Experimental Prototype bass... I hope

[mhoss32]

"Boredom is the mother of invention"

I have been bored. very very bored.

So i started thinking about the next Bass build, and thinking turned to planning and planning turned into scheming. Ive had a couple of bass playing friends reach out to me and ask in the past if id ever build a bass for them, and ive always said no. essentially i just never felt qualified to build something to a standard that i would want to charge someone for it, and ive always liked my bass builds to be suitably "home made", plus i never have enough free time to get it finished in a reasonable timescale.

Plus, the workshop id normally use to do all of the work, with all the big power tools (Bandsaw, Router table, Table saw etc) has been closed all the way through lockdown, which makes the whole thing even more of a pain. but this is where i came up with an idea. i decided that what i'd do, is take the time and build a prototype, a pattern bass if you will, in order to try out all of the ideas ive had, get the design correct, work out any kinks and complications, and if anyone likes it and it turns out good, then i can use it to show people what theyd be paying for. And if i can do it in a garage on a workbench with fairly basic power tools, ill feel confident in being able to repeat the feat once the proper workshop is back open. Im certainly never going to go full time luthier, but id love to be able to do this as a hobby where i can recover the costs!

So....

The design.

This is one i spent most of the first lockdown (in march) planning and thinking about. i had a few basic parameters that i wanted to stick to:

1.Not crazy over the top - my last bass turned out great, and i love it, but its design is a pretty aquired taste. this one needs to be a little more universal in its appeal

2. Lighweight - whatever happens i dont want a bass i make to stay hung on a wall for all its life because it breaks its owner's back every time he/she plays it. this means making sure the aesthetic design is fairly compact, but also that the material choices and construction are considered from day one

3. comfortable - this kind of ties into the lightweight aspect, this needs to be comfortable to play standing up and sitting down, with easy to use controls and fairly normal dimensions. i dont want it to have crazy narrow string spacing or a mile long scale length

4. Unique. this is my big focus for this project. i want this to be something special. ive got a few ideas for it, that i will share as we go through the build and see what people think. in the end this is what this prototype is for, to see which experiments work and which don't!

 

With those in mind, heres a quick rundown of the specs (although these are subject to change depending on the aforementioned experiments)

Neck through construction - (experiment number one, the neck through blank will have carbon fibre laminated directly into it to save material, reduce weight and improve stability)

33" scale length, 26 frets

Body - laminated from walnut, maple, Padauk with a curly redwood top (experiment number two, as opposed to a book match top, this will have a "swan matched top", i will explain below)

slotted headstock - similar to Bolin Steinberger bass

macassar ebony fretboard with tree/leaf inlays

tune-o-matic style bridge with custom graphite saddles - paired with customised bigsby with bass guitar string and tension bar

electrics:

2 Multi coil custom pickups (experiment number three) - similar in construction to sims super quads (switchable coil combinations) but with 8 individual coils (a la Wal pickups). there are reasons for this which i will explain in due course

stereo filter based preamps (experiment number four) - active filters with variable frequency, resonance and independent mono and stereo outputs (these have a few interesting qualities whih again, i will explain in due course)

internal, replaceable lithium ion battery pack, and integrated 24V phantom power connection and accompanying pedal (experiment number five) that will allow for extremely high power draw, hi fidelity op amps to be used in the preamps

Im taking some interesting inspiration for the body design, little bit of CT, little bit of Wal, little bit of some of ther other boutique scroll basses out there:

 

The flamed redwood will be divided along the S-shaped curve, and have a sandwich of veneers in between them. the white areas in the upper horn and left hand side will leave the wood below (black walnut) to show through. this is to show off the lines of the bass, but the cutaway on the left will act almost like a thumb rest just at the upper edge of the pickups. this is obviously a pretty rough representation, as the edges will be carved and rounded to expose the various coloured laminates underneath.

this build isnt going to be happening in real time, ive been sitting on this for a while so that i could get some of the more time consuming and boring bits out of the way first, so im hoping that updates will be fairly regular moving forward. im super excited, and have at least 3 full notebooks of sketches and drawings and notes and diagrams for all of my crazy hair-brained ideas!

and on a final note, there will be experiment number 6... which is i think the most ambitious and least likely to work of all of them... but i will play that one fairly close to the chest. for now ill say this: if it works the back of this bass is going to be more impressive to look at than the front

Look forward to sharing this one with you guys!

