curtisa

I read that as them saying, 'you're welcome to return the blade for us to assess', but they do not say they will replace it without question. The decision as to whether or not to do so is entirely theirs, and would likely be based on the date it was purchased, how many times it was used, how it was used, what it was used in etc. The warranty expressly states that their products are warranted '...to be free from defects in materials and workmanship, under normal use and maintenance, for the lifetime of the product... (emphasis mine). That means that the warranty only applies for the duration that the product is expected to last under normal, reasonable use. It can also mean for the duration the product is available in its current form. So if Stewmac release a revision to the blade design and retire the previous version from sale, they have no obligation to replace the old version with the new if it fails in some way. Saw blades wear out over time and would have a finite lifespan that both Stewmac and their customers would accept as reasonable, so it's unlikely that they would replace that blade into perpetuity every time it becomes blunt at their own cost. The use of ...'lifetime of the product...' in the warranty explicitly gives them this escape route. Note, it's entirely possible that Stewmac would replace the blade for you as a one-off as an act of good faith. Many people speak highly of their post-sales service, so I wouldn't put it past them to do a replacement to keep everyone happy.

I think buying Stewmacs product once and expecting them to replace them for you indefinitely might be a little optimistic. The warranty says '...for the life of the tool', not '...for life'. If Stewmac has determined that the saw blade will give acceptable performance for 1000 cuts (or whatever) then 'the life of the tool' is 1000 cuts, after which it's their decision as to whether or not to replace the tool at their expense. The warranty is limited, not unlimited.

Make more use of shielded wire. Yes, it's more of a fiddle to put together, but depending on the electronics you're using you have the potential to wire the entire thing without even reaching for the shielding paint or copper/foil. If I were building a twin humbucker guitar I probably wouldn't bother with shielding and just use shielded wire instead. Or if building something like a Strat, use shielded wire in a more targeted fashion - the bullet jack cavity for example doesn't need it if you run a shielded wire from the jack to the volume pot. If the pickups come already fitted with shielded wire there's no reason to also shield the pickup cavities or the wiring channels from the pickup cavities to the control cavity. ...or just make your cavities bigger so that nothing has a chance to touch a grounded portion.

Only if the original neck was also a 22-fretter. The required move-back is actually about 1/5 inch, but near enough in your case.

Close. Gain on the inverting input is R4/R3 = 6.8x, but gain on the non-inverting input is 1+(R4/R3) = 7.8x. There's deliberate mismatch on the two inputs that EMG have put in there; the Electrosmash analysis mentions this as well. You can experiment more with the mismatch if you like by adding the missing resistor on the non-inverting input as shown in the LM4250 datasheet and changing the value to be bigger or smaller:

It's not...as such. Yes, it boosts the signal which I guess makes it a 'booster' in the traditional sense. But it's not configured to act as a regular pedal-style booster. It's what it's doing with the two inputs that sets it apart. Yep, they're all the same (or near enough to be considered the same).

The EMG circuit is different to your average opamp 'booster'. It's configured as a differential amp, ie it amplifies the difference between its '+' and '-' inputs. The Electrosmash analysis of the circuit pretty much explains it all, but in a nutshell the EMG circuit is relying on the two coils of the humbucker to be wound anti-phase and the voltages at the 'tops' of the two coils L1 and L2 to be moving in opposite directions as the string wiggles in the magnetic field. The opamp then amplifies the difference between the two signals and out pops 2x string signal multiplied by gain. Say the top of L1 goes down to -1V and the top of L2 goes up to +1V. The opamp is going to try and work out the difference between the two, so you get -(-1V) + (+1V) = an output of 2V. If the opamp also has gain (which the EMG does, 5x) you can multiply the 2V by 5 to get an eventual output of 10V. Consider also that there might be 0.1V of induced noise at the same time (hum, buzzes etc). In that case the noise appears on both coils in phase with each other, ie noise signal on the top of L1 goes up to +0.1V at the same time as noise signal on the top of L2 goes up +0.1V. The opamp will take the extra noise voltage and do the math on it again and give you -(+0.1V) + (+0.1V) = 0V of noise. (Gross oversimplification of what's actually going on, but you hopefully get the idea). A regular garden variety (pedal) booster will just take the output of whatever it is fed and boost it. If the pickup is noisy as well as carrying guitar signal, naturally all you get is a bigger version of signal+noise at the output. All the linked versions of the schematics discussed so far are not this.

Correct. I guess EMG just made it a 'thing' by squeezing the preamp into the pickup housing itself to make it more appealing to the masses. By that definition I suppose you could call any guitar plugged into a booster pedal an active guitar with an extension cable Another link to some useful info, including suggestions for tweaking the response of the pickup without butchering the windings: https://www.electrosmash.com/emg81

Could be, not sure what is buried in the epoxy. If the schematic on freestompbxes is to be believed it looks like it has a gain of only 5x. With that much negative feedback you could get away with all sorts of different ICs in that situation. You'd probably be more interested in battery longevity. LM386 would be...colourful to try?

