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HORN SUBWOOFER
DIGGING the HOLE for the SUB WOOFERS - more than
60 cubic meters
HORN SUBWOOFER: chamber building
HORN SUBWOOFER: chamber building. The horns have been designd to obtain a
very narrow low pass filter
HORN SUBWOOFERS MADE IN BRICKS
In Italy all the houses
are made in bricks and not in wood as normally made in other
countries so it is easier to do and sometimes cheaper. But out of
this the very big problem is the compression chamber of the horn.
The pressures here are very high and the compression chamber
itself will resonate and the same is for the back volume of the
SUB Woofers. This will give big problems. You could surely ear a
BOOM BOOM coming out there instead of coming from the mouths (with
its own coloration) and this is not controllable unless you are
able to hold and fix steady everything. With very very big SUB
horn this is quitly impossible.
Where we did put wood (the
closures of the compression chambers) 2" thick multilayers
reversed one to the others and 2 " anti resonating material
fixed on the wood itself plus everything fixed on the 6 mm metal
borders also fixed into the concrete borders with N.16 X 8 mm
screws per each closures ( 4 closures) plus a fixing in the in
the center of each closure towards the underneath floor, well we
had problems. To make the closures not moving ( nearly at all or
let's say no more earable) and remove resonances we had to put
700 Kg staff on it, it is the pink pavement you see in the photos
with a carpet on the top.
Remember this and be
careful in building big sub horns.
10 Hz FULL POWER
An error normally made is
to consider the speaker by itself (or the amp or the cable).
There is people that do not sleep at night because still is not
satisfied of what he has made or bought. The final result of an
audio system is proportional not to the money spent to make it,
but to the amount of thinking and research one does consider
from the start as the all lot of components he must at the end stuck
together. As normally HI-END Audio manufactures do not provide
everything and people likes to put "this" connected
to "that" because " have read here and there"
or "heard from somewhere else" still the problem to get a
very good final result is far away to achieve.
Many times to build bass
horns everybody follows manual and books (and thats good to do,
theory always teaches, experience is something else), we also
have books but experience is much more worth and in this case the
horn MUST not be seen by itself.
Talking about a BIG HORN
SUBWOOFER there is something that I think people normally forget
or do not take into consideration (and maybe books do not explain) that is the dimension of the room and the position of the
horn mouths toward the listening point plus the shape of the room.
The second thing is that the bass or sub horn calculations are
normally valid (as usual) in open air and that the room itself,
if correctly used and shaped, can be considered part of the total
horn below frequencies as 20 Hz.
Due to these factors a sub-horn
that is designed on paper to have the low frequency cutoff at 30
Hz could reproduce also 10 Hz as well or even better than 30 Hz ( I
mean in amplitude), if the mouth of the horns are placed in a
correct way (we are talking of sub horn not bass horn - a bass
horn is normally designed to be placed where the loudspeaker is,
reproducing all the bass frequency range and cut in the range
of 350 - 600 Hz. A sub horn instead will reproduce starting from
"as low as possible" up to 50- 80 Hz only and can be
placed sometimes where you like (if you can of course). The room dimensions are effectively important in the very low range, so it
is for the mouth positioning. If you try to calculate (for our
Audio Room) the lenght of the wave starting from the throat of
the SUB horn to the listening point you will understand what I
mean. If you have been looking seriously at the final photos of
the Audio room, maybe you will also have noticed that the frontal
exponential panels of the frontal speakers are placed where the
horn mouths are. These panels effectively continue the horns
after sound comes out from the floor at frequencies below 25 Hz.
On the ceiling (on the top of the mouths) there is another
folding too. On the listening position there is the last folding
on the top of the sofa (maybe this is not visible on the photos).
Other foldings are in the back corners.