 

 

 

 

 

 

 

 

 

[SpondonBassed]

Enter the boffin zone...

I'm loving the initial sketch.  It flows well.

[AndyTravis]

Well. I want to see this. I’m in.

[Hellzero]

I'm in too. Great project well thought, except for one point that in fact is a two point : the lower horn.

With your design, the bass will always slip when played sitting without a strap and the access to the dusty end will simply be impossible...

Rethink the lower horn and you'll have a very appealing design which I really love and an ergonomic bass.

Think also about the placement of the output jack, which is too often the stupidest place ever. 😉

[mhoss32]

Ah, thats interesting, i thought the lower horn was big enough to give a comfortable curve over the knee, which way do you think it will slip?

im less concerned about access to the upper frets, the thin horizontal line on the neck is the 26th fret position, so the 24th is actually above where the lower horn meets up with the body.

And also an intersting point regarding the jack socket position, i hadn't planned that aspect yet. ive never thought of jack socket positioning to be a big deal ergonomically, where is the ideal spot do you think? not one ive thought out fully yet, but it will need to be as this will have two output sockets, one for mono and one for stereo with phantom power.

Here are a few pics of the first stage of laminating:

the centre is Padauk, and the first strips on are a constructional 2.5mm Cherrywood veneer. I ran a bead of liquid CA glue along the edge join to make sure there was no splintering or chipping out as the edge was planed flat.

The plan is to laminate 3 edges of the padauk with cherry, and then repeat the process with a layer of 2.5mm black walnut

The idea is to create laminations that give good contrast along the carved edges, but also when looking at the upper and lowe edges of the bass, similar to this:

In the first picture above, you can see in the background a mitre saw and a big collection of cut pieces and CA Glue, these relate to experiment number 6, which is well under way!

Im also in the process of drawing up the neck inlays:

the falling maple leaves will be made from abalone and Gold Mother of pearl, which im hoping will create some good contrast with the macassar ebony fretboard. Ive sent this drawing off to Bruce Wei, the guy who normally does the inlays i do, hes a great guy to work with and always produces amazing stuff, even from drawings as rough as mine!

Next post ill run through some of the pickup design/some of my initial work on the preamp as well, so stay tuned!

 

 

[Hellzero]

One of the best placement is, to me, this one. And I've owned and played over 300 basses... 🤦‍♂️ : 

Edited January 16, 2021 by Hellzero
With the photo it's better

[Hellzero]

The lower horn pointing outside will help prevent slipping towards the head and allow total access to the 26th fret. 😉

[TheGreek]

Very Ritter Cora...

[mhoss32]

Thats really interesting... I have a bass with that jack socket position as well! One of my buzzards has it and youre right its certainly one of the best ways... Im surprised it isnt more common as just as TheGreek says, on Ritters basses they are mounted on the rear cavity cover. 

 

The problem may be space related however, with the preamps and switches in this bass i will have to see how much space is available on the back, and how deep the control cavity is.

 

Its a really good point though, as i said its never been something ive thought about too much, given your experiences what would you say are the bad, good, better of jack socket placement? Would be really interesting to get the opinions of some more experienced bassists than me!

[TheGreek]

This is the back of my Psilos bass - built by our own @Andyjr1515 - note how all the controls are hidden in the back of the bass giving the bass a minimalist look. The jack is left of the 3 knobs and can just be seen.

The headless bridge in the back is NOT an issue whether standing or seated.

[Andyjr1515]

LOVE this!!!

And don't worry about the lack of workshop - 50% of my builds to date were done on a workmate on the back patio (including @TheGreek 's above ). 

