home built DB (warning carbon fibre content)

richtea · #1 02-13-2011, 11:05 PM

HI guys,
Some of the guys in Luthiers corner suggested that I post here, as you guys are way more knowledgeable about all things DB. I appreciate that most traditionalists will find my bass an affront to the genre, but any help you can give will be much appreciated.

First I need to say that I built this bass more than 10 or 15 years ago. At the time DB's here were stupidly expensive. I saw a new Asian one in a shop with the back separating from the sides, massively discounted to about $2.5k. So I decided to build one. I knew NOTHING but the scale length, and my skills with plastics were much stronger than with wood at the time. This was the result so please don't judge to harshly.

My question is this. I get “reasonable” tone out of the A D & G, but the E is lacking in "definition", if that's the right word, it somehow just seems to lack presence in comparison to the other strings.
I few weeks ago a friend's wife who plays violin, looked at the bridge and said why don't you get a decent bridge? This got me thinking, Does any one think that It would be worthwhile? What does a "decent "bridge look like and what are they made of? The current one is a lump of hard maple that I shaped into what I thought a bridge should look like. I am pretty sure that the string spacing and FB radius are so far from standard that I will have to make something from scratch.

The top is around 3mm thick. It is a laminate of .5mm carbon skin, 2mm honey comb core .5mm carbon, there are no ribs of any kind. It is SUPER stiff and resonates really well, far better than my expectations at the time. Inside the body (from the front) there is an alloy tube that runs from top to bottom, the spike runs inside this and it goes into the neck heal, then a horizontal alloy tube around the bridge area, forming a crucifix with the spike tube, tying the sides together about 2" bellow the body/top joint. Neither of these tubes come into contact with the top They are there because at the time I was worried about compression on the top forcing the sides apart and causing the top to fail. I shouldn't have bothered the top is rock solid. After its initial tuning to pitch it stayed in tune for a couple of months.

The back of the body is a woven drapable glass mat but laid up using the same Hi-Tech (read very expensive) epoxy. The neck, heal and head stock are oak. I have no idea about the make of strings that are on the bass they are rounds, at the time I had a choice of one. (and they were REALLY expensive)
There is no bass bar or sound post.(I only discovered what a bass bar and a sound post were from answers to the OP). It would be possible to post fit both.

Like I said I knew nothing when I built this bass, I decided in the confidence of youth that my Hi-tech materials and bowl back design would allow me to get away with a smaller body for ease of transport.
The body volume is halfway between a cello and a DB. So I suppose its no surprise that the frequency response is deeper than a cello but not as deep as a DB. Sounds like a no brainer, but a 25 year old is a 25 year old, and what do hundreds of years of luthiers really know, right. Thankfully, I am not young enough to know everything anymore.
The smaller than standard body is my first call to blame for the dead E. But, I am stuck with it. So I know that really I am looking for a band-aid for a gunshot wound. I would just like to see if I can make some small improvements to the tone, really not expecting miracles.

Empryrean · #2 02-13-2011, 11:11 PM

Hell, it looks pretty damn good to me sir; regardless of the E trouble, I bet it feels pretty damn awesome to play something you've made!

richtea · #3 02-13-2011, 11:19 PM

Quote:

Originally Posted by Empryrean

Hell, it looks pretty damn good to me sir; regardless of the E trouble, I bet it feels pretty damn awesome to play something you've made!

Thankyou, It is pretty cool to pick it up and play knowing that it is all your own work (regardless of how misguided the design).

Andrew McGregor · #4 02-14-2011, 12:33 AM

Well, for a start... cool!

Anyway, you could try for better strings, and a sound post might help too. If anything, the top may well be TOO stiff, so a bass bar might not help. But in any case, change one thing at a time and see what happens.

Jsn · #5 02-14-2011, 01:05 AM

Has anyone told you it looks like a giant rabbit?

(Not dissing in the slightest, just saying I saw it and went whoa: giant rabbit.)

richtea · #6 02-14-2011, 01:12 AM

Quote:

Originally Posted by Jsn

Has anyone told you it looks like a giant rabbit?

