Diagnostic help: Vibration at lowest F

[Rees Chapman]

I drove an hour last night, then wandered a strange town for another hour, waiting to meet up with an ebay seller of a Mathias Thoma MT-1 double bass. Here was the listing:
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Beautiful upright Mathias Thoma MT-1 bass. This is a 3/4 flatback bass with solid top made in Romania. It is a deep, loud boomer if you're playing bluegrass and is has clean, upper end for jazz. I have Obligatos on it because I like their warm bottom. It is about 3 years old, but has not been played out more than 2 or 3 times, just at home mostly. The condition is immaculate. Adjustable bridge makes it easy to set up for any style. Lists at around $4000.00 I payed $2850.00 and selling at a very fair price. Here are a few specs:

Hand Carved of Selected maple back and sides

Selected Spruce Top
Hand Graduated Top
Italian Shape with Violin Corners
Gamba-Style Flat Back
Kolstein Adjustable Bridge
Massive End-Pin
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When I actually saw and played the bass, I was about to buy it ($1800 was the starting bid, and their had been no bidders by the time it closed) when I remembered to slow down, play every finger position of every string, and listen. I started at the high E, and worked my way down to the lowest F.

For that note, and that note only, a noticeable rattling vibration accompanied the tone. Not unpleasant, it seemed to be a higher C note that resonated along with the F; damping the E string caused the vibration to stop, too. We checked all hardware, and found nothing loose; it seemed that adjusting the endpin made the vibration disappear and reappear, but nothing made it stop altogether; it seemed to happen with and without the rubber tip. Holding the fingerboard seemed to stop it with some consistency. Moving around his home, the bass' F rattled on linoleum over concrete and on concrete itself, but seemed OK on thick carpet.

He seemed genuinely surprised, and told me that there had been no such problems he'd noticed before, and no repairs. I'd read of endpin vibrations which bass players utilize deliberately, but I wasn't sure this the same thing. I'm doubting I'd ever notice it playing with my bluegrass band. I said I had been very close to making an offer, but didn't want to buy a bass in which something was coming loose inside. He's agreed to take the bass to a luthier (many hours away) to have it looked at, but that won't happen for weeks.

I'd like some advice: am I overreacting to a minor irregularity, or wisely wary of a problem which could worsen and necessitate major repairs?

[Eric Hochberg]

A couple of thoughts: It could be the string itself, change it and see. Did you play it with the endpin fully extended? If that stops the noise, there's probably too much after-length inside the bass and it can be shortened. If that doesn't work, you really should have it professionally diagnosed as it could be any number of things, some of which could require expensive repairs, such as a loose bass bar.

[Rees Chapman]

>It could be the string itself, change it and see.

Good idea. I'll suggest that.

>Did you play it with the endpin fully extended? If that stops the noise, there's probably too much after-length inside the bass and it can be shortened.

Actually, I first noticed it with the pin fully extended. It also buzzed with it at it's shortest position.

So, I'm waiting to hear about a trip to a luthier.

[Rees Chapman]

I'd like to hear other suggestions. . .

[jfv]

Are you a new player? Cuz half position on the E is difficult
when you first start out, its not inconceivable its you.

Regardless, this sounds like a setup issue, and unless you
buy a bass from a great shop that does such things in the
first place then your bass would need it anyway.

You have a risk, but nothing anyone here says is going to
eliminate that risk, when you buy a bass this way.

You just have to embrace the risk, decide, and act on that.

Good luck,

[drurb]

Originally Posted by jfv

You have a risk, but nothing anyone here says is going to eliminate that risk, when you buy a bass this way.

You just have to embrace the risk, decide, and act on that.

Good luck,

+1!