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elmo7sharp9

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Everything posted by elmo7sharp9

  1. Frank Zappa had this done to a Stratocaster. I tried it myself. Handling noise (Including the Pick Attack) swamps the string vibrations, You get artificial reverb off the Springs. You can "play" the lacquered body with the friction of your fingertips (And hear the friction of your clothing against the rear of the body). VERY unmusical, even if you're Avante-Garde, just UGLY. Still glad I tried it as now I *know*. Piezos need to see a higher impedance than a guitar amp input - FET preamps are normal - the "Treble-only" sound and low volume is a direct consequence of impedance mismatch. Prostheta is entirely correct about piezos needing to be under direct pressure from the source of the sound (Underneath a fixed Fender bridge is ideal) - the Gel Pack idea is a non-starter - filtering by electronics is cheap and easily repeatable.
  2. You'll not gain magical hum-reducing properties in this way. You'll sum the hums of the individual pickups. Expect to hear roughly as much hum as a single coil on its own.
  3. Beware... There's still some research required. Some synchronous logic chips clock on the Positive-going edge, others on the Negative. Ideally, you'll choose all chips in your system to share the same clock behaviour and it'll work like Clockwork.
  4. There's a clear representation of the system that Curtisa describes here: http://wilsonminesco.com/6502primer/potpourri.html Replace that 6522 VIA with a simple oscillator (Google "simple ttl oscillator" - there's endless choice) driving a decoded counter to drive the LOAD and CLOCK lines. Use the raw oscillator signal as your CLOCK line for the counter and for the CLOCK inputs of all the shift register chips. The counter circuit works like this: We ignore all counter outputs except for bit 6 (Weight=32) and bit 1 (Weight=1). We derive two signals from the counter: Use the Counter's bit 6 as the Load/Shift signal. Logically AND counter bits 1 and 6 to generate a counter reset pulse. THE SEQUENCE IS AS FOLLOWS... During states 0-31... Permit one-bit-per-state data transfer across during states 0-31 (That includes the 2 unused bits) On state 32... Handily, the counter outputs xx100000 - use the Counter's bit 6 as the Load/Shift signal. This will need inverted to drive the '165s, but can be applied directly to the '595s. This will simultaneously LOAD the Input State (Key-side '165s) AND transfer the JUST-FRESHLY-SHIFTED bits to the output pins of the '595s. On state 33... RESET the counter. The counter outputs xx100001, so logical AND counter bits 1 and 6 to generate a counter reset pulse on reaching state 33. This signal may need inverted, depending on the polarity of your counter's RESET line. With the counter reset to xx000000, the cycle starts again from state 0. The speed of the clock oscillator is up to you. To avoid logic-defying mystery faults... Use one 100n supply-decoupling capacitor for each chip, mounted physically close to each chip's positive supply pin.
  5. Now that *IS* interesting. Have anyone tried that here? Talk about feedback! That's feedback gone wild. Perhaps some filtering will tame that feedback. I wonder how well it behaves though, especially when playing clean with lightly played and long sustained notes (none of that in the video). That demo sounds like an uncontrollable mess, with lots of noise and some overpowering microphonic feedback. Look at the alignment of the magnets... the WEM Fifth Man sustains the side-to-side vibration of the strings, the Roland sustains the more usual up-and-down vibration. From memory, the Roland has a Common-Collector driver for each string with a different current-limiting resistor value for each channel (Presumably to achieve some balance across the strings - I don't see there being a significant variation in resistance-to-ground through different string gauges!). I tried it out on a piezo-equipped acoustic, using a variety of magnets at the neck - couldn't get sustain at all - tried different power amps, too. The usual "Too Many Variables To Account For" that DIY Sustainer enthusiasts know well.
