Engel Sound Experiment

Rhythm guitar
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Space Charger
SE amps
Bass 5670 preamp
ECH83 preamp
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Shmitt Wha
Bone Tender
Transwap booster
Electroacoustic machines
Menorat Menorot

Stereo guitar

April-June 2011
A project that allowed me to get rid of the bass player. This is a guitar with stereo output that sends guitar and bass signals to separate amplifiers. I think this thing is one of my greatest projects - not because it's odd or complicated or innovative, but simply because this thing really works.


  • Preface
  • Repairing the source guitar
  • New electronics
  • Sounds
  • Ground loops


    The whole thing started with a heavy downtuned project I've planned with my friends from Rabies Caste. Me and Dave were switching guitar and bass not sure who plays what, my 4-string Jazz bass and Les Paul couldn't get any lower than drop-C tuning (I'm also playing in standard in other bands) etc. Even after playing in drop-C I wasn't impressed with the whole band sound - it was very familiar, nothing special.

    So one day I realized the following: in heavy riff-oriented music bass usually plays the root of the chord. If I can find a device that extracts the root from everything I play on guitar, I may create a virtual bassist. Well, there seem to be way too many of those devices on the market - all the guitar synths with midi pickups etc. Of course, making your guitar sound like a cheap digital synth is very original and creative, but there's a little thing called "latency" which destroys all the fun. Converting guitar signal and changing its pitch, especially at low frequencies, results in a terrible delay. The lower the note the bigger the delay, and even the best converters are always behind the original note. So this direction was not even considered.

    Then, I've found about hexaphonic pickup. Each string is picked by a separate mini-pickup and you have six outputs, one for each string. That sounded good, so I've thought I can make a switch to send, say, only the lowest string into octaver, and the whole pickup (plus the lowest string) into a guitar amp. After I've found out about the prices of those pickups ($250 and up), I was a bit disappointed.

    The next stage was to make an actual experiment with what I've got and see if it works. First, I simply took my guitar and sent it into two amplifiers, one via distortion and another via octaver. As simple as it was, that was nice. I could not play chords (the octaver would fart out), but single note runs with octaver sounded almost like a bass player joined me. What I needed was a pickup for the low string only.

    So I just took some noname humbucker I've had lying around and stuck it there. Actually, I was playing with position first. I usually play on the neck pickup, so the original idea was to put the bass pickup at the bridge. Unfortunately, the signal from the bridge position made the octaver mad sometimes, and the bass signal was obviously much thinner.

    Here's my hookup: bass humbucker goes into EHX Bass MicroSynth and then into some Radiohead amp I've cooked from an old tube radio, and the guitar is plugged into Marshall Guv'nor distortion and comes out from my Space Charger amplifier.

    Well, I must say this sounded soooo good I was struck. Like, wow! Suddenly every chord you play gets a massive bottom. Of course, you need to keep your playing simple and you need to have a root on the 6th string, but still that sounds so FAT I kept playing for some time before I could put the guitar down. And I also loved that you can avoid plucking the 6th to stop the bass sometimes and then pick it again, which produced nice dynamics in the bass lines.

    The same night I understood I must build me this instrument. I just didn't wanted to play without the bass signal anymore. It felt good, it sounded interesting and suddenly I felt like a whole band.

    The source guitar

    I like Les Pauls, and honestly, I'm afraid you cannot find anything better for heavy stuff. I don't have tools and skills to build me a guitar from scratch, so i've thought about finding a proper wreck. I went fishing on ebay and at some point stumbled across this:

    Gibson Challenger I, 1983. No tuners, no pickups, no pegs, no bridge and a crack in the neck pocket. Just what I needed. The most important part was the bolt-on neck: it costs twice less to ship a guitar with the neck unscrewed, and we're talking about shipping from USA to Israel, so it's a lot.

    I've got it cheap and I think Challengers are a bit underrated. The maple neck on mahogany is just what you need - I don't understand all those carved maple top complications. The main Challenger drawback is that the body is too light - too much wood is taken for routing. Everything under the pickguard is hollow - this was made before CNC and it was probably easy to work like that. Challenger I (one) had only one bridge pickup, and Challenger II had both bridge and neck pu's, but still Challenger I 's body was routed for the neck pickup. The difference was only in the pickguard. My Challenger I was modified by the previous owner who installed the neck pickup and added controls and switches. I love the output jack location - right between the volume and the switch.

