Experimental Prototype bass... I hope

[BassTool]

I've just realised that your profile logo is your initials 😖😖😖😖😖 why did I think it was the top of a gearstick???

 

D'oh 🤪

Edited January 29, 2021 by BassTool

[Richard R]

51 minutes ago, BassTool said:

I've just realised that your profile logo is your initials 😖😖😖😖😖 why did I think it was the top of a gearstick???

 

D'oh 🤪

"I'm delighted to inform you Mr. BassTool that you have passed your tractor driving test on the 13th attempt.  You picked up a minor failing due to occasionally missing  one of the three cross-linked reverse gears. Otherwise well done."

Edited January 29, 2021 by Richard R

[mhoss32]

Hahaha I'd never noticed that before, damn you now thats all i can see now I look at it too 😂

Preamps are now all soldered up!!

all box caps in place, tested for the right inputs and outputs, all seems to be working as expected thus far. lots of tests to happen now to muck about with component values and make some final decisions about the filter profiles. this first setup is the widest frequency sweep, from around 100hz at the bottom up to 6.8khz at the top. if i find that either end sounds wrong or wouldn't be useful, i can just change a few resistors/caps and try again. at this stage im thinking i may have them tuned differently from eachother, with the bridge pickup having a much wider sweep to allow for more top end.

The Opamps ive got in here are LME49720's, which are some seriosuly good Hi Fi opamps. these are the kind i have in my headphone preamp on my desk, and they sound phenomenal. Much faster slew rate and much lower distortion than those normally used in onboard preamps, but that comes with the downside of much, much higher power draw. not many preamp makers give exact details on the predicted battery life or power draw of their preamps, but Noll for example quotes typical draw of 1.5mA, which is pretty good. a typical 9v battery would hold about 600mAh of charge, meaning about a 400hr battery life.

compare that to these beasts

the LME49720s have a draw of about 5mA per channel, each. and theres 7 channels being used by the preamp. and theres 2 preamps.

oh dear that means about 70mA of power draw at maximum...which, Maths fans, means battery life on a single 9v of less than 10 hours. not exactly great

so lets talk solutions. as mentioned before, the plan is to have a phantom power input, running at 24V that will power the preamps most of the time. Sorted!!

but... what about the one in a hundred time when i want to just plug and play without the phantom power?

Ta Da! this is a Battery protection and charging board that takes 3 18650 sized Lithium ion batteries, the kind you might get in powerful torches. the plan is to mount this in the other side of the bass, and have the same 24v power input to the preamps run to this as well. this will:

1) charge the batteries in place whenever the bass is plugged in

2) protect the batteries from under voltage and over voltage, and ensure the power is cut once they are fully charged (very important for lithium cells)

3) allow me to carry additional batteries and swap them out if needed

4) run the preamps at a reduced 12v when a normal jack is plugged into the bass. 18650 cells have some serious capacity. a 9v battery- about 600mAh. these bad boys - about 3500mAh. and thats at 12V, not 9. meaning that i can get 50 hours of play time with the hi fi opamps on a full charge, not too shabby!

Again, if youre only here for the sexy wood stuff, i must apologise for the electrical nerdery. i assure you there are dullards like me who really find this stuff interesting!

but, here you go:

the fairly nerve wracking process of slicing that 50mm block in half on the mitre saw. clamped carefully and then sawn slowly. measure 9 times, cut once!

but the patient left surgery in good shape! well... sugery number one. this now needs to be repeated... twice... on even thinner pieces.

admit it. own up. who was watching up to this point thinking this was all going to go horribly wrong?

I certainly was, and im sure glad it didnt. there are a fair few hours invested in this up till this point!

then its just a process of glueing them end to end with some CA Glue, and glueing the little extra triangles in place in the remaining gaps, letting it all set up nicely, and then planing down one face nice and flat 😁

honestly, im pretty chuffed with this. im very much ooking forward into turning it into a proper neck blank and getting moving on the body of the bass properly. by my measurement its about half an inch longer than i was aiming for, but thats fine and should run perfectly from the headstock to the body.

roll on the next experiment!