Neat! I guess this is a little bit like what EMG do with their Retro Active line, essentially just 'activating' a passive pickup. Any particular reason you went with the LM386? Seems a slightly left-of-field choice.

The perpendicular fret can be any one you like on a fan-fret guitar. The 12th fret harmonic will still be at the 12th fret no matter what angle it sits at. But the bridge also needs to be angled accordingly for this to be true.

Interesting - I wasn't aware of that phenomena, although it appears to be largely a property of multi-layer ceramic capacitors with particular dielectrics. P1 won't alter the voltage to the cap. The capacitor will still charge to whatever the voltage of the battery is; it will just change how quickly it gets there. You shouldn't need S1/R1 to get the cap to discharge to a lower battery voltage. The cap should follow the battery to whatever voltage it is set to (notwithstanding my observation that P1 won't adjust the battery voltage). Where does 'in' and 'out' connect to in the guitar?

I don't think there *is* a shortcut as such. Intonation is governed by the fret spacing relative to bridge position. As a builder you have some leeway in most bridge designs to apply compensation for any discrepancies that need to be ironed out afterwards (ie adjustable saddles), but the rest is down to the accuracy of setting out the relative locations of fret slots, nut and bridge. Is the issue that you have with this guitar is that you are having trouble getting the instrument to compensate acceptably using the usual method of 12th fret harmonic vs 12th fretted note? You mention that you used a mixed scale length for bass and treble, essentially making it a fan-fret instrument - was the bridge also angled to match the 0.5" variance between nominal scale lengths when it was installed?

Applying DC to a capacitor doesn't change its capacitance. Its value is constant irrespective of the applied voltage across its terminals. Your circuit looks a little like a capacitance multiplier, but the implementation looks odd. Normally a cap multiplier circuit increases the apparent capacitance by the gain of the transistor (hFe) and can't be adjusted by a resistor. In your circuit all the pot is doing is providing a variable resistance for AC signals (ie the guitar signal) to bypass the cap/transistor through the battery. I'm not even sure the transistor will even be doing anything as the base appears to be grounded.

What is the issue you're having with fret spacing? Accuracy cutting? Intonation? Feel? Something else?

What's your circuit trying to achieve?

It's more to do with the fact that interrupting the circuit will result in excess noise while the button is depressed, akin to leaving a guitar lead dangling on the floor. The noise would naturally be worse if you were playing with a lot of gain, and worse again if the interruption point was in the ground wire rather than the hot wire.

No. The correct way to do it is to short the hot signal to ground via the switch (the linked article also advises this as the preferred method). Essentially a killswitch in an EMG-equipped guitar is the same as a killswitch in any other guitar - the switch is wired across the hot and ground wires at a convenient spot where the effect is the same as immediately winding down the volume pot to zero and back up again. The complicating factor will be the EMG Quick Connect system that their pots use, which makes it physically difficult to solder raw wires to the volume pot lugs. In that instance it may be easier to wire the killswitch across the hot and ground lugs of the output jack (depending on how easy it is to run wires to the jack from your preferred location of the kilswitch). The linked article shows this in the second of the two circuit images. A treble bleed mod can be done in the same way a treble bleed can be applied to any passive pickup circuit - a capacitor wired across the top and middle lug of the volume pot. But again, you'll be stymied by the Quick Connect system making it difficult to do the soldering. If you're feeling brave you can try it out anyway, but some experimentation with the cap value might be required. My gut feel is that if you'd normally use, say a 470pF treble bleed cap in a passive guitar, you should try a cap with a value 10x larger as a starting point for EMGs (ie 4.7nF) and tweak from there.

Note that if you try the resistor-in-parallel trick with a pot the resistor needs to go across the wiper and outer lug, not across the two outer lugs. Putting the resistor across the outer lugs does weird things to the taper of the pot (you'll actually get a volume drop right at the top of the rotation). Putting the resistor across the middle and outer lug will also affect the taper but you can use it to your advantage to create a logarithmic (audio taper) pot out of a linear one that can have better logarithmic tracking than an off-the-shelf log pot. The only caveat is that the parallel resistor imposes a heavier load in the pickup at lower volume settings than the equivalent log taper pot, which could result in more darkening of the tone at low volume than you'd otherwise expect. More info here: http://www.geofex.com/article_folders/potsecrets/potscret.htm

I guess ideally you'd plan your build for the hardware you wanted to use. Even then I'd still consider retrofitting new hardware to an existing design on its merits and problem-solving the second install as the issues arose. In the original installation I'd still site the bridge based on 'saddles all the way forward'. If the retrofitted saddles mean I had an issue with them no longer allowing correct intonation adjustment based on my first install, I'd have to find a way to make it work after the fact (maybe use longer/shorter intonation screws, removing the intonation screw spring to squeeze a little more range out on the lowest strings, plug/redrill the trem pivot screws or simply use different saddles that were a better fit). If you were trying to retrofit a 351 into a Honda Civic, you wouldn't design the Civic to take the 351 in the first place. You'd be looking at ways to modify the Civic take the engine The saddles-all-forward guideline would still hold true on a cold install, though - you'd just pick the longest saddle(s) to do it with. The shorter ones I assume are reserved for the G and low-E, where you need more room at the rear to pull the compensation back in line. As a retrofit I assume the Vega is primarily designed to just drop in place of an existing Strat-style bridge (that's certainly the way they word it on their product page). If it were me I'd still check everything was going to line up, but I'd have more confidence that Vega have offered a product that by its very nature is designed to fit straight in without any extra math or sawdust creation.