Takes a bit longer but where there's a will there's a way

Love the design thoughts.  Can't wait!!

[Hellzero]

2 hours ago, TheGreek said:

Very Ritter Cora...

That's just the opposite, Mick. Leduc idea since the mid 80's... But that's not the point as it's, to me, the best location for the output jack as it works perfectly sitting or standing.

The bad positions are on the side pointing to the ground, at 45 degree or 90 degree.

The Fender output jack on the table is a good one if there's a metal plate holding it.

An excellent position is on the side pointing up à la Ibanez AFR, which is my favourite design ever for a bass. Look at the ergonomics. Yes it's mine. Original one from the early 90's.

Edited January 16, 2021 by Hellzero
Ouput jack photo added

[TheGreek]

....and Bass Collection Nanyos.

[AndyTravis]

And my new tune (made by Deviser) - mine is blue though...

Edited January 16, 2021 by AndyTravis

[mhoss32]

Thanks Andy! I figured i can do it just as well as if i had a workshop but faster, but its good to get confirmation from someone as skilled as you! 

I remember reading the psilos build log at the time and drooling the whole way through, absolutely gorgeous build

Hellzero, that Ibanez is a cracking looking thing, ive seen them before but never realised the jack was positioned that way, and ive never seen a deviser before andy, but that looks amazingly comfy too. Basses where ergonomics are the number one focus always have a certain elegance to them i think. That socket  position is a clever idea, i shall see if i can make it work!

Excellent to get some proper useful feedback from you guys on stuff like this i just dont play long or often enough (or own enough basses) to get a full picture of how details like that can make a big deal to how easy a bass is to live with long term. 

Edited January 16, 2021 by mhoss32

[mhoss32]

Okie dokie, lets talk Filters

(if youre only here for the pretty pictures of woodwork, don't worry this part wont be on the test)

The idea for the controls on this bass are as follows; each pickup will have its own preamp, which will have controls somewhat similar to alembic's filter preamps. that means that each pickup will have its own Low pass filter, with adjustable cutoff frequency, and adjustable resonant peak. the layout for each pickups will be like this:

This will be achieved with 2 potentiometers, 1 which controls the frequency sweep such as this:

as the control is turned, the cutoff frequency decreases and more and more of the treble and Mid frequencies are filtered out, leaving only the low end. you can see from the graph above there is a 12 decibel "peak" at the cutoff point. this is often referred to as the 'Q' or Quality factor, and can also be varied.

The second potentiometer will control the 'Q' factor or resonant peak such as this:

These controls should allow for a very wide range of tones, especially with one filter for each pickup. the exact range of both the frequency sweep (from maximum to minimum frequency cutoff) and the range of the resonance control are yet to be decided. once i have a test board made i will try a number of different vlaues to decide which sounds best. it may be that i use different values for the bridge and neck pickups to achieve a greater range of adjustability.

My thinking at the moment is that i will try 3 different frequency ranges:

Low - 250Hz through to High - 3.8kHz (from the research i can find online this is similar to the range sweep of Wal's current electronics)

Low - 300Hz through to High -4.8khz (again, from my research this is similar in range to that of alembic's filters, although it also seems this varies from one set of electronics to another in alembic's case)

Low - 100Hz throught to High -6.8khz (this is a far wider range of a sweep, but may be useful with one filter per pickup as it allows the resonant peak control to boost high treble frequencis on one pickup. this is close but not quite as wide a range as ACG's EQ01 and 02 i believe. i have an ACG EQ02 in one of my Buzzards, and i absolutely love it, but the sensitivity of the frequency sweep control takes some practice to get right)

I want to balance a wide range of tones with the frequency controls not being too sensitive, as its important to have a control setup that allows people to easily recreate sounds accurately without too much effort

For the Resonant peak control, ive decided to go with a potentiometer rather than a switch. again this is based on my own experience with the EQ02, being able to sweep the resonance from low to high i find that at least half of the time i have the control not at either extreme.

