Orange Sqeezer Problems?

[GuitarLord5000]

I just build the Orange Squeezer using tonepad's layout.  The differences are...
1.  Used a 5k trimpot instead of a 10k.
2.  Only connected two arms of the trimpot.  One arm to signal and one to ground.  I dont really know a lot about trimpots, so this may be wrong.
3.  2N5486 JFETs instead of the ones listed.
4.  A 5k volume pot instead of a 10k.  (Too late to run out and get one at the ratshack.)

When I use the effect, the volume is much lower than it should be.  I have to really crank my amp to get the volume up to decent listening level, which increases the amp noise.  I dont notice any increased sustain or obvious compression.  Adjusting the trimpot doesn't make any noticeable difference.  I checked the pinout for the transistors...and doublechecked...and doublechecked again just to make sure.  I know they are pinned correctly.  I'd REALLY like to get this compressor working correctly.  Any help'd be appreciated.  
There is a bonus side to all this.  When I remove the JFETs from their sockets, I get a GREAT boost!  It's the only boost I've ever used that makes my crappy amp distortion sound decent.

[Boofhead]

The only possible problem with the subs you made is the 5k trimpot instead of the 10k.  To be sure you could solder a 4.7k resistor *in series with the 5k trim pot*.  If it comes to life then good!  Otherwise you might have made a mistake somewhere - perhaps there's an issue with the JFET pinout, something to check anyway.  (The JFET sub should be OK too.)

[smoguzbenjamin]

If you only wired two lugs of the trimpot you're doing something wrong. You wire a trimmer just alike a pot, except that a trimmer requires no wires and is far tinier than a regular pot.

[Boofhead]

In many instances it's actually OK to use two terminals of a pot.

A rough guide is if the pot is a variable resistor then you only need two terminals (as is the case for the 10k trimpot on the OS), if the pot is used as a variable voltage divider then you need three.  These are over generalizations of course - you should judge each pot in each circuit on  a case by case basis.

[dubs]

I just built one using GGG layout using 2n5457 and 4558 ic and found:
1. Volume knob has to be maxed to get equivalent volume as bypassed level.
2. A lot of background noise especially in front of distortion?
Is this normal for the OS?

[Mark Hammer]

The OS causes the FET to act as a low resistance element, shunting signal to ground, thereby reducing the input signal level going to the op-amp.  The FET, in turn, goes low in resistance depending on the output of that op-amp.

Ideally, the (fixed) gain of the op-amp, paired with the "perfect" input signal level, produces an appropriate reduction of the FET resistance so that the boost from the op-amp and the attenuation of what goes into it, yield an effect output that is a little hotter than the initial guitar signal.

Of course, predicting whether what you plug into the pedal is the "ideal" signal (for the specific FETs and trimpot settings you have) is difficult, and for that reason there is an output volume control on the OS.  On the other hand, the amount of gain provided by the op-amp may not be perfect for any and every input signal, so I personally opted to have variable gain in that first op-amp, and an additional op-amp gain stage after the first one, in case the resulting output of the first stage is too low.  This is illustrated at GGG.

It may, however, simply be the case that you've set the trimpot wrong and produced too much attenuation.

[Paul Marossy]

I don't have to turn my volume up all the way! Maybe 60% or so to match bypassed volume. Mine seems to distort the signal a little bit. But now, I actually have some 2N5457s to try in it, so I think that problem may go away. I just need to sit down and give it a try...

[Chris R]

has anyone experimented with different op amps in this circuit ?

[bwanasonic]

Using only two legs of the trimmer is OK, as long as its the correct two!  :wink:  I soldered the wiper to one leg and grounded them, with the third leg going to Q2/C3.

Kerry M

[GuitarLord5000]

Well, I dont have any 10k trimming pots, so I wired a 100k (with all three legs connected this time).  I marked on the pot the spot where resistance was 10k (measured with a DMM...Boy those things are nice!)  I used this as a 10k variable pot and still didnt have any luck.  The sound is still pretty far below the normal gain of my guitar/amp signal.  (Is this what is referred to as "unity gain"?)  There was a spot on the pot while turning that, when passed, would make a popping type of noise.  Perhaps this is the sweet spot for the JFETs I use?  Maybe the 100k just doesnt have enough variable in the lower resistance ranges to hit that sweet spot dead on?  Also, would putting a 10k volume pot in place of my 5k give me the extra volume I need?  What d'ya think?

[Paul Marossy]

Perhaps the 2N5486 JFETs that you used do not have enough gain for the circuit to work as intended. I used a pair of MPF102s, and they seem to have too much gain. I have heard thet the 2N2457s give the best results. You should be able to use virtually any dual opamp in this circuit with minimal effects, other than noise.

