orange squeeze compressor just boosts the signal. what's wrong?

[funkbass187]

i built an orange squeeze compressor, but when i plug in my bass, all that happens is that the signal gets a very large boost.  the only thing that i can think of is that i might have used the wrong transistors for this. any other ideas?

[markm]

Did you adjust the trim pot?

[funkbass187]

i forgot to mention. i put the trimpot on the outside, so i have a volume and compression level knob. but turning them doesn't seem to do anything.

[markm]

The compression adjustment is very "finicky".
There's a real fine line in finding the sweet spot.

[funkbass187]

but the overall volume comes out 3 or 4 times the normal output of my instrument. i'm just affraid of blowing out my preamp.

[markm]

Maybe the pot forlevel is wired incorrectly......
I'm stumped 

[vanessa]

It's more like a bias than a compressor control. It's used to bias the JFETs. When dialed too far out of range its more like squish than compression. I think it is the reason the effect has got a bad rap being just a country compression "effect". When dialed in properly it should sound very transparent. Someone on the board showed me how to bias it correctly a while ago.

Turn the dial max clean (no squish). Put a clean boost pedal in front of it and set the boost so that it pushes the OS hard but not enough so that the OS distorts. Now dial the OS back until you hear the compression 'just' kick in. That's it. That's the optimal setting and the most transparent.

[funkbass187]

Maybe the pot forlevel is wired incorrectly......
I'm stumped 

and that means...? sorry i'm not that informed about all the terms,i'm new to all this. i'm almot positive all the wires to the pots oare in the right place.  i just can't figure out what would make a compression circuit boost the signal so much.

[markm]

This circuit does have quite a bit of gain to it.
I can't really help you anymore as I am unsure of what the problem would be.
I had originally thought that the Volume pot was wired incorrectly but, from what you say I guess not.
I think you require the aid of someone who is more familiar with this circuit and how it functions.
I have built 3 O/S comps but, they all functioned without a problem.

[petemoore]

  OS Can be Decieveingly transparent.
  Even when it's working right, which I suspect there's a good chance yours is.
  With the Jfets not in right it'll clean boost, with 'em in right it's hard to tell the difference sometimes between 'boost' and comp/boost of OS, it's a subtle compression effect, but even clean it's just noticable.
  To further confuse matters, there's the trimpot, which by some to many accounts might as well be a fixed resistor, as turning the trimpot seems in many builds to do nothing...I've built a couple OS's, there were replies on both sides of the issue sometime ago, I can't remember if there was any consensus on it, perhaps with the certain 'match' of Jfets [no, I don't think matching is necessary for the OS, or what would even not matter], anyway the inconsistancies of JFets may cause one builder to notice the trimpot influence.

[vanessa]

Why don't you read this thread and then post your findings. After you do we might be able to help you. Otherwise you're just swimming around in the lake.

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[Mark Hammer]

pete is right.

The JFET, in tandem with the 82k input resistor, forms a kind of input level control.  The op-amp stage boosts the signal x23.  The output of that is used to adjust the JFET and turn down that electronic input level control.  If the JFET is wired up wrong (and you have no idea how many ways that can happen ), it becomes simply a x23 booster.  This seems to be your problem.

[funkbass187]

i'll go double check the JFETs, and if that isn't what's wrong, i'll try and get some pictures up. thanks for all of the help so far.

[analogmike]

  OS Can be Decieveingly transparent.
  Even when it's working right, which I suspect there's a good chance yours is.
  With the Jfets not in right it'll clean boost, with 'em in right it's hard to tell the difference sometimes between 'boost' and comp/boost of OS, it's a subtle compression effect, but even clean it's just noticable.
  To further confuse matters, there's the trimpot, which by some to many accounts might as well be a fixed resistor, as turning the trimpot seems in many builds to do nothing....

if you built it right, the trimpot makes a huge difference in sound. And it is a critical adjustment, within about 2 degrees are the optimal settings. Turn it down 2 degrees and sound should drop off quickly. Turn it up 2 degrees and you get an unsteady compression (fluttering). Dan Armstrong told me how to use a scope but ears can be good enough

[petemoore]

  ...and there you have it, the solid lowdown on it. 

[lovric]

the expression 'huge differences' in sound of an OS is an overstatement.

if you checked that everything is connected properly stick other two FETs. they are notorious by their loose specifications. try bf245, sk30, 2n5457 or mix any two as some types or their combinations won't give you compression and some will even give you distorsion at the extreme setting of the 'bias' pot.

[funkbass187]

so i went to try flipping the jFETs around, but after i unsoldiered one, i heard a popping sound and my soldering iron got cold. i guess thats what i get for shopping at a dollar store for one of those. hopefully when i get a new one i'll be able to fix things.