  6. "I guess it's the same for the GK3. Are the low pass filters not bypassable? " On the GK-2A, It's the simplest single pole RC filter, between the pickup and an op-amp input. Snip the capacitor's ground leg and the filter is defeated. "Are there schematics (or at least block diagrams) available?" http://www.vguitarforums.com/smf/index.php?topic=73.0 There's a GK3 diagram as well. "Do you know what the cutoff frequencies are?" I have never calculated them. I see that on the GK3 diagram, each of the 6 channels is identical. My memory of per-string values comes from earlier dedicated Roland guitars (G303, G505 and the G707). Prior to the GK-series, Roland's dedicated synth guitars had similar onboard filtering. When used with the GR-100 (No synth - just Polyphonic Chorus and Compression), the signal was crisp and clear- no ill effects from the rolloff. Interestingly, the earliest Roland guitar synth had POLYPHONIC SUSTAIN. The GR-500 guitar had strings that were isolated from Ground at the bridge. The strings were grounded at the nut and, when Sustain was switched on, each string carried a 15 volt sine wave of its detected fundamental pitch. The strings passed over a broad permanent magnet, located where the Rhythm pickup is on a Les Paul. http://en.wikipedia.org/wiki/Roland_GR-500 It's an unusual configuration for a sustainer, but not unique... Watkins Electric Music made an ultra-rare guitar, called the Fifth Man, around 1967. It featured a similar arrangement, but with opposing permanent magnets mounted at each side of the neck joint. The guitar was self-contained and the circuit was powered by a heavy-duty (and heavy!) rectangular torch battery in a cavity on the rear of the guitar. http://www.youtube.com/watch?v=NqBaW1qMs4w
  7. "it's easy to chop an envelope to achieve the muted banjo like effect." I keep forgetting the Polyphonic scope - the ability to treat each string separately... The Vo muting, then, is a rather "moot" science-demonstration of the power of the system. Oh, if only there was some way of using the edge of my hand to tame the string vibration . Regarding previous comments about using a Roland hex pickup as a source: I have done this, in combination with a monophonic power amp and driver coil, in order to achieve a more consistent response across the strings (Fully polyphonic sustain was beyond my grasp - I used trimmers in a summing amplifier to achieve balance). The GK2A, that I used, is not PASSIVE... It has active buffering for each micro-humbucker on board, with different low-pass filtering for each string (to aid Fundamental Detection). The GK2A takes a +7v/GND/-7v supply in normal use - it DOES work with a 9v battery and a resistive divider to provide the GND tap. Regarding the possibilities of stimulating a string with samples etc... We can only stimulate the harmonic series that is physically present in the string. This usually results in the string sustaining a close-to-sine tone - a musically uninteresting result, once the novelty wears off. I have had freak occurrences of a string sustaining BOTH the Fundamental and the Octave-plus-a-Fifth harmonic - a musically interesting result that can surely be made repeatable by controlling the proportions of each harmonic in the stimulus signal. It would be interesting to have a slowly-shifting transition through the harmonic series as a note sustains. This is already achievable, using an E-Bow, by pinging a "weak" harmonic and observing the string vibration "morph" to a pitch that has a stronger resonance - but the effect is a one-shot, one-way and monophonic. The effect would be far more impressive on a Polyphonically Sustained chord - a Tamboura-like drone of incredibly complex texture. Naturally, I'm imagining different rates of change on each string... It's a just a short step away from what you've achieved already... I look forward to future developments.
  8. Steel-wrapped (versus Nickel) strings made my AGC-less Bass Sustainer spring into life - it's a significant step up in efficiency. But it really shouldn't be a requirement. For 6-string guitar, Nickel-wrapped strings are all that's available in most stores now. I'm guessing that a nickel 9-42 set, in regular tuning, is what most potential users will have on their guitar, and want to continue using. I'm impressed with Cycfi's "synthesised excitation signal" approach and must ask - have you tried to replicate Moog's "mute" response?
  9. 100k is the standard value. During a period of "try all known mods", I tried 470k - no discernable difference in sound or operation.
  10. "...maybe distorting the signal being fed through the strings might result in a similar "raspy" "zingy" tone..." Sadly, this is not achievable by simple electronics - to achieve "buzziness", interference with the string envelope is necessary and electromagnetic interference with the string envelope (The Moog Guitar, for instance) is a lot harder to arrange than physical interference.... My own experience with DIY Sustainers suggests that 1) You can only excite a string with a signal that is coherent with one of the natural, physical harmonic series of that string's current condition. 2) In the regular Sustainer feedback loop, the string will settle to a sine wave that is related to the drive signal - the physical resonances of the mechanical system (including the physical location of the drive transducer along the string length) largely determine whether you get a Fundamental or Harmonic out of the string. 3) Using a square wave drive signal is just a less power-efficient way of supplying the string with the sine wave that would get the same result - if the string rings at the Fundamental, all the energy you're supplying in the Square Wave's harmonics is wasted (and similarly for the string ringing at a harmonic - you'd be more efficient just supplying a sine wave drive signal at the frequency of that harmonic). The Electromagnetic Harp could easily utilise a per-string drive signal that fades between sinusoids of the the harmonic series. Incidentally... Having said all of the above, I have had - with both fixed sustainer and e-bow - freak occurences of single strings sustaining two frequencies at once - usually a natural Fifth interval (which is logical, when you consider the relative energy levels of each harmonic within a ringing string). There are too many variables to make it an easily repeatable event - I'm just happy when the magic happens...
