leswatts
Well-known member
Well, I use a '90's vintage 2144 dual channel analyzer for acoustical measurements and the thing went on the blink.
I think it's a disk drive, but no schematics are typically published. Called in and left a message with them, bu frankly i'm not in a position to pay them thousands for repair right now. The thing is horribly expensive.
( I used to use it for car NVH at the corporate acoustics lab and made a deal to trade consulting services
to buy it when I started my own business)
Really I just need the power supplies and preamps for the calibrated mics, so in the meantime I think i'll just build some up. I usually use a PC these days anyway rather than the clumsy 2144, which has no line outs. I only used it with the B&K mics and intensity probe.
From what little my manuals document, They list the pre as 28V supply, 0.25pF input capacitance FET, and 1G input impedance.
So I'll use a doubler on a 120V little Isolation transformer ( actually two PC board mount little 1VA 120:24V power transformers back to back) and regulators for the 28 and 200v. Have some in the lab.
Have to find an appropriate FET (low input capacitance) so I don't spoil my mic calibration. Calibration is done "unloaded" acording to my mic paperwork.
I have a pistonphone but can't find where the #%& I stuck it.
Really need 2G to +200 and ground (or divider) but may just use 1G.
Anybody know what's inside the things? Is it just a Fet Follower with Unbalanced output as I suspect?
Honestly I don't think there's anything particularly special about them other than the outrageous price.
I tried to disassemble one, but they seem not very takeapartable. Didn't push it.
Might machine some of those ridiculous B&K connectors they used in the '90s too. I'm not paying hundreds for them.
I wonder if anyone else here has a need or interest in shop made B&K type measurement mic pres and supplies?
Les
L M Watts Technology
I think it's a disk drive, but no schematics are typically published. Called in and left a message with them, bu frankly i'm not in a position to pay them thousands for repair right now. The thing is horribly expensive.
( I used to use it for car NVH at the corporate acoustics lab and made a deal to trade consulting services
to buy it when I started my own business)
Really I just need the power supplies and preamps for the calibrated mics, so in the meantime I think i'll just build some up. I usually use a PC these days anyway rather than the clumsy 2144, which has no line outs. I only used it with the B&K mics and intensity probe.
From what little my manuals document, They list the pre as 28V supply, 0.25pF input capacitance FET, and 1G input impedance.
So I'll use a doubler on a 120V little Isolation transformer ( actually two PC board mount little 1VA 120:24V power transformers back to back) and regulators for the 28 and 200v. Have some in the lab.
Have to find an appropriate FET (low input capacitance) so I don't spoil my mic calibration. Calibration is done "unloaded" acording to my mic paperwork.
I have a pistonphone but can't find where the #%& I stuck it.
Really need 2G to +200 and ground (or divider) but may just use 1G.
Anybody know what's inside the things? Is it just a Fet Follower with Unbalanced output as I suspect?
Honestly I don't think there's anything particularly special about them other than the outrageous price.
I tried to disassemble one, but they seem not very takeapartable. Didn't push it.
Might machine some of those ridiculous B&K connectors they used in the '90s too. I'm not paying hundreds for them.
I wonder if anyone else here has a need or interest in shop made B&K type measurement mic pres and supplies?
Les
L M Watts Technology