LA500 Slow attack mod

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nicosquid
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Re: LA500 Slow attack mod

Post by nicosquid »

saxmonster wrote:Nico,
It looks like your black wire coming off of the new Capacitor is not going to the same spot on the PCB as Joe's black wire is, in fact it kinda looks like there might be a soldering bridge there too with the soldering point above it. Hot solder might have dripped down causing it to bridge.

Also your red wire going to the leads on the threshold should be bridged I think. Just like originally but now that I look at it it looks like Joe snipped the bridge between the two front leads on the threshold pot but there is no mention of it. Maybe it just looks like it is snipped. The two leads closest to the knob. Please confirm Joe.
Thanks for your reply saxmonster, I went ahead and added a jumper where you mentioned it was missing on the threshold pot.

nicosquid
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Re: LA500 Slow attack mod

Post by nicosquid »

nicosquid wrote:
Hi, sorry for the delay with better pictures. Here they go, hope you can see better.
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Re: LA500 Slow attack mod

Post by Joe Malone »

nicosquid wrote:
nicosquid wrote:
Hi, sorry for the delay with better pictures. Here they go, hope you can see better.
Wires seem to be correct but bad practice to solder the bare wire across the pcb like you have as it can short to other tracks or ground plane under the soldermask if heated to much. Best to stand the wire on to the solder pad so it only solders to it and touches nothing else on the pcb
Joe :-)
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StephenLam
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Re: LA500 Slow attack mod

Post by StephenLam »

Hello Joe,

Thanks for activating my login! I've been a happy owner of an original LA500 for 10 years now (bought used in 2012, not sure if it was built by JLM or otherwise). My unit does have the Threshold pull-knob, but there's no wires connecting it to the "comp link" pins. Also, the opamp does not have the JLM99V sticker on it - it's just a black box.

I'd like to install the Slow Attack mod and turn it into an LA500A, then purchase another LA500A (kit or built) so I can run them in stereo for buss compression and mastering (I'm the mastering engineer for a small indie label). I'd also like to continue to use them as 2 separate compressors for tracking and mixing.

I have a few questions for you:

1. Am I to assume that, with the Slow Attack mod installed, the LA500 will 100% function as an LA500A, and can be used as part of a stereo pair with another LA500A?

2. Do you sell the LA500A faceplate so I can also have the LEDs for comp link and slow attack?

3. I also assume that, in order for the 2 units to be a stereo pair, I should replace both sets of opto cells? Do I need to replace both U1 and U2 with 2 matched pairs?

4. Do I need to worry about the no-sticker opamp?

5. Is there anything else I need to do, besides the above, to turn these into both a stereo pair and separate mono compressors?

I am attaching a photo of my LA500 for reference.

Thank you in advance for your reply! Thank you also for designing the unit! - it's my favorite tracking compressor to date!

- Stephen Lam
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Re: LA500 Slow attack mod

Post by Joe Malone »

StephenLam wrote:
Fri Jul 29, 2022 12:24 pm
Hello Joe,

Thanks for activating my login! I've been a happy owner of an original LA500 for 10 years now (bought used in 2012, not sure if it was built by JLM or otherwise). My unit does have the Threshold pull-knob, but there's no wires connecting it to the "comp link" pins. Also, the opamp does not have the JLM99V sticker on it - it's just a black box.


I'd like to install the Slow Attack mod and turn it into an LA500A, then purchase another LA500A (kit or built) so I can run them in stereo for buss compression and mastering (I'm the mastering engineer for a small indie label). I'd also like to continue to use them as 2 separate compressors for tracking and mixing.
From the photo cannot tell if it was a kit or built by us. I need photo of the front panel to tell.
1. Am I to assume that, with the Slow Attack mod installed, the LA500 will 100% function as an LA500A, and can be used as part of a stereo pair with another LA500A?
Yes it will give you the slow attack function so will make it like a LA500A
2. Do you sell the LA500A faceplate so I can also have the LEDs for comp link and slow attack?
There is nothing to hold the leds or to switch them in a LA500 so changing front panel will not work.
3. I also assume that, in order for the 2 units to be a stereo pair, I should replace both sets of opto cells? Do I need to replace both U1 and U2 with 2 matched pairs?
I need to see what type of optos your compressor has on the green pcb. Need photo. As this old is probably has old vactrol which we cannot get any more or match.
4. Do I need to worry about the no-sticker opamp?
No idea. Need you to unplug it and send me a photo of the bottom of the opamp to confirm it is a JLM99v.
5. Is there anything else I need to do, besides the above, to turn these into both a stereo pair and separate mono compressors?
We have nothing to match this old comp as it uses a different output transformer we no longer have and also optos we no longer have. The slow attach works a bit different in LA500A so will not match LA500 slow attack.