  11. The closest, in the electric guitar world, is the bridge on a Coral/Danelctro Electric Sitar guitar. You'd need some means of fine-tuning the bridge's interference with the the string's vibrational envelope. I have Rockinger Sitar saddles installed on a cheap Telecaster copy (I can't believe I spent £35 to make a cheap guitar sound buzzy ) and the correct angle for buzziness is a very fine adjustment and is no match for an actual Sitar bridge. There's an entire ancient craft - called "Jawari" - pertaining to the science of shaping Sitar bridges to produce the best buzzy drone. An on/off system for a Sitar bridge could operate like the adjustable mutes in this Fender patent: http://www.google.com/patents/US3427916?printsec=drawing#v=onepage&q&f=false ...set to buzz only when engaged.
  12. I have followed the Electromagnetic Harp since its first appearance on Project Guitar. It's a great technical achievement and looks fantastic. The actual music in this clip reminded me of Robert Fripp's Frippertronics music - specifically the "Let The Power Fall" album. The slow attacks and the looping nature of the piece were similar -though Fripp used 2 Revoxes, a volume pedal and a Les Paul, the end result is a select pallette of notes, overlapping in time. It'd sound great with a Sitar bridge...
  13. My Ibanez RG doesn`t have my favourite Fender tones as stock. I didn`t want to drill any holes in the only guitar I possess that has any resale value, so I used this variation on the Peavey Tone Control Coiltap. The guitar acts as normal with tone set anywhere between 0 and 9. With the tone at 10: Position 1 is Neck North Coil for Jimi-style warm leads Positions 2, 3 & 4 are SILENT, for killswitching Position 5 is Bridge South Coil for Fender-style sparkle. Using this diagram http://img13.imageshack.us/img13/6495/rg470.jpg Just add a wire from the unused lug on the tone control to the unused lug on the pickup selector switch. Easy to do and undo...
  14. I have read the Brosnac book (and have had it since the 1980s !). It's a bit simplistic and the information in it is (nowadays) freely available on the web. I recommend http://www.scribd.com/doc/64028088/Electronics-for-Guitarists which starts with an exploration of the effect of component values in passive circuits within guitars, proceeds through how classic effects pedals work and ends with how valve amps are designed. There are example schematics for the effects and amps.
  15. If you can source a 13-pin DIN socket, you might be better off starting from scratch, rather than cannabilising a gk2a (especially one with "issues"). I reinforced my gk2a with epoxy at the weak spot you mentioned (the tiny retaining screw had chewed the thread in the casing), and it has lasted over 15 years. I built a "13-pin to 1/4" sockets" breakout box to pan the strings in stereo (which was boring, because of the sterile sound) sum the pickups through a mixer to be able to vary the string balance in the drive signal to a sustainer (with, sadly, results roughly equal to using a conventional pickup). recreate the hex fuzz of earlier Roland guitar synths (which I STILL haven't got around to doing). I rarely use my Roland GR-50 guitar synth, as its Linear Arithmetic synth engine sounds "dated" to me and nowadays, freeware VST plugins do a faster job of note-following (not surprising, considering the comparative processor power)
  16. The gk2a does not allow direct access to the pickups at the 13-pin socket. See http://img141.images...k2schem1da0.jpg for details. You'd need to hack the SMD-scale PCB to access the nodes where the mini humbuckers of the hex pickup connect. Even then, the mini humbuckers are (comparatively) low impedance devices and piezo saddles are the opposite. You'd probably need to add a FET preamp for each separate saddle (and there's NO SPARE SPACE in the GK2A casing).