(Not dissing in the slightest, just saying I saw it and went whoa: giant rabbit.)

no, but looking at the photos, I can see where you are comming from, lol. Eyes, it just needs the Disney eyes,"Bad Wabbit". That might be cool, at the moment it tends to scare small children and animals.

just looked again, thats it youve ruined it for me. I cant look without laughing now.

tyb507 · #7 02-14-2011, 06:35 AM

No, it looks like the evil rabbit from Donnie Darko!

richtea · #8 02-14-2011, 06:39 AM

now I'm back to scaring small children and animals

eerbrev · #9 02-14-2011, 06:44 AM

Do you have a soundpost? that might help in terms of volume. (Not a Luthier).

richtea · #10 02-14-2011, 06:48 AM

Quote:

Originally Posted by eerbrev

Do you have a soundpost? that might help in terms of volume. (Not a Luthier).

no, there is no sound post, it is one of the things that is on the list to try, I'm going to see what everyone thinks, then work through all the points logicaly.

shadow_FIX · #11 02-14-2011, 07:02 AM

If you're looking to improve unamplified tone, a soundpost and F holes would help out quite a big I think. This is being said from a musician's perspective, who knows nothing about anything luthier related.

Cool bass!! Definitely has the unique factor!

antkiller · #12 02-14-2011, 07:17 AM

really cool! and Nice work...

The first thing I'd try is a different set of strings.. I've owned string sets that lack tone from the E.. If your playing pizz only, there is a wide array of strings to choose from.

The afterlength(distance from tailpeice to bridge) has a direct relation to string tension.The afterlength should be 1/6th of the Scale(nut to bridge). Maybe try en-longing your after length..
Also with out a sound post your probably not getting any response from the back. It should be placed just under an inch below the treble side of the bridge.. Slight adjustments L, R, or up and down will help shape your sound..
Most bridges are Rock Maple, Just make sur its not too thick and absorbing all of the sound before it makes it to the soundboard...

Melik · #13 02-14-2011, 09:11 AM

From esthetical point it looks awesome! From ergonomic point not that awesome..

PaulCannon · #14 02-14-2011, 09:48 AM

Sound post and f-holes. They don't have to be "f" shaped, just needs some holes.

Does anybody on here have experience with the Luis and Clark carbon fiber basses? Do they have sound posts and bass bars? They clearly have f-holes.

**Matthew Tucker** · #15 02-14-2011, 02:26 PM

I think, adding a soundpost might even out the response by muting the higher strings a little, but I don't think it will increase the volume or improve the tone of the E string. A bass bar might spread the energy from the E string across the top plate a little. But I think the problem is that the structure is probably too stiff for good bass response.

I assume those hollowed things at the sides are ports. if so they are way too big for a box that size and so it won't help bass response either. The fact that the edges are thickened doesn't help the top stiffness issue either..

If it came to me I would try tuning the strings down a semitone or two to see if the response improves with lighter tension, then tune it UP a semitone to see if it likes MORE tension. Start with the simplest adjustments.

The other thing is how you play it. It has a flat bridge and fingerboard. Are you playing it like a bass guitar, only upright? With fingertips? To get decent tone out of a double bass it's all about how you pull those strings. Try raising the bridge 3mm and pull really hard on the strings. Does it make a difference?

Andrew McGregor · #16 02-14-2011, 02:26 PM

Yes, Luis and Clark CF basses have sound posts and bass bars. The post is conventional, the bass bar seems to be part of the layup for the top (not exactly integral, as I bet it's a core laid between the laminations of the top).

They have rather wimpy E strings too...

s_mcsleazy · #17 02-14-2011, 02:33 PM

Quote:

Originally Posted by tyb507

No, it looks like the evil rabbit from Donnie Darko!

FRANK THE BUNNY FOR THE WIN!!!!!!!!!!!!!!

chris1125 · #18 02-14-2011, 03:25 PM

Is that thing hollow? If it is a solid piece I can't imagine how a sound post or F hole would work out...

forester · #19 02-14-2011, 04:13 PM

it would sound better if you move two steps left...

almaxwell · #20 02-14-2011, 07:09 PM

Richtea, you've got skills and guts. You made an upright guitar. But without holes in the belly (top), it would probably work better electrically than acoustically. Your top is too stiff to project low fundamentals There are several U Tube videos on carbon fiber string instrument construction, and DB setup. Make another bass; get it right; start a second career/hobby. The best Jazz basses are amplified, so you might thumb thru the hundreds of pickups. Start with the Soundpost.