Experimental Prototype bass... I hope

[Richard R]

1 hour ago, Andyjr1515 said:

Interesting stuff

It's worth considering whether a truss rod is needed at all.  That is going to be an exceptionally stiff construction - maybe into Vigier territory (which I seem to remember don't have a truss rod).  

Presumably though, you can't adjust the action if there is no truss rod. Other than the bridge height?

[Andyjr1515]

8 minutes ago, Richard R said:

Presumably though, you can't adjust the action if there is no truss rod. Other than the bridge height?

Adjusting action with the trussrod is a 'quick fix' in certain situations (generally if your frets aren't level) but isn't the way to do it all other things being equal.  Ideally, the neck should be within a gnat's whisker of flat in any case. 

[BigRedX]

22 hours ago, mhoss32 said:

BigRedX, Thats a good point, i hadn't really considered, obviously with the EQ02 i use there is no blend between the pickups, but i do find myself just setting and forgetting once i have the tone the way i want. do you find the controls on the EQ01 to be too sensitive? or is it useful to have such a wide range of frequency sweep?

Whilst I never really used the extremes of the filters, I didn't find it too hard to adjust the controls to find the sound I wanted on each pick-up. I was using mine with two very different basses - a Pedulla Buzz with the typical P-J configuration and a Sei fitted with Ibanez GW1 pickups, so having a larger range of adjustment could have been beneficial, but ultimately wasn't needed (by me).

[Hellzero]

To answer your question @mhoss32 I've only played the old Alembic's with the Q switch. That said the continuously variable Q is certainly working even better...

And most of the Alembic's are clear sounding because they are using single coil pickups with a dummy coil (like my favourite basses which are the Leduc's) to cancel almost any unwanted parasite noise. The single coil pickups also have to advantage of sensing the string at only one point avoiding the typical (light) phase cancellation of humbuckers and their tendency to be muddy (stacked humbucker is another story).

[SpondonBassed]

34 minutes ago, Hellzero said:

To answer your question @mhoss32 I've only played the old Alembic's with the Q switch. That said the continuously variable Q is certainly working even better...

And most of the Alembic's are clear sounding because they are using single coil pickups with a dummy coil (like my favourite basses which are the Leduc's) to cancel almost any unwanted parasite noise. The single coil pickups also have to advantage of sensing the string at only one point avoiding the typical (light) phase cancellation of humbuckers and their tendency to be muddy (stacked humbucker is another story).

Again, those few nuggets of information have made a lot of sense to me where folk have spoken volumes before and got nowhere with me.

Thank you.

Edited January 20, 2021 by SpondonBassed

[mhoss32]

Thank you all for the information, love reading through informative stuff like this!

Its a good Point regarding whether the truss rod is needed andy, but the plan is to use 10mm square carbon fibre rods with an 8mm hole down the centre, which by my calculation should be stiffer than a normal hardwood neck, but not completely immobile. this way i can add some releif with the truss rod if needed, and if the neck isn't stiff enough i can add additional carbon down the centre hole (either an 8mm carbon tube or 8mm carbon round rod):

with that said Hellzero, lets talk pickups. this is a reeeeally big experiemnt, but the plan is to build 2 multi coil pickups (8 individual coils, in two rows of four), with anico 5 magnets and 10,000 rounds of 42AWG wire per coil. the overall idea is to build pickups with the clarity of multi coils, but with a wide range of adjustment built in, both in terms of coil configuration (similar to Sims super quads) and adjustable coil height per string.

let me explain

The first part of this is the bobbins for the pickups:

The bobbin itself will be made from a single 19mm x5mm alnico 5 rod magnet, with 2 fibreglass pieces making up the top and bottom (part 1 in the picture above). these are going to be 1mm fibreglass pcb with two eyelets to soldre that start and finish of the coil to. these will be wired in pairs next to eachother:

and will then be attached to one another vertically using the bobbin mount (another 1mm thick fibreglass piece) with a 3.5mm hole in its centre. this hole is to accomodate a screw and a spring will be mounted under each bobbin mount, that will allow for each string pair to have their height individually adjusted, in much the same way you could with steel polepieces and a ceramic or neodymium magnet. this is probably just me over-engineering things but alnico magnets have always sounded more natural to my ear.

