G.A.S.

Amp Projects

2x12 Tweed Cab

Amps

Tech21 Trademark 60
Fender 75

Effects Pedals & Mods

COMPRESSORS
BBE OptoStomp
MXR Dynacomp
Boss CS-2
Boss CS-3

DISTORTION (etc)
Big Muff
Boss BD-2
Boss DS-1
Boss SD-1
Digitech Bad Monkey
Fuzz Face
Ibanez TS-808
MI Audio Blues Pro
MI Audio Crunch Box
Proco Rat B
Tube Driver
Tube Works Blue Tube

MODULATION
Boss CE-2
Boss CE-3
Elec Mistress Deluxe
MXR Phase 90
Univibe Stereo Chorus

OTHER
Boss GE-7
Morley Wah

Effects Projects

Valve Preamp Imitation
Line Buffer
Buffered Switch Box

Effects Settings

Guitar Projects

Red Strat/EMG DG20
Blue Strat/Custom 54s
P90 Strat
Sunburst Strat/L280s
Rickenbacker 4001
SX Precision Bass
Legend Fretless/EMG P

Guitar Shielding

Rants

Vintage Stagger
Pole Spacing

buffered true-bypass box

 

On the second Tunisia album I'm paying a lot more attention to the guitar sounds this time (for better or for worse). This means I need to audition different pedals quickly and easily, and not deal with a huge chain of pedals with mismatched impedances and different varieties of non-true bypass.

The choice of pedals is continually being refined, so I'm not considering a Pete Cornish-style floor board with hardwired effects. Yet. This thing would be designed mainly for the studio, using an evolving pedal lineup.

So, here it is. The Desert Comb buffered-true-bypass-box, two thousand.

Wishlist

• rack-mounted main unit for desk-mounted effects
• multiple true-bypass send/returns in main unit with relay switches
• remote pedalboard with foot switches (and indicator lights) for controlling relays in main unit
• input buffer for each send/return combination (for impedance matching)
• input buffers bypassable via toggle switches on main unit
• tuner out
• clean out for re-amping
• two outputs (for recording different amps)
• power supply output connections for pedal

Buffer characteristics

• high input impedance (1M)
• low output impedance
• RFI rejection
• unity gain

OK now let's get real

It would be easy to get carried away with a project like this, but I need to spend more time actually playing than building. So right away I'll make the following concessions.

• remote pedalboard limited to 16 switches for easy muxing
• which means 16 send/return combinations
• in fact, remote pedalboard descoped altogether
• relays and debouncing circuitry replaced by toggle switches
• descope impedance-matching buffers in each send/return. Limit to input and output buffers only.

So now for the refined requirements.

Refined requirements - or the fastest way to get back to playing

• rack-mounted main unit for desk-mounted effects
• 16 true-bypass send/returns controlled by toggle switches on front panel
• buffered input (bypassable)
• buffered tuner out
• buffered clean out
• buffered output 1 (bypassable)
• buffered output 2
• external dc power supply to reduce hum

Proposed signal path:

• Input ->
• Input Buffers
  • Buffer 1 (bypass = off) -> Clean Out
  • Buffer 2 (bypass = off) -> Tuner Out
  • Buffer 3 (bypassable) ->
• Send/Returns x 16 (bypassable)
• Output Buffers
  • Buffer 1 (bypassable) -> Out 1
  • Buffer 2 (bypass = off) -> Out 2

Parts

• 1 input jack, 1 tuner out, 1 clean out, 16 sends, 16 returns, 2 outputs = 37 jacks
• 16 DPDT toggles for send/return bypasses, 1 for input buffer bypass, 1 for output buffer bypass switches = 18 DPDT toggle switches
• 1.5m cable x 16 pedals x 2 (send & return) = 48m

Equipment specific parts:

• right angle plugs x 12 pedals = 24 plugs
• line plugs x 32 + tuner out x 2 + clean out x 1 + outputs x 4 + pedals ?
• rca clean out x 1

Construction

Quick and dirty prototype PCB with 5 buffers (3 parallel input, 2 parallel output). Based on a simple unity op-amp circuit. TL072s used here. Not a great deal of bad colouration or extra background hiss I could hear. Good enough. If I had my time again though, I'd be tempted to use simple JFET buffers. Not quite unity gain but simpler and it would be easier to sleep at night.

Front panel with 16 bypass switches for 16 send/returns. Plus another 2 for input buffer bypass and output buffer bypass. Yes, the box is plastic, for ease of drilling and mucking about.

The shielded mess of wiring inside. Don't worry - the switches are grounded too, and ground loops are kept at a minimum. Amazingly enough, any noise this thing adds doesn't worry me in the slightest, and you'll be able to hear it for yourself on the next Tunisia album!

Pedal selection

• Reversed wah (optional)
• BBE Opto-Stomp
• Boss CS-2 (modded)
• Big Muff (modded)
• MI Audio Crunch Box
• MI Audio Blues Pro
• Boss BD-2 (modded)
• Butler Tube Driver
• Boss CE-2 (modded)
• Script Phase 90
• Electric Mistress (modded)
• Univibe Stereo Chorus
• Slow Gear
• Boss DD-3 (modded)
• Tremelo
• Boss GE-7 (modded)

 

 

Free download!
New Tunisia EP
Under Deconstruction

Debut Tunisia album
Two False Idols
available in our Store
and iTunes

".. Catchy hook laden melodies, brilliant songwriting, and richly orchestrated arrangements." Prognaut.com

".. Anyone who can sound like Pink Floyd or Porcupine Tree one minute and The Jayhawks or The Humblebums the next has to be worth a listen." Classic Rock Society

"Craven really has come up with something very different and ingenious here and, as such, ‘cinematic rock’ is pretty much a perfect description." HardRockHouse.com