Double Bass Aluminum Bass Build

[InReds138]

Hello everyone. I am building a welded aluminum bass in the upcoming month or two or five and would like your opinions on so many things. I have never built anything like an AAUB but have an extensive metalworking background. I have done lots of repairs on my old and long gone Jim Laabs Vienna, as one would expect, using hide glue on split seams then resetting the sound post etc.

I purchased life sized blueprints of a 3/4 Matteo Goffriller bass. I plan on using these dimensions but with lots of structural designs of the 1929-1930 Alcoa of which I have only seen pictures of as well as that repair video on YouTube. You know the one.

I'm really excited to see what questions can be answered from you guys. I don't mind a little trial and error either which is equally exciting. I will throw in some fun/dream stuff too. Here we go.
- What thickness or gauge was the material used? I am guessing it's over 1/16th but under 3/32 so that would be about and 14 or 15 gauge. I could be way off though.
- Is the bass bar the same thickness material as the top and back on the Alcoa?
- Would welding the sound post to the top and back as opposed to setting it benefit or inhibit vibration? Welded aluminum or set carbon fiber?
- Do you think completely polishing the inside and getting rid of surface imperfections could allow for greater vibration or would it be a waste of time?
- Rip off Alcoa and not completely cut out the F holes or keep it traditional?
- I should probably splurge on the Sloane machine tuners right? Right? Hopefully they are available when the time comes.

This will take a while to complete. I expect most of the time will be spent on the neck and scroll since I will have to fabricate it all by hand with no access to milling equipment. I will post pics as this monstrosity unfolds. Thanks for any responses, answered questions, or ideas. Cheers!

 

[birgebass]

Well, I know nothing about aluminum basses really, but as a player I don’t think I would ever want a sound post that was not adjustable. Sorry man, that’s really all the advice I got. Good luck on the build and take pictures lots of pictures for us!

 

[RSBBass]

A couple of things, Alcoa wasn't the only company to make aluminum basses. Pfretzscher, a German company, also made them. They followed more traditional bass design, using aluminum for the the top, ribs and sides but having a wood neck and bracing. Although the Pfretzscher have a reputation for being a bit bette than the Alcoa, neither is known for the sound quality. You may want to let us know what your goal in making one is.
I am very slowly restoring a Pfetzscher. If you are interested I can measure the gauge of the metal. Be aware that the formulation of aluminum has changed since before WWII and the gauge may not be applicable now. I doubt that polishing the interior would have a noticeable impact on the sound.

 

[InReds138]

You may want to let us know what your goal in making one is.
I am very slowly restoring a Pfetzscher. If you are interested I can measure the gauge of the metal. Be aware that the formulation of aluminum has changed since before WWII and the gauge may not be applicable now.

My goal is to make an upright that isn't susceptible to cold, heat, or dry conditions. I want to make it as best as I can with the materials stated for a decent sounding bass. It's a challenge and has the cool factor for me. It will have magnetic pickups and be in a loud metal band on stage at times as well as on recordings. It will be tuned to low B standard but will switch out the nut and bridge and go back to EADG often. I plan on using T6061 aluminum. I would be grateful if you got a measurement for the Pfetzscher top material. Thanks very much.

 

[RSBBass]

I will be happy to measure it for you. It is in storage but I will be there this week. I suggest you get in touch with James Cordino, who is the resident expert on aluminum basses here on TB. I also would suggest that while they aren't impervious to heat and dry conditions, plywood basses can take a fair amount of variation in temperature and humidity. Aluminum in my experience becomes very unpleasant to play when it is hot or cold.

 

[james condino]

Matt: I received you message.

Feel free to give me a phone call and we can nerd out on your project and I can offer some perspective and also give you all of the engineering specs that I have extensive notes on in terms of alloys and thicknesses and how the produced the ALCOA necks. You might also want to communicate with a fellow in Australia who goes under the commercial name of Alley Cat basses. He makes a limited production of aluminum double basses as well as a few electric guitars and such.

 

[Don Hergert]

^^THIS^^

@james condino has seen and handled more Alcoa and Pfretzscher DBs than probably any other living person. If you're in contact with him, you're in contact with The Source. Most of us who own Alcoa DBs only know a little about our own and what has been done to them individually to make them playable. In addition to repairing, setting up and playing lots and lots of them, James has seriously researched about just about every detail related to these unique instruments

A couple of general things...

