/ Setup CD Version 3
NEW as of July 16, 2021
first... a tiny shameless plug...
As per last weeks discussion regarding my experiences
with your surround system calibration technique/subwoofer
results of the Soundoctor sound system calibration technique
are nothing short of transcendental. In addition to
jaw dropping improvements in sonic punch
and visceral impact, phantom center coherency and soundstage
imaging for frequencies well above the subwoofer crossover
frequency are also vastly improved, even on real-world
systems with non-optimal geometry or acoustic environments
now on a quest to re-calibrate every system Ive
ever installed using the Soundoctor method!
Owner | Chief Technician
Mogul Media Systems LLC
a CD order button at the bottom of the page.
Here's a clean
PDF of the latest instructions: Soundoctor_Test_CD_v3.pdf
13 pages, 320k
The PDF has clickable links, and the WHITE NOISE
instructions have been greatly expanded for this latest
Thank you for
ordering this TEST CD !
You are in for
a unique audio experience. This CD represents more than
35 years research into the best methodology for the
easiest and most comprehensive subwoofer integration
and system alignment, including speaker imaging.
You will GET RESULTS
where everything before has been disappointing or a
failure. If you have been frustrated because you have
a sub and "it never integrates properly" or
"the bass is always muddy and/or boomy" then
you have come to the right place.
This Version 2.7.2
has been redone in both track order and content from
the earlier versions. These frequencies are all digitally
generated in Wavelab and the CD is manually recorded
(burned) individually, at a slow speed
for the highest possible quality. This CD also has free
bonus music partial sample tracks on it. There's also
a new unique BLIP test, and dual white noise tracks,
one "in" phase, one "out" of phase
are included to assist you.
The OVERALL setup
procedure for any sound system is:
a) room acoustics
b) mains placement and alignment
c) Sub placement
e) Sub integration with a 2-channel system (if you have
Sub integration with Home Theater / Surround system (if
you have that)
You actually have
3 places to put a sub (or subs).
1) where you think it / they should go
2) where your spouse tells you to put them
3) where they ACTUALLY belong.
Sub placement is
FAR more critical than most people would like to believe.
Even though the bass wavelengths are long, (an 80 Hz wave
is 14 feet long) a ONE foot difference in sub placement
might amaze you.
Please do not obsess
about flat response in a living room. It is essentially
not possible. You might find Ethan Winers page VERY
entertaining. It's here: https://ethanwiner.com/audio_minutiae.htm
Find the section where he says YOUR ROOM IS LYING
Here is an empirical
test you can do which requires NO test equipment and it
can be done at any time, whether or not your sub is in
a good or bad position: Play ANY sine wave freq, (for
example 70 Hz). Now walk completely across your room right
in front of your chair from the left wall to the right
wall. Notice all the peaks and dips (holes). Your room
is a 5-dimensional grid. EVERY frequency has peaks and
nulls at EVERY DIFFERENT SPOT in your room. Scary, isnt
And further, for
an interesting discourse on sub placement (and many other
acoustic phenomena) I also suggest reading Art Noxon's
articles here: www.asc-home-theater.com/ht-articles.htm
You do not actually
NEED any test equipment other than your ears to use this
disc, although you may find an SPL meter or a frequency
measuring device interesting. (If you have an RTA system
hide it in a closet.) BECAUSE you have purchased a JL
Audio Sub (or even another good brand of sub) the sub
is simply powerful enough to cancel the bass in your room
coming from your main speakers, leaving you with sound
worse than when you started. You MUST carefully and correctly
set up and integrate modern sub(s) to both the room (first)
AND the rest of your system (second) in order to receive
the results you paid for.
If you haven't done so, please read
my "SUBS" white paper here: www.soundoctor.com/whitepapers/subs.htm
Room acoustics is
the major part of the overall equation - perhaps 70%.
SUB PLACEMENT is at least 20% of the rest of the equation,
and everything else (that means ALL the gadgets
you think you need) is 10% or less. IF you have the ability
to place the sub(s) WHERE THEY BELONG, then you will do
yourself a great disservice if you don't. If you purchase
two subs and each is coupling only 3 dB less than it could,
you are throwing away the equivalent of one entire sub.
There is one more
phenomena which everyone ignores: REVERBERATION TIME.
You CANNOT fix issues in the TIME (phase) domain with
equalization. Further, with ANY room
correction software (which is a lie; its NOT
correcting your room, its messing with your speakers
while you CAN assist in smoothing the frequency response
by pulling DOWN a peak, you CANNOT fill in a hole: that
hole in the frequency response is the physics of your
room, caused by the reflections canceling each other out.
