April 29th 05, 02:46 AM
>> LOUDSPEAKER SYSTEM COMPONENT COMPLEMENT
(4) 2242H subwoofers (2.1% conversion efficiency each or 8.4% in
tandem)
(4) 2227H high-efficiency 15" woofers (one pair each side, about 17%
efficient each pair)
(2) 2123H high-efficiency 10" midrange (3.5% efficient each)
(2) 2382A horn with 2450H compression driver (30% efficient each)
Efficiency or "conversion efficiency" is defined here as the
ratio-expressed as a percent-of the acoustical output obtained for a
given electrical input. Thus a transducer that delivers 5 acoustical
watts to the air when fed a 100-watt electrical input signal is said to
be "5% efficient."
In case you're wondering if the poor 10" mid with its mere 3.5%
efficiency, can keep up with the horn, rest assured I needed 10 dB of
attenuation on the mid to get flat frequency response.
For amplification, I used two BGW SPA-3 triamplifiers. BGW was happy to
set up the triamplifiers to provide high-pass filtering for the two
15's at 80 Hz, band pass for the 10" midrange from 300 Hz to 1200 Hz,
and band-pass and horn EQ filtering with the lower end of the high
frequency band at 1200 Hz. The crossover slopes are Linkwitz-Riley type
24 dB/octave.=B9 The amplifier's input section also includes switched
attenuation and built-in signal delay to adjust the acoustic time of
arrival for acoustically aligning the cones and compression driver.
Although the amplifiers are each only 5.25 inches of rack space, they
each produce up to a total output of 1000 watts, providing 600 watts
for each pair of fifteen's, 200 watts for the mid and 200 watts for the
horn. This represents an average of around 30 dB of headroom above
normal living room listening levels, which generally range in
milliwatts for these speakers. Even though this much headroom and power
seem to be overkill, I assure you that is not the case. I include here
a table from my Audio Engineering Society workshop on basic audio-it
includes the results of about 130 hours of measurements I did of live
and recorded material using a $7500 Br=FCel & Kj=E6r true-RMS voltmeter
and a $40,000 Br=FCel & Kj=E6r audio analyzer to record the
peak-to-average power ratio of various signals. (1997 note: these are
no longer available except on special order. I recommend using four
solid-state amps of your choice-my choice is Adcom-and building a 48
dB/octave (8th order) Linkwitz-Riley crossover).
In order for untrained listeners to perceive no obvious squashing of
dynamics, audio reproduction systems should be capable of the following
peak-to-average ratios for these stimuli:
SOURCE MATERIAL CREST FACTOR
ROCK MUSIC 10 dB
HORNS (legato notes) 10 dB
REEDS (legato notes) 12 dB
STRINGS (bowed) 15 dB
SPEECH 20 dB
PIANO 30 dB
POP MUSIC 40 dB
STRINGS (plucked) 40 dB
DRUMS 40 dB
ORCHESTRAL MUSIC 50 dB
INDIVIDUAL PERCUSSION INSTRUMENTS 60 dB
GENERAL HIGH-FIDELITY REPRODUCTION 60 dB
=B9 Linkwitz-Riley 24 dB per octave (fourth-order) or 48 dB per octave
(eighth-order) crossover filter slopes produce flat acoustic energy
summation through the crossover frequency region.
The BGW SPA-3 turned out to be the elegant and simple alternative to a
large rack of gear. Having done similar projects many times in the
past, I can honestly say I would not go back to the racks and cabling
and connectors and ground-loop chasing always necessary as long as the
SPA-3 is available to eliminate all the little gremlins that tend to
pop up when one builds up complex systems.
Note to builders: I don't recommend trying to build passive crossovers
for these units. Acoustic time-of-arrival delay of sufficient time is
not practical with passive devices and system performance really
suffers without it. Additionally, to obtain anywhere near the
performance of the tri-amped system using coils, caps, power resistors
and such, the crossover would be far more expensive than a pair of
SPA-3's and would probably weigh somewhere in the neighborhood of 100
pounds-because of all the huge coils.
There have been many questions in the letters I've received about doing
this project some other way, with modifications, with different
components etc., perhaps to accommodate someone's favorite component or
fit some particular space or budget. I cannot address these questions
individually without addressing the particular goal of the individual
asking. I can do this-it is in fact, my livelihood-I will be happy to
design a custom system for you, but be aware that this must be done on
a consulting time basis. This project however, is what it is, and as
such, it pleased all the audio golden ears at Disney enough that they
insisted on using my lab pair for the yearly Halloween show with an
audience of 2500 people spread over an outdoor area covering 235
degrees, as well as company meetings with Eisner and Wells in huge
tents with thousands of people in the audience. This with a sizable
company inventory of all manner of THX-rated large theater systems,
rock-concert boxes form various manufacturers, etc.<<
Do I really want that much SPL available? Personally, no.