    It took my daugter some time to clean the guitar as it arrived (nobody probably cleaned it since '83, gobs of grease!). The crack in the neck pocket was a pain to repair, and another nice upgrade the previous owner made was two bolts screwed into the neck heel inside the pocket. The bolts' heads stick between the neck and the body, raising the neck angle. A cool and original alternative to shim. I took the screws out and blessed them. It's possible those screws were the reason the guitar was sold, because with no connection between body and neck it should have sounded dead.

    The original finish is hilarious - it's silver which yellowed, greened and checked over the years. As you can see, it's more silver under the pickguard, and almost original in the neck pocket. I'd call it "poisoned goldtop". A very cool color indeed.

    I've had no pickguard material, but I've had a piece of transparent plastic from a broken bust stop advertisement window. I've taken the old pickguard, put it on that plastic and cut the shape. The only thing I've changed was the lower bout, which is straight on original Challenger design. Cutting the pickguard was the major challenge - the first one cracked, and it took me several evenings to do it.

    New electronics

    I was planning to wire the bass pickup myself, but finally bought a noname P pickup on ebay from HongKong for $8.Hong Kong sells cheap guitar parts that may not be the same quality as original Gibson or Fender parts, but they're pretty close. I've had another P pickup from Squier bass I've upgraded some time ago, the $8 noname sounded way better that Squier, and the most important - it was noiseless, while Squier had some buzz.

    The body was routed for a humbucker and to put in a Precision pickup in I've had to get rid of the rectangular plastic cover which was too big. Finally the pickup was fitted inside.

    I've made something reminiscent of a regular pickup adjustment mechanism, and it sort of works. The second half of Precision humbucker simply rests inside the body, fighting hum and not picking the signal.

    Here's the dark side of the pickguard. The bridge humbucker was another noname Hong Kong wonder ($21 for a pair). It won the bang for the buck contest (the loosers were Tonerider Alnico IV - too weak and too vintage-sounding, and Gibson 490T that I simply wanted for another project). The wiring goes like this: Precision pickup -> 250K volume pot -> Ringe sleeve of the output jack. Bridge humbucker -> 500K volume pot -> tip of the output jack. I've also make a switch to send the bridge pickup signal to both ring and tip, allowing to play in simple octave mode. The switch is a push-pull part of the bridge pickup's volume potentiometer. No tone pots, so additional switches, everything is as simple as it gets, which also means more tone and less noise.

    I was thinking about all sorts of colors for the pickguard, but in the end it became black. To make a black pickguard out of transparent one all you need is to pait it black from the inner side. I've borrowed this method from Soviet guitar builders - Borisov plant was painting their pickguards this way. The paint doesn't scratch off because it's inside, and the thickness of transparent plastic adds depth to the colors.

    The black box on the side is the second half of the P humbucker. The output jack is stereo, but if you use a regular mono cable you simply get a guitar with one bridge humbucker and a volume pot.

    The rest of the hardware consists of Gibson Deluxe tuners left from my other Les Paul I've upgraded with Bigsby and Klyson locking tuners (see the pictures above) and a $7 wraparound bridge, noname copy of BadAss design. Good enough for me. So here I am, finally testing the guitar. I've bought Erine Ball Baritone 72-13 string set, which allowed me to go down to drop G tuning (G-D-G-C-E-A, low to high), which is a tone lower than your Korn A and one semitone higher that Meshuggah 8-string F#. The lowest G is minor third higher than 4-string bass' E and the 1st string is A, which is one tone lower that regular guitar's 2nd string. But remember, with the octaver you've got one octave below that, which is the low G. I still haven't heard any 5-string bass with low G, so it's way low.


    How it sounds like? While I've thought it sounds like an orchestra of behemotes, the other guy said it's a wounded dinosaur. In any case, I love the sound and it allows me to play with a drummer alone. IMHO, all those White Stripes, Anal Cunt, Black Keys and the rest of the drums-and-guitar bands must get this guitar. But if you do have a bass player, it allows additional things to be done, like playing with two effect chains independently and fattening up your riffs.

    Below is a sound sample I've made with two small and quiet amps (see the picture above):

    Sound sample

    While it's not as thunderous as through big amps, it makes a right general impression. I will record some more stuff and upload it here later.

    That's all, folks!


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