If these reflections
continue for so long that the bass notes dont die
away, and then the next note appears, then you will get
muddy response or worse. The common knee jerk response
is to add more subs in order to get more
bass. This is exactly backwards. Lets say
you are playing a dance CD with 120 BPM. Thats two
bass (or kick drum) hits per second. If the reverberation
time in your room is 1.5 (or more) seconds then the first
note will not die away before the 2nd note shows up, and
this will reverberate and repeat, and you will get mud.
With ANY assistive
software, such as the JL Audio ARO or DARO or others,
I SUGGEST learning everything NEUTRAL FIRST, and setting
everything up according to these guidelines, THEN run
ONE software at a time and discern if it helps or if you
like it (or dont like it). DO NOT ASSUME that if
you run all these computers in a row it will
be either correct or you will like it. Flat response in
a living room is NOT the holy grail of audio: impulse
SO PLEASE, if possible,
do the empirical tests. Even if you later put the sub
where your spouse suggests, you will have first learned
whats actually best. Some people call this the "crawl
around" test. That's the next step.
THE CRAWL-AROUND TEST: Here
is how you most EASILY move the sub: go to a hardware
/ home improvement store and get some Waxman Super Sliders.
They come in multiple sizes AND versions for carpeted
floors AND/OR hard floors. If you have a medium size sub
such as a JL Audio e110, e112, f110, or f112 there is
a version which STICKS on the bottom of the rubber foot
of the sub. Larger versions simply sit on the floor and
the sub rests on them. You can slide a JL f113 sub around
a carpeted room easily with one finger. On carpets the
larger ones will slide easier.
Track 24 is very
helpful for the "crawl-around" test because
it covers many frequencies AND it is repetitive. Place
one sub AT YOUR LISTENING POSITION, FACING FORWARD.
Using the analog outputs of a CD player, plug them directly
into the sub. Turn the sub's filters to off, and the
e.l.f. trim to "0". Manually adjust the volume
level of the sub to a good perceivable loud but comfortable
level. Sit right in front of the sub and LEARN what
it is capable of. Now walk and crawl around the perimeter
of the room, and any place you think a sub could go,
and listen for the various couplings of the sub. You
should notice a few areas where the bass is thin and
weak (the nulls) a couple of areas where the bass is
boomy and the fundamentals are louder than the harmonics
(often too close to a corner) and then a couple of spots
(2 or 4 places) where the bass sounds GREAT! Those are
the spot(s) to put the subs so they inverse couple the
best to your listening chair. You can't fight with the
laws of physics!
Some people say they
are going to put a sub in the corner because there is
room gain. WRONG! There is no GAIN ! There
is no AMPLIFIER ! The corner simply has the most efficient
coupling at all frequencies (because the 2 walls act
like a huge horn) and everywhere else in the room has,
in comparison, loss. Try not to put a sub in the middle
of a wall or space.
Also I suggest never
putting subs BEHIND your main speakers. The low frequencies
will mechanically vibrate the mains causing frequency
modulation (doppler modulation) of the higher frequencies
coming out of the mains. This is exactly one of the
types of distortion you are trying to eliminate by NOT
putting bass frequencies in your mains in the first
THEN, if you have JL
Audio subs, adjust the ARO for EACH sub relative to
its position in the room, THEN adjust the phase relationship
between the sub and its main channel using the method
outlined below. However, as a suggestion, you might
want to NOT USE any ARO or other computer setting (such
as Audyssey, etc) until you LEARN the characteristics
of your system at its neutral settings FIRST. Then you
may wish to experiment by making ONE change at a time,
or ONE computer "adjustment run" at a time.
It is very difficult to determine a result if you change
more than one thing at a time.
A note about the master/slave
hookup for JL Audio subs: If your room is SYMMETRICAL,
perhaps a 2-channel system, and the room is like a shoebox,
and you can close the door, and you are sitting on the
center line and your speakers and subs are placed symmetrically
then yes, you can get away with it. And it works very
well. If your setup is anything OTHER than symmetrical,
I highly suggest using each sub as a master and adjusting
each ARO by itself (and each phase knob by itself, too).
Why? If the room is NOT symmetrical then the low freq
sound waves from each sub will have different multiple
reflective pathlengths from each sub to you the listener
(and the test microphone) and to the left wall to the
test microphone, and to the right wall to the test microphone,
and so on. Therefore the necessary EQ to assist in the
flattening out of one sub CANNOT BE THE
SAME as for the other sub. Therefore copying
the EQ from one to the other will not work well.
