525 build thread

You need small format pots for the new build. Omegs are way too big.
I'll start a new thread for the latest version.

finally finished just one problem , when compressing the audio crackle as the leds turn on , even with no output  as you increase the input pot the leds begin to turn on and hear crakling as the leds turn on and off  , any thoughs  thank's

Have you done the mod... wire to edge connector?

yes peter done the mod , removing A3 the input pot has no function and no reduction , but the output works great lots of gain
thank's

hey peter, got one of your older kits here.  hope to get it together soon... are the VCR2Ns available anywhere besides goldmine?  If not, is there a workable replacement that you know of?  Didn't seem to find anything here..  cheers!

Goldmine is the only place I've ever seen them.
A better man than I will have to pipe up with an alternative.

electrochronic's web store, a little more expensive tough:

https://sites.google.com/site/diypartsstore/catalog/misc-components

Hey guys

I've seen most of the 2520 opamps with 1/2w or greater resistors.
Is this a requirement?

Only Rs 16 & 17.

I really like how these comps sound, thanks again

Does anyone have a source (or spares laying around) for the trimmers?

I've checked Mouser, Digikey, and Farnell and can't find any in stock that fit the board.

Thanks!!

I've used the small round vishay (other brand make them).
The issue they are 1 turn which makes it tricky to callibrate btu it's doable.

Ah, I'm an idiot.. I didn't realized I could get a slightly larger trimmer and "trim" it back.

Hardy, harr harr

Got mine all fired up and working yesterday. These things sound pretty damn good!

The only thing that's not functioning correctly is the ceiling control. I get more compression as I turn it up but the ouput doesn't automatically compensate for the extra compression. Also the output knob itself has a very low gain range (maybe 10dB at most) that seems to change with the ceiling control. Step 20 is also weird, I get way less compression and the output knob fully functions. I looked over the rotary and all is correct. I think it might be a short between the two wafers or with the switch board right above it.

I haven't done the meter board grounding mod or the attack mod but I haven't noticed any hum or noise and I do get a little attack control so I'll probably leave as is (100k pot).

Great project Peter!!  8)

Edit: I found two solder blobs on the rotary connecting the wafers. Works great, now I'll probably try out the attack mod.

Indecline said:

I haven't done the meter board grounding mod

Click to expand...

Which one are you referring to? please do tell more as mine doesn't work well with fast attack times.

Indecline said:

Works great, now I'll probably try out the attack mod.

Click to expand...

Let us know what you think. I think with the mod the pot works as you expect and gets the ridiculous fast factory setting.

jplebre said:

Indecline said:

I haven't done the meter board grounding mod

Click to expand...

Which one are you referring to? please do tell more as mine doesn't work well with fast attack times.

Indecline said:

Works great, now I'll probably try out the attack mod.

Click to expand...

Let us know what you think. I think with the mod the pot works as you expect and gets the ridiculous fast factory setting.

Click to expand...

The grounding mod for the meter board is to seperate the pot ground from the meter cap ground, running a wire from the cap to the edge card ground. The information is posted in the thread around page 22 or so. In my OSA rack and CAPI's rack mine work fine, but in my buddies OSA rack he gets an unuseable amout of noise. I'll probably investigate that further to find the discrepencies between our OSA racks, but that's a different thread.

I really like the fastest attack setting when you really want to clamp on something like rap vocals or distorted guitars. To me the attack (the way it sits unmodded) feels a bit weird. It works enought to notice the change but it feels like the envelope isn't quite right. Besides that they are insanely good and honestly I'd be fine with just the factory fast attack.

I'd love to pickup another for 2 bus duties if anyone has one for sale

To me the attack (the way it sits unmodded) feels a bit weird. It works enought to notice the change but it feels like the envelope isn't quite right.

Click to expand...

Yes, exactly what I felt. THe mod I suggested makes it 1176 ish stupid fast (factory) or something less, but the meter starts working weirdly.
Might try to see if the meter mod solves the issue

We addressed why the meter acts weirdly with slower attack earlier in the thread. No easy way around it, basically variable attack is a hack at this point, which would require greater redesign to have the meter follow properly.

Hello all,

I just finished building one of these cool compressors. I am seeing one bug.
My In (Threshold) pot does nothing if the Ceiling is down at zero.
I am not sure if this is normal or if I still need to trouble shoot a bit more.
Otherwise, it sounds wicked.

Thanks

I recently picked up a pair of these that a previous member tried to assemble and couldn't get working. I've rewired everything and get signal. I see gain reduction on the meter, but not hearing output gain reduction, just keeps getting louder as I turn up the 20 pos switch. Any ideas where to look for issues?