[SpondonBassed]

That is really nice.

[BassTool]

38 minutes ago, SpondonBassed said:

That is really nice.

And the 'understatement of 2021 thus far' award goes to @SpondonBassed😆😆😆👍🏼

[Simon.]

O.M.G. ! 😲

That is so good. 😎

Have I got it right that this is the back of the neck, we are looking at? I'm very intrigued as to how well this will carve into a neck profile, and how the pattern will look.

Edited February 1, 2021 by Simon.

[Richard R]

The electronics for this are phenomenal! This a a bass which will freak out FOH engineers as it has it's own PSU, freak out airlines with the Lithium batteries, freak out the drummer who is the only other person to see the back of the neck, and hopefully freak out the audience with the sound.

This has got to appear at Bass Bashes up and down the land when we are allowed them again. Or we will find out where you live and descend en masse.

[Si600]

3 minutes ago, Richard R said:

Or we will find out where you live and descend en masse.

And steal it.

[Hellzero]

The electronics nerdery is very interesting, and everything on this bass build is simply amazing.

Can't wait to see and hear the final result.

And I'm getting more addicted each time...

[Si600]

Do you intend to make the pickups available to all and sundry?

[Daz39]

It's amazeballs - the lengths people will go to make hard work for themselves.

When will the toblerone be ready? I'm hungry just looking at all these triangular slices...

[Hellzero]

1 hour ago, Si600 said:

Do you intend to make the pickups available to all and sundry?

No, only to the one(s ?) knowing that the slices of wood were intended for marquetry. 

[Andyjr1515]

Awe-inspiring 

[mhoss32]

Yes, thats the plan Simon! to be honest i dont know how well it'll carve or how it'll look as a rounded neck profile... but thats all part of the experiment! i am not looking forward to attacking it with a bunch of sharp tools mind... that will be a nerve wracking day!

Don't worry Richard, I will be sure to make it to every one i can, if this is going to become a semi-business of mine i need all thr feedback from experienced players i can get!

Im glad it isnt JUST me interested in the nerdery, its very satisfying when you get things to work the way you intended!

with regards to the pickups, the answer is eventually most likely yes. half of the point of this bass is to see what people like but also work out any kinks, and some kinks you can't really work out on paper. you need to wind the pickups and hear them and wire the preamps and try lots of different configurations... so im hoping that a MKII version of both the pickups and the preamps can be made available after this is all finished.

I already have a couple of things id change slightly, including the coil height (they didnt really need to be that tall) and maybe re do them with 1/4 inch magnets for greater output but similar DC resistance.

with the preamps this is actually the third circuit i simulated, the first was a copy of wal's current control layout; 2 frequency sweeps with pick attack and resonance, and the second was similar to an alembic with 3 mode preamp: Low pass/High pass/Band pass, so id be interested in actually building those to see if anyone had any interest as well!

[Richard R]

7 minutes ago, mhoss32 said:

Don't worry Richard, I will be sure to make it to every one I can, if this is going to become a semi-business of mine I need all the feedback from experienced players I can get!

Please allow us cack-handed buffoons a go too!

[MoonBassAlpha]

Is your preamp balanced output? 

[mhoss32]

There will be two outputs, one balanced stereo and one mono. The preamps will run independent paths through an MN balance pot and a stereo volume pot, with a switch to choose between the mono or balanced stereo output.

the switch then acts as a mute switch when flipped the other way

[bloke_zero]

On 31/01/2021 at 19:43, mhoss32 said:

if youre only here for the sexy wood stuff, i must apologise for the electrical nerdery.

I came for the electronics nerdery but stayed for the wood! You're making me consider a lot of things that I'd toyed with coming from the modular synth world but haven't really followed through on - filter slopes and opamps!

[mhoss32]

Glad to hear it @bloke_zero always nice to meet some fellow electro-nerds

The Opamps are really an interesting point when it comes to this kind of thing. obvously the main factor in choosing them for most manufacturers is how long they can last on a single 9v, but take a look around online and you will find that the tried and tested TL062 and LM358 that are often used are a bit behind the times. annoyingly, the best of the best of opamps available right now are surface mount only, as opposed to socketed, but maybe ill try and get a board made up with them in the future

[Hellzero]

Try a pure transistor approach, it takes much room, but sounds way better than any opamp...