There is one more subtle
difference between so-called Home Theater/Surround
setups and 2-channel - inasmuch as correct
audio is correct audio no matter what the situation.
In HT situations you are dealing with bass management
and that signal contains all the bass below the crossover
point (which you have selected) from all 5 (or more)
channels AND the LFE channel IF IT EXISTS on the DVD
or Blue Ray. (There is no LFE channel on a CD since
its only 2 channels) LFE noises in movies (typically
20-80 Hz) have very little phase coherency with signals
above 80 (what is being fed to your main speakers).
The DESIRED results in a HT setup is to get those sci-fi
noises of planets blowing up convincingly at your chair.
One other industry bit
of confusion: the signal coming out of your Home Theater
Receiver/Processor IS NOT LFE!!! It is MANAGED BASS!
It is everything below a defined frequency from ALL
the channels (L C R Ls Rs Lb Rb and more
into mono, and added to the LFE channel from the DVD
if it exists. (it does not exist on every DVD) You are
NOT (nor should you) run your mains full range
and attempt to send ONLY the "LFE signal"
to your sub. This only works in large movie theaters
because of their size; the walls are so far away that
for all practical purposes there are no standing waves;
exactly the opposite of a living room.
In 2-channel stereo,
there is often a very tight relationship between the
bass notes (coming out of the sub) and their harmonic
structure (coming out of the mains). For example, a
kick drum has a fundamental around 60 Hz; a subharmonic
component an octave down (therefore around 30 Hz); and
a series of both even and odd harmonics extending up
to 8000 Hz. Your mechanism of hearing feels the fundamentals
(which are coming from the sub) and localizes the harmonics
(which are coming from your main speakers). All of this
is MOST apparent in well recorded acoustic bass (perhaps
jazz) and cello (perhaps classical) music. If the phase
relationship of the sub(s) are set correctly, even if
the subs are behind you in the room you will perceive
the musician playing the bass to be in the
front of the room where he/she belongs.
All modern, powered,
sealed subs have an analog phenomena called group delay
(in the digital world this is often referred to as latency)
so to best integrate sub(s) you must fix that timing
issue so the sub lines up in time with the mains at
the crossover frequency area. Since you cannot remove
this inherent delay in the sub you must add this delay
to all the top channels. The PHASE knob on a modern
sub ADDS MORE delay to the sub than its intrinsic approximately
IN A HOME THEATER
SYSTEM you do this by
manually setting the speaker distance settings in the
setup menu. Since consumer equipment operates sort of
backwards, when you increase the distance setting of the
sub you are adding delay to all the other channels. (!)
I suggest setting all the speaker distance settings THE
SAME and to 7 feet; then add 12 feet to the SUB distance
only (so the sub distance now = 19 feet). Now you have
added a bit more than the correct amount of delay to the
REST of the system (the L C R Ls Rs) so you can then properly
use the PHASE KNOB on the sub to FINE TUNE the timing
match. This will give you the best possible impulse response
through the entire system; the imaging and focus should
then should be uncanny, and the bass focused and as tight
as possible. Again, if this is done correctly, even if
the subs are behind you, you will NOT localize them; it
will seem as if the bass is playing from the front of
the room, where it belongs, and this is true even if the
crossover frequency is as high as 120 Hz. Heres
another audio non sequiter: people say that bass
is non directional. This is completely wrong. Audio
is more or less directional; the phrase should be bass
is NON-LOCALIZABLE because the wavelengths are so much
larger than your head and therefore there is no phase
difference between your ears relative to the wavelength
size. The higher you cross over, the more you MAY localize
the bass IF the timing of the sub is so far off from the
mains that it almost becomes a separate musical event
in time. If the timing is correct you will feel the bass
and localize on the harmonics.
IN A 2-CHANNEL
SYSTEM you cannot usually add
delay to the tops (mains) therefore the subs will always
be 1 cycle (or 360 degrees) late at about 100 Hz. If you
have a DUAL HT/2-channel system then set the distances
for the HOME THEATER part as above and then both parts
(HT and 2-channel) will essentially line up. The HT part
will be exactly in-phase and the 2-channel
part will most likely be 360 degrees late, but still apparently
IF YOU HAVE BOTH
SYSTEMS do the phase/level match
for the 2-channel part FIRST. Now leave the level control
on the sub WHERE IT IS, and when you do the HT part use
the SUBWOOFER LEVEL control in your setup menu or on the
remote to match. Then when you go back and
forth between HT and 2-channel you (essentially) wont
have to adjust anything!