this whole assembly of 4 pairs mounted together and wired together in series-pairs will then be mounted to a PCB baseplate, and a 3d printed pickup cover:

the 4 holes on the top are where the screws that will adjust the height of the bobbin mounts will be (these will be standard m3 hex bolts), and they will screw into brass standoffs mounted to the pcb baseplate.

you might also notice that these are quite wide, and that there are 4 holes on the left hand side, and a slot on the right hand side.

This is to accomodate the switching mechanism for the coils. The Sims way requires an additional hole to be drilled in the bass for the 4Pdt switch that selects the coil configuration, and the pikcup mode is displayed via a 3 colour LED on the front of the pickup. my way is somewhat different. there will be a slide switch mounted into the pickup itself to change the configuration, and a small display on the upper edge of the pickup (somewhat similar to gibson's pickup ring tuner for guitars). there will be a single box LED in each of the 4 square holes, which will correspond to a letter cut in the upper edge of the pickup

this allows me to:

>have no extra hole for a toggle switch

>have 4 different coil configurations instead of just 3

>have the configuration displayed with an illuminated letter instead of just a colour:

This is what theupper edge of the pickup will look like (the red areas or the recesses for the screws)

the modes are (left to right):

1) P pickup (pair 1 and pair 4)

2) Reverse P pickup (pair 2 and pair 3)

3) J pickup (pair 1 and pair 2)

4) Humbucker (all 4 pairs)

 

Pairs 1 and 3 will be North up and Clockwise wound, and pairs 2 and 4 will be south up and counter clockwise wound, meaning that all 4 configurations will be hum cancelling

Ive got my PCB's off with the manufacturer, and the pickup cover is off with the 3d printers:

and ive got some more pieces for my nutty experiment cut up:

Can you tell what it is yet?

 

 

 

 

 

 

 

[SpondonBassed]

59 minutes ago, mhoss32 said:

Can you tell what it is yet?

Er... a steel rule?  Heeheehee.

[Hellzero]

Love your pickup idea !

Are your pieces of wood intended for some marquetry at the back ?

[itu]

On 19/01/2021 at 20:13, Andyjr1515 said:

...an exceptionally stiff construction - maybe into Vigier territory (which I seem to remember don't have a truss rod).  

Neither do older Modulus Graphite. Vigier's modern construction is mostly wood, but Patrice has developed and standardized his production and the necks are stable - without a truss rod.

How about aluminum necks, Vaccaro, TB et al.?

[mhoss32]

Hellzero, that is absolutely correct!

as the carbon fibre laminations in the centre of the neck are providing the majority of the stiffness and stability, the long "beam" that runs down the back of the neck can be mostly decorative. the plan is to use a series of pieces laminated together, along with the rosewood triangles cut on the mitre saw to create a marquetry pattern that runs the entire length of the neck from headstock to body.

I spent a few hours planning it out in large scale, using the known thicknesses of the various pieces of veneer that i have available to me:

what im aiming for is a central band, made from black walnut and a purple dyed constructional veneer, with a 5 band "rope" pattern criss crossing it up the neck something like this:

the first stage in this process was laminating up several pieces for a test, and then cutting enough for a couple of repetitions of the pattern:

This was the first stack of laminates I tried for the rope: the centre is Obeche, and the laminates are Koto (very similar colour to the obeche) and a black dyed veneer. it quickly became apparent, however, that although this combination was fine for the purposes of a test, these lightweight woods have a grain that is far too coarse for this kind of detailed marquetry. the small triangles that need to be cut simply splintered and disintegrated at the fine edges, so the material choice will have to be re-thought for the final piece.

but once id cut the test pieces and glued them up with some CA glue, the effect doesnt look bad:

