VOX V847 Mods

      Source circuit:     MXR Distortion+
                   Style:     distortion
                    Built:     October 1995
Source Schematic:    MXR Distortion + (Gif format, 10KB)

                                           
                                    Close up                  Circuit

Comments: 

This was my first home-brew effects pedal that I did in 1995. The build quality is pretty shoddy but I had fun with it... It's inspired by the old MXR Distortion+ but with a switch to toggle between two different sets of clipping diodes. 

The parts all came from the local Radio Shack except for the cast aluminum box which is a standard Hammond 1590B. Several coats of automotive primer and lacquer finished it off. See the toggle switch strapped to the footswitch, that's used to select either silicon diodes or red LEDs for the clipping circuit. A status LED is used with the DPDT switch, so no "true bypass". The label was done in Excel and printed onto label stock.

The tone of this isn't my favourite. It's a bright and brash in-your-face style of distortion. With the germanium diodes it offers more grit and is smoother, with the LEDs it's louder and rougher sounding.

Sounds:

Sound samples recorded using the Daphne Strat and Traynor YGM-3 (2 x EL84 amp with 12" speaker). Two SM57s were used, one at the grill, one several feet back for ambience). For each sample, a "pedal off" reference sound is recorded before the pedal is engaged.
 

      n = neck pickup
      b = bridge pickup
      Level, Drive settings are as on a clock. 2 = 2 o'clock on the dial.

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      Source circuit:     Dallas Arbiter Fuzz Face
                   Style:     germanium fuzz
                    Built:     10 January 1996
Source Schematic:    Fuzz Face (Gif format, 9KB)

                                           
                                    Close up                  Circuit

Comments: 

I'm a fan of Jimi and Stevie so the Fuzz Face was my second build. The Fuzz Face is a very simple circuit but in the details lurks some amazing sounds. At the time I knew nothing about the vintage-voodoo "correct" germanium transistors to use so it's not as good as it could have been. It lacks some punch and doesn't have near the gain or distortion as a Fulltone '69 (for example). Still sounds ok for some applications though.

I first built with an indicator LED, but found out I needed both poles of the Carling DPDT for full bypass which this circuit requires - so the LED is just for show now. The batter location was a little tight so I taped of the exposed poles of the switch to prevent any interaction with the battery. The perf board is taped to the inside chassis with black electricians tape!

Again, label in Excel and most parts from Rad Shack and another local electronics supplier. This case is the Hammond 1590BB and the jacks are Switchcraft.

Sounds:

Sound samples recorded using the Daphne Strat and Traynor YGM-3 (2 x EL84 amp with 12" speaker). Two SM57s were used, one at the grill, one several feet back for ambience). For each sample, a "pedal off" reference sound is recorded before the pedal is engaged.
 

      n = neck pickup
      b = bridge pickup
      Level, Drive settings are as on a clock. 2 = 2 o'clock on the dial.

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      Source circuit:     ProCO RAT
                   Style:     distortion
                    Built:     19 November 1996
Source Schematic:   ProCO RAT (Gif format, 10KB)

                                           
                                    Close up                  Circuit

Comments: 

In late '96 I had a good TS-9 overdrive and wanted a good distortion pedal. I read good things on the 'net about the Rat and located the schematic at Leper's archive (actually, these first three schems came from there...if you were into effects and had 'net access back then, you know about Leper!). 

This was the most elaborate by far because I designed a PCB (printed circuit board) using an old DOS-based board layout program. I laser printed the result onto clear overhead stock and used a pre coated circuit board. I went through the photo and etch process and ended up with a good looking board. All chemicals plus the board and other material (including UV light tube) came from a local electronics shop. Finally, I used a Dremel tool to drill the mounting holes and installed the components.

I wasn't satisfied with the stock clipping diodes (once again), and used a slightly different arrangement. The switch on the top side selects between these two diode arrangements: 

   (1) silicon + silicon (in parallel)
   (2) silicon + red LED (in parallel)

Version (1) is smoother and more "vintage" sounding while (2) is more aggressive. This pedal is capable of copious amounts of distortion and sounds great with single coils and humbuckers through all my amps. With the gain (BITE) way down and level way up on setting (1) it provides a great Overdrive tone as well. Excellent tone!

Versatile pedal and was by far the favourite of my home-built pedals until I built the Skildrive. Once again, label in Excel, 1590BB Hammond box, Carling DPDT foot switch, and auto lacquer. No LED and true bypass switching. 

