joe for your help (and confirming I was on the right track,hahaha).

Have a nice weekend,

best regards,

Udo.

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

Postby Joe Malone » Fri Dec 02, 2016 10:38 pm

kante1603 wrote:
Joe Malone wrote:
HI Udo Great to hear from you. Sorry to hear about the LA500A playing up

First unplug what ever is plugged into the input of the LA500A to make sure the noise is not coming from further up the chain. But since bypass removes the noise this should be not be the case but always best to double check with no input plugged in.

Does the noise reduce with compression? (You can hear this by putting a 20Khz tone in to compress)

If the noise reduces with compression then it should be the OPA2604AP

It is doesn't reduce with compression it should be the JLM99v

Unplug and reseat the 99v opamp just to make sure the 6 pins have good connection. I have often seen noise floor raise very high due to the JLM99v become half unplugged.

If the noise remains best to swap the JLM99v with one of your other comps to see if the noise follows the JLM99v.

If you take 2 x OPA2604AP and 1 x JLM99v with you maybe stolen from one of your other LA500 you should have it going again in a minute or two.
If not let me know what you find so I can help some more.


Dear Joe,

thank you very much for the fast reply indeed!

Noise reduced with compression when putting in 20kHz sine,so the 2604 had to be inspected.
It turned out that it became really hot after seconds,at least so hot that I wasn´t able to touch it.Still working but introducing the mentioned noise floor.
So I swapped it out to a new one from my shelf,all seems to be o.k. now.
For reference I pulled out our second LA500A and have them now side by side,attached via extender cables and heavily feeding them with music program for about 3 hours now,no breaks.
Both OPA2604APs now feel the same temperature-wise,and both seem to have a "healthy and identical" noise floor when totally "mistreated" (meaning makeup gain fully cw…..not a usual setting of course….but the only way to get the noise visible on a meter now,giving me a -70dBFS or so).
Noise goes to invisible by turning back makeup to 3 o´clock position latest.
Perfect I´d say.And completely inaudible.

So the 2604 must have been on the edge I think.

Thank you very much again Joe for your help (and confirming I was on the right track,hahaha).

Have a nice weekend,

best regards,

Udo.


HI Udo Cool great to hear you got it fixed easily :-) And it wasn't our JLM99v :-)
Joe :-)

JLM Audio

Capturing Audio without Injury

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

Postby Tom » Fri Mar 10, 2017 3:18 am

Hi Joe,

I just finished two LA500A! Everything went really well, there were no issues at all. I want to congratulate to this good sounding compressor.

Are you planning a DIY-Kit of the PEQ500? :D :D

Greetings from Vienna!
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Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Postby Joe Malone » Fri Mar 10, 2017 2:07 pm

Tom wrote:Hi Joe,

I just finished two LA500A! Everything went really well, there were no issues at all. I want to congratulate to this good sounding compressor.

Are you planning a DIY-Kit of the PEQ500? :D :D

Greetings from Vienna!


HI Tom Great to hear you liked the build and the sound of the comps. Nice photo as well. I am working on several new 500 kits at the moment.

I had a great time when I was staying in Vienna many years ago :-)

Please if you have a comments and/or photos of your JLM Audio gear in your rack or JLM stickers please put them up on our facebook page at the link below or send them to us by email as we work completely by word of mouth with no paid advertising. Feel free to add your website link and other details if you like 

https://www.facebook.com/jlmaudio1

Thanks again for taking the time to comment.
Joe :-)

JLM Audio

Capturing Audio without Injury

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

Postby yannlu » Sat Mar 18, 2017 1:16 am

Hello,

I just assemblied my first LA500A kit but I had some issues with it by testing:

1. The LA500SCv3 was not properly power supplied.
2. So I checked the voltages from the cable (BIO500 -> LA500SCv3) and indeed the end was inverted...
3. Then I took the other cable (LA500SCv3 -> LA500POTv4) and the LA500SCv3 is well supplied
4. But by swapping the both cables I burnt the POT A200K by pulling to supply the LED and check everything was working...

Here some pictures of the received cables. Are they good ?

Image
Image

And as I burnt the A200K pot is an Alpha 250k log pcb DPDT is suitable ?

Thank you very much for your help !

Yann Lu from Belgium

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

Postby Joe Malone » Sat Mar 18, 2017 10:44 am

yannlu wrote:Hello,

I just assemblied my first LA500A kit but I had some issues with it by testing:

1. The LA500SCv3 was not properly power supplied.
2. So I checked the voltages from the cable (BIO500 -> LA500SCv3) and indeed the end was inverted...
3. Then I took the other cable (LA500SCv3 -> LA500POTv4) and the LA500SCv3 is well supplied
4. But by swapping the both cables I burnt the POT A200K by pulling to supply the LED and check everything was working...

Here some pictures of the received cables. Are they good ?

