Pulling up this old thread 
I got an ACH-01 yesterday so I can do some cabinet panel vibration measurements. I think I need to make a pre-amp for it though. I tried connecting it (see images) to my audio interface mic in (M-Audio Fast Track Ultra) by using the ACH-01 shield to XLR pin1 and the 'V-Out' lea to XLR pin2. XLR Pin 3 was NC. I then connected a 9V battery across ACH-01 shield and the V+ lead.
It works, with the mic gain high, but there is a lot of noise and the signal is still very low. Doing a panel measurement the modal peaks are max. 20dB above the noise.
There is a schematic in the datasheet so I think I will try building that. So my first question is, do you think this is the best circuit to use? I also found a slightly different one on LibInst site. Second question is, I read in the above post that shielding the circuit is important, presumably because of the high 10X gain. So is it better to run this from a pair of 9V batteries, or to use a small TX? The 9V batteries don't leave much room for regulation,so would be used as is. If I use a 12V TX I can use some regulators but the TX EMI might be a problem?
Also, I don't really get how the other diagram on LibInst works, apparently with bias from the Turtle Beach soundcard. How can it work with the signal output and shied tied together on the RCA ground, and the bias V+ lead going to the centre pin?
ACH-01 sensor diagram:
ACH-01 datasheet suggest pre-amp:
Suggested pre-amp from LibInst site:
http://www.libinst.com/ach01hl.gif
Strange way to connect ACH-01:
I got an ACH-01 yesterday so I can do some cabinet panel vibration measurements. I think I need to make a pre-amp for it though. I tried connecting it (see images) to my audio interface mic in (M-Audio Fast Track Ultra) by using the ACH-01 shield to XLR pin1 and the 'V-Out' lea to XLR pin2. XLR Pin 3 was NC. I then connected a 9V battery across ACH-01 shield and the V+ lead.
It works, with the mic gain high, but there is a lot of noise and the signal is still very low. Doing a panel measurement the modal peaks are max. 20dB above the noise.
There is a schematic in the datasheet so I think I will try building that. So my first question is, do you think this is the best circuit to use? I also found a slightly different one on LibInst site. Second question is, I read in the above post that shielding the circuit is important, presumably because of the high 10X gain. So is it better to run this from a pair of 9V batteries, or to use a small TX? The 9V batteries don't leave much room for regulation,so would be used as is. If I use a 12V TX I can use some regulators but the TX EMI might be a problem?
Also, I don't really get how the other diagram on LibInst works, apparently with bias from the Turtle Beach soundcard. How can it work with the signal output and shied tied together on the RCA ground, and the bias V+ lead going to the centre pin?
ACH-01 sensor diagram:
ACH-01 datasheet suggest pre-amp:
Suggested pre-amp from LibInst site:
http://www.libinst.com/ach01hl.gif
Strange way to connect ACH-01:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.