  17. I did somethimg similar... I bought a broken TSL footswitch and converted it for use with my Peavey Deuce. I stripped the TSL PCB of everything except the LEDs and their limiting resistors. I've now got (from left to right): SW1 - UNUSED (FOR NOW - MAY BE A CONTROL SWITCH FOR A STROBE, in the future) SW2 - BOTH CHANNELS ON SW3 - CH1/CH2 SW4 - PHASER (YES, MY AMP IS FROM THE 1970s...) SW5 - REVERB I had to ditch most of the Marshall footswitches, as they were MOMENTARY CONTACT types, not LATCHING (which is what I needed). I replaced a couple of the (dud) Marshall LEDs with modern equivalents. The difference in brightness is amazing.
  18. (1) When you plug a passive pickup into a guitar amp, does the amplifier send power into the guitar's circuit? No. (2) What kind of power is flowing inside a guitar circuit between the pickups, pots and output jack? Very little. Is the electricity generated by the magnetics in the pickup? As a reaction to the vibrating strings. Is there still power flowing in the guitar's circuit even when the guitar is not plugged in (assuming it's a complete circuit)? Yes, if you strike the strings, it's dissipated internally as microscopic levels of heat. (3) What is a "line-level" signal? Whatever your equipment manufacturer says it is, there's no universal standard. (4) Is there a scientific specification for line-level sound? No, see (4), above. (5) Is the signal coming out of the guitar before amplification considered line-level? For most audio gear, it's a little lower than Line Level (but far higher than Mic Level!) (6) How do you know when you're dealing with a line-level signal or an amplified signal? A "line-level signal" is a good match to the expected input of the equipment... Not too much (which leads to distortion) or too little (where it'll get lost in background noise). If in doubt, can you use a voltmeter or something? Input level meters on each piece of equipment are usual. (7) What does an amplifier actually do to the signal to make it louder? Takes your 0.5 volt, high-impedance guitar signal and amplifies it through gain stages. (8) Why is it that you never hear about amps or volts when dealing with guitars or amplifiers? You only hear about X wattage @ X ohms. Because that's the information you need to have to select the correct loudspeakers. (9) Is an electric audio signal AC or DC? AC (10) Is an audio signal considered analog any time that there is a real, electrical current flowing? (For example, the output directly from the guitar.) Yes. It would only be digital when converted to a bit-stream for processing. (11) When I look at the internals of an amp, the wiring consists of little, thin wires and circuit boards up until the actual amplification. After amplification, I begin to see thick, beefier wires. What is the difference between pre-amp and post-amp wiring? Just a larger gauge/thickness of wire? Thicker wires carry heavier currents without overheating. In the POWER stage of your amp, there are heavier currents. (12) Why is a larger wire necessary after amplification? See (11). (13) How do you know what type of wire you need? Is there only pre-amp and post-amp wire types? You can use the heaviest gauge wire throughout if you want. It makes economic sense to use thinner wire when you can get away with it. Early in the signal chain, where the signals are weak, SHIELDED CABLE is used to prevent electrical interference. (14) Why is only copper wire used in guitars/amps? It's a good-conductivity, relatively cheap wire. No need for gold... (15) What happens if you accidentally touch the live wires inside of a guitar while it is plugged into an amp? Will it zap you? Only if your amplifier is faulty and leaking high voltages up your guitar cable. (16) If you temporarily short the circuit inside a guitar, can you ruin some of the electronics? Not with only a magnetic pickup and passive electronics (pots and capacitors). You may ruin onboard active electronics by careless handling (but it's not likely). (17) What about post-amplification wires? I have an amp that outputs 120 watts @ 8 ohms. Is that enough to zap you if you accidentally touch the live wire? 120w at 8 ohms means a signal voltage of approximately 31 volts AC... No, that will not result in a lethal current passing through your body. (18) Can you ruin the amp if you temporarily short circuit the wires? You can ruin a Valve Amp if you run it without a speaker connected. Most amps can recover from running into a short circuit for a short time. You can't damage your guitar amp by shorting-out the guitar cable. how did you originally learn this stuff? Like you- asking questions, reading, experimenting...
  19. Use another solution. The LM386 is fairly bad, distortion-wise and, even as a headphone amp, doesn't produce sufficient level for use in a band situation. I tried several designs for a 6-way headphone distribution amp, and the LM386 was definitely the worst-sounding. If you're after a low-power amp, have a look here... Headwize, where there are many better alternatives.