And as I burnt the A200K pot is an Alpha 250k log pcb DPDT is suitable ?

Thank you very much for your help !

Yann Lu from Belgium


HI Yann
Looking at your photos you are correct the cable between the BIO500 and LA500SC pcb has one end on wrong. This should not be able to happen as we have 100% testing but the guys seem to have had a few wrong ones slip past so we will have to review the cable testing again :-(

So you can power up for now and see if evrything else is ok, cut the locate tab off the end that is reversed with sidecutters for now and turn that end 180 degrees and replug it in so the cable will work for now. The wrong cable end is the one the red stripe is at the opposite end to the triangle symbol. (All triangle on plugs should be the end with red stripe if correctly made)

Also check the 2 x 10R on the BIO500 and LA500SC pcb are not burnt?
With the cable corrected you should be able to power up and get audio but no compression due to threshold pot removed.

Switch from LA off to GR or VU should light the meter and switch the hard bypass so the audio path in in circuit and makeup gain should turn up the output level?

Let me know what you find and what parts you need you need as we will send everything you need for free.

Or feel free to ship it to us and we will factory repair it and send it back to you.

Sorry again for the stuff up.
Joe :-)

JLM Audio

Capturing Audio without Injury

yannlu
Posts: 2
Joined: Fri Mar 17, 2017 3:38 am

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

Postby yannlu » Tue Mar 21, 2017 5:03 am

HI Yann
Looking at your photos you are correct the cable between the BIO500 and LA500SC pcb has one end on wrong. This should not be able to happen as we have 100% testing but the guys seem to have had a few wrong ones slip past so we will have to review the cable testing again :-(

So you can power up for now and see if evrything else is ok, cut the locate tab off the end that is reversed with sidecutters for now and turn that end 180 degrees and replug it in so the cable will work for now. The wrong cable end is the one the red stripe is at the opposite end to the triangle symbol. (All triangle on plugs should be the end with red stripe if correctly made)

Also check the 2 x 10R on the BIO500 and LA500SC pcb are not burnt?
With the cable corrected you should be able to power up and get audio but no compression due to threshold pot removed.

Switch from LA off to GR or VU should light the meter and switch the hard bypass so the audio path in in circuit and makeup gain should turn up the output level?

Let me know what you find and what parts you need you need as we will send everything you need for free.

Or feel free to ship it to us and we will factory repair it and send it back to you.

Sorry again for the stuff up.


Hello Joe,

Thank you for your quick reply.
No problem this kind of issue could happen !
I modified the cable. I tested the meter it seems OK and there is an audio signal in the input but not symmetrical. Actually phase inversion is OK but the voltage are different... I guess the make up pot also suffered...
So the better thing is to ship the complete pot PCB kit with all the parts (both pots, LEDS, resistors and the connector). And also a new cable ;-)

Thank you very much.

Yann Lu

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

Postby Joe Malone » Tue Mar 21, 2017 7:34 am

yannlu wrote:
HI Yann
Looking at your photos you are correct the cable between the BIO500 and LA500SC pcb has one end on wrong. This should not be able to happen as we have 100% testing but the guys seem to have had a few wrong ones slip past so we will have to review the cable testing again :-(

So you can power up for now and see if evrything else is ok, cut the locate tab off the end that is reversed with sidecutters for now and turn that end 180 degrees and replug it in so the cable will work for now. The wrong cable end is the one the red stripe is at the opposite end to the triangle symbol. (All triangle on plugs should be the end with red stripe if correctly made)

Also check the 2 x 10R on the BIO500 and LA500SC pcb are not burnt?
With the cable corrected you should be able to power up and get audio but no compression due to threshold pot removed.

Switch from LA off to GR or VU should light the meter and switch the hard bypass so the audio path in in circuit and makeup gain should turn up the output level?

Let me know what you find and what parts you need you need as we will send everything you need for free.

Or feel free to ship it to us and we will factory repair it and send it back to you.

Sorry again for the stuff up.


Hello Joe,

Thank you for your quick reply.
No problem this kind of issue could happen !
I modified the cable. I tested the meter it seems OK and there is an audio signal in the input but not symmetrical. Actually phase inversion is OK but the voltage are different... I guess the make up pot also suffered...
So the better thing is to ship the complete pot PCB kit with all the parts (both pots, LEDS, resistors and the connector). And also a new cable ;-)

Thank you very much.

Yann Lu


HI Yann ok we will ship out a complete pot pcb kit today. Sorry again for the stuff up.
Joe :-)

JLM Audio

Capturing Audio without Injury

kante1603
Posts: 85
Joined: Wed Jan 20, 2010 6:12 pm

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

Postby kante1603 » Tue Mar 21, 2017 2:42 pm

Hello Joe,

don't know if this has been covered,but do you by accident have some numbers for attack and release times in both "normal" and slow attack modes for us?

Thank you in advance,

best regards,

Udo.

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