DIY Audio Analyser

[chrispenycate]

THD can point out a variety of problems, not just tape distortion. I've used it very successfully with a sweep generator finding rattles in loudspeaker cabinets (without blowing my ears out)

How portable is this unit intended to be?

List of things I've found useful in the past (no, I don't expect all of them, just throwing out ideas).

Generators

Pink noise
Low distortion sine wave
Sweep frequency sine wave
Repeated pulse with polarity/phase information.
Repeated pulse of bandpassed noise, choosable frequency bands
Prerecorded speech loop on ROM
Idem music; three different.


Inputs

Phantom powered mic preamp
Hi Z switched sensitivity input
Line level balanced input
Domestic level unbalanced input
AES/EBU digital input, selector channel one, channel 2 and mix
SPDIF, optical or coax, same selection
SDI input, selection from channels one and two as above
Mike multiplexer to average the frequency response over a large space.

Tests

Frequency response
Gross distortion at high speed
Polarity
Multimeter; analogue/digital readout of DC voltages, resistance, diodes; yes, we all own one but it's a convenient extra. And you can switch the meter to oscillator output, or whatever
Wow and flutter; you'd have thought that with the demise of magnetic tape that would have gone away, but a variety of audio compression techniques produce equivalent effects when not working perfectly,
Rt60
Waveform memory with overlay function, and built in recommended cinema curve

Outputs

Scope driver
Headphone driver (switchable after filter in THD mode)
Power amp for driving external loudspeakers.
USB computer feed

Oh, yes, of course I want a Dolby spec long term surround loudness meter EBU 3341 included, but I'm not going to get it ()