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Double Bass Luthier ideas please

Eric Hochberg

Eric Hochberg

Jul 7, 2004
6,343
2,457
Chicago
www.erichochberg.com
#1
The feel of one of my basses constantly changes. The strings go from loose to tight and I never know how the bass will respond until I start playing it for the day. I haven't determined a pattern in terms of weather or anything else that might be affecting it in this way. I was wondering if there could be something in it's construction that contributes to it's instability?

If I brought the bass to you to check out, what might you look for?

BTW, sound is not particularly affected. It always sounds good.
 
#3
Yes, I've had a few consults on this with no definitive answers, just ideas on possible things I could do. From the lack of response to this thread, I would say I'm not going to learn much new on the subject. I've concluded that wood has a mind of its own and can behave it unpredictable ways when made into a bass.
 
#4
Here's a suggestion: keep a journal. Note things like time of day, temp and humidity, and what you think the bass is doing at that time. If its possible to take measurements ( even a pencil mark on an index card for, say, string height at end of fingerboard) make note of that with the other info. Note the tuning before you start and when you are finished. Did you end your last practice with the bass in tune and come back the next day to find it a bit sharp or flat? After a while you might see some patterns that could be helpful to know. Best of luck to you!
 
#5
It sounds like you have some wood movement induced by changes in humidity. The most likely culprits are the back, neck and fingerboard. If it is the neck you could try having a carbon fiber rod installed, if it is the fingerboard you could replace that, nothing to do about the back though. 360's idea about keeping a journal is probably the best way to diagnose this problem, I would also include measuring the fingerboard relief and use a long straight edge to measure the straightness of the fingerboard to neck joint.
 
#6
I've suspected for some time that strings might play a role. My cello is strung with two types of strings. The Thomastic Superflexible on A is a roller coaster, and the Dominants on D through C are solid as a rock. Also, my Kay is much more humidity sensitive than my carved bass. I wonder if synthetic strings would help, as it seems that they need more stretch for the amount that their pitch changes.

Oddly enough one of the things I do for my day job is study the stability of instruments -- of the scientific kind. And I have a rule: "Never record data without also recording the temperature." That could apply to humidity too. There are devices that will automatically record temp & humidity. I'll see if there is an affordable one.
 
#7
All good ideas, guys. Thanks. 360, I may take your suggestion. I' know humidity is a culprit in wood movement and this bass can go loose to tight within a set of a gig, I don't know if the humidity changes that quickly around here, but probably. I could bring a meter to my gigs and watch for a correlation. The fingerboard is new and has very little relief. I do think the bass has settled down a bit since I had it installed.

I have used both steel and synthetic strings on this bass and have had both act similarly. I had gut D/G for a time and I don't recall a tight feel while they were on. Maybe something there... Soundpost fit has also been pointed out as a possible culprit, and that of course changes with wood movement. I do know a guy who fiddles with his post almost daily, but I don't want to go there...
 
#8
Hmmm... there are a couple of temperature / humidity loggers available for under 100 bucks. I might just get one and try it out. My kids are always interested in this kind of stuff, and with the number of string instruments in the house, 100 bucks is probably cheaper than the risk of a trip to the luthier.

Chicago... I'm betting that the humidity swings all over the place. For one thing it changes with temperature.

All high-end DB's should be sent to the Midwest for a trial period before being sold to the customer. ;)
 
#10
Eric Hochberg said:
All good ideas, guys. Thanks. 360, I may take your suggestion. I' know humidity is a culprit in wood movement and this bass can go loose to tight within a set of a gig, I don't know if the humidity changes that quickly around here, but probably. I could bring a meter to my gigs and watch for a correlation. The fingerboard is new and has very little relief. I do think the bass has settled down a bit since I had it installed.

I have used both steel and synthetic strings on this bass and have had both act similarly. I had gut D/G for a time and I don't recall a tight feel while they were on. Maybe something there... Soundpost fit has also been pointed out as a possible culprit, and that of course changes with wood movement. I do know a guy who fiddles with his post almost daily, but I don't want to go there...
Click to expand...

Its possible that if the sound post fit was say, just a hair tight at high humidity, then when it got drier it might be too tight. Or vice versa. Keeping track of the temperature and humidity will help make sense of the situation and lead to the solution. That was a great suggestion.
 
#14
If your neck block is part of the problem it would probably mean something is loose, from what you've described I don't think that is likely. Neck blocks are usually made of spruce which is a very dimensionally stable wood, plus the orientation of the grain of the block prevents any movement that might happen from effecting the neck angle.

I asked if the bass was a round back because round backs are more likely to have these kind of problems. The arch creates a situation where the back can shrink and expand along its length, pushing and pulling on the back of the neck heel and therefore messing with the neck angle and feel of the bass.