I'm sure James can also discuss this with you, but tone is an big consideration with these instruments if you're wanting something that sounds like wood. Mine has been powder coated on the outside and treated with acoustic textured paint on the inside back, both which significantly reduce the "normal" steel trash can tone of these instruments. That and synthetic or gut strings helps a lot...

On the other hand, any of this kind of tone adjustment to an aluminum double bass is going to really be muting them in some way. If you play them as is, especially with the right kind of steel strings, their metallic low voice will carry for miles -- they are literally sound cannons.

Also, I would 2nd @birgebass's recommendation for an adjustable sound post (I've got one on my Alcoa), and I'd also highly recommend some form of access port so you can easily adjust the sound post and other things inside -- in addition to possibly reaching an attachment mechanism for a removable neck, which is one of the things I really admire about the AliKat double basses that James referred to. (I'm assuming the AliKat wooden neck is removable since there's an access port on the driver side upper bout right near the neck joint.)

Good luck with this project, the concept is great!

 

[james condino]

For a bit of inspiration:

 

[InReds138]

^^THIS^^

@james condino has seen and handled more Alcoa and Pfretzscher DBs than probably any other living person. If you're in contact with him, you're in contact with The Source. Most of us who own Alcoa DBs only know a little about our own and what has been done to them individually to make them playable. In addition to repairing, setting up and playing lots and lots of them, James has seriously researched about just about every detail related to these unique instruments

A couple of general things...

I'm sure James can also discuss this with you, but tone is an big consideration with these instruments if you're wanting something that sounds like wood. Mine has been powder coated on the outside and treated with acoustic textured paint on the inside back, both which significantly reduce the "normal" steel trash can tone of these instruments. That and synthetic or gut strings helps a lot...

On the other hand, any of this kind of tone adjustment to an aluminum double bass is going to really be muting them in some way. If you play them as is, especially with the right kind of steel strings, their metallic low voice will carry for miles -- they are literally sound cannons.

Also, I would 2nd @birgebass's recommendation for an adjustable sound post (I've got one on my Alcoa), and I'd also highly recommend some form of access port so you can easily adjust the sound post and other things inside -- in addition to possibly reaching an attachment mechanism for a removable neck, which is one of the things I really admire about the AliKat double basses that James referred to. (I'm assuming the AliKat wooden neck is removable since there's an access port on the driver side upper bout right near the neck joint.)

Good luck with this project, the concept is great!

I saw some pictures with the access door cut in the side of an AAUB and I was apprehensive because in my brain I assume that it would take away from vibration in some way. Maybe I will add this next to the end pin. Although having it at the C bout makes sense structurally speaking.

"they literally sound like cannons". In the bands that I play in this is ideal. That sentence alone reinforced my decision to proceed 10 fold. I want this thing to be obnoxiously loud. I will use the heaviest steel core strings I can find. I am looking at Thomastik Spirocore Stark since they make a low B. If possible I will even drop tune the B down to A. If anyone knows a heavier gauge steel core string please shout it out. Obviously the lower register is super important in this build.

AliKat does fantastic work! He's super inspiring. I will definitely hit him up.

I may have it powder coated in clear if that will bring in some warmth. A removable neck is appealing but not necessary. I will have to do some thinking in regards to that. I am not opposed to attaching a wooden neck. What are your thoughts on tonal and volume differences between wood and aluminum?

 

[marcox]

I own both an Alcoa and a Pfretzschner aluminum bass. The Alcoa was an impulse buy 10 years ago and has never been played regularly. After initially trying weedwackers (what a joke!) to tame the metallic tone, it's been wearing Helicore Pizzicato strings. It sounds like an upright bass with a built-in reverb tank.

By contrast, the German bass was the previous owner's daily driver, with a killer setup by Williams Violins in Nashville. It's wearing Evah Pirazzi Gold/Slaps, which seem to be a great match. They're my first satisfactory experience with nylon core strings and I'm loving the lower tension (coming from Spiro Mittels). The bass sounds like an upright bass with a slightly metallic tone.

While I don't doubt the tone of the Alcoa could be improved with more string experimentation, or the modifications @dhergert mentioned, my personal experience is that the Pfretzschner's sound is warmer and more pleasing.

