The big question -
Is this a true acoustic bass guitar or this an acoustic bass (upright)?

If it's an acoustic bass guitar, take the sound out of the pickup, but supplement with a good mic or two in front of the instrument.

Without question, I'd use the UM70 roughly a couple feet in front and above but aimed down. Do not aim to the middle of the body - the signal you get from the pickup will provide enough low-end, you're looking to get the overtones and the attack of the strings. Aim just below where the neck meets the body.

The distance means that you may have to play a slight time-alignment game with your pickup or the attacks may seem a bit odd.

Take some pictures of this if you can and post them when you're done.

BTW -
If it's acoustic bass (upright), then ignore everything I just said and let us know so I can modify my answer.

Cheers-
J.

This is the way I do it too. We usually have a Martin acoustic bass and micing it with a nice condenser at a couple of feet helps with the sound 'bloom'....lets it develop. Take a DI off the pickups if it has one and send it to a nice fast preamp. I REALLY like the True Systems in this setup both mic and DI.

Hi guys. Thanks both for your excellent suggestions. The acoustic is a true acoustic bass guitar, rather than an upright bass.

I will certainly try the method mentioned with the UM70. I've always had great success with UM70's using in an XY configuration on ordinary acoustic guitar, so hopefully by following the placement method suggested, I will be able to capture the overtones and attack of the strings accurately. (as mentioned i appreciate an acoustic bass guitar is quite a different animal) I'll certainly let you know how it goes and will take a snap of the setup if possible on the day.

Thanks again, much appreciated.

I've had to cope with recording several types of acoustic bass guitars in my travels. The advice given so far is spot on as far as miking goes, although I would probably go in a little more: somewhere between 18 - 24 inches depending on the sound you are getting and how good the pickup is to blend with the mic signal.

One thing I found that made a difference was the phasing of the pickup relative to the mic. There is the usual effect of delay due to distance (1 - 2ms needed on the pickup signal), but also, since most pickups transduce the horizontal string motion and the guitar body top vibrates with the vertical string motion, the pickup and acoustic sounds are inherently 90 degrees out of phase. An all-pass 90 degree phase shifter applied with one eye on a phase display (X - Y of acoustic vs pickup) can clean up the sound markedly. I've tried this technique on normal acoustic guitars as well, but the results there have been very mixed, and usually not worth the effort.

Boswell is completely right in this point.

The last time I recorded one of these instruments I had access to a True Systems P2 Analog mic pre which has the MS metering involved. It was very handy to use even though it wasnt an MS type of micing.It did show the phase relationship between the mic and the pickup and helped with placement a ton.

And apparently, the low frequencies in a setup like this are the ones that smear. I tried it with my Taylor six-string and it showed almost no phase effect whatsoever.