Orange Squeezer Noise

[Blues Lyne]

I recently purchased an Orange Squeezer clone that someone had built from the GGG schematic and PCB.  It cost about what it would cost me to build one, so I figured it was a good deal even if I had to do some work on it. 

I used it at rehearsal last night and it sounded great and was just what I was looking for on certain songs.  However, there was a lot of noise.  It was fine while we were all playing, but as soon as the band stopped it was pretty obnoxious.  I know compressors tend to amplify any noise, but I've also read that the OS was fairly low noise.  At first it was after a modded COT50, but I moved it so that it was before everything except a DIY Octavia and Soiled Dove (Mossrite variant) that are both True Bypassed and where not on at the same time as the OS.  The noise didn't change at all.  I use a Nash Strat with Lollar Tweed single coils, but even in the 2 and 4 position, there was a lot of noise.

So does this sound normal for an OS?  This is my first experience with one.  And if not, what should I look for.  I've modded and built boosters, OD's and fuzzes, but have no experience with compressors. 

[plankspank]

I've built the GGG version and it is my favorite compressor- it is pretty quiet on it's own. If you put anything before it it will tend to be noisy-that's just the compressor doing it's job- it doesn't know guitar signal from backround noise. Try it with just guitar & amp- it should be pretty quiet

[markm]

I could be mistaken but, if it's anywhere but first in line in your signal chain, it's apt to pick up some noise from cords etc.
And whatever noise it picks up, it's going to amplify because, that's it's purpose in life!
For quietest operation of just about any Compressor, put it first.

[Blues Lyne]

I'll give that a shot.  I didn't think a couple of true bypassed pedals would add noise.  I doubt I'd ever use the OS and the fuzzes, so it shouldn't hurt to put it first.  I'll give it a try at the gig tonight.

Blues

[markm]

My thoughts are, the comp has more in front of it's input that has the possibilty of adding noise.....bypassed or not.
Just as too long of a guitar cable *can* introduce a bit of noise into the signal.
Two true-bypassed pedals add a few more cords, 2 stompswitches, 4 jacks, plus a host of small diameter wiring that I beleive is introducing noise into the signal chain.
When at idle, the O/S's gain is full-bore so, it'll amplify whatever is there and then some!

[Processaurus]

My OS is noisy too, it is a noisy design.  Meaning it creates a good amount of its own hiss, beyond whatever it amplifies... just a trade off from using so few components, it's just not going to perform like an 1176.  It may be better to break the rules and place it after high gain effects.  Then the high gain effects aren't amplifying the OS hiss.  It doesn't seem to do anything special feeding a distortion pedal (not like the dynacomp/ross, which has turned out to be a great distortion accessory), because the compression is subtle rather than over the top.

It has about 3x the number of parts but the Ross comp with the clean blend mod that is in my gallery (and MarkM did a layout for), along with Mark Hammer's notion of adding a 3 way toggle to change the release time has started doing my OS's old job, of giving a subtle compression with a nice attack transient, but with a more manageable amount of noise.

[markm]

Oh Yes.
The "Hammer-Switch" will make the Dyna/Ross circuit perform much like the O/S.

[Rmanen]

My bass-modded OS (tonepad & LOADS of mods) is dead silent, I only get noise when I place it behind my EHX muff pi. Gotta love quality pedas

[Paul Perry (Frostwave)]

If you compare a simple comptresser - like the OS - with a more complex one that has a built-in downward expansion noise gate, then yeah, it souns noisy!

I don't suppose we will ever stop talking about compressors - and why should we - but, accept that like fuzz & distortion, different people are looking for different things.
This long compressor shootout has some good technical stuff toward the end: http://www.tonesafari.com/id42.html

[Blues Lyne]

Thanks for the info guys.  I put the OS first in line at my gig Saturday night.  I still got the same amount of noise, even with the Strat in the 2&4 positions, so I'm pretty sure the noise is coming from the pedal.  In doing some more internet searches, seems some peoples experience is that the OS is less noisy than most and some that it is more.  I looked inside and can't see anything that looks off, so I'll just assume the noise is in the normal range for the pedal.  It obviously gets less as I turn the volume knob on the pedal down, but then it's below unity.

Like I said, it's only a problem when the band stops and I'm only using it for certain songs, so I'll just make sure I turn it off right away at the end of the song.  I'm not much of a compressor guy.  I just got the pedal on a whim.  I was buying a pedal from a guy and he had this for sale also.  I'd never tried one and it was cheap so I thought I'd give it a whirl.  I was surprised by how nice it sounded on a couple of funky numbers and one that is laid back and sparse where I play a sparse rhythm with licks thrown in here and there.

[plankspank]

A couple of things you could try to see if you can lessen the noise: try tweaking the trim pot on the PCB for optimum. Also, if the I.C. is on a socket, try popping in another 4558; you may have a noisy Op amp. Last- as standard build practice to lessen noise, I like to wire the input (and output) to the PCB with shielded wire (single strand RCA jack cable works great: wire the shield to the input jack ground, leave the other end of the shield open.