You might observe this problem in the middle of a gig because of humidity difference between your house and the venue, it should take a few hours for the wood to soak up/ dry out. I don't think this kind of thing happens in a matter of minutes, but stranger things have happened.
 
#15
uprightben said:
I asked if the bass was a round back because round backs are more likely to have these kind of problems. The arch creates a situation where the back can shrink and expand along its length, pushing and pulling on the back of the neck heel and therefore messing with the neck angle and feel of the bass.

You might observe this problem in the middle of a gig because of humidity difference between your house and the venue, it should take a few hours for the wood to soak up/ dry out. I don't think this kind of thing happens in a matter of minutes, but stranger things have happened.
Click to expand...

Makes sense, thanks!
 
#16
if you brought the bass to our shop, we would first check the neck to make sure that there is no movement. If everything seems to be intact, then we would check the tension of the strings produced by the set-up

We had a bass in once that responded like yours. New strings, a higher saddle and shortened the afterlength by an inch(from 6 to 5). all of which seemed to even it out. This was a small 3/4 French. Not sure if all of them contributed or helped, but i suspect that the higher saddle did the most.

Humidity is always an influence on the sound of the bass.
If there are some changes in the wood, which seems to be the case here, then maybe changing the tension on the wood might stabilize the sound some.
 
#17
Eric Hochberg said:
The feel of one of my basses constantly changes. The strings go from loose to tight and I never know how the bass will respond until I start playing it for the day. I haven't determined a pattern in terms of weather or anything else that might be affecting it in this way. I was wondering if there could be something in it's construction that contributes to it's instability?

If I brought the bass to you to check out, what might you look for?

BTW, sound is not particularly affected. It always sounds good.
Click to expand...

This is an interesting dilemma , and possibly a 'psycho acoustic' one.
I have had the exact same issue as you describe. I set up my bass to exactly what my ideal is , but also constantly go through the dilemma that the feel of the instrument changes .

Then a couple of weeks ago I was in my main rehearsal room wondering why my bass felt tighter and that perhaps that the neck camber was increasing due to weather or simply due to the neck not being strong enough.
Then I started playing in another part of the room and my bass felt like I knew it should .
In my situation I realized that maybe the bass was not really at fault but simply the acoustic environment was influencing my perception of what my instrument should sound and FEEL like.
Its so much more relaxing and easier to play in a great sounding space than say for example outdoors where ones acoustic sound can seem so small.
So it got me thinking that maybe I am imagining problems with my bass simply because I am subconsciously trying to over extend my technique to 'pull' the sound out of the bass when I'm in a less that perfect acoustic place.
Maybe its worth trying playing your instrument in a totally dead room and then in a nice live space ....? :)
 
#18
Gene Fryer said:
We had a bass in once that responded like yours. New strings, a higher saddle and shortened the afterlength by an inch(from 6 to 5). all of which seemed to even it out. This was a small 3/4 French. Not sure if all of them contributed or helped, but i suspect that the higher saddle did the most.

Humidity is always an influence on the sound of the bass.
If there are some changes in the wood, which seems to be the case here, then maybe changing the tension on the wood might stabilize the sound some.
Click to expand...

Well, I've tried all of these tweaks. Shorter after length had a subtle effect, the raised saddle didn't do much of anything.
 
#19
bassedsouth said:
This is an interesting dilemma , and possibly a 'psycho acoustic' one.

Maybe its worth trying playing your instrument in a totally dead room and then in a nice live space ....? :)
Click to expand...

I think this is an interesting and valid point. When ever I play in a bass friendly room, or certain area of a room, and can hear the instrument well, including the low end, it allows me to play with more ease as I'm not trying to coax sound out that just won't.

In my current situation, I'm playing daily in the same room, relying mostly on amplification. Sound pretty much stays the same but feel changes.
 
#20
Eric Hochberg said:
The feel of one of my basses constantly changes. The strings go from loose to tight and I never know how the bass will respond until I start playing it for the day. I haven't determined a pattern in terms of weather or anything else that might be affecting it in this way. I was wondering if there could be something in it's construction that contributes to it's instability?

If I brought the bass to you to check out, what might you look for?

BTW, sound is not particularly affected. It always sounds good.
Click to expand...

I would check out the finish on the neck heel, as well as the orientation of the annular rings there. I wonder if the finish is a bit permeable, and if the end grain might be soaking up and/or releasing moisture faster than normal. Neck heels are all end grain; think of the science experiment most of us did in elementary school, where you put the end of a piece of celery into colored water. The color travels right up the celery stalk. It could not hurt to have a few coats of oil varnish applied to the neck heel.
 

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