"Phil Allison"
" I have been doing just such tests, with pink noise, on a pair of ESL63s
this week."
** Further to the above - this is basically how I carry out response and
sensitivity ( dB /w/m) tests to Quad ESLs ( and others) in a domestic
environment.
Tools:
1. The "Denon Audio Technical CD, 38C39 7147 " with octave & 1/3 oct pink
noise bands.
2. A CD player, Sony CDP101 in my case.
3. A power amplifier with known flat response ( +0 ,-1 dB 10Hz to 50 kHz)
and low output impedance.
4. A "true rms" AC voltmeter with response flat from 5 Hz to 100 kHz +/-
1% of reading - this is an ESSENTIAL item.
5. A Rode SPL meter with 1/2 inch true condenser mic capsule & modified
electronics to give *flat* response rather than C weighted - which is
nearly 10 dB down at 20 kHz (
http://en.wikipedia.org/wiki/A-weighting).
6. A camera tripod for the Rode meter.
Procedu
Position Quad ESL (or box speaker ) on a stand so the central (or tweeter)
axis is 1.5 metres above the floor - all speakers are kept well away from
adjacent walls.
Position SPL meter *exactly* on axis and 1.5 metres in front of the ESLs or
1 metre for box speakers.
Connect AC meter to speaker terminals to monitor the input level in volts
rms.
Play octave band noise centred on 500Hz and adjust signal level to get a
reference reading of around 80 dB SPL.
Play each octave band in turn and note readings on BOTH the AC meter and the
SPL meter - any drop in the AC meter reading is used to correct the SPL
meter reading.
Do same as above for 1/3 octaves and plot on a graph.
Sensitivity can be tested with full audio band pink noise or preferably by
averaging the SPL readings in the octaves from 100 Hz to 8 kHz - in each
case the level is adjusted to show 2.82 volts rms on the AC meter
corresponding to nominal 1 watt / 8 ohms.
For Quad ESLs, the SPL meter is moved to a position exactly 2 metre away,
6 dB is then added to the reading to give an SPL figure referenced to the
usual 1 metre distance.
........ Phil