from what ive read and from videos ive watched, both ACG and Wal filter preamps have a resonant peak adjustment from 0-10db at the cutoff point. (thats the peak you can see being adjusted in the second graph), and Alembics (take this with a pinch of salt because ive heard a lot of different answers for this from different people) have an adjustable peak up to 15db

again, i think i will test with a number of values, allowing for a peak of 10, 12, 15 or 18Db (18db being the highest boost commonly available on preamps from aguilar, bartolini etc)

and then we come to the "experiment" part of this design. Im confident i can get a compact circuit to achieve all of the above, but i also want to try something different.

as far as i'm aware, all of the aforementioned filters are what is referred to as "2nd order" filters, which have approximately 12db of rolloff per octave (this is the steepness of the rolloff at the filter frequency). it is possible, however to create Higher order filters with a steeper rolloff. a 4th order filter for example would have a rolloff of 24db per octave:

In terms of tone, this control would not necessarily be particularly useful if it were applied to both pickups at the same time, but with individual filters per pickup, this would allow the neck pickup to have more of the midrange harmonics filtered out at the bottom end of the frequency sweep, giving a cleaner bass tone, and at the upper end of the frequency sweep, this would allow for the resonant peak to attenuate high treble frequencies whilst filtering out unwanted high frequency noise more effectively.

Thats the theory anyway... it remains to be seen if this works the same way in practice

This plot shows the frequency sweep with the filter in both modes, the red traces are in 2nd order mode, and the blue traces are in 4th order mode with the resonance control set to a max peak of 12db.

as i said before, this is an experiment, but im excited to see what this sounds like in practice.

I will cover the preamp in a bit more detail once its been put together and ive decided on component values.

Meanwhile the strips of Cherry are all glued up around the Padauk, and the layers of the wlanut are next

 

[SpondonBassed]

Thanks for the detailed explanation of low pass filtering.  I'm one of those who is easily overwhelmed when presented with too many options but your explanation has helped my understanding somewhat.

Cheers!

[Richard R]

12 minutes ago, mhoss32 said:

(if youre only here for the pretty pictures of woodwork, don't worry this part wont be on the test)

😁  TBH that's me.

But it's good to be reminded that these are Electric Bass Guitars,  and you get more change in sound from twirling the knob than you would from changing the neck.

[bloke_zero]

How it sounds (for me) is more important than how it looks - I really like the LP filter per pickup approach as EQ can really mess up a sound in my opinion making it smeary where simply removing frequencies feels cleaner to me. For me the aim of the electronics would be to let the sound of the pickup/wood interaction sing through as much as possible.

Personally I'd go with the lower dB per octave slopes as I think you might find that the steeper slopes really colour the sound - but who's to say that is a bad thing? Not me!

The one I have tops out somewhere above 4K and I think that really works as you still geta  lot of the snap and buzz from the string but not too much of the string noise from higher up.  It's a tricky balance - thanks for the research and figures on the different versions - most enlightening!

The only worry with this LP filter set up is that I can see some bad amp accidents happening with a big resonant peak smashed out at very low frequency - people never let you forget it if you blow their bass bins!

[mhoss32]

That is a very good point, Zero, i will have to give these a good range of testing to make certain that there isnt some crazy overboost too low in the frequency ranges. the Aguilar OBP-3 claims +-18Db at 40Hz centre frequency, it would be interesting to hear from some owners of that preamp to see how they feel the Bass boost sounds cranked all the way.

With regards to the steeper slope colouring the sound, you're spot on. the 12db/octave slope is fairly unobtrusive to the sound, and i think that probably if you had both preamps onboard switched to their 4th order slopes it could end up sounding pretty unnatural, but the hope is that with the ability to switch between them there will be situations where dropping certain frequencies from one pickup is desireable while allowing the other one to handle wider frequency ranges. excellent to get your feedback though, im sure that there are loads of people who prefer the filter-controlled approach to tone shaping, and others who prefer the more traditional boost/cut.