Im pretty confident that with some minor adjustments to the measurements and to the materials, i can make up a beam for the back of the neck with a very similar repeating pattern. i found some 5mm oak panels at a model makers, and some tighter grained maple veneer to amke the "rope" pieces out of, which should hold together much better than the Obeche and Koto. the only issue is the oak is slightly thicker, and so the rosewood triangles will have to be re cut slightly larger, and the walnut/purple stripe will have to have an additional layer of cherry veneer added to either side to make sure the pattern continues to line up:

the plan at this stage is to create a block with 6 or 7 repetitions of the pattern about 50-60mm thick, which i can then cut and lay end to end to create a single long beam with 24-28 repetitions around 10-12mm thick. ill then extend this at either end with some more rosewood and the purple/walnut/cherry pattern so that it extends all the way through the body and headstock.

by my count, if you divided this neck into every single individual piece this would count as a ~660 piece laminate neck! might not be a world record but id say still pretty good!

Meanwhile here are some pictures of teh PCB's for the electronics/pickups, fresh from the manufacturer:

The small squares on the left are the Bobbin top/bottom pieces, which are 1mm thick. these are still really stiff and the manufactureer quotes less than 0.1mm tolerance so the holes in the middle should be bang on the 5mm needed for the magnets to fit snugly. another advantage of having these manufactured by the PCB manufacturer is the small "start" and "finish" eyelets for the copper wire are also pre drilled and have solder pads, making the whole business of making the bobbins a fair bit simpler.

the third benefit of this approach is that these being pcb board have a full layer of copper top and bottom, meaning that if i finish each coil by wrapping the coil in layers of insulation and copper tape, they will be surrounded top, bottom and sides in copper shielding, to reduce EMI noise.

The bobbin mount is at the bottom. when i put the bobbins togetehr, the magnets will sit proud of the top of the squares by 1mm, and then this will be connected together using the 1mm thick bobbin mount. this will mean the magnets will be flush with the top of the whole assembly, and the thickness of the pickup cover is only 1.5mm. this should mean the distance from the strings shouldnt be an issue.

The big PCB is the pickup, obviously. the holes on the left hand side are to accomodate the slide switch:

the holes on the right are where the LED's will be soldered, and the holes in the middle are where the coil pairs will be connected. at the top left you can also see three additional solder points; which are for the Hot, cold and an LED voltage in from the preamp PCB. the Preamp pcb will have seperate power circuits for the external power and battery power, so that the LED's dont draw battery power if the bass is running on them.

Finally in the bottom left is the PCB for the preamp. this one im extremely pleased with. the final measurements were 90 x 34 mm, with both of the potentiometers (filter frequency and resonance) mounted directly to the board, and the toggle switch to change between filter orders will be connected by a wire. the spacing of the pots is 50mm, so i should be able to have the controls on the bass nicely spaced out (bearing in mind that there will be two of these boards: one for each pickup)

next time round ill be putting some of the bobbins together and getting ready for winding, and also going through some of the component choices for the preamp

 

 

 

 

 

Edited January 25, 2021 by mhoss32

[Richard R]

49 minutes ago, mhoss32 said:

.. with a 5 band "rope" pattern criss crossing it up the neck something like this:

Just to be sure I understand- that's going on the back of the neck? 😲

[mhoss32]

18 minutes ago, Richard R said:

Just to be sure I understand- that's going on the back of the neck? 😲

That's the plan!

[Hellzero]

@mhoss32 This is becoming a Mad Professor project and I absolutely love it 😍 . The marquetry idea for the neck is simply awesome ! Indeed boredom is the mother of creativity ! 👏👍👌

[Richard R]

6 hours ago, mhoss32 said:

That's the plan!

Respect! 👍

[AndyTravis]

Absolutely bonkers. Love it.

 

[mhoss32]

As it turns out, the whole thing seems like its a hell of a lot easier the second time around. chalk that up to a combination of experience, the oak panels being a lot cleaner cutting than the obeche ones, and doing things in a different order.