Sounds:

Sound samples recorded using the Daphne Strat and Traynor YGM-3 (2 x EL84 amp with 12" speaker). Two SM57s were used, one at the grill, one several feet back for ambience). For each sample, a "pedal off" reference sound is recorded before the pedal is engaged.
 

      n = neck pickup
      b = bridge pickup
      Level, Drive settings are as on a clock. 2 = 2 o'clock on the dial.

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      Source circuit:     -none-
                   Style:     A or B or A+B passive switch box
                    Built:     29 January 2001
Source Schematic:   ABY Schematic

                                           
                                    Close up                  Circuit

Comments: 

I'm a self-confessed guitar tone freak and wanted to be able to compare amps, effects, etc., with an A/B box, or switch to a tuner between tunes. I explored R.G. Keen's switching boxes on his GEOfex page but ended up abandoning the more complex buffered designs for a really simple passive one. Please note that there is no isolation from amp to amp, so if you get hum with 2 amps connected you'll need to seek out and eliminate any ground loops you might have.

The first poles of the DPDT Carling foot switches the input signal to the following:

   (1) A/B  - switches between output A or B
   (2) BOTH - connects both outputs together

The second DPDT poles control the indicator LEDs which are essential for a box like this. Since I wanted to be able to leave everything plugged in I used a power switch. I still wired it so that the guitar must be plugged in to enable the power (as on most effects pedals and all the ones I build). 

This was the first pedal where I really took time to lay everything out properly with neat wire runs and component locations. Still room for improvement though...

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      Source circuit:     -unknown - found on web
                   Style:     clean boost
                    Built:     27 May 2001
Source Schematic:   Clean Boost

                                           
                                    Close up                  Circuit

Comments: 

Next up was a clean boost. In early 2001 there were HUGE ongoing debates on the various guitar web BBSs about which clean boost was the best. It seemed like every month there was a new and better option available with devotees trying to persuade the world at large that their favourite was the best! Fun stuff. I decided to build a clean boost and came across this circuit on the net and thought I'd give it a go...

Wow! This circuit can really bring a new dimension to an existing guitar/amp setup. It performs a clear and loud boost but also adds a very tasty sparkle to the tone. A friend called it "Fender tone in a box" when demoed with his Marshall. With the volume close to the max setting a decent crunch can be obtained.

Another perf-board build for an extremely simple but effective circuit. I didn't use a DPDT switch or LED since I thought I'd probably have it on all the time when in use. The cool finish was done by pulling the aluminum Hammond box along fine sandpaper - I believe this idea came from Joe Gagan - thanks Joe!

Sounds:

Sound samples recorded using the Daphne Strat and Traynor YGM-3 (2 x EL84 amp with 12" speaker). Two SM57s were used, one at the grill, one several feet back for ambience). For each sample, a "pedal off" reference sound is recorded before the pedal is engaged.
 

      n = neck pickup
      m = middle pickup
      Level, Drive settings are as on a clock. 2 = 2 o'clock on the dial.

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      Source circuit:     Dallas Rangemaster
                   Style:     germanium treble boost
                    Built:     01 June 2001
Source Schematic:   Dallas Rangemaster  (This will take you to the GEOFex schematics page)

                                                     
                                    Close up                 Close Up                 Circuit

Comments: 

The Dallas Rangemaster is not very famous, but it should be. It is a treble booster that was used extensively by Brian May during his work with Queen, and also by Eric Clapton on the Bluesbreakers "Beano" album. When engaged, it adds an edge to the guitar tone that is quite distinctive. 

R.G. Keen at GEOFex has an excellent article describing the history, function, and construction of the Dallas Rangemaster. Check out the link (above) to his vintage schematics page where you can find the Rangemaster information. His PDF file contains a schematic as well. Thanks for sharing this RG!! 

I built a clone of the original circuit, but with a few differences: 

    1. True bypass with 3PDT Fulltone footswitch 
    2. LED indicator (effect engaged) 
    3. 3-position rotary switch for changing input capacitor values (more detail below) 
    4. 1M pull-down resistors to eliminate footswitch "popping" 

I called my clone a "Space Ranger" because Rangemaster and Texas Ranger were already taken! 

It can be difficult finding the correct germanium transistor for this circuit so I ordered one from Steve at Small Bear Electronics. His packaging indicates the correct values of the biasing resistors so this took out the guesswork (the bias of the transistor determines the nature of the frequency response you'll get. RG has excellent detail on how to accomplish this in his PDF document). 