Thank you in advance for your reply! Thank you also for designing the unit! - it's my favorite tracking compressor to date!
Since it is your favorite comp I would just add the 100uF cap for slow attack pull on the threshold and leave it as it is. For a matched stereo pair it is best to buy a built pair or kit pair at the same time. As we then for free match output transformers, optos and more so the audio and sidechain paths match each other which is what you need for mastering.
Joe :-)
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StephenLam
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Re: LA500 Slow attack mod

Post by StephenLam »

Hello Joe,

Thanks for the detailed reply.

Just a follow up question: what if I purchase from you a new output transformer, 2 new pairs of opto cells, a new JLM99v, and the Slow Attack mod, and install all of these on my LA500, would it still not work with a new LA500A as a stereo pair?

I'm just trying to see if I can avoid purchasing 2 new kits and building 2 full units.

Thanks!

- Stephen Lam

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Re: LA500 Slow attack mod

Post by Joe Malone »

StephenLam wrote:
Sun Jul 31, 2022 4:50 am
Hello Joe,

Thanks for the detailed reply.

Just a follow up question: what if I purchase from you a new output transformer, 2 new pairs of opto cells, a new JLM99v, and the Slow Attack mod, and install all of these on my LA500, would it still not work with a new LA500A as a stereo pair?

I'm just trying to see if I can avoid purchasing 2 new kits and building 2 full units.

Thanks!

- Stephen Lam
You could but the new transformer is pcb mount so will not mount in your old comp and slow attack will still on work between the 2 comps as they do it differently and there are other small changes. By the time you buy all other extra parts you are not saving much $ and end up with 2 comps which may kind of match where as you could have 3 comps. Selling your original comp off after would fund usually 1 and half kits. The sound of the new optos to the old optos is a bit different as well.

Otherwise I may have enough old parts here to put together one old LA500 comp kit but I am not sure and it would take a while to find everything.
Joe :-)
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StephenLam
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Re: LA500 Slow attack mod

Post by StephenLam »

Hi Joe,

Thanks - your explanation makes perfect sense.

I'm not in a huge hurry to get this done, so I can wait until you let me know when you can find the parts for an second LA500. Either way, I'll get the Slow Attack mod for it soon. Whether this ends up being a 3rd comp or part of a pair, I'd still want to have the Slow Attack mod done.

Please let me know when you find out if you can put together an LA500 kit.

Thanks again!

- Stephen Lam

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Re: LA500 Slow attack mod

Post by Joe Malone »

StephenLam wrote:
Sun Jul 31, 2022 10:41 am
Hi Joe,

Thanks - your explanation makes perfect sense.

I'm not in a huge hurry to get this done, so I can wait until you let me know when you can find the parts for an second LA500. Either way, I'll get the Slow Attack mod for it soon. Whether this ends up being a 3rd comp or part of a pair, I'd still want to have the Slow Attack mod done.

Please let me know when you find out if you can put together an LA500 kit.

Thanks again!

- Stephen Lam
ok send me an email so I remember to look for the parts
Joe :-)
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StephenLam
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Re: LA500 Slow attack mod

Post by StephenLam »

Hello Joe,

Just sent you a PM here.

Thanks!

- Stephen Lam

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Re: LA500 Slow attack mod

Post by Joe Malone »

StephenLam wrote:
Mon Aug 01, 2022 4:56 am
Hello Joe,

Just sent you a PM here.

Thanks!

- Stephen Lam
Need to send it to my email on the webshop or I will never remember to look in the forum or pm from forum
Joe :-)
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StephenLam
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Re: LA500 Slow attack mod

Post by StephenLam »

Thanks Joe - just sent you an email via the webshop.

c1184701
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Re: LA500 Slow attack mod

Post by c1184701 »

I'm finding the slow attack mod just a bit too slow on my pair of LA500s. Would it be possible to tweak the attack time by swapping the 100uF capacitor for another value?

-Ross

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Re: LA500 Slow attack mod

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c1184701 wrote:
Fri Nov 11, 2022 12:26 am
I'm finding the slow attack mod just a bit too slow on my pair of LA500s. Would it be possible to tweak the attack time by swapping the 100uF capacitor for another value?

-Ross
HI Ross
Yes smaller value caps = faster attack. If you do not know which way +/- is then use Non Polar cap type.
Joe :-)
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