main indications of a sound post being too tight

Visually, the upper wing on the f hole may be higher than the surrounding top.
An A string than is hard to bow and wolf tones may indicate a tight post.

 

I have a theory that seems to work for best tone and volume on my bass, that if you're using low-tension strings you need a slightly higher-tension soundpost (or soundpost setting if yours is adjustable). And the corollary would be just the opposite, that for high-tension strings you need a slightly lower tension sound post.

Although my bass is somewhat of an aluminum oddball, because it has a trap-door for access and an adjustable sound post, I have been able to test this quite a bit... But I just don't know if this theory also applies to wood basses. (Of course then weather comes into play and can change everything.)

Has anyone had any similar observations regarding a relationship between string tension and soundpost tension?

 

It makes sense that higher tension strings, since they give more pressure on the top, need a shorter soundpost to have a similar pressure on the soundpost that lower tension strings have with a longer one.

 

My impression is that with a (too) tight soundpost the strings feel like having more tension and beeing stiffer. The tight soundpost - light strings theory seems to make sense, but I am absolutly not sure about that. I´m afraid you have to give it a try. An experienced person can tell you if it´s maybe too tight when trying to move the soundpost.

 

The most obvious sign of an overly tight post is bulges in the top and back, but that’s mostly a plywood thing. Plywood is floppy.

If you drop the bridge, put the bass on its’ back and jostle it, and the post doesn’t fall over, it’s too tight.

If the bass sounds choked and lacks low end, the post is probably too tight.

 

My Bass sounds best when the top is raised about 2-3mm/0,1" by the soundpost. It definitly won´t fall over when the bridge is droped. I´d rather say if the soundpost will fall over it is too loose. I know that opinions on this are different, but this is my experience with my instrument, and I did a kind of test series over several years to find the best soundpost setup. My main indicator is how much effort it takes to move the soundpost using a proper soundpost setter. This is based on experience, hard to tell from the distance.

 

@Matthias Hacker, just so we can get a broader sense of your instrument's setup, would you be able to tell us what tension (or what kind of) strings you use?

Thank you!

 

Of course, though that might not help much to answer the question if the soundpost might be too tight. I´m playing Presto Balance Orchestra Light right now. Those might be the best hybrid strings I played so far, but time will tell. 3 weeks on now. And cheap!

 

https://contrabassconversations.com/2016/12/16/287-bill-merchant-luthier-chat/

Bill talks about the relationship of post tension and top thickness.

 

This starts to get interesting at around 12min. He definitly likes to set the soundpost really loose. I´m far away from saying this is good or bad, I am more surprised how much opinions on this subject do vary. I´ve seen experinced and well known luthiers setting a soundpost into my bass with much more tension than I would dare to do. Maybe the best way is to get an adjustable soundpost, so it´s possible to find out what suits the best, depending on the thickness of the top, the strings and what ever. Plus those adjustable soundpost have movable "endpins", which will garantee a perfect fitting, no matter how humid or dry the weather is. I guess thats the greatest advantage. And a general problem with traditional soundposts, imagine you have a perfect fitted soundpost, now you put the bridge and the strings back on and tune up. Will the top move under the tenison? Yes of course, not that much, but it will. The perfect plane fitted soundpost will than only have contact towards the bridge, there will be a gap between the "southern" soundpost surface and the top. Not good. I´ve seen that quite some times.

 

Fit is an interesting soundpost sub-topic. Before I acquired it, my Alcoa had some major welds and patches applied to repair an abuse-related crack on the treble side of the top plate. The occasion of these repairs was also when the trap door was installed on my Alcoa. These welds left the underside of the top plate very uneven and rough, and frankly not as solid looking as I would have liked.

Concerned about protecting the top plate, I put together a "Virzi-style" soundpost with the thought of spreading the soundpost tension over a wider area of the top plate: I carved out a robust rectangular sheet of aluminum to use as a platform, put folds in it to support tension without bending, put initially 6, later reduced to 4 individually adjustable-length wooden (ash) feet on it and set it up with a long adjustable-length oak dowel which reaches to the back plate. Then I set the length on each of the feet based on the uneven top, and set the length of the oak dowel to reach the back plate.

Clearly the presence of the trap-door on my Alcoa has provided the opportunity for me to experiment and install this unique type of sound-post and I've been thankful for that.

The platform and feet spread is wide enough that this soundpost's support is actually supplied under both bridge feet, so there are some interesting new things to consider related to tone. I've adjusted the soundpost total length a few times, starting with a loose enough fit to allow slipping around easily, to now, a tight enough fit that it doesn't move easily at all. I've been using the same low-tension strings during this whole period, so my length testing related to tone and volume has remained consistently reliable.

The current tight setting is producing the best acoustic volume and tone that I've heard with this bass. Where I had been concerned about being heard without an amp with the primarily acoustic bands that I play with (banjo, mandolin, multi-guitars, piano, etc.), since adjusting the soundpost tight, I'm getting heard very well among 3 to 5 other acoustic instruments, even including piano.

So I've been very pleased with this tight soundpost setup... And this is the reason I've been wondering about others with potential soundpost tension / string tension related experiences.

 

Might be the position as well. A bit south might loosen the feel and reduce a bit of percussive attack. Maybe both, position and soundpost tension.

 

Moving the post in toward the centerline is pretty much the same as shortening it, unless your bass is VERY sensitive to placement, and it’s reversible.