COMPRESSOR FAQ:
Q: What is this thing?
A: A compressor pedal for guitar based on the original Dan Armstrong Orange Squeezertm Compressor manufactured by Musitronics in the 1970s.
Above: A pre-logo Musitronics Dan Armstrong Orange Squeezer
Q: What does it do?
A: The basic function of any compressor is to reduce the dynamic range of the signal: the level of loudness is limited and the level of softness is boosted. The result is the same sound but within a narrower dynamic range. By applying make-up gain after the signal has been compressed, the net effect is one of an apparent increase in volume (you can hear the quieter details as well as the loud ones). Also, because notes get quieter as they decay, the compressor acts to increase the volume of the signal as it decays, resulting in increased sustain. With little to no compression dialed in and gain cranked up, it makes an astonishingly good overdrive as well.
Q: Is this an exact clone of the Orange Squeezer?
A: Yes, though it's worth noting there are differences between the early squeezer we cloned and at least one of the Musitronics Logo units I've serviced. We collected units from different eras and documented differences here.
The Armstrong Orange Squeezer used an RC4558T metal-can op-amp for its gain. In the Hartman Compressor, we are using chips manufactured by Raytheon (date code 43rd work week of 1973). The Musitronics logo units used plastic DIP JRC4558s. The Raytheons are indistinguishable from the JRC's when the pedal is run clean, but overdrive without the latter's prickliness.
The other interesting difference between the Artmstrong and the Musitronics logo versions were the rectifier diodes in the envelope sensor. The Musitronics used a Germanium diode but the Armstrong was Silicon! These aren't used for clipping, they do not produce audible artifacts, and the differences in their voltage drops are more than compensated-for by circuitry that tunes the compression ratio. Our version sticks with the earlier of the two designs: Silicon.
Because we've externalized the Ratio control, our Compressor comes with a way to tune the Ratio knob's action to give a suitable range of compression on the outside. Ranges to explore go from deep squeeze to wide open overdrive. Simply externalizing the original squeezer's trim would work too, but it would leave you with a finicky knob that you could accidentally dial clear out of its functioning range into silence. Not necessarily a good thing for the stage.
Q: Is anything else different?
A: We mentioned the external controls already. Basically, the only other differences are the kind of things you could reasonably expect from a pedal in this century: true-bypass (the original was always on), LED, external power.
As far as internal construction goes, we also use plated-thru hole circuit boards instead of the single-side laminate of the originals. After modding and repairing so many old (and not-so-old) pedals with factory-cold solder joints, or whose copper traces have started to delaminate from their board, it is difficult to express in words how superior plated-thru construction can be. Because the solder bonds the component leads not just to the surface pads of the board, but to the interior walls of the holes through which those leads pass, the mechanical and electrical integrity of the assembly is greater. It makes a difference in soldering dwell time as well. Properly tinned and isolated through hole pads require less time to solder well than large flat exposed copper laminate. Components are less stressed; there is less drift from rated value during assembly.
Q: What's this "overdrive" thing you keep mentioning?
A: Frankly, it's the coolest thing about these. IMO what sets them apart from Ross etc. of the same era. There is a ton of gain on board. When pushed, the op-amp on board starts to soft-clip. It is a musical effect. Much as a good tube compressor's tube distortion compliments and extends its natural compression range/curve, the pedal's transition into overdrive is smooth and fairly subtle.
The pedal also has good low output impedance. In this respect, the Hartman Compressor is deep in 'plays well with others' territory. Its output, even clean, can be set to tickle the input of a pedal or amp downstream into breakup. If you've ever used and overdrive or clean boost pedal in this way--same principle.
Q: Are there any options/mods available?
A: If you play bass we're happy to modify the tone capacitors to adjust the frequency range of the pedal downward at no extra-charge.
Q: I still have questions.....
A: Happy to help with them: mailto:info@hartmanelectronicstore.com or call (415) 652-8260.
Copyright 2009 Hartman Electronics.