Just like SpondonBassed said, too many options can be overwhelming, especially if it isnt clear how they actually translate into tone!

 

 

Edited January 18, 2021 by mhoss32

[BigRedX]

Having owned basses with filter pre-amps on them (ACG EQ01), the ability to "tune-in" each pickup for the sound you want and then use the pick-up blend control the adjust between them is the biggest strength (IME) of this system. It's initially a lot of daunting-looking controls but the Cut-off Frequency and Q controls for each pickup tend to be "set and forget" and then you just have one control (blend) to get a wide variety of sounds.

[Hellzero]

Regarding the OBP-3 bass boost at 18dB, I think nobody has ever tried this as even with just a pinch of boost, it's already too much, so all the way up, it will destroy your speaker for sure. This preamp is known for being a kind of "too much of everything" and I can confirm.

I've played basses with the 3 above mentioned filter based preamps and my favourite has always been the Alembic approach which sounds more "natural" to me, but again it's a question of taste. I like the Wal preamp because, with the Wal pickups, it sounds massive and powerful. The ACG is certainly the most complete of all...

[mhoss32]

haha i love posting on this forum, ask and you shall receive!!

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?

In terms of pickups blending im juggling a few ideas. obviously with both stereo and mono outputs the blend control would be slightly different from a normal setup. at the moment im thinking about either an 11 or 23 position rotary switch with resistors to turn it into an MN taper pot. this should allow for very careful matching of the different switch positions to different outputs from each of the pickups

HellZero, thats very helpful. i do have a bass with an East Preamp, which also quotes 18db Boost and Cut, and your'e right its probably the last used of all of the knobs.

The wal Pickups are certainly part of their particular "magic" tone. Multi coils have a very distinctive sound to them, and the filter controls work brilliantly in wal basses as they are specifically matched to those pickups placed in thheir exact positions.

Im not surprised to hear you say the alembic approach is the most natural sounding, that has always been the main focus of their pickups and their electronics, and the ones ive heard are so clear and clean its really surprising. out of curiosity what control layout were you ujsing? ive seen alembics with 3 way switches for Q control and ones with a seperate Pot.

Edited January 19, 2021 by mhoss32

[mhoss32]

While that discussion conmtinues in the background, let's talk about the neck through construction

The idea here is to integrate carbon fibre rods into the lamination of the neck woods, to allow for greater stiffness, a simpler construction and a reduction in the wastage of materials.

here is a rough sketch of the neck cross section and the proposed way of building up the blank that will run the length of the bass:

The principle here is that the two 10mm carbon fibre square rods and the 1mm carbon fibre strip will be epoxied together to create a U channel around a normal double action truss rod, running the length of the neck. this will be laminated to the side pieces and an additional strip down the back that will run the full length of the bass to create a blank with a central core of carbon and wood around the three sides.

Ive seen a very similar principal to this employed by another Luthier local to me in the construction of acoustic guitar necks, with excellent results. Excellent in terms of stiffness and stability, yes, but in additon the stiffness provided by the carbon fibre and the hardwood pieces (in this case Namibian rosewood) will mean that the 9mm strip that runs down the rear of the neck can be made with decorative laminations... at least that is the theory.

the whole blank is only going to be around 20mm thick, and so additional pieces will be added to make up the bulk of the rear of the body, and the headstock will have additional pieces laminated front and back.

so to keep you patient wood people happy heres some lumber porn:

This is the Namibian rosewood that will make up the rear of the body, as well as the 2 main laminates along the sides of the neck

And here are the 2 pieces of flamed redwood that will become the top of the bass. the figure on these is insane. and especially along the upper horn the flame should look absolutely awesome.

and meanwhile... without giving too mcuh away, ive been working on my lunatic idea for experiment number 6, so stay tuned for what could be a spectacular failure or success

 

 

 

 

Edited January 19, 2021 by mhoss32

[Andyjr1515]

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).