Double Bass Need 190mm width bridge!

[bshaw]

Hi,
Have not been having luck finding a bridge with a width of 190mm and so am reaching out for help! Despau (sp!) sent their widest, which was not wide enough; Robertsons said they have nothing in the ballpark, Teller in Germany seems unresponsive to my luthiers requests.

Am trying to have the bridge feet sit appropriately on the top table for best sound and response; currently, the bridge bass bar side does not reach the bar, never mind sit on top of it.

Any ideas or direction would be sincerely appreciated!

Thanks!

 

[SAlcott]

Have your luthier contact some of the other shops-Gage, AES, Cincinnati Bass Cellar, etc.

 

[bshaw]

I believe they've already tried a few other shops, even made inquiries at Ithaca / ISB convention. Apparently this width may need to be custom made / is not a stock item most shops can order. Thought I'd reach out to TB community for help, thanks for your post!

 

[1st Bass]

Would your luthier consider buying a billet of plane-tree sycamore, and making the bridge from scratch? There is no rule that says it has to be from one of the bridge suppliers...

 

[bshaw]

I'll ask them, that certainly hasn't come up as an option! They may have concerns about getting high quality wood. The bass itself is a big old Italian job from the late 1700s.

 

[1st Bass]

Well...the point, of course, is that all those bridge manufacturers begin with wood, too. Very hard, perfectly quartered sycamore, I think. Some sort of treatment is probably made, though that seems to be cloaked in a bit of trade-secrecy. It would certainly be feasible, and it is what I would do...but that is just me. I know that the master bridge-makers are better at it than I will ever be, so, if I can get a blank for what I need, I will go that route.

 

[Ortsom]

... but if you can't find one, you'll make it yourself.

If no suitable standard blank can be found for the dimensions of your instrument, it just means a dedicated model has to be hand-carved, to fit the instrument. That can be done: it doubtlessly was done originally. It just takes time and that makes it a bit more expensive. But what's the alternative?

The bridge should probably also be placed a bit further down than shown in the pic.

 

[1st Bass]

Please do start with wood cut perfectly on the quarter, so that the medullary rays are parallel to the side of the bridge toward the tailpiece. But I expect that your luthier already knows that.

I am curious as to why the bridge is so far north, though...?

 

[bshaw]

Thanks 1st & Orsom!
To clarify, on this bass the bridge is placed to have a string length of 42.5" and keep a gated low B extension in tune. There are old markings on the bass showing bridge placement all the way from 41.5" to 44.5", so the bridge has lived at different locations in its life. I personally found 42.5 to be most accommodating for both sound and playability.

 

[jmpiwonka]

can we see some other pics of the bass? is quantum doing the work on the bass?

 

[bshaw]

Here (I think if this goes through from my phone) are some pics.
And yes, Quantum Bass Center in Houston will be fitting a new bridge....again, if I can find / make / build / buy one with a 190mm width!

 

[Ortsom]

Thanks for showing those pics.

To me, this does appear to be a non-standard & uncommon instrument. The f-holes seem to be further south than commonly, compared to the outline of the instrument.

Please forget my remark on bridge placement; that was based on what I saw of the f-holes only. But based on the outline of the instrument, the bridge might even have to come further north. So offhand I don't know where the bridge should best be placed on this instrument. Suggest trial & error, as has apparently been done over the last 200+ years. And if you like this 42.5" scale best, that's what it should be then.

Yet it still makes sense to have the E-foot of the bridge sit on top of the bass bar, and be otherwise largely east/west symmetric. So: the bridge should still fit the instrument proportions. And with non-standard instrument proportions, that may not be adequately achieved with a standard blank, in which case making a dedicated bridge is required.

That would be the common approach, and my first preference. But it is possible you can achieve good results on this instrument with a non-symmetric & narrower bridge. That would then still sit with the E-foot over the BB, but the G-foot (& SP) would then be more towards the centre, and the bridge crest would lean towards the G-side (to still position the strings properly over the FB). The G-foot would then carry substantially more load than the E-foot, which increases the risk of an SP crack (the flatback bracing is probably strong enough?). Then you could probably use a standard bridge blank. Nevertheless, that would not be my first preference: mediocre chance on success (and with dubious success you would still want to try making a dedicated symmetrical bridge), and a bit risky.

And maybe another compromise is possible. What does your luthier advise?

 

[bshaw]

Hi Ortsom,
Thanks for your reply, I should have posted a complete picture of the instrument earlier. What my luthier is suggesting we do is reach out to find someone who is able to custom create a bridge for the bass, as even the widest commercially available blanks aren't sitting optimally on the top table. Teller in Germany said they could do it, but then have become unresponsive for some reason. Just thought I'd reach out to the TB community to see if anyone might have leads to a modern maker who may be inclined to custom carve a bridge.
The bridge currently on this bass works, and the instrument sounds well, but we believe it's just not at it's full potential.
Thanks!

 

[Ortsom]

Sounds like a good plan.
Sorry, I can't help you. Though I've made several bridges, I'm not commercial, far away (Belgium), and have no suitable wood.

