Orange Squeezer .. strange sound

[hardi_ami]

Hello everybody !
I just finished building an orange squeezer compressor (schematic found on tonepad.com) and I'd like to know how it's supposed to sound. When I plug it in, I have a sound that seems much warmer (and more noise, but the parts are still lying outside their aluminium box) than without, but the 10k linear pot (bias/sustain pot) doesn't seem to do anything. I've tried moving it from no resistance, to 10k and .. nothing... I think I've got a little problem here

Can anyone help me ?

Thanks
Michael

[Gil]

Looks fine. You'll have to adjust the attack and volume timmers till you get the desired compression. Turn the attack trim back to minimum, and the volume trim to about 20%. Than start rising the attack trim to the point just where sound is starting to be  heard. Rise up the volume trim to the desired volume level. Now you can fine-adjust the attack, be careful as its useful range is about 10% up or down from where its at, at that point.

[Rob Strand]

IIRC as you vary the 10k pot the voltage across the 4.7uF cap (ie. across the 10k pot) should vary from about 0V to 5V.  The voltage across the 2.4k resistor should be roughly about 1V and shouldn't vary too much as you vary the 10k pot.

[hardi_ami]

thanks I'm going to check that, since this pot seems really really useless now ..

[hardi_ami]

Hello !

I've checked the voltages... and I've got problems

I always have 0V across the 4.7uF cap, even when I turn the 10k bias pot...
Actually I also have 0V across both the transistors. I've checked the circuit again, but I didn't find anything wrong, I've checked for shortcuts, neither did I find one ... I really don't know where the problem comes from..
Anyone ??

Thanks
Michael

[Rob Strand]

Check these:
- triple check your JFET pinouts.
- check you haven't got the 4u7 electrocap around the wrong way.
- make sure you have't got any soldering problems on the JFETs or the pot.
- check your resistor values.

The problem is definitely around this part of the circuit.

[brett]

The JFETs in the OS aren't amplifying anything - they act as variable resitors, and it's normal to have 0V across them.  The gate will also be close to 0V.  Weird but true.  I have a simple design for a compressor/limiter which uses a MOSFET instead of a JFET for the same purpose.  The 2 JFET system used in the OS doesn't seem to work any better than my 1 MOSFET or simple 1 JFET systems.  

The bias pot is usually sensitive only in a limited range.  Like you, I made it an external control, but it is really a set-and-forget type control to get the thing working properly :roll: .  If you continue to have hassles, replace the JFETs with some nice mid-range Vgs ones, like 2N5486s or MPF102s (which are good, but a bit variable :? ).  A little perserverance will definately pay off.

Have fun!

[Rob Strand]

Brett, one of those JFET is a current source and should have voltage across it, the other is the variable resisistance.  The main problem is,

I always have 0V across the 4.7uF cap, even when I turn the 10k bias pot...

[ethniccheese]

My problem with the Orange Squeezer is that it is VERY noisy.  It hisses like crazy.  All of my resistors are 1% and I am using decent Box Metallized polyester film caps.  The 4558 that I used was an NJM4558CN I believe.  Any guesses as to why this is so noisy?

[hardi_ami]

I have to check again and again to see what's wrong in my squeezer ...
ethniccheese, actually, mine is very noisy too.  but mine isn't in a box at all, I'm using low cost pots and 5% resistors (same I used for my tube screamer and it works like a charm, even though it's not in a metallic box grounded)

anyway thanks for your help guys
I'll post again when I will have had the time to check

Michael

[Paul Marossy]

When I get a real noisy opamp based circuit, I always check Vref. Sometimes it will be something less than 4.5 volts, the circuit will still work, but it can noisy as heck! I had that problem on the Phuncgnosis that I just built...
You could also try using an OP275 or NE5532, they are quieter opamps. An LF353 seems to work well in most circuits, too. (has a wide bandwidth)

[Deep Blue]

This is sort of off topic, but I also have a question about the orange squeezer.

On JDSleep's (excellent) site, he has a layout of the Orange Squeezer that doesn't seem to have a bias pot.  Am I reading this wrong?  He has another layout that has a volume knob.  Is that the same thing?

Sorry about the stupid question - I'm new to this stuff.

[Rob Strand]

To keep the noise down I recommend using a JFET-input opamp like the LF353 or TL072.  There's some further mods in the archives how reduce noise further which have a minor impact on the behaviour.

I looked at JD's schematic it had R7 = 10k trimpot.

[hardi_ami]

There's no stupid question
JD's schematic uses a TRIMMER Potentiometer for the Bias (that's a pot you turn with a screwdriver) that's all!!

[ethniccheese]

If the 4558 can be substituted pin for pin with an OP275, NE5532, or I think a TL072, and have lower noise, why do the schematics always call for the 4558?  Is it because that is what the original manufacturer used, because it is cheaper?

[Gil]

My O.S is damn noisy, we actually had a long discussion about this a few months ago, of which I concluded this may be the natural behaviour of the circuit... Not much to do about it only cutting highs which degrades the overall sound. I can additionally say that with some guitars the hiss is almot isn't heard at all.

[hardi_ami]

Hello everybody
I found a problem in my schem.. I had soldered the diode (+ side) to the ground .. I must buy new glasses (yeah I'm not using the PCB, I'm using test bakelite... that's a lot harder)
anyway, it seems to work better, but the pot is REALLY REALLY subtle (or maybe it's still not working, I'll fetch my multimeter tomorrow again).

I think the schematic says 4558 because the original had it... I also think TL072 is way better, I use it in every pedal I make (that requires an opamp)

and Gil ... mine is very noisy too
Actually I don't really like this circuit in the way it works now...

Michael[/url]