It is important to get the
maximum from the room. In our room, when you play Jurassic park
cinema track, when there is the dynosaurous coming, you orribly
feel all the walls crashing down (many people got scared, now I
normally ask if they are ready to be scared) is something that
you cannot even get in a cinema show, this is because all the
frequencies (low bass also) are focused all to the listening
point, while in any cinema show you normally are not able to do
it. The full 10 Hz frequency response depends on this. 5 Hz we
cannot measure, but you can feel them easyly on your body. 30 Hz
is lower in amplitude because of the phase of the emission made
by the frontal speakers bass horn. Nothing in this Audio room has
been done by a case and this is one of the topics that has been
well thought before building it.
If you have a look to the
room again you will notice that it looks like that horns are
continuing after the sub horn mouths for 10-20 Hz frequency range.
The room itself as it has
been shaped is a horn below 20 Hz, then actually the holes in the
floor are not really the final mouths below this frequency and
the length from the throat to the listening position is half of a
wavelength of 10 Hz. That is why we are getting response down to
10Hz better than 30 Hz.
HORN SUBWOOFER: ONE SECTION SHOWN
HORN for the two SUBWOOFER: TWO SECTIONS SHOWN - top view
HORN SUBWOOFER: TWO SECTIONS SHOWN - top view
- before making the floor
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THE
REAL TOTAL HORN has to be seen just following next figures
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The real
mouth of the LEFT SubHorn channel (same as the right channel) |
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View of the
TOTAL HORN
It
has to be considered also CEILING FOLDINGS and SIDE WALLS FOLDINGS plus BACK
WALL as last folding. For this purpose on the ceiling angle toward the
vertical walls we have some wood air folders (see figure).
At the
listening point (sofa) air pressure is stopped by 2,2 meters high and 1 meter thick glass wool cubes to avoid
sofa to vibrate too much. Antivibrating foam cubes also under the sofa. The
2 LAURAs in the middle of the room are for TRI-DIMENSIONAL STEREOPHONY. They
are positioned at half lenght from the frontal and central speakers. The 4
Lauras speakers used as central channel are placed on the back of the two
internal wood side panels (see next figure where they are indicated by the
"C" letter and 2 arrows) |
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The TOTAL HORN
hope to
have given interesting material by drawing also the underneath horn design (only
one section shown)
TOTAL
LENGHT OF THE HORN is roughly 9,3 + 2,7 + 6 + 2,5= 20, 5 meters (61,5 feet:
the full waveleght of the 16 Hz sound wave, half the wave of 8 Hz) - click
for the
COMPLETE TOP VIEW - lette C
indicates the 2 speakers of the left central channel |
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The RD Audio Room during
set-up
The AUDIO room is 6.95 x 8.70
meters. Front LEFT + RIGHT speakers are 8 x LAURA speakers per
channel (read
Constantine Soo Laura reviews) with a total of 16 loudpseakers. Center channel is made of 6 Laura
speakers, in tridimensional stereophony, plus other 2 Lauras speakers as
backward channel for HT. Total 24 speakers.
Lauras are placed in
couple of two, one on top of the other in Delle Curti's
configuration.
FRONT CHANNELS AND
CENTRAL CHANNEL TUBE AMPLIFIERS (future will be with Single Ended Solid
State Blu Eyes Amps completely no F.B. even locally and output trasformers -
see schematics):
- 4 stereo
Royal Device
BLU EYES 50 Watts S.E. dynamic CLASS A completely
NO F.B. Solid State AMP especially designed for this purpose.
- 1 stereo
Royal Device BLU EYES 33 Watts S.E. dynamic CLASS A completely
NO F.B. Solid State AMP especially designed for this purpose for back channels and tridimensional stereophony
More than 500 meters (
1700' ) RD cables involved expressely designed for the system.
Two cables are used for each speaker and each one is made of
8 wires AVG 24 OFC + shield, particularly assembled and
twisted to perfectly match speaker and amplifier needs,
manufactured with the same technique of the RD-BW cables.
Signal cables are made
by 32 wires AVG 24 OFC + 4 internal shielded foils.
....before opening the compression chamber
of the SUB WOOFERS. The 8 Lauras - The central RD Horn -
and the 16 X 47 cm WOOFERS. It can also be seen all the acoustic
wall and ceiling treatment before the curtains finishing.