  20. So, do small/skinny guys hum less? Does Leslie West hum less than he used to?
  21. Excellent article. YES ! Not quite there yet... Your body is the capacitor and, unless you've bought Elixir strings or omitted the string ground connection, you are grounding your body through the strings, eliminating the electrostatic coupling by effectively shorting your body to ground - you've just eliminated the hum signal from your body by shorting that electrostatically-induced potential to ground. Don't be unsure, you're nearly there! The player is insulated from the strings by Elixir's non-conductive coating. So, when the player touches Elixir strings, the 11v AC from the article is not conducted to ground (as regular strings would do), and so still exists as an AC potential along the dimensions of the player's body and, in the absence of an effective electrostatic shield between the player's body and the guitar's circuit, couples electrostatically with any nearby unshielded part of the guitar's circuit (e.g. unshielded pickup coils and unshielded wire in unshielded cavities). The upside of all this is that the logic behind one of the OP's options (use active pickups) is now perfectly clear: You can get away with omitting the string ground... If you have good electrostatic shielding (like the all-enclosing brass shielding in EMGs) around ALL parts of the guitar's circuit (though the pickup coils are the most susceptible point, shielding cavities and all connecting wires contributes the last 5% to hum avoidance).
  22. I agree with most of the above. I have never suggested that the human body is radiating EMI. Your body is, indeed, "acting like a capacitor to ground" - one which concentrates the ambient EMI. Your body is right next to the guitar, so the guitar picks it up. When you ground yourself, you eliminate your body's portion of the total EMI, anything left buzzing/humming is direct radiation from the source of the EMI. Think about the fallacy in the reasoning that by touching the strings you are conducting the hum to ground through your body... Why would attaching a capacitor-to-ground to an already grounded point improve matters?
  23. No, hum comes from the guitar picking up EMI which is all around it - things like motors, air conditioners, wall warts (which have transformers inside them which radiate lots of EMI), CRTs, etc. Single coil pickups don't need your body to hum, they do it all on their own. You don't have to be touching anything, they will do it all on their own. Your example about an amp with a loose cord plugged into it is not the same thing as the grounding in a guitar, and the human body is definitely NOT the source of hum in an electric guitar. Paul, I'm surprised at you, with your wide and deep knowledge of guitar electronics... Think about this: Guitar player wearing rubber-soled sneakers (so not grounded, himself) experiences diminished hum when he touches the strings. I was NOT referring to an amp with a loose cord plugged into it. Humbucker/Single Coils are not part of it either - the issue affects both types of pickups (unless your humbuckers are precisely wound to 100% cancellation). The situation is: a guitar with grounded bridge. You're still a big ball of hum that needs grounded because you're a local concentrator of EMI, and especially mains hum from the wiring in the walls. After you've grounded yourself, eliminating some low-frequency hum, the noise that's still being heard is the direct radiation from wall warts, monitors, motors, flourescent lights and dimmer switches (a real nasty treble edge on those last two). You needn't ground yourself to local amp ground to notice this effect... Ground yourself to a water pipe and hear the noise (largely) disappear, too (but don't touch any other exposed metalwork at the same time, for electrical safety!). At the risk of muddying the waters: A strong case for having a string ground is when your pickups don't have an electrostatic shield (Strats, Humbuckers minus casings...) the un-grounded strings are an antenna for all the above-listed sources of EMI, and the pickups will receive it. EMGs, for example, have a brass electrostatic shield inside the plastic casing and are wound to precise 100% cancellation, so you can use them, noiselessly, without installing a string ground.
  24. I believe so. Touching the portion of the string between the ball end and the bridge saddle removes the buzz, so the coating is not on the whole string, just the playing portion. I have my doubts about that. Why would you be getting a buzz with that brand of string then? I mean if the bridge is grounded, and if as you say, the strings are exposed at the ball ends then they should be having contact with ground and you shouldn't be getting a buzz at all. See what I am saying? Not trying to be argumentative, it just doesn't make sense to me. This is because the purpose of the string ground is to ground the source of the hum - you! You can prove this by plugging into an amp, note the difference between touching and not touching the strings, then - with absolutely no contact with the guitar - touch another ground point (a socket on the amp would be fine) and hear the hum diminish to the same extent. The player is a giant ball of hum and needs grounded.
  25. If you're confident enough to do regular guitar control-cavity wiring, you'll not need any further skill to wire up a Varitone.
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