The main circuit is on perf-board, then I used point-to-point construction for a few of the resistors. I used a vinyl standoff to mount the circuit board to the chassis. This is the first time I've done this...usually I just leave it hanging in free space with electrical tape on the back, but I like this method better. The input jack (on the left) also turns the pedal by closing the battery circuit - standard approach with effect pedals. 

On the top of the circuit board you can see the 8-pin socket I used for the input and output capacitors. For input caps, the stock Rangemaster value is soldered to the board (0.0047uF), but I've socketed the other two so I can experiment with different values and cap types. The output cap (0.01uF) is also socketed so I can mess around with this value too. The transistor and one of the bias resistors is also socketed so I can try different substitutions here as well. 

The finish is one coat of automobile primer and three coats of automobile paint. I baked it in a toaster oven for 45 minutes at 200 degrees to harden the paint. The result is a glossy rock-hard finish that lasts. I've used this method on all of my pedals and it works nicely for me. The box is a standard Hammond 1590BB which leaves plenty of room for laying the components out. 

The controls are LEFT: boost level, and RIGHT: three-position tone switch for changing the value of the input capacitor between 0.0047uF (close to original stock value of 0.005uF), 0.01uF, and 0.15uF. The sound gets progressively thicker and bassier as the value increases...0.15uF is TOO bassy. Right now I'm diggin' the 0.01uF setting the most... 

The Label was made in Excel and printed onto label stock. I sprayed it with lacquer this time prior to sticking it on (this helps resist moisture). 

Sounds:

Sound samples recorded using the Daphne Strat and Traynor YGM-3 (2 x EL84 amp with 12" speaker). Two SM57s were used, one at the grill, one several feet back for ambience). For each sample, a "pedal off" reference sound is recorded before the pedal is engaged.
 

      m = middle pickup
      b = bridge pickup
      Level, Drive settings are as on a clock. 2 = 2 o'clock on the dial.

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      Source circuit:    Ibanez TS-808 and John Greene Screamer+
                   Style:    IC-based overdrive with boost switch and other mods
                    Built:    21 March 2002
          Source Info:   Ibanez TS-808 Tube Screamer (GEOfex technology of the Tube Screamer)
Source Schematic:  John Greene's Screamer+  (You can also visit John's new page)
   Build Schematic:  my build schematic  (this include the several modifications I've made)

                                           
                                             Close up                                     Circuit

Comments: 

The Ibanez TS-808/TS-9 is easily the most famous Overdrive pedal on the market. The original puke-green versions are sought after and command high prices on eBay and from vintage dealers. As a result there are many boutique effects gurus who are producing their own versions of the design, with improvements. The Fulltone Fulldrive 2 is one of the more successful examples and sounds fantastic!

My version is mostly based on the Screamer+ schematic by John Greene (see link above), plus some additions to the circuitry for extra options. John documents some of the changes to the TS-808 design and what the benefits are. 

I made a couple of changes from John's schematic: 

    1. changed the resistor values in the output stage to TS-808 values (100R + 10K). 
    2. Used a 500K pot for the overdrive control. 
    3. Added three push-pull potentiometers to switch in the options documented below...
 

Push-pull options:

Fuzz - inserts two 1N34A parallel diodes to ground right after the 1K leading to the volume pot. I've also put a .01 cap here to tame some highs.

Headroom - inserts a 500K in series with the feedback loop diodes which raises the clipping threshold and effectively cleans up the signal. Great for clean boosting. I'd love to use a 500K pot here which would add even more flexibility. John Greene gave me this idea.

Clean - a DPDT switch to switch in a MOSFET Switch booster before the rest of the circuit. Same circuit as the Clean Boost pedal above. Actually, I scavenged the perf board out of that pedal 'cause I didn't want to build it again. There's a small trim pot to set the level, which is just over unity gain at the moment. Nice spanky clean boost, but can also drive the rest of the circuity into a more aggressive sounding state.
 

Sounds:

The overdrive tones of this circuit are extremely good, and the boost circuit adds a richness that is way beyond any other overdrive pedal I've played. Rolling back the guitar volume cleans things up nicely too. 

The fuzz is most effective when you engage the headroom as well...this makes the 1N34As do most of the clipping and provides more of a fuzz tone. Engaging all three pull options gets close to RAT territory - great rawking distortion sounds!
 

Finish & Graphics

The enclosure is a a standard Hammond box, but taller, wider, narrower than the 1590BB. I sprayed with metal primer then 4 coats of automotive laquer, baking in the toaster oven at 200F 45 min between coats.