I also wonder if the 5K volume pot is too small. There is less resistance to ground than a 10K pot. This might be enough to weaken your signal too much.

[petemoore]

The 'other' [no vol] pot on the OS is reputed by many to do nothing.
 I couldn't tell any difference with any settings of this pot.
 Seems like a 10k fixed there would do the same thing..then you could short across it with a wire or a 4k7, just to see.

[GuitarLord5000]

I have already tried the MPF102's in this circuit, but without much luck.  It does pretty much the same thing as the '86s.  Perhaps someone might be willing to post some DMM readings across their working Orange Squeezer to give me a clue?  (I dont really know how to use a DMM to take readings across circuits yet.  :oops:  I just bought the darn thing a couple days ago.)

[GuitarLord5000]

Uh.....I just realized that the diode that I have in my Orange Squeezer is not 1N100 or 1N34A.  Its the silicon switching diodes for the rat shack.  (1N914 possibly?)  Would this be a major contribution to my problem?

[MarkB]

low-volume is definitely NOT normal for an OS..

I wired mine with an external volume pot (instead of the 10k trimmer) and it's a pretty good booster as well as a compressor... WELL above unity gain with the pot cranked.
"-)

[brett]

Uh.....I just realized that the diode that I have in my Orange Squeezer is not 1N100 or 1N34A. Its the silicon switching diodes for the rat shack. (1N914 possibly?) Would this be a major contribution to my problem?

Yep, that's a problem, but probably not the gain problem you're sescribing.  Change the diode to a Ge diode or a Schottky (eg 1N5819).  Otherwise you'll need heaps of signal to get the compression happening.

As far as gain goes, my OS has plenty.  Basically, when the controlling FET is turned off (ie at low signal levels) the gain is about 20.  Especially in your case where you used an Si diode, that figure shouldn't reduce until the output reaches about 1.2V p-p and some feedback to the FET starts to occur.  That implies you should get quite a lot of boost (you'll get much less when you go back to the Ge/Schottky diode).

Concerning the trimpot/pot, you should find that there is a sweet spot just to one side of where the signal cuts out.  Keep it set to that sweet spot.  Depending on the FET, the sweet spot will be when the gate and source of Q1 are at about 2 to 3V, and 3 to 4.5V,  respectively.  For Q2 the voltages for the gate, source and drain are about 0V, 2.5V and 1 to 2.5V.

Just a wild guess, but check your 10k and 220k resistors in the feedback loop and ground.  If they were the wrong way around you'd be stuck at unity gain.

Hope this helps

[Mark Hammer]

The diode is simply to remove half the audio waveform so that what is left varies from some zero baseline to some positive voltage (known as half-wave rectification).   The type of diode used will not affect this process per se, but will cause the signal available to control the FET to be different.  Germanium diodes in series with the signal will chop off about 200-280mv from the amplitude.  Silicon diodes will chop off about 450-600mv.  Diodes of different types rarely overlap i terms of voltage drop but do show considerable variation within type/number).  If you have a meter or access to one, pick the silicon diode with the lowest voltage drop from among those you have.  As is noted, you may want to boost the gain of the op-amp a bit to assure enough signal is there to drive the FET after being reduced by the diode.  That can be done by either reducing the value of the 10k resistor to ground, or increasing the value of the 220k feedback resistor, or both.  Gain is presently set to 23 ( [220k+10k]/10k ).  You can probably hike it up to 30 (240k + 8k2) or so (or even a little higher (270k + 8k2) without much penalty to compensate.

[Paul Marossy]

"Uh.....I just realized that the diode that I have in my Orange Squeezer is not 1N100 or 1N34A"

The Ge diodes have different characteristics than the Si ones do. That is the biggest suspect at this point. You could probably use a 1N34 in place of the 1N100. The NTE equivalent is for either one of those GE diodes is NTE109.

EDIT: That is, if everything else checks out OK.

[Boofhead]

Perhaps you have a wrong resistors values, say 22k instead of 220k.  There's an error in there some where. As already mentioned, the diode will change the behaviour but won't cause the lack of output.

[GuitarLord5000]

I'll double check my resistor values once more.  However, I checked most of them with my DMM prior to installation.  

Anybody out there willing to trade a couple of 1N34 diodes or 1N100 diodes for some JFETs, MOSFETs or NPN Transistors?  I have a few of them laying around and dont really feel like making an online purchase for a few diodes.  (Which is all I really need at this point.)

EDIT...Email me at GuitarLord5000@aol.com if you are interested.  I have some 2N7000, 2N7008 and 2N6660 metal can MOSFETs, 2N5089 Transistors and 2N5486 JFET's.