I've been looking at acoustic bass guitars lately. As such I've tried a few recently, and have some questions!
My interest lies in getting a bass that sounds a bit like an upright, but is a lot smaller than a real upright. It would be used sparingly in my collection!
Getting into ABG territory can be tricky, especially once you have some tonal qualifiers on your mind already.
To elaborate, take the phrase 'sounds like upright' - then go listen to Paul Chambers, then Ray Brown, then Niels-Henning, and ponder for a moment exactly
what that means. One instrument with the same set of strings isn't copping all of those different tonal profiles.
There's a heck of a lot more variance in the tone of different ABGs than there are with solid body basses. Relatively speaking, a P Bass is going to sound like a P Bass. Not so with acoustic basses. There are a number of different designs from different builders, some which may suit your needs better than others. Due to the organic nature of wood and the greater degree that resonance/vibration of said wood plays the the tone of an acoustic instrument, there also is often some small variance in tone even among different builds of the same make and model of an instrument.
String choice is of primary importance with any ABG. In your case, flats or tapes will likely get you much closer to your goal than phosphor bronze.
Of the fretless ABGs I've been fortunate to try, three have really caught my ear:
The Breedlove solo. Really nice tone with flats and a pleasure to play unplugged with the side sound hole. Also relatively affordable at under $1K. Unfortunately for me the balance put the neck too far out for me to play comfortably for any extended period, which sadly was a deal breaker.
Rick Turner Renaissance. Great tone, plays very easily with the ultra-low tension Acousticore strings.
Rob Allen MB-2. My current ABG. I am a big fan of the tone, simplicity of controls, playability, and balance - the bass hangs more like my solid body basses than most other ABGs I've played, which becomes really important to me on the later part of a long gig.
If I could give two additional bits to ponder:
1) Finding the right ABG is a trial and error process, both with finding the right instrument as well as the right set of strings. You will likely have to try many, and perhaps own and flip a few. The MB-2 I have now was not my first venture into this tonal realm, but I'm glad I stuck it out to find an instrument that is satisfying to play.
2) Ultimately an ABG is going to sound like itself and nothing else. It's not quite a slab, not quite a DB either. Others may disagree, but as someone who plays both BG and DB I am of the conviction that trying to get a bass to sound like something it is not is only going to lead to disappointment. The best designed ABGs may get close to the DB sound but as of today I have never heard or played one that made want to put my Shen up for sale.
I do hope, though, that on your ABG journey you will find a new, different sound that fills a niche for you.