FWIW, I start by drawing (hand, pencil & eraser) the bridge outline on paper. This design stage is probably the most important part of the process; to a large extent the bridge outline determines the acoustic/strength/stiffness aspects of the bridge. You can verify symmetry by folding the paper, & adapt as required. Then cut out the edges & use the paper as a template onto wood.

Wood as 1stbass says, quarter-cut face to the TP, and the outside of the tree pointing towards the back (so that you'll also get a quarter-cut face pointing to the FB). I like to start off with a rectangular piece of wood, a bit thicker than the bridge feet, so that you can more easily cut out the shape perpendicular to both the top (later sanded to shape on a belt sander, to point to the FB) and the back (to largely remain unchanged, to point to the TP). The belt sander only comes into action after I'm satisfied with the outline shape (and here that can include the feet/soles). Then the bridge gets thinned to the desired thickness @ the feet, and only then the bridge gets it's wedge-like shape, as seen from the side (the FB-side is not necessarily flat, the TP-side is). Then finish the crest (leave spare initially) & string notches, adjusters (?), and finish the surface as desired (v. fine grid, scraping). Others may do it differently (please share).

Hope this helps in any way.

 

[james condino]

Cool old bass.

Contact Despiau directly and they will sell you a massive rectangular uncut bridge blank- just a hunk of wood with no basic shape milled out. If your luthier gives you an excuse about not being able to make one from that, then find another luthier. It is not that complicated.

 

[Matthew Tucker]

FWIW, In my experience a bridge that wide is just as likely to shut down the bass as it is to work properly. There are many large basses with widely spaced Ffs that work beautifully with narrower bridges. including the huge 1550 DaSalo bass in the poster.

 

[bshaw]

Hi Tucker,
Thanks for your note. I think results would be speculation at this point, but based on feedback I've received from people much more knowledgeable than myself, a wider bridge is certainly worth trying. The bass sounds great as is, I just want to see if it can be improved.

Also, thanks James Condino, I will check this out with the shop--(working with the wood hunk). Quantum Bass Center has been great to work with and I'm so glad to have a bass shop right in my city! BTW, I think you may know Taka Moro? He just did an amazing job on a Fender Jazz (ugh--wrong forum, wrong everything) for me. He spoke very highly of you and I'm sure he'd want me to say "hello".

 

[Ortsom]

Ffs? Is it not so that the ff's are rather irrelevant, and that the BB drives the width of the bridge legs? Coupling E-foot to BB?

I agree that if the width/height ratio increases, the instrument tends to become less responsive to lateral string vibes (as in arco & jazz pizz), yet I presume that bridge height & BB placement are a given here. So indeed, too wide a bridge may make the instrument less responsive (and more guitar-like), that's what I hinted at with 'maybe another compromise is possible'. Maybe a bridge whereby the centre of the E-leg is approximately above the inside edge of the BB would be optimal in this case. I dunno, trial & error.

So far, I have only ever placed the centre of the E-leg roughly above the centre of the BB, but of course there is a bit of freedom there. Matthew (or anyone else), do you have experiences to share on placing the E-leg offset wrt the BB? That would be quite relevant for the OP.

 

[Matthew Tucker]

As the bass bar is firmly attached to the top, and therefore moves as one unit in the region of the bassbar, i believe the placement of the bridge foot relative to the bass bar is less critical than some people believe. It is rarely possible to place the bridge foot exactly centred on the bar unless the bar is too far inwards, or the bridge is too wide for the FFs. I think the placement and thickness and shape of the bassbar has a far more significant effect on sound. The bridge must of course be of a reasonable width and height to pump the bassbar side of the plate efficiently, but unless the plate is too thin and flexible, anywhere near the bassbar is probably good. I don't believe that the foot must always be centred on the bassbar. To optimise the pumping effect of the bass foot, its position relative to the soundpost is probably more significant, and I believe some flexibility in the toes of the bridge on the treble side particularly is a good thing too.

 

[Ortsom]

Sure there is some freedom here. Tap the top in the region of interest & hear the range of tap tones as a result of where you tapped it. This works both (and same) on a free top + BB, as well as on a complete instrument w/ strings (but I only tested this with instruments with the E-leg right on top of the BB). I would want the centre of the E-leg to be roughly in the centre of the region where the tap tone is fullest & strongest.

A thicker top gives you a wider region, and on a thin (solid) top there would be more structural risk associated with offset placement.

In my perception, ff's, or cc's [so Gamba-like sound holes looking like: ) ( ] have nothing to do with it. It's just where the brace is on the inside, probably in combination with the arching, which drives the location of the sweet spot. While a much offset BB would commonly be associated with wide ff's, the opposite is not necessarily true (wide ff's do not necessarily mean a much offset BB).

I don't know where BB's are most frequently placed (you have seen many more instruments than I have), but in my limited experience it has never been a problem to place the E-leg quite reasonably centred above the BB, also with standard 3/4 bridges. Of course everyone can easily see in his own instrument (just feel the BB with your finger through the upper eye of the E-side f-hole).

So I think there is a region of E-leg placement, and indeed, if this region is far from the centre, that could necessitate a bridge with an undesirably high W/H. That could be a reason to stay a bit towards the inside of the region, with a narrower (standard) bridge. That may be where the OP currently is. But I too would at least want to try a bridge with the E-leg centred in that region (but for me a bridge is cheap).