For recording double bass, it makes a big difference whether you are talking about recording concert performances, live studio (all performers playing in the same acoustic space) or studio with performers in separate rooms.

My performance recording technique changed for a lot of instruments of this type when I got a some DPA 4099 microphones with mounts for a number of different instruments. The B mount is the appropriate one for double bass. I had originally thought that this would work only for stage use, but actually the sound for solo recording is really good, and, to add ambience, it can be mixed with either a spaced omni pair at a few feet away or be used as the M mic with a fig-8 as the S mic in an M-S pair. In both cases it's really important to delay the instrument-fitted mic by about 1ms/ft of distance to the other mics so the phasing is correct.

That said, for your stated objective, you can't consider the bass in isolation, in that your problem with using distant microphones for the bass is going to be replicated for the piano. Presumably you are considering something like an omni condenser pair or a stereo ribbon for the piano, and these are going to collect some of the bass sound as well. To some extent, you can position the instruments to reduce the cross-bleed, but there is actually a lot to be said for a single X-Y pair in front of the performers with spotting if necessary (e.g. using the DPA4099B for the bass) plus delay.

Good luck, and let us know what you decide to use and how it turns out!

Beyer MC740 works well as do Neumann TLM170(R) .

Boswell and Keith, thank you for yours answers...

The plan is a recording in the same scenario that is then edited in the classic style: in the same room and at the same time. Effectively the plan to mix: (a) mono recording and M / S for the bass, (b) along with a stereo pair on the piano, and (c) a general system for the ensemble have important problems phase and delay . The recording room is acceptable.

I especially appreciate your contribution on the placement in this case: 1 Spot on the double + general XY, is a very sensible solution although perhaps the piano loses detail. I'll try it.

I will seriously study the TLM 170 R and DPA 7099 (B) microphones.

thanks again.

For low frequencies you really need a good omni mic.

A directional mic. tends to start rolling off around 60Hz - and omni will go down to around 10Hz or so.

My first choices are the Gefell M 221 or Sennheiser MKH 20/8020, but the Neumann KM 131-A/D is also good as are the Schoeps omnis.

On a budget, the new Gefell M 320 is worth considering.

I agree with John that omnis are prefered for a static instrument such as a piano, or particularly for a full organ, where the lowest pipe is around 16Hz. However, for solo instruments that inherently move around a little when played, I prefer the supercardioid DPA4099 types that I mentioned above, as these attach to the instrument, so follow any movement. They have a response that is -3dB at 20Hz and 20KHz, and are flat down to below 41Hz, the lowest string on a standard double bass.

I haven't had the chance to try the Gefell M320 omni, but I was surprised to see from the data sheet that it has a broad +5dB bump centred around 8.5KHz. I know you are a UK dealer for the Gefell mics, John, so what's been your experience in using these for string instruments?

As an omni has no proximity effect you can attach it to an instrument without any bass tip-up to give a natural sound.

So if you want a small mic. attached to an instrument, you could use a DPA 4060 or Senneheiser MKH 1 or MKH 2.

Personally I have not used the M 320 yet, my omnis of choice are the M 221 and the MKH 20