Little Rock

Great, lush phaser, now 50 years old

 

   

 

The GT Little Rock phaser rack effect module compares to the Electro-Harmonix Small Stone phaser, one of the most popular phasers of all time since its debut in 1974.  The simple controls and lush, liquid swirl have spiced up everything from jazz, blues, and country to pop, grunge, and rock.

 

Description

There have been multiple versions of the EHX Small Stone over the years.  The basic circuit design stayed fairly consistent through the first few versions, but had minor variations in part values, as is typical with older EHX pedals.  The first version had an extra op amp in it that was replaced by transistors in subsequent versions.  Although most analog phasers have some noise, the first version of the Small Stone may be a bit noisier than later versions.  The second and third versions are often favored.  The Russian versions also have fans, but there are claims that they were inconsistent.  The reissue which added the LED to the old NYC box style is pretty good.  We haven't looked into the new Nano series.  Our Little Rock compares most closely to the v2 and v3 Small Stone pedals.

In addition to the possibility of noise, most versions of the circuit also have a noticeable volume drop when you turn them on.  It's unclear why they left it that way for so many years, but it seems they did.  The pedals weren't true bypass and seemed to have some tone-sucking problems when turned off.  We addressed all three of those issues in our circuit.

The circuit is a four-stage phaser that uses OTA op amps.  The original op amp is the CA3094.  It is getting difficult to find, as it has been out of production for many years.  EHX had some made for them that were labeled as EH1048.  The CA3080 is nearly the same, but requires a few extra parts to work the same was as the CA3094.  Adding those parts basically makes it a CA3094, and it sounds great that way.  Our board is designed to work with either op amp, depending on availability or choice.  If we have CA3094, we'll use them.  Otherwise we'll use CA3080.

The standard controls are simple.  There is a Rate knob and a Color switch, just like the originals.  Also like the originals, one setting of the Color switch has a little noise while the other is pretty quiet.  Of course, it wouldn't be a phaser without some noise - they all seem to have a bit, especially as they cycle through the higher frequencies.  It's not really that phasers are noisier than other effects as much as it is that they make the noise more apparent by putting it in motion.  We stay close to the original circuit but have some minor mods to help reduce noise.

A few mods and options are available.  This original was simple, and we recommend sticking with just the default Rate control and Color switch.  We've experimented with some additional options, but found most of them don't have as much impact as we wanted. 

 

Configurations

  • Little Rock - compares to EHX Small Stone phaser, closer to v2 and v3

 

Options

  • Slower Speeds - The standard Rate control range seems good for both slow and fast speeds at either extreme.  However, if you like sssslllloooooowwwwww phasing, we can change the range of the Rate control to provide more adjustment and range on the slow end.  The fast speed is unchanged.
  • Bright Mod - We first added this mod because many players feel that the sound is too dark.  This mod cuts out a bit of the low end in the wet path.  The effect can be subtle, depending on the amount of bass in your signal.  However as we looked into this further, we found another capacitor in the circuit that had very different values in different versions of the pedal.  One value is definitely dark and a bit dull.  The other value sounds great, more natural.  The first value is so dark we chose to only use the second value in our builds.  With this second value, the Bright Mod seems largely unnecessary and has less impact.  It just shaves off some of the very low end, perhaps keeping you from getting stuck in the mud if you have a bass-heavy rig.
  • Switched Bright Mod - Same as the Bright Mod, but with a switch to turn it on/off.
  • Input Level Control - This is one of the mods that had less impact than we wanted.  The idea is that high output pickups could cause the Small Stone to clip or distort a bit.  This mod lets you dial up the input resistance a bit when that happens.  If you have a Small Stone and it clips in your rig, then this might be helpful.  We just didn't get much out of it in our testing.
  • Univibe Mod - The Small Stone and Univibe are both 4-stage phasers.  Each stage is largely defined by a particular capacitor.  This mod changes the Small Stone capacitor values to the Univibe capacitor values.  It won't turn the circuit into a Univibe clone, but does create a new and different phaser with a Univibe flavor.  Check out our SwirlOVibe phaser if you want full-on Univibe magic.
  • Switched Univibe Mod - Same as the Univibe Mod but on a switch so you can change between the Small Stone and Univibe capacitors.  It's not meant for switching during a song, as you could get a switch pop.  Also, it involves a lot of wiring, so we have to bump up the cost for the considerable amount of extra work and switching involved.

 

Front Panel

  • On/Off indicator LED
  • Rate
  • Color Switch
  • Input Level Control (optional)
  • Bright Switch (optional)
  • Univibe Switch (optional)

 

Rear Panel

  • Audio In
  • Audio Out
  • On/Off Footswitch
  • On/Off Override
  • DC Power
  • DC Power LED

 

Module Width

  • 1.5" standard or with options
  • 2" left wing and 1.5" right wing available for some configs

 

Power Consumption (aprox)

15 - 20mA

 

Base Configurations

Part # Description List Price
MOD-LROCK Little Rock module $250

 

Options

Part # Description List Price
MOPT-LROCK-SLOW Slower Speeds $9
MOPT-LROCK-BRIGHT Bright Option $0
MOPT-LROCK-SWBRIGHT Switched Bright Option $19
MOPT-LROCK-LEVEL Input Level Control $19
MOPT-LROCK-VIBE Univibe Mod $0
MOPT-LROCK-SWVIBE Switched Univibe Mod $39