DECIDING ON THE
CROSSOVER FREQUENCY: I suggest
never going below 80, even if you think your speakers
go down to 40, or below. Even in a room where the existing
"mains" have a pair of 12" drivers (each)
you will get far better results if you correctly seal
the ports and correctly cross them over at 80, (or higher)
and of course you MUST match the phase and timing relationship
so the whole transition between the sub and the mains
will be valid. For Home Theater setups set the Mains=SMALL,
Sub=YES, XOVER=80 Hz (or 90, or 95) and if you have a
choice, 24dB/octave. Feed each sub with the same signal
placing "Y" cords anywhere. For JL Audio subs,
if the room is symmetrical and everything in it is placed
symmetrically you may use the master/slave system, but
it is far better (and yes, more work) to use each sub
as a master and then adjust the phase of each to match
with the main it is closest to carefully.
You may (hopefully)
experiment with different crossover freqs. With MANY mains
which have drivers smaller than 8 I suggest 90 or
95 Hz. You MUST always do the (next) phase step as the
LAST adjustment. If you change the crossover freq to experiment
you MUST do the phase test again by playing a sine wave
at the crossover freq and following the steps below. One
more time: The PHASE test MUST ALWAYS be last.
If you have a 2-channel
only system if you do not correctly use a crossover you
are both wasting your time and you will be frustrated.
You simply CANNOT match a modern, sealed sub to an existing
so-called full range, probably ported speaker system unless
it is done CORRECTLY. You CANNOT just use
the Low-Pass filter in the sub. It is NOT a crossover.
But you be the judge. At least with this test CD you have
a guide to work with. Please investigate the JL Audio
CR1 crossover, here: www.jlaudio.com/collections/home-audio-subwoofer-crossovers/products/cr-1-home-audio-subwoofer-crossovers-96020
If your speakers are ported, you SHOULD close (seal) the
ports. Towels will do for a test but you might consider
purchasing a 3", 4", or 5" thick slab of
"foam" at a notions / sewing store; then using
a suitable circle template (food can, peanut butter jar,
etc) mark the foam and cut with a bread knife slowly.
Then spray paint with flat black barbecue paint and you
will have a professional port seal. Some better brands
of speakers (B&W for example) come with port plugs
for just this purpose. What you are trying to accomplish
is to NOT have multiple sources of differing phase relationships
(the main driver, the port air, and the sub driver) at
or near the crossover freq. The filter slope of both the
sub and the mains should be a mirror image in both the
frequency and phase domain, and there should only be two
LF sources attempting to couple and cross over: the LF
driver in your main speaker and the driver in the sub
TRACK 8: 80 Hz, 2 min @ -1dBfs Using 80 Hz is an easy
way to set the relative phase of the JL Audio and other
modern subwoofers to match the "mains". If you
are using a different XO frequency, use that frequency
track, not 80!
|Next we set the phase
Method A (easier, but
less accurate) After you have placed the sub where you
want it, put YOUR HEAD equidistant between the sub and
the speaker it is CLOSEST TO (for example the LEFT FRONT).
Disconnect the 'other' front speaker. Play the 80 Hz tone
and adjust the PHASE CONTROL of the sub and the POLARITY
SWITCH until the bass is loudest and cleanest - in other
words, the peak.
Method B (FAR
more accurate, and more work...) Invert the polarity of
the MAIN speaker the sub is CLOSEST TO. Disconnect all
the other speakers in the room. Place your head equidistant
between the sub and the speaker it is closest to. Play
the 80 Hz tone. Adjust the phase control AND the
level control and both settings of the polarity
switch until you hear a distinct NULL. (IT MIGHT EVEN
DISAPPEAR COMPLETELY) There should be some setting of
the two controls on the JL sub which will provide a rather
sharp null - this is a CRITICAL setting and you might
find it to be very sharp. Now put the wiring back
the correct way to that one speaker. Reconnect the other
speaker and you're done.
If you have 2 subs repeat either of the above procedures
with the mains speaker the 2nd sub is closest to. All
the sinewave tone tracks are recorded exactly the same
on both channels therefore you can disconnect either L
or R speaker for your convenience.
The REASON for
Method B? When 2 waveforms are IN PHASE and
they sum they may get 6dB louder, but when 2 signals are
OUT OF PHASE and they sum, theoretically they cancel completely,
therefore It is much easier to hear the NULL. In practice,
LF signals coming from 2 spots in a room won't sum 6dB
louder; they will sum perhaps 4 or 