For the artwork, I created the "picture" in PaintShop Pro then saved as a TIF file. We've got a local engraving/trophy shop with a laser engraver. They loaded the b/w tif into Corel Draw, then sent it to the laser which etched away the paint down to the bare aluminum. After that I sprayed with 3 light coats of clear lacquer. 

It's the first pedal I've done this way so it took some trial and error when setting up the dimensions and orientation for the laser. The first try was off by 1/8" and I had to sand and repaint for the final attempt which went well.

This was an expensive pedal to build since the push-pull potentiometers and footswitches are all around $10 each, but the results have been beyond satisfaction. Many of the parts including footswitches, caps, and transistors were ordered from Steve at Small Bear Electronics. Footswitches are Fulltone 3PDT units and this pedal is true-bypass with LED indicators. 

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      Source circuit:    Tychobrahe Octavia
                   Style:    germanium octave fuzz
                    Built:    12 March 2002
Source Schematic:  Octavia  (drawn by Justin Phillpott)

                                           
                                    Close up                  Circuit

Comments: 

The Tychobrahe Octavia was made famous by Jimi Hendrix and original examples are extremely rare. The story goes that English pedal legend Roger Mayer developed the original circuit which Tychobrahe copied when it was brought in for servicing in the US. As with the TS-808 design, there are many fine boutique examples of octave+distortion pedals. 

All parts are easy to come by except the interstage transformer. RG Keen recommends a Mouser part number of 42TU011 which is what I used. I replaced the MPS-A18 transistor in Justin's schematic with a 2N5088 and used two 2N3906 for the other two.

Sound:

If you've played an octave distortion pedal before, you know the ballpark we're playing in here. Distortion that jumps out of the speaker and grabs ya! The octaving effect is more prominent as you play single notes up the fretboard using a neck pickup. Chords tend to create ring-modulator like sounds. Jimi used an Octavia on several recordings and SRV used it frequently in concert later in his career. More recently, Kenny Wayne Shepherd used this effect in the solo of his major hit "Blue On Black".
 

Finish & Graphics:

It's difficult to see in the photo but I tried a different spray painting technique on this pedal. Using automotive lacquer, I sprayed a base coat of a dark cherry colour, then applied a lighter red colour while still wet. The result is a nice mottled look. The graphics are hand painted with white Testors model paint. The toaster oven was utilized to dry and harden the paint (as usual).

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One of the favourite topics of Fulltone FD2 owners is the change Mike Fuller did to his excellent design to slightly "flatten" the mid frequency response. These versions have an FM prefix to the serial number where the original ones did not. Old FD2s can go for stupid money on eBay because some players think they sound sweeter or cut through a band mix a little better.

I own a FM model and I've modded it to enable or disable the FM function using a switch. I believe that the change I made makes it equivalent to the older non-FM models when in that mode. However, take this with a grain of salt because I'm just going by some advice I picked up on the net (always suspect!).

To my ears, the difference is subtle. There is definitely a more pronounced mid-range hump in non-FM mode, but it's only really noticable with the Overdrive control turned up past 12, below that and it's very difficult for me to tell the difference.
 

Mod details:

Instead of drilling a hole for a toggle switch, I chose to replace the Overdrive pot with a push-pull switching pot of the same stock value, 500KB. On a stock FM FD2, there is a single bare wire that is visible on the top of the circuit board, right next to an electrolytic cap. Leave it intact and you've got your stock FM FD2, snip this and you've got the old non-FM version

My switch simply breaks this circuit when pulled out, ie. Pull for non-FM version! If you look at the picture below, you'll see a red circle surrounding a couple of orange leads with green heatshrink. These are leading to the 2 of the DPDT lugs of the new pot (yellow circle). 

                                 
                               Mod Close Up

Unfortunately, I didn't take any pics prior to the mod but if you look inside it's easy to locate the correct wire. 

Regardless, it's a simple mod and it's worth a try to see if you like it.

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I really like my VOX Wah Wah but have improved it in two ways:

(1) Replaced the 33K resistor in parallel with the inductor with a 68K (see red circle in picture below). This gives a more vocal quality to the wah and I really like the difference! Some Vox Clyde McCoy wahs apparently had 100K resistors here. I found this idea at this excellent Wah Wah Mods  page.

(2) Replaced the SPST footswitch with a DPDT for true bypass. This makes a dramatic difference for any wah because this circuit seems to be very effective at loading and muddying guitar tone when in bypass mode. See the Fulltone tech page for info on doing this mod.

See the picture for a scan of the innards of the modded circuit.

                                 
                                           Mod Close Up