LA500 opto comp leveling amp BUILD THREAD 500/51X

[Jerome]

I've just align the 2 comps with the good la 500, and again everything's fine with just this changement, the faulty ones now see 3:1 and 5:1 ratios.

La 500 good back to good unit, and faulty la back to faulty unit. I've linked the comps, at 3-1 ratio sc. flat and the good one returned immediatly to 0 (was in gr) and worked only at 10:1 ratio, like the faulty one. And when unlinked it returns to a normal working conditions.

So, unlinked the 2 comps have the same output (-0,40 dB drift).

Linked, the good one function as the faulty one: no compression at 3:1 and 5:1, at 10:1 they react each on the other.

Unlinked, at -5db of gr, i have the same level on output on the 2 comps, and when Linked the good one jump to -3 dB of gr and the faulty one -4db of gr and with 1 dB of difference on the output.

Thanks

[Jerome]

"Unlinked, at -5db of gr, i have the same level on output on the 2 comps, and when Linked the good one jump to -3 dB of gr and the faulty one -4db of gr and with 1 dB of difference on the output. "

This last example was at 10:1 both sc. flat and the difference of 1db on the output was between each other.

Just to be clear. Thank you again and again...

Jérôme.

[Joe Malone]

"Unlinked, at -5db of gr, i have the same level on output on the 2 comps, and when Linked the good one jump to -3 dB of gr and the faulty one -4db of gr and with 1 dB of difference on the output. "

This last example was at 10:1 both sc. flat and the difference of 1db on the output was between each other.

Just to be clear. Thank you again and again...

Jérôme.

HI Jerome I didn't hear back from you to the last email I sent you below awhile ago. So just checking to see what was happening with the LA500 kit?

"Have you got a chance to take a look at the photos?
[Joe] Yes cannot see the problem which I have to say is the first time here.

In case i must send it to you, is there a procedure like rma numbers or anything that i must wrote on the package for the customs?
[Joe] Mark returned for repair with AUD value of $390AUD. Use trackable post and send to our PO box address below.
Probably best to send whole LA500 that is not working. We charge $90 an hour + shipping which is all that is needed to fix a LA500.

One thing you can do before you ship is measure the ohms to 0v on all 10 pins of the IDC header on the LA500 PCB that the MAC ribbon plugs into.
Just might show something up if you do this test on the good and bad LA500 PCB."

[drew571]

Question,

Just completed my first LA500. Is it normal for the GR Meter to be bobbing back and forth slightly, even when no gain reduction is occurring? Even when no audio is being sent, it's bobbing back and forth from probably around +1 to -1.

When i'm in VU Meter mode, it stays nice and steady on the floor until audio passes through and then does it's thing.

Thanks!

Andrew

[Joe Malone]

Question,

Just completed my first LA500. Is it normal for the GR Meter to be bobbing back and forth slightly, even when no gain reduction is occurring? Even when no audio is being sent, it's bobbing back and forth from probably around +1 to -1.

When i'm in VU Meter mode, it stays nice and steady on the floor until audio passes through and then does it's thing.

Thanks!

Andrew

No it is not normal. Turn the threshold fully off ccw and see if GR meter still moves?

If this stops with the threshold fully turned down then the input is pickup up some noise from something else electrical

or the threshold pot wires have NOT been kept short and tightly twisted which can cause oscillation in the side chain. If it is oscillation it will usually be worst at mid threshold pot travel.

[ajsteel]

Just wondering what the correct procedure is to stereo link a matched pair of LA500 compressors in an API 8 Slot Lunchbox that has a link switch on the back?

Thanks for our time.

A.J.

[Joe Malone]

Just wondering what the correct procedure is to stereo link a matched pair of LA500 compressors in an API 8 Slot Lunchbox that has a link switch on the back?

Thanks for our time.

A.J.

The link switches on the back of the 8 way API box are audio in and out linking between each modules in and out and have nothing to do with the compressor link.

The 8 way box like the New 6 way API box have all comp link edge connector pin 6 linked across the back panel by zero ohm resistors.
So if you have only one pair of comps in the rack you do not have to do anything to link a pair.
Set both LA500 to the same settings and adjust threshold for the same GR reduction and pull both threshold pots outwards so they are linked.

If you have more than 1 pair of comps in the rack cut out the link resistor between the pairs of comps to isolate the 2 sets of comps link edge connector pin 6's

Usually when setting up racks here cut out ever second zero ohm link resistor so 1&2, 3&4, 5&6, 7&8 link pins are left connected in pairs.
The zero ohm resistors in the 8 way box are numbered R21 to R27. So to set for pairs like above. Remove R22, R24, R26.

[ajsteel]

Great, thanks Joe. I only have one pair of LA500's in the rack so it appears I'm good to go just by pulling the threshold knobs out.

Thanks
AJ

[Danes]

Hi guys.
Looking at getting an LA500 kit to see if I can make it work. Just wondering what level of experience/skills/knowledge is required generally to put it together.
I have a soldering and desoldering station. Have some experience with the following:
-making cables/looms (xlr, trs, d-sub etc..)
-installation studio wiring (multicores, wall plates etc..)
-changing over a power supply in an EQ unit
-changing faders and latching switches on a mixing console
-can follow instructions (the instructions on the first page seem very clear and easy to follow)

With this kind of experience/knowledge, do you reckon I could make it happen with the LA500 kit?

Thanks very much.

Senad

[Joe Malone]

Hi guys.
Looking at getting an LA500 kit to see if I can make it work. Just wondering what level of experience/skills/knowledge is required generally to put it together.
I have a soldering and desoldering station. Have some experience with the following:
-making cables/looms (xlr, trs, d-sub etc..)
-installation studio wiring (multicores, wall plates etc..)
-changing over a power supply in an EQ unit
-changing faders and latching switches on a mixing console
-can follow instructions (the instructions on the first page seem very clear and easy to follow)

With this kind of experience/knowledge, do you reckon I could make it happen with the LA500 kit?

Thanks very much.

Senad

The main thing is good soldering. The rest if you follow the step by step photos is simple enough if you take your time. And always if not sure ask any questions before soldering rather than after.

We just had a first timer build the LA500 and leave some great comments on our facebook page the link below.

https://www.facebook.com/jlmaudio1?ref=hl

[Danes]

Thanks Joe.
Might bite the bullet, and have a go. There has to be the first time for everything, and I need some comps, so.... Will order one to try after the next payday . Should it go smoothly and sound as it seems it does (by the reviews), I can't see a reason not to get e few more after that

[Joe Malone]

Thanks Joe.
Might bite the bullet, and have a go. There has to be the first time for everything, and I need some comps, so.... Will order one to try after the next payday . Should it go smoothly and sound as it seems it does (by the reviews), I can't see a reason not to get e few more after that

Cool

[rockprocess]

In the process of building my kit, I've noticed that all my little blue .1 capacitors measure from .14 to .15 on my meter. (about 50% over spec) Are these safe to use or do I need to source some others that do measure .1 (+/-10%)?

[Joe Malone]

In the process of building my kit, I've noticed that all my little blue .1 capacitors measure from .14 to .15 on my meter. (about 50% over spec) Are these safe to use or do I need to source some others that do measure .1 (+/-10%)?

The 0.1 mono caps which are either blue or yellow are only used for power rail low impedance decoupling smoothing and have a tolerance of -20 to +50% and on average measure +40%. So yes these are perfectly fine.

[PeteJE]

Finished my first of two; really happy with these kits and Joe's great support! It sounds very, very good!