True Temperament (TT) necks are actually a bit of a red herring. The frets are compensated to give better harmonic purity to certain intervals and chords. But because of the way our western-ised 12-tone equal temperament (12-TET) system works, the compensation applied by TT makes some intervals better at the expense of making others worse. Equal temperament means that any interval is exactly the same frequency ratio no matter what the base key is. The result of this is that some intervals are already 'pure-ish' (eg, 4ths and 5ths are pretty close) and others are slightly out (major 3rds and major 6ths are some of the worst). TT attempts to even some of these discrepancies out, but because it's impossible to re-calibrate all ratios in any fret position the intervals in some keys get notably over- or under-corrected. Short story is that if you only ever play your guitar in 'friendly' keys like E, A, B, G, D etc TT can have a useful impact on the purity of intervals played. But if you start including 'off' keys like Bb, F#, G#, or chords with extended and complex intervals TT can actually make the situation worse. Steve Vai was an early exponent of the TT system and had one of his Jems fitted with a TT fretboard, but you never see him with it anymore. Considering he's a player not afraid of exploring melodically awkward things, I suspect this 'incompatibility' with equal temperament is possibly one reason why he dropped it. There's actually no reason why any old guitar can't be set up to intonate perfectly within 12-TET and sound as pure as our western ears need it to in any key; all it takes is decent construction and adjustment. TT by and large just puts a bandaid on a problem that doesn't really exist in the first place.

The problem with the Stewmac calculator quoting those positions based on some feature of the bridge is that it doesn't help you if the bridge you want to use isn't listed there, or if the manufacturer of the bridge decides to change the design of the bridge slightly (unlikely, but could happen in the name of 'continual product improvement'). The easiest way is to simply move the saddles as far forward as possible and use the breakpoint of the saddles themselves as the scale length point when positioning your bridge on the body. Intonation compensation will only ever result in the saddle moving backwards, so the saddles being forward gives you maximum leeway for setting intonation as you need to.

You could potentially pre-drill the pot mounting holes in the top before 'closing the box', maybe even add the cutouts for the pickups. But as @Bizman62 says, the rest would just be a case of pre-wiring everything outside the guitar, sticking your arm in through the soundhole and feeding everything in place from the inside. Realistically the original D18 would have been modified the exact same way. They wouldn't have removed the top and reattached it just to make installing the electronics easier. @Andyjr1515 - I wonder how the bridge pickup interfers with the bracing? Isn't that pretty much where the major X-brace crosses through?

1 - 1.5mm is typical. It doesn't take much, but because it's a global compensation applied uniformly to all strings it has more benefit to some strings than others. The most notable improvement tends to be switching between an open-E major chord and an open-G major chord, where the change between the G# major 3rd of the E chord (3rd string 1st fret) and the tonic of the G chord (3rd string open) is more harmonically pure. Without compensation the typical error is that the G# tends to be mildly sharper than expected. But because it's a global compensation, if taken too far it will have a negative impact to the overall intonation as some strings get progressively worse while others get closer to 'perfect'. Ideally you'd apply nut compensation per string (look up Earvana nuts for example), but it is fiddly to do right, and many players don't feel the excess work is warranted. Of course, we could be overthinking what's happened here and the neck is just made...well, wrong. 1.5mm error at the nut could be half the thickness of the nut itself, which might happen if the nut was positioned centrally over the initial 'zero' cut when the fretboard was slotted, instead of butted up against the edge of the cut like it probably should have been. In an age of 'CNC everything' these kinds of errors are hard to imagine slipping by, but without knowing the true history of a no-name neck I guess anything's possible? Yep. Given the sheer volume of Partscasters suppliers out there it's probably a miracle that so many guitars (apparently?) get put together without any issues. I guess it'd be pretty foolproof buying both the body and neck from a single reputable supplier known for that kind of thing (eg Warmoth, Mighty Mite etc). But I'd personally be a bit squeamish about trying to marry any old Strat body with any old neck without worrying about fit and intonation.

Are you sure the nut is positioned correctly? Nut-to-12th measurement x2 as a measure of scale length only holds true if the nut is positioned exactly at the 'zero'. If the nut is cut closer to the first fret it will throw the nut-to-12th reference short. Note that some manufacturers purposely move the nut closer to the first fret by a small amount to apply a degree of intonation compensation for the lower frets without changing the nominal scale length (PRS for example is notable for doing this). The blue cells in your spreadsheet are largely irrelevant to scale length and only matter assuming the body is made to match a particular neck and bridge. The correct way to marry *any* bridge to a body (whether it be a Floyd Rose, Tele bridge, Tune-o-Matic or anything in between) is to position the screws/routes/distance to heel cutout based on where *the saddles* satisfy the scale length and work backwards from there.