I've Compared my O.S. build  to an off the shelf MXR DynaComp and it is a hair quieter....  Hope this helps... 

[Blues Lyne]

Thanks, I'll give those a try.   The IC is socketed and I have some other 4558's around I was going to try. 

[Hanglow]

Are you using batteries or a power supply? My OS hates powersupplies, it's really noisy then.

[Blues Lyne]

I'm using a fresh battery.

[Mark Hammer]

1) You haven't really specified what you mean by "noise".  Is it just hiss, or is there hum and other things in there too?  Knowing what gets boosted will help identify the source and likely courses of action.

2) The 4558 is as good as the op-amp needs to be to do the intended job, but there are other chips with better noise specs that might be worth considering.  A 5532 might be suitable, though use a bit more battery current.

3) I don't expect miracles, but certainly switching the assorted resistors on the audio signal path to metal film type might help a bit, or at least rule out noise generated by the input as a potential problem.

4) You will note the complete absence of feedback cap in the op-amp portion of the circuit (http://www.generalguitargadgets.com/pdf/ggg_osq_sc.pdf).  Sticking a cap in parallel with R9 shold help to roll off some of the hiss without necessarily detracting from the treble response of your instrument.  A 100pf cap rolls off starting around 7.2khz, an 82pf cap starts around 8.8khz, and a 47pf around 15.4khz.  Most guitar speaks start to run out of bandwdith around 6khz or so, so it's a tossup as to whether a cap big enough in value to deal with the hiss would yield audible results with such speakers.  At the very least, something like 82pf shouldn't hurt a normal guitar signal.

5) In some respects the noise performance of the unit could be improved by adding a bit of boost before the input and turning down the gain of the op-amp a bit.  That could be built into the pedal itself, or take place in the form of on-board preamp in the guitar tself or anywhere between guitar and OS.  At the very least, I'm thinking a JFET buffer on the input would significant improve matters.

6) There appears to be pretty much nothing between 9V battery and the V+ pin on the op-amp.  That can't be good.  Stick some capacitance in there for goodness' sake.  A 10uf-100uf cap between V+ and ground should stabilize power a bit.  Sometimes whatwe hear as noise is not noise on the input signal but rather subtle constant modulation of the power supply lines by other sources.  Smooth those power lines!

[Blues Lyne]

Thanks Mark, that gives me some other things to try. 

The noise is a hiss not a buzz or hum.  Like saying shhhhhhhhhhhhhhh.   I'll have to check when I get home, but I'm pretty sure the resistors are already metal film.  I haven't had a chance to change the op amp yet.   From messin'  with it Saturday before the gig, there is no change in the noise based on where it's at in the chain, first, last after a buffered pedal, after a boss TU-2 set to mute, with guitar or without guitar, volume up on  guitar volume down.  It does increase as the volume knob is turned up on the OS, but I've had it set to what sounds like unity, not using it as a booster.  At 1/4 on the volume pot the noise is pretty noticeable, but not obnoxious yet. 

[Blues Lyne]

I got a brief chance to try some things with the OS tonight. 

Tried several JRC 4558's, no change. 
100uF from V+ to ground, no change. 

Adjusted trimpot.  There was a point where the hiss got much louder, but from there on up staid pretty much the same.  From that point lower there was less hiss, but not progressively so.  The trimpot was already set at the point where it got less hiss.  I found a post where Mark had listed voltages for setting the trimpot.  When set to get these voltages, it was in the "even more hiss" range.

The resistors look to me like blue metal film 5% resistors.

One thing I did notice is that C1 and C4 are .47 instead of .047
C6 is 10uF instead of 4.7uF.  RG talks about increasing one of the 4.7uF caps to slow attack and decay and get less ripple, but I can't tell if he's talking about C6 or C7.   

Didn't get a chance to try the cap across R9, or the sheilded input and output wire.

Blues

[Rob Strand]

There's a very old thread somewhere in the archives that goes through many mods to reduce noise in the OS.  IMHO one of the better ideas is to replace the 4558 with a TL072.

As I recall the problem in that old thread turned out to be something else, nonetheless many ideas were discussed.

[MartyMart]

I've built about three, one for a bass player with a few mods to it.
IIRC we rolled out some top end, was way above bass freq and probably gtr too !
I think I used an 8n2 or similar to ground before the output, worth a try ... oh and I also
used a TL072, as Rob suggested along with a lot of good poly caps, 1uf's in the bass version I/O

[Mark Hammer]

I think you probably should change the .47uf caps for .047.  Both C6 and C7 can stay as they are.  The chief concern is what you are applying a gain of x23 to at all times, and that may include noise contributed by the .47uf caps.

Incidentally, nothing wrong with sticking something like a 220pf cap in parallel with the 1.5M input resistor.  If that sort of fix is good enough for the Dynacomp/Ross, it's good enough for the OS.