(4) 2242H subwoofers (2.1% conversion efficiency each or 8.4% in
tandem)
(4) 2227H high-efficiency 15" woofers (one pair each side, about 17%
efficient each pair)
(2) 2123H high-efficiency 10" midrange (3.5% efficient each)
(2) 2382A horn with 2450H compression driver (30% efficient each)
Efficiency or "conversion efficiency" is defined here as the
ratio-expressed as a percent-of the acoustical output obtained for a
given electrical input. Thus a transducer that delivers 5 acoustical
watts to the air when fed a 100-watt electrical input signal is said to
be "5% efficient."
In case you're wondering if the poor 10" mid with its mere 3.5%
efficiency, can keep up with the horn, rest assured I needed 10 dB of
attenuation on the mid to get flat frequency response.
For amplification, I used two BGW SPA-3 triamplifiers. BGW was happy to
set up the triamplifiers to provide high-pass filtering for the two
15's at 80 Hz, band pass for the 10" midrange from 300 Hz to 1200 Hz,
and band-pass and horn EQ filtering with the lower end of the high
frequency band at 1200 Hz. The crossover slopes are Linkwitz-Riley type
24 dB/octave.=B9 The amplifier's input section also includes switched
attenuation and built-in signal delay to adjust the acoustic time of
arrival for acoustically aligning the cones and compression driver.
Although the amplifiers are each only 5.25 inches of rack space, they
each produce up to a total output of 1000 watts, providing 600 watts
for each pair of fifteen's, 200 watts for the mid and 200 watts for the
horn. This represents an average of around 30 dB of headroom above
normal living room listening levels, which generally range in
milliwatts for these speakers. Even though this much headroom and power
seem to be overkill, I assure you that is not the case. I include here
a table from my Audio Engineering Society workshop on basic audio-it
includes the results of about 130 hours of measurements I did of live
and recorded material using a $7500 Br=FCel & Kj=E6r true-RMS voltmeter
and a $40,000 Br=FCel & Kj=E6r audio analyzer to record the
peak-to-average power ratio of various signals. (1997 note: these are
no longer available except on special order. I recommend using four
solid-state amps of your choice-my choice is Adcom-and building a 48
dB/octave (8th order) Linkwitz-Riley crossover).
In order for untrained listeners to perceive no obvious squashing of
dynamics, audio reproduction systems should be capable of the following
peak-to-average ratios for these stimuli:
SOURCE MATERIAL CREST FACTOR
ROCK MUSIC 10 dB
HORNS (legato notes) 10 dB
REEDS (legato notes) 12 dB
STRINGS (bowed) 15 dB
SPEECH 20 dB
PIANO 30 dB
POP MUSIC 40 dB
STRINGS (plucked) 40 dB
DRUMS 40 dB
ORCHESTRAL MUSIC 50 dB
INDIVIDUAL PERCUSSION INSTRUMENTS 60 dB
GENERAL HIGH-FIDELITY REPRODUCTION 60 dB
=B9 Linkwitz-Riley 24 dB per octave (fourth-order) or 48 dB per octave
(eighth-order) crossover filter slopes produce flat acoustic energy
summation through the crossover frequency region.
The BGW SPA-3 turned out to be the elegant and simple alternative to a
large rack of gear. Having done similar projects many times in the
past, I can honestly say I would not go back to the racks and cabling
and connectors and ground-loop chasing always necessary as long as the
SPA-3 is available to eliminate all the little gremlins that tend to
pop up when one builds up complex systems.
Note to builders: I don't recommend trying to build passive crossovers
for these units. Acoustic time-of-arrival delay of sufficient time is
not practical with passive devices and system performance really
suffers without it. Additionally, to obtain anywhere near the
performance of the tri-amped system using coils, caps, power resistors
and such, the crossover would be far more expensive than a pair of
SPA-3's and would probably weigh somewhere in the neighborhood of 100
pounds-because of all the huge coils.
There have been many questions in the letters I've received about doing
this project some other way, with modifications, with different
components etc., perhaps to accommodate someone's favorite component or
fit some particular space or budget. I cannot address these questions
individually without addressing the particular goal of the individual
asking. I can do this-it is in fact, my livelihood-I will be happy to
design a custom system for you, but be aware that this must be done on
a consulting time basis. This project however, is what it is, and as
such, it pleased all the audio golden ears at Disney enough that they
insisted on using my lab pair for the yearly Halloween show with an
audience of 2500 people spread over an outdoor area covering 235
degrees, as well as company meetings with Eisner and Wells in huge
tents with thousands of people in the audience. This with a sizable
company inventory of all manner of THX-rated large theater systems,
rock-concert boxes form various manufacturers, etc.<<
Do I really want that much SPL available? Personally, no.