Thanks, Francois and Nichola.
A sponge seems like a great idea, obvious enough for me to have overlooked it. (Fender and Rickenbacher electric basses I've had in the past came with one form or another of tailpiece string damping.)
... I'd really recommend trying sponge(s) in all sorts of different positions...be brave
I'm not sure how to use compression to decrease sustain though. My limited understanding of compression was that by decreasing the transient volume of the attack it allowed overall volume to be slightly greater and more consistent throught the length of the note, thereby increasing rather than decreasing sustain.
My "understanding" is limited to twiddling with knobs til I get a sound I like... So, I'm not a sound engineer... And I run the risk of getting out of my depth if I explain the "why" of it. But I have engineered most of my recordings. So I have practical experience.
Yes, in the "Loudness Wars, it's true that, compression is mostly used to "compress up"... i.e. to boost lower volume so that it is more detectable, without raising the volume of the loudest element. i..e. "Raising the floor".
But... you can compress down - which has the effect of lowering the ceiling. i.e pushing down the loud bits.
Doing both at the same time creates a narrower band of sound "above X and below Y"
This squished down band of sound in itself doesn't affect sustain, but it does affect timbre. And this can create a more percussive or thumpy feel as opposed to a more tonal or melodic feel. I got a sense from your note (and listening to your tunes... outstanding BTW) - That this is what you were looking for.
In addition, what _does_ affect sustain is how quickly and aggressively these compression effects kick in and kick out. This is the attack and release... the back end is also sometimes referred to as "decay"
Usually engineers are trying for a smooth transition, so that "clipping" doesn't occur, or is minimized. This smooth decay, combined with upwards compression may actually increase the perception of sustained sound. i.e. it increase the perception of those faint lingering tones.
However, in your case, you don't want a gradual effect, you almost _want_ it to clip. So, you can go the other way... Squish the sound (top and bottom) to get your thumpiness ... Use a fairly steep attack (too steep and it sounds like you're coming in halfway through a conversation)... and a really steep decay which cuts off all that lingering subtlety. Voila...
...Anyway, there are probably REAL engineers out there who would develop a nose bleed reading my attempts to explain something that I am not trained for...
Bottom line is that if you twiddle enough knobs, you'll likely find a sound you like. And, it really does seem to me that what you are venturing into is "modeling" your sound rather than revisiting string choice.
There's some info here (including sound samples) which may be of interest... although this guy's emphasis is on slower attack and BIG sound... so it's not the application you'd be looking at, but you will get sense of it.
Link Removed
Cheers,
N
p.s. The free recording/engineering software I use is Audacity:
http://audacity.sourceforge.net/
It's a fantastic (free) way of "twiddling knobs"