Re: Question about oscilloscopes for audio
- From: "Harry Dellamano" <harryd@xxxxxxxxxxxxx>
- Date: Wed, 15 Nov 2006 23:40:09 GMT
<panteltje@xxxxxxxxx> wrote in message
news:1163530864.583885.234510@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Sorry if my post baffled you, I am known to do that. A post by Ben Bradley
Harry Dellamano schreef:
This is what works for me. A USB audio interface unit for your PC, a
good
one is the M-Audio Audiophile -USB found here for $150.
http://www.fullcompass.com/product/255063.html
This will give you 2 input channels and 2 output channels of 24 bit-
96KHz
performance, fully isolated.
Then get a software package to interpret and display the data on your PC
in
scope or spectrum formats. Here is a good one for $100.
http://www.trueaudio.com/index.htm
This setup will output sine waves with harmonics down >90db and has an
input noise floor of -110db at 1.0KHz and will do a full frequency
response
with one keystroke in <1.0 second. Perfect for headphone design. I am
designing transcutaneous power and data transfer for implanted hearing
aids
using this setup.
Sorry for the plug but I am looking for more work in the medical arena,
power electronics gets boring after awhile.
Cheers,
Harry
Harry, your posting sort of baffled me, I had it in the newsreader,
then decided to erase it and convince myself I had never seen it :-)
There are several reason for wanting to do that, first I started
wondering
'What headphone has 110dB range, my Sensheiser HD201 does not dampen
for example room (PC fan) noise enough to get to that, given distortion
at the upper end'.
Then why all the expensive stuff, while every PC has a 16 bits
soundcard, and programs
that are free like 'oscope' (Linux) exist, also there are free fft
packages.
Realy I have done audio with a normal analog scope and may still prefer
it to a digital
one in some cases.
As to 16 bits scopes, OK, lets say most sensitive range is 10mV (1mV
for a good
analog audio scope existed too) per division.
So if 10 divisions on the graticule, 100mV, and 65536 steps (2^16), the
lowest signal
would be 1.525 MICRO Volt.
Now maybe somebody here can make a headphone amp with that low noise,
but I cannot.
So that is why I wanted to forget about what you wrote, but something
in me looked it
up in google (sorry if google reformat my text in weird ways), and as
I am very old, maybe I
have been missing some important new audio topics.
Hell you can get a good idea about distortion simply by substraction
output from input.
And since mp3 nobody hears anything anyways.
There were days of HiFi and .000001 % (;-)) harmonic and crossover
distortion,
but since the appearance of the 10 cc PC speaker I am not sure it makes
a difference.
So, for what it is worth: And you can take a metal screw, drill it in
the skull,
wind some coper wire over it, bias with a magnet.... just like chewing
cookies.
(This last sentence was a joke OK A JOKE).
Pfff.
So please correct my simplistic audio views if you find thse flwaed.
But in my days audio sounded a lot better then mp3 on PC speakers.
24 bit, 48 bit or whatever...
in this thread said best what I was trying to relate. You do need a scope
for design of audio equipment but for final test and verification your
client my need data in the frequency domain. Using a PC based sound card
normally has high audio and EMI noise levels. The USB sound card that I
proposed is at the end of a 5 meter cable and electrically isolated from the
host PC. This allows gain and distortion measurements from any node in your
DUT. The -110dbu noise levels are nice even if you only require -50dbu. The
software I suggested controls output waveforms and crunches input data
yielding great printable curves of the DUT's performance.
YMMV
Harry
.
- References:
- Question about oscilloscopes for audio
- From: PPP
- Re: Question about oscilloscopes for audio
- From: Harry Dellamano
- Re: Question about oscilloscopes for audio
- From: panteltje
- Question about oscilloscopes for audio
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