 

[Don Hergert]

I saw some pictures with the access door cut in the side of an AAUB ...

If it's my Alcoa that you were looking at, don't judge all access panels on aluminum double basses by how mine looks -- my whole Alcoa was functionally restored by a dune buggy / sand rail specialist -- really, and it looks like it. Don't get me wrong, I really like my Alcoa and it has its own charm, but tasteful really isn't the way I'd describe it. Mine has been hot-rodded in just about every way, and as it stands it has more the look of a steam-punk Dali/Picasso creation. I've seen some very very tastefully done access panels in aluminum double basses, in particular the AliKats. And while I haven't seen any Alcoa or Pfretzscher access panels that James has installed, I bet that if he were to do an access panel on an aluminum double bass, it would be extremely functional and extremely tastefully done.

... I will use the heaviest steel core strings I can find. I am looking at Thomastik Spirocore Stark since they make a low B. ...

Yup, Spiros were what I had in mind when the word "cannon" came up. I'm using Innovation SilverSlaps EA and SBW Deluxe medium DG and for my mostly acoustic playing they are great for tone and touch. Volume-wise they are fine for acoustic bands and jams, but they are definitely quieter than Spiros would be. But I can plug in with either a mounted piezo/pre-amp system or a mounted mic anytime I want to, so volume isn't a big worry for me most of the time.

I may have it powder coated in clear if that will bring in some warmth.

Not that I don't like my Alcoa's powder coat, but it isn't a piece of artwork in the sense that James' (or other peoples') mirror hand-polished beauties are. From a tone standpoint it's hard to estimate how much my powder coat warms things up, especially since my Alcoa has other more seriously dedicated provisions for that.

Powder coat is a nice, very hard, very thick, very long lasting plastic-like finish that adheres well to aluminum, and my Alcoa never gets uncomfortably hot in the sun because of it. But if you chip or ding up a powder coat finish, it's nearly impossible to touch up to a point of being unnoticeable, so there's that. The powder coat process is very specialized and complicated, so I would not recommend trying to do a powder coat at home, especially on something as big as a double bass. Having studied up on it, I'd take it to a powder coat specialist, there are lots of them around.

On the other hand, a mirror hand-polish job would be a constant thing of beauty that everyone who sees it will marvel at. It also won't chip off, and it will leave your aluminum double bass completely un-muted. It may require polishing touch-ups every year or so, depending on the climate that you live in. And it will get hot in the sun, so you'll want to watch that, especially if there are any glue-to-metal joints involved, since many glues let loose at about 130°F.

... I am not opposed to attaching a wooden neck. ...

If I were capable and interested in making my own welded aluminum double bass, I'd strongly consider a removable wooden neck. While they are really striking to look at, the necks on Alcoas have proven to be their Achilles heel; in their stock conditions they tend to have internal support structure failures that allow bending of the aluminum neck. Mine had this problem; it has been fixed pretty permanently with a relatively crude steel pipe running inside the length of the neck so it isn't a worry for me, but stock Aloca DB necks should be looked at very carefully to identify if this problem exists. And, there's nothing like the portability of a DB with a removable neck. I drool over those all the time.

As mentioned before, your time talking with James will probably be worth more to you in planing than any advice that I can provide. He's a great resource!

 

[InReds138]

I just spoke with James today. I will now refer to him respectfully as Condinopedia. He's incredible at explaining things to a novice. He is really open minded and thinks outside of the box on a few of his own projects. I agree that he's a great resource.

After about 20 seconds of talking about removable necks it is a must now. With a standardized neck pocket you can replace or swap out necks in the future. Just the option to play around with different woods is appealing plus the obvious increase in portability is great.

On the subject of powder coating or not: I am leaning towards a slightly brushed look without powder coating. Clear seems to be about the worst choice because it will yellow in time as well as be a nuisance in the case of repairs on the aluminum. Clear coating for the sake oxidation is not necessary. An access port is happening, flat plate for the sound post to sit, gussets for the end pin, extra bracing around the neck pocket are about the only additions to the blueprinted measurements. I will figure out the edges once I start on them but pounding it out with a hammer is what comes to mind.

At this point I will wait for the prints to arrive, order the sheet aluminum, and keep researching. Thanks for all of the input especially Mr. Condino. Standby.