curtisa

Well, maybe not popped fuses, but it would certainly sound ugly.

The grid at "A" is being referenced to 0V by the master volume pot preceding it. With the LTP grid resistors returned to the tail ("bootstrapped") rather than directly to 0V, the grids are actually sitting higher than ground, maybe 25 volts DC or so. The cap needs to be installed to prevent the DC biasing being upset by the volume pot trying to pull the grid back down to ground.

Ah. Yes, I missed that too in your schematic. The cap will also interact with the grid resistor to determine the LF behaviour of the LTP too, and is also another good reason to replace that 10k grid resistor in your schematic with something at least 10x bigger and the same value as the other side. I think you need a cap in series with point "A" too (see my sim), otherwise the DC biasing gets all screwed up by the preceeding stage(s), and ruins the operation of the LTP. 22n-100n will work fine here.

FWIW this is what I get when I sim a LTP using "standard" values. The green plot is from the lefthand plate, the blue from the right. The two halves are within 0.6dB of each other and flat from 18Hz (1dB down) out past 100KHz, with a gain of around 28dB. If I add the following stages' coupling caps (100n) and grid resistors (220k) I lose about 0.5dB of gain and increase the LF cutoff point to 23Hz. Something is definitely amiss in your sims if you're getting results like you have been.

Sorry. The 1M resistor between point "A" and the junction of the 470R/10K/10K resistors High frequency roll-off doesn't sound right. A bog standard Long Tail Pair should be pretty flat well out beyond the normal audio band without any additional caps involved. If anything your 2u cap in parallel with the 78K resistor will make it worse. I'd be looking at your simulation software for strange results. 3dB difference is a factor of 1.4x in voltage circuits like your LTP. A factor of 2 would be 6dB. On reflection I'm not sure if the mismatched grid resistors will have that much of an effect on the output swings if the second (unused) grid isn't driven. It does look a bit odd though, and if you do decide to implement negative feedback into this grid later on it will have to be increased back up to match the grid resistor on the first half of the LTP. My preference would be to just make the two grid resistors equal and be done with it. A LTP should be good for an open-circuit gain of 24-28x or so. Gains of 2-3 sounds like there's something funky going on in your simulation. Does your triode model also simulate heater warmup time? Plotting only the first 20mS may not be presenting you with true results if the simulator is trying to model the behaviour of the heaters as well (this may account for your strange HF droop as well). Can you force the simulator to only start plotting results after 30 seconds? 1M will work OK there too if it makes it easier to to keep them all the same value.

Grid resistor on upper portion of LTP can be reduced to 220k - 470k. The input impedance in an LTP is bootstrapped by virtue of the reference point of the grid resistors being returned to the cathodes of the tubes rather than ground, and the apparent input impedance becomes much larger than the resistor by itself. Not sure about the massive mismatch between the two grid resistors of the LTP. The "normal" practice is for these resistors to be the same value, otherwise the two halves of the LTP will inherently have mismatched outputs. Any mismatch in signal output from the two plates is then usually compensated for by making one plate resistor lightly smaller than the other (typically 82K vs 100K). The split plate resistor on the top half of the LTP is possibly only adding complexity to the compensation you're trying to achieve. 2u in parallel with 75K will also nuke a lot of highs. Even if you choose to match everything (plate and grid resistors) the net difference in output is around 1dB, good enough for rock 'n roll. Still, in true rock 'n roll fashion maybe this amp is destined to break some rules. Consider making the gain and master pots 250-500K

I actually spent a bit of time over the last few days looking into the possibility of DIY-ing a drum sander myself, which is probably the least onerous of the projects listed there. I guess I find his projects fun to watch more than anything. The bandsaw is impressive from the standpoint that something made of ply, MDF and pine can resaw a 3mm slice off a 10" tall block of maple. They may not be the worlds most precise tools, but you have to admire his tenacity.

I feel your pain. I just bought myself a new 6" jointer over the weekend. Getting it into the vehicle was a snap as the shop had a set of electric forks. Getting it out of the car once back at home was a challenge to say the least. The packed weight was over 120 kilos! Had to break apart the chipboard packing crate and remove as much as possible off the unit while still inside the the car before I could drag it out onto a trolley.

Have a look at Strandberg's Endurneck profile. Supposedly designed to encourage relaxed wrist muscles in your fretting hand at any point on the neck, although if you're the kind of guy that regularly employs the Hendrix-thumb-hooked-over-that bass-strings technique it would probably be quite uncomfortable unless you forced yourself to "retrain" your left hand.

Looking for new shop tools? Build yer own out of plywood! http://woodgears.ca/tools.html (Don't try this at home, kids)

My suggestion of 10x factor was just arbitrary (makes the math easy). 3-4x factor would still offer an improvement, and you can use 250K pots for the band controls. Splitting the cathode resistor has the side effect of lowering the signal entering into the EQ, defeating any amplification you put in front of the cathode follower, but the output impedance becomes roughly equal to the two cathode R halves in parallel. Reducing the cathode resistor overall does not have as much of an effect on the output impedance either as the cathode resistor is in parallel with the tubes' cathode output impedance. You need to reduce it a lot to get any real effect. Reducing it too much introduces other problems (cooking the plate, need big wattage cathode R etc) Be careful when you do your simulations that you are using a model of your "target" tube instead of the default triode model - default SPICE models are notorious for presenting impossible real-world results. Bogner do a similar thing in the Ecstacy with the "structure" control (or at least, it's a switched element - just a fixed series-RC that can be added in parallel to the cathode resistor of that stage). Any reason you're not just using the pot to directly control the resistance? Seems to me you could achieve the same thing without the LDR at all.

The output impedance of your cathode follower is probably not low enough to drive so many stages in parallel cleanly. Try reducing the number of filter stages, or increasing the R values of your filter stages by a factor of 10 (and corresponding 10x reduction in associated C values to maintain the same frequency cutoff) and see if the response improves. Your pots are marked as "10" - I assume that means postion at 10%, not resistance = 10. What pot values are you using?

I would have thought a go-bar system would struggle to develop enough pressure to glue a carve top to a body blank, especially with the small amount of distributed force exerted at the end of each rod?

More than happy to explore unconventional tone controls, I was merely raising the posibility that a 5-band passive EQ made up of first-order stages may not work quite as expected.

100K input resistor is pretty low for interfacing with high impedance guitar pickups. 1M is better suited in that position. Input cap should then be reduced by a factor of 10 to compensate for the increase in resistor to maintain the same cutoff frequency, or omitted altogether. 5-band EQ is an interesting idea, but may yield unpredictable results as each control will load the other. All controls at max will not necessarily result in an even response. Experimentation will be required. May work better if limited to 3 bands. My personal preference would be to simplify things to one EQ section (EQ before gain for early Boogie-style drive, or EQ after gain for Marshall), but for me that's more to do with having too many knobs to play with (oooerrrrr...) 6AU6s (and pentodes in general) have much more gain than a 12AX7. My gut feel is that with the circuit as shown (2x preamp stage, 2x boosted cathode followers, 2x pentode stages) you're going to have more than enough gain to the point where you'll probably find it a bit too over-cooked. Even the Soldano SLO100 only uses 3x voltage stages and 1x boosted cathode follower, and you couldn't call that amp mildly overdriven.

Good to hear it was an easy fix. Time to roxxorz

Looking pretty spectauclar, Scott. The stepped carve almost gives it a muscular look. If your camera takes photos and imprints orientation info into the JPEG EXIF properties, photobucket will faithfully reproduce your photo in that orientation, even if you've rotated it to correct the 90 degree flip. Always caught me out when posting pics taken on my mobile. Only way I've been able to get around it is to use something like Irfanview to resave each image before uploading and delete the EXIF orientation flags. There may be easier ways to get around it.

Might also be worthwhile trying the guitar with the Toneshaper board removed and wiring it up as a "normal" Les Paul. One other thing worth having a look at - double-check your wiring from each pickup to the Toneshaper. I notice that the manual mentions that the colour codes marked on the Toneshaper terminal block are for Seymour Duncan pickups. The Dimarzio colour codes are quite different.

Is it a new pickup? You could probably get your money back or an exchange if it's actually faulty. The only humbuckers I've ever heard go microphonic were extremely poor quality ones to begin with. A modern Dimarzio shouldn't suffer from those issues. Can you swap out the pickup to see if the microphony follows the pickup? Even swapping neck and bridge temporarily? Do you have any other issues with the pickup (excess noise or buzzes)? Always good to check for wiring errors - it'd be a shame to write off an expensive set of pickups if it was just a case of a simple wiring mistake.

As others have already suggested, shelving, hangers and wheels are your friends. I'd also add allowing yourself 30 minutes at the end of each session in the workshop to clean up. Even if you don't gain any physical extra space, a clean workshop feels bigger. Regularly clean out any crap that builds up too - wood offcuts that are too small for anything useful, damaged tools that you promised yourself you'd repair 10 years ago, packaging, bags of rubbish... This post by user "ozwood" over on anzlf.com is probably over the top for most people, but I reckon some of the storage ideas for tools and equipment is pure genius. Maybe some of them could be adapted for your space?

Thanks for clarifying, chaps.

I use a Rotabroach for making small wood plugs. They're really meant for drilling holes in sheet metal, but the cutting teeth work so much better in wood than "proper" plug cutters, and you end up with a perfect 1/4" tall cylinder in the middle of the cut that can just be popped out for use as the plug. You can find small kits in eBay fairly easily for 30 bucks or so. The smallest bit in the set I have will make a plug 4mm in diameter. I was considering a multiscale 7 for my next project. I have a query regarding the scarf in the headstock - do you just build up a straight scarf as you would for a standard perpendicular nut and leave a triangular "flat spot" behind the treble-side of the nut before the headstock angles down (eg, Conklin), or do you angle the scarf to twist the headstock to meet the nut angle (eg, this pic)?

Rg sets the gain of the opamp, and to a degree is not dependant on the type of opamp you use.. The bigger the resistor the more gain. I only mention experimenting with this resistor because you may need to dial in a certain amount of amplification to get the sustainer to operate correctly. Too little gain and the sustainer won't move the strings. Too much and you'll end up with something that is a noisy, oscillating mess. Prostheta's suggestion of a trimmer in its place is a good idea. I did, and while I did manage to get it to work it wasn't without its problems. It was never capable of "clean" sustain, which is something I was really keen to have it do. When the sustainer was operating with a clean guitar tone there was always a lot of distortion superimposed on top of the guitar signal. Reducing the drive to the sustainer removed a lot of this unwanted overdrive, but killed off the responsiveness of the sustainer. If I was playing the guitar through an amp on a distortion channel it wasn't so bad as I could mask the noisy sustainer in the amp distortion, but if I wanted to use it for more "ethereal" clean sounds it would sound like mud. The driver needed to be set quite close to the strings too, and if I were bending strings on the highest frets it would often bottom out on the strings. Uneven string response was often experienced by many users - the sustainer would work beautifully upwards of the 12th fret on the 3rd string, but there'd be nothing on the 6th string below the 5th fret. The driver and circuit is quite low-tech (the driver is nothing more than a couple of hundred turns of enamelled copper wire on a hunk of steel, and the basic circuit is lifted straight from the datasheet of a 30 year-old chip), and probably contributes largely to the varying experiences that everyone has with it. In the end I let the DIY sustainer go and bought an Ebow. For the occasoinal use I got out of the sustainer it ended up being more useful to me to use a sustaining system that I could apply to different instruments. Knowing what I know now about building and modifying guitars, If I were to go down the sustainer path again I'd probably buy a commercial system like the Fernandes or Sustainiac. If you think you can work around its quirks and idiosyncrasies, and don't mind a bit of experimentation, I still think it is a worthwhile project to undertake. You learn a lot about electronics and modding guitars along the way, and when it does eventually work to your satisfaction it opens up a lot of interesting possibilities in your playing style. My suggestion for the TL0x1 opamp was more about the higher input impedance being more suitable for loading guitar pickups but yes, current demands of the LM741 should also be considered in a battery-powered system such as the sustainer, and the TL0x1 will out-perform the ancient 741 on that, and many other points too.

Many N-channel JFETs will work in that position. The Fetzer/Ruby schematic gives three possibilities - MPF102, J201, 2N5457. Others that will likely work (ignoring pinout differences) are BF244, BF245, 2N5457, 2N5458, 2N3819... If it's hard to find the TBA820 don't bother with it. Given the same operating parameters there's nothing it offers that the LM386 can't do. Yes, it will work at the expense of added circuit complexity. Use a FET input opamp (TL071 or TL081) for best results. Experiment with different values of Rg (between 22K and a couple of hundred K). Be prepared to do a lot of experimentation with a DIY sustainer. While many managed to get the circuit to work the basic design is quite temperamental, and there are just as many people who weren't as successful. Don't set your sights too high and you won't be disappointed

Years ago I installed an Eyb Guitars sitar bridge on a Yamaha Pacifica 112. http://www.eyb-guitars.de/Eyb-English/Hardware.html. Just about everything on it is adjustable, so it takes a while to dial in the right amount of buzz/action/intonation, but once set up it works really nicely if the sitar sound is your sort of thing. Interesting presentation, úlfur. Thanks for posting!