[mhoss32]

Thats an interesting point, ive never been one for fully discreet solutions but as you say thats mainly due to size. you can also buy fully discreet transistor based "discreet" DIP-8 package opamps, although they are eye-wateringly expensive, and their power draw is similarly huge.

if i remember correctly, Orange sells discreet replacement opamp chips for their amps, would be interesting to see how much different something like that would make.

maybe in the future i will experiment with a design that can fit those kinds of solutions inside a control cavity, but that would almost certainly have to be phantom power only.

[Hellzero]

Indeed, there are 3 factors to consider : price, space and power consumption. And even if a full transistor preamp will sound way better than anything, all parameters will be on the far right indicator. That said, I've tried almost every onboard preamp and, to date, the best one and most transparent is the Richter BassXX which is a ... filter-based cleverly designed preamp with surface mount components.

http://www.richter-ee.de/preamps1.html

[mhoss32]

Thats a good bit of information, @Hellzero, ive never tried one of their preamps, ill have to look into it. some very interesting stuff on the PDF for the bassXX preamp though

The next stage in the marquetry work for the back of the neck is to finish off the pattern at both ends, and extend the beam so that it runs the length of the body and the headstock. first off, i cut another strip from the walnut/purple veneer that will extend the central stripe. the idea is to have this exend all the way down the back of the body and the headstock as well:

 

i also cut strips from another fretbaord blank to exend the rosewood parts. i then cut two more triangles from the oak/maple rope laminate so that it looks like it wraps around at either end:

 

then, using a hardwood board as a backstop, its all clamped and glued together

then, once both ends are extended this way (the body extension is longer than the headstock, for obvious reasons), i planed each side flat and glued a strip of the light veneer down either side:

and finally, carefully remove the excess with a sharp chisel

  

Very pleased on how this has turned out. im looking forward to planing one side dead flat and glueing the Carbon rods in place as this will ensure everything stays flat and straight. this may look pretty but it isnt stiff

ive carried on winding my pickup bobbins in the meantime, and started to do the first bits of work on the pickup PCB's as well:

this is the 4 position switch for the pickup in place. the pickups are going to be fairly large, but i wouldve struggled to save much more room than i did.

These Brass standoffs are then attached the the PCB base with some black nuts. these are M3 standoffs, and the 4 Hex bolts screwed into them will be used to adjust the coil heights for each string (this is what the 4 holes in the top of the pickup cover are for)

the plan later on is to replace these with some shiny gold screws, but for now these black ones will work just fine. so far everything lines up nicely as expected

The leaf inlays arrived in good condition, and im really pleased with them. they should look lovely in a macassar ebony board. ive decided that i want to add something else to these however, to really make the fretboard stand out. the plan is to inlay 2 tree branches cut from a brown Malee knife scale blank to add some additional detail and contrast to the fretbaord.

doing this on the dining room table, the little one wanted to come and do drawing too, so a pleasant evening spent all round! the next step is to cut the branches from the burl and then inlay these into the fretboard, and then move onto the shell laminates. im also shortly going to cut the two rosewood beams for the neck as well, and hopefully finish one set of coils so i can get one of the pickups wired up to make sure everything fits... busy busy busy

 

 

 

 

 

 

[Si600]

Holy cow! Is your workshop flag floored and rough stone? Looks lovely from the little bits I can see.

That rope veneer is alright as well.

[TwoTimesBass]

On 01/02/2021 at 20:11, mhoss32 said:

There will be two outputs, one balanced stereo and one mono. The preamps will run independent paths through an MN balance pot and a stereo volume pot, with a switch to choose between the mono or balanced stereo output.

the switch then acts as a mute switch when flipped the other way

Loving this build and the complexity of the electrics!

How does a stereo output on bass work, across the pickup or between pickups? Are you using a 5-pin XLR for the balanced stereo output to get enough connections?

Great work!