Firstly glueing up the laminates again with the oak in the centre. i also used a bleached maple veneer for the outside instead of the Koto, for the same reason. a tighter grain means less splintering and cleaner cuts:

I think i actually prefer this colour combination to the yellower woods, it just seems a little more subdued.

these are then cut up into the cross pieces and the little triangles needed for the rope pattern:

and once we have them and check them for fit with the walnut and purple veneer core...

i then start to glue them together. this is kind of a slow process. these are all cut by hand and are 50mm deep, so no two are 100% identical. this means carefully matchingand sanding 10ths of a mm off if bits dont line up perfectly. they're glued up with some high viscosity CA glue, which doesnt soak into the grain

the upper middle triangle here is a good example, i had to bring it down by a tiny bit to get it to fit better

but slowly but surely, with lots of measuring and lots of waiting for glue to set...

here we are, 5 repetitions in. by my measurements, 7 repetitions of this and ill have a pattern that runs from the bottom of the headstock pretty perfectly to where the neck meets the body. the triangles will be made from some namibian rosewood fretboard blanks that are exactly the right thickness

 

back in pickup land, im starting to assemble the bobbins. First, take a 5mm alnico 5 rod magnet, mark the north pole with a mark and then add a bead of CA glue around the bottom:

then set it into one of the bobbin pieces, like so:

i then use one of the bobbin holders as a spacer to ensure a perfect 1mm proudness to the magnet at the top, with only a drop of ca glue this time:

and once the top is held in place with the drop of glue, i can remove it and carefully run a bead of glue around the seam using a cocktail stick:

This is where it really helps to have CA glue of varying viscositites, the gel glue holds its shape and wont drip down when glueing the first piece, and liquid glue will wick into any tiny gap when glueing the second.

and finally, a bit of a preamp update. the pots im using for this are Bourns 10% tolerance mini pots, which are approximately 10mm in diameter. this means that i can use components up to 10mm tall (10mm proud of the PCB) without taking up unobstructed space in the control cavity. as the opamps i want to use are high end, hi-fi opamps, i want the other components to be similarly appropriate for high audio fidelity.

im therefore using 63vDC Nichicon fine gold electrolytic caps for the power circuit and decoupling cap, and some 10% tolerance box caps for those in the signal path:

you can see ive also added the 4 IC sockets for the Opamps, and pins at either end for the power inputs, signal inputs and outputs and ground connections. the 3 pins in the middle are to connect the 2nd/4th order mode switch.

i then start to add the resistors, which for this im using 1% metal film, 1W resistors. i chose these as they were the highest wattage i could fit on the board and in the 10mm vertical space:

theres a lot of these to solder, and then another board to do for the other preamp before i run a test to finally decide on component values

next step... winding some coils!

 

 

Edited January 27, 2021 by mhoss32

[Hellzero]

Terrific job ! 👍 

I often use cyano activator when I need the glued items to be as stiff as possible. The CA glue is then as hard as rock with this and cure in no time.

[Simon.]

The level of skill and attention to detail in this build is jaw-dropping! 👍

Always fancied the idea of winding my own pickups.

[Andyjr1515]

7 hours ago, Simon. said:

The level of skill and attention to detail in this build is jaw-dropping!

Agreed.  Pretty much every element is off the scale.  Love it

[SpondonBassed]

I have to agree as well.

The work here is right down to the nitty gritty both in the woodwork and the electronics.  It's more usual to see one or other of the two skills in a build thread but this is a real treat for having both aspects of the build so beautifully worked out.

[mhoss32]

Haha i am going to feel like ive led everyone up the garden path if this all goes wrong! All fingers and toes crossed please

[SpondonBassed]

4 minutes ago, mhoss32 said:

Haha i am going to feel like ive led everyone up the garden path if this all goes wrong! All fingers and toes crossed please

Might take a while...

[BassTool]

Incredible work, the whole build package is jaw dropping in skill and inventiveness (if that's such a word?) 👌🏼

Awesome stuff 👏🏼👏🏼👏🏼

[mhoss32]

Thanks so much guys... please do not uncross those appendages haha

the next step in the marquetry laminations is to add the namibian rosewood triangles i cut earlier to fill in the gaps. at this stage the pattern is 7 repetitions long, and much the same as the rope pieces these triangles are cut and sanded one at a time to ensure they fit as closely as possible. at this stage the edges dont have to be 100% perfect, as they will be planed flat and a veneer strip will run either side of the pattern, but the closer the better as it will require less faffing later on:

("T" stands for top, the number tells me which fits in which gap and the arrow tells me which edge should lie closest to flush)

i found it easier to line them up this way, and although they arent perfect, once theyre cut flush it should all look pretty tidy:

with one edge cut off you can see that for the most part the gaps aren't too bad. this piece is still pretty much bang on 50mm deep, so the plan is to cut it into 4 slices and lay them end to end, filling in the missing triangles as i go. colour wise im very happy, the contrast between the different woods is good, but its not over the top. all in this experiment is going pretty well!

meanwhile in pickup land...

the magnet of each bobbin is wrapped in masking tape, which is then sealed with another bead of liquid CA glue at the top and bottom. these are then ready for winding. my home-made winder has a maximum speed of 1000RPM, which on a normal pickup bobbin would probably be uncomfortably fast and produce a LOT of vibrations. with these individual bobbins though, it seems like 900ish RPM is just fine... if a little noisy. process wise it couldn't be simpler. tie the 42AWG copper wire 5 or so times round the eyelet marked "S" (for start), stick the bobbin to the winder with some double sided tape, check the winding direction (clockwise for north up, and counter-clockwise for south up) and let rip!

900RPM, with 10000 winds per coil... means about 11 minutes of winding per coil.

then just cut the wire, tie it off at the eyelet marked "F" (for finish) and voila:

one bobbin, nice and tidy! one down and 15 more to go... this should keep me busy for a couple of evenings. i used a soldering iron to melt off some of the insulation around the eyelets and tested the DC reesistance. one coil is pretty much 1.6k ohms. a little less than expected but that means a bit over 6k for each single coil mode. should be about right when matched up to the preamps, and give a nice natural sound. one thing a lot of multi coil pickup makers do (i am told) is use a heavier (41AWG) wire, which gives the pickups more upper mid-treble clarity (or so i am told), so that will definately be an experiment for MKII

even more excitingly... check these out!!

pickup covers! boy am i happy with these. they are printed out of a high strength nylon, which is then Vibro-Polished for a smooth finish. the website describes the freshly printed finish as similar to an extra strong mint, and the vibro polished finish as similar to a soft mint, and theyre about right. nice and smooth and a very consistent colour. and these things are hard as nails. the thin strips that divide the coils are 1mm thick, and they are noticeably stronger than injection moulded plastic. you can see in the picture on the left the switch tips in place. these lie flush eith the top of the pickup for a cleaner look (they wont actually be right up against the end of the slot like in these photos), and should allow the pickup modes to be switched easily whilst staying well out of the way.

the plan is to colour in the little MH logo gold, and have gold mounting screws and 4 gold coil height screws in the middle as well, which i think will look great

Also, the pots are now soldered onto the preamp:

the Blue one is the frequency sweep, and the green one is the resonance. you can probably see the green one is actually a push-push clicky swtich as well, which will allow for a higher (16+DB) boost at the resnonant frequency when in 4th order mode. the reason for this is that the height of the resonant peak naturally changes when the preamp is switched from 2nd to 4th order mode, and this switch will allow the user to choose whether they should be even at the bottom of the resonant sweep, or at the top. not always totally useful, i know, but certainly useful in a prototype to work out the correct component values, and keep variables the same when testing for different sounds.

This is the second one underway as well. i ran short on a couple of resistor values so had to buy some more, which were green (hence the different resistor colours), but still 1% metal foil. the one resistor between the two IC sockets is a bloody tight squeeze. just the box capacitors to go on, and then i can mount one in a pedal to test with a couple of different basses which i am really looking forward to!

 

 

 

[Hellzero]

I'm totally addicted to this thread ! 😊