Woofer mounting phase into the SUBHORN
compression chamber
The RD Audio Room during set-up: Woofer mounting phase into the SUBHORN
compression chamber
to the top
The compression chamber of the SUBHORN: Subwoofer connection
to the top
Into the compression chamber of the SUBHORN with the 16 woofers
assembled
(1.0 meters deep + 20 cm concrete floor on the top)
 
View of the right & left side
woofers
HORN SUBWOOFER:
Into the compression chamber of the
SUBHORN
ONLY one SECTION SHOWN - in the front: the
horn throat - View of the left side woofers (partial)
to the top
The UPTODATE Royal Device Audio and AUDIO-VIDEO room
On the front walls are visible the
UP TO DATE stereophonic central Channel. 4 LAURAS in D'appolito configuration.
The 2 x LAURAs frontal
stereo speakers are for TRIDIMENSIONAL STEREOPHONIC LISTENING set at 1/2 length
from the listening position
 
Picture shows the
BE 120 MONOBLOCK with the 900 Watts
external PSU (center), and on the TOP the 70 watt/CH
BLU BAY integrated amp together with the
BE 5
tone control
completely no feed back Royal Device preamp
The SUBwoofer AMP is still a
100+100 Watts S.S. Amp by Roberto Delle Curti
Thorens TD 160 decoupling
CD 85 decoupling
picture on screen taken from dark on second exposure and digitally
overpositioned only for clearness purposes. The small marbel table is no
more used either the RD 300B on the top of it.
Someone during
concert performaces had clap his hands !!! - to the performers... isn'it a bit
strange?
View of the center channel without the cinema screen for
STEREO listening. The center channel is still used in the stereo system.
where real
music and emotions live
to the top
The RD Audio Room - back wall anechoic
treatment on the back of the sofa
the DVD player it is visible: output stages completely modified for no-feedback.
Video projector on its left.
to the top
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The Listening position at 5.8 meters
from central and frontal channels |
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The Studio
recording section
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Studio Recording section (partial)
with TASCAM 244 with dbx + variuos mixers |
Studio Recording section
with TASCAM TSR8 with dbx + 16 channel mixer |
The ROYAL DEVICE JFET
(MOSFET are F.B. devices) Single Ended COMPLETELY NO F.B.
6 channels
CUSTOM STEREO & A/V PREAMPLIFIER with output transformers and multiamp
feeding
Frontal knobs are ALPS motorized 6 total section potentiometers,
center knob is the input selector. All inputs have resistor load selection for
right matching towards previous feeding stage. All inputs and outputs are used.
Left internal vertical knobs are for different sensitivity regulation between
STEREO and A/V inputs. Right internal vertical knobs provides a total passive
(R-L-C) mid-frequency selectable equalizer (1,5 - 2,2 - 3,5 KHz) for A/V equalization for the
front and center channels to restore linearity on pre-equalized sw material.
Cabinet made on aluminum die casting and glass covering and external
transformer. Internal volume potentiometer knobs for HT channel balance. No SW
regulation.
THE INTERNAL VIEW OF THE ROYAL
DEVICE STEREO and HT PREAMPLIFIER
Clean and Smooth the Royal Device Unique
Preamp
to the top
The INTERNAL VIEW of the MARANTZ CD player used in the AUDIO ROOM
In this CDP all the feed back output stages have
been eliminated. In their place it is visible the new circuit based on the
Ev3
EXTERNAL MODULE using 2 STEP up transformers per channel, each one driven in
CURRENT MODE (NOT Current generators). The 2 SIngle ENDED transistors are UNable
to control the current thru the low input impedance of the transformers (36 ohms),
so avoiding current local Feed BAck. The S.E. transistors are fed by means
of 8 INDUCTIVE pi-grec cells. The signal transformers used are the new Royal
Device RD 15 -4
Ev3
FREQUENCY RESPONSE
Ev3
10 KHz square wave response
to the top
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