3below

The bar has been set high

Another small step, self explanatory. Home made bobbin clamps worked well. Yet another silly error I had remembered that I must put a drawstring in to ease later wiring. Got the string and sorted to fit etc. Proceeded to glue top on and noticed I had not put the string in. Marks on the oak top are just water from sponge used to clean up glue squeeze-out.

Super job and so satisfying to be able to DIY (in this case not destroy it yourself )

[quote name='samhay' timestamp='1477212786' post='3160519'] High pass and low pass are easy - you only need a resistor and capacitor. For high pass, put a capacitor between the pickup and volume pot (i.e. in series with the pickup). If you are using a 500k volume pot, then try cap values of about 2.2n (0.002). Bigger values give more bass/lower corner frequency and vice versa. [/quote] Following on from this, combining the two filter types will give a notch just using RC if you want. [url="http://www.learningaboutelectronics.com/Articles/Notch-filter-calculator.php"]http://www.learningaboutelectronics.com/Articles/Notch-filter-calculator.php[/url] (this is just the first site I stumbled across). Too much choice, too little time left

[quote name='White Cloud' timestamp='1477124370' post='3159954'] Electronics, mweh....a necessary distraction from wood loveliness [/quote] Occupies the time while glue is setting, varnish is drying or I am too tired and will make irreparable mistakes in wood. samhay and Andjr, thank you for providing insight, advice and encouragement for problems that I can not let go of. Spurred on by samhay I have spent some time playing with QUCS circuit simulation (which uses ngSPICE) and the original diagram Andyjr started with. Diagrams and data to follow, but the broad picture is that the early circuit is a high pass filter. Having owned a 58 EB2 many years ago this is exactly what the 'baritone' switch did - removed some 'muddiness'. What is interesting is the effect of the inductance of the 'mudbucker'. Although I measured the voltage output iof my EB2 at 1.5V ish E string (Sixth form Physics) The modelled values give an output voltage way below this. I did not measure the inductance of my EB2 nor have I found the inductance on the internet either. More thinking, modelling and some diagrams to follow. I need to find the inductance of the DiMarzio as well.

Samhay, thank you. Looking at your model you have LCR in series (which makes sense as a 'notch' filter). From my several trace throughs and redraws of the EB3 mk1 filter circuit I end up with pickup output into the parallel RC network in series with L to ground. The output to jack tip is taken from the node between RC and L. I am still on the learning curve of understanding what it does. The mk 1 circuit is where Andyjr started from which is why I am following it through (and pure curiosity and reminding myself of what I used to be able to do a long time ago).

The inductor has some 'mystery' with the published figures. Allegedly a wrong value was published to lead competition astray.. I would go with the 1.5H that Andy has. What software are you modelling with? Thanks

The power of BC, if the rest of life was this positive and helpful..... samhay any chance of a bit more modelling - see my earlier post. Thanks.

[quote name='Andyjr1515' timestamp='1476997359' post='3159198'] That's very kind of you, 3below I think I'm OK - I've ordered a 20k trim pot and a .001 cap that were only a couple of £'s. A three year course in electrical systems and electronics would be useful, though, if you've got a spare one of those lying around [/quote] Can provide you with a set of course notes for A level electronics (or just the analogue sections) if you are suffering insomnia Could do with the three year course myself, I have forgotten so much, so much I have not studied.

Andyjr: If you have a shopping list of resistors and capacitors pm me. You never know what might turn up in the post

Andy, are you now getting useable or even better tones from the varitone? Samhay, would you be able to model the mark1 RLC circuit? [url="http://www.flyguitars.com/gibson/bass/EB3_schematic.php"]http://www.flyguitar...3_schematic.php[/url] I am still intrigued what tfrequency response this circuit will produce taking account of the pickup as a voltage source with inductance and impedance. I do not have access to suitable modelling software (this tells me I should get some for the day job). Thanks.

[quote name='BigRedX' timestamp='1476915336' post='3158547'] Which EB3 circuit are you modelling? AFAICS the [url="http://www.flyguitars.com/gibson/bass/EB3_schematic2.php"]version 2 circuit[/url] has the choke and capacitor in series which should give a notch filter effect. I don't know what the value of the EB3 chokes were, but using the 1.5H choke from the 355 circuit and a .47µF capacitor gives me a 190Hz notch unless I've got my decimal points in the wrong place... The [url="http://www.flyguitars.com/gibson/bass/EB3_schematic.php"]version 1 circuit[/url] appears to do something slightly different since it taps into the filter circuit between the capacitor and the choke. Of course given what we've been told previously it could all be Gibson misinformation! [/quote] Attempting to model a version 1, which when 'redrawn' / deciphered appears to be a parallel CR in series with L. Version 2 makes much more sense as a series band pass filter.

[quote name='Andyjr1515' timestamp='1476913347' post='3158518'] Got that wrong. The site is here, Rothstein Guitars http://www.guitar-mod.com/rg_eb3.html I think what they are saying is that is is supposed to be a notch that lets all frequencies though except the target range? Their range they say they are trying to block are the frequencies around the 800hz, if I've understood their blurb correctly. [/quote] Your understanding is correct in my world of Physics / Electronics, you have described a notch filter. They have a very interesting looking varitone wiring diagram for the 'CT' bass on the website. Might be useful? http://www.guitar-mod.com/wiring/ctimages/ctbass_wiring.gif

[quote name='Grahambythesea' timestamp='1476903707' post='3158376'] I haven't heard of a full bodied acoustic bass guitar which doesn't come with a built in piezo pickup in the bridge................. [/quote] First series of EKO BA4 with the trapeze type tailpiece. Jazz bass pickup fits in soundhole nicely (with diy adapter plate). They are certainly full bodied in terms of size.

[quote name='BigRedX' timestamp='1476909342' post='3158463'] Surely the varitone circuit should be a high-pass filter? Certainly the one I made copied (and expanded) from a Gibson 355 circuit sounded that way. The more usable settings made my DiMarzio Super Distortion humbucker sound as tinny as a Telecaster single coil! [/quote] This is what 'surprised' me when I put the LRC configuration and values into the simulator. More so when you think about the 'mudbucker' in an EB3, why would you want to further remove high frequencies. I have treated the pickup simply as a source of ac emf and not factored the pickup's resistance (impedance) and inductance into the circuit. I wonder if my simulation was too simple. More research / exploration needed (or an EE on BC).

[quote name='Grangur' timestamp='1476908010' post='3158449'] Many thanks. The chips in the neck are really just rough edges. I'll see what happens when I get sanding, but I doubt there's anything there to worry about really. This is the first time I've defretted Wenge. I've done maple and rosewood and done those cleanly. But with the tangs it won't ever come out totally clean. Thanks for the tip though. I'll see how the sanding goes. [/quote] Save the sawdust - you never know.... My experience with rosewood was refretting a defret that someone else had done, hence chip filling.

If you have any big lift outs / chips it might be worth exploring the PTFE sheet, CA & sawdust method. It has worked really well on my refret and the ebony bridge I constructed recently. Body looks super

The filter circuit appears not to be a 'notch' but is a [b][low pass] WRONG[/b] . The idea that it is a 'notch' filter is stated elsewhere on websites/forums. Using this website [url="http://sim.okawa-denshi.jp/en/RLClowkeisan.htm"]http://sim.okawa-den...LClowkeisan.htm[/url] [b][edit for correct link] [/b]and the following values: R = 220 Ohms, C = 0.02 uF and L = 1.5 H gives a low pass filter result. I used 30Hz to 12000 Hz as the frequency limits. I would like to model it in some other simulations before drawing firm conclusions. Quite why you would want to low pass the 'mudbucker' is debatable (and counterintuitive). More research to follow. [b]Edit for sense and correctness: [/b]After thinking and exploring the correct simulation I have realised that it is a low pass filter. The digram on the website takes the output voltage across RC. The Gibson EB3 circuit modelled takes the output voltage across the inductor L. This 'inverts' the filter to a high pass filter. My rhetorical question at the end of post was right.

Andy, I am just back from visiting various teachers I work with ('touring' Wales, very scenic 4hrs in car plus meetings). I will see if I can model the notch filter tomorrow and see what it should do.

Left arm or right arm? Whichever, it is probably due to a slightly changed playing position. I have done the same, right arm, changing from 34" to 30" bass. Do you want the bad news? You need to be really careful with the arm and elbow now. I got to the point where I could not lift pans, cases, mow lawn etc. Take real care now otherwise the injury can take forever (months or even a year) to fix.

How well is the BLO taking to the existing finish? How much existing finish did you take off? I also have a bubinga corvette and it would benefit from a 'light' refresh. Refrets with the right tools (Hosco cutters, tang nibblers etc) are not that difficult, I did my first this year on a 'project bass' with bound fingerboard. Am pleased with the results (though I could improve).

[quote name='spectoremg' timestamp='1476737199' post='3156883'] That's a hell of a 'saved from the bonfire' story. Could you find out a bit more about it? Might be interesting. What's that screw on backplate all about? nb. saw a JB Rick 4-string in dark blue at the NEC guitar show around '02/03 - looked lovely. [/quote] The screw on backplate was a JB feature to prevent buckle rash. As a young man (The Who) in the late 1970s and early 80s I was wearing Levis and Wranglers complete with large buckled belt. Fashionable at the time I am told, great for guitar backs. My JB EB/SG bass (in my hands circa 1980/81) had the same feature, the complete back 'scratchplate, it seemed to work well. Whatever JB used as finish was 'interesting', my bass (black) had lost a fair amount of neck finish, leaving some white coloured undercoat showing. JB did an excellent job of refinishing neck (and electrics) for not much money. This was when they were based in Bromsgrove.

Owned a JB SG / EB3 bass somewhere around 1980. Even had the man himself rewire the electrics (they were way to complex). It was a really 'solid' bass, had a feel of quality build and last a lifetime. Downer was the neck dive, really bad. Hope the restoration goes well.

[quote name='BigRedX' timestamp='1476725506' post='3156696'] What value choke are you using? IIRC the Gibson circuit diagrams only give a Gibson part number rather than the actual value of the choke. [/quote] A further element of subterfuge / chicanery was alleged on the part of Gibson: The inductance values were stated incorrectly on the circuit diagrams to mislead other manufacturers. I have picked up this statement from internet research so it may have no credence whatsoever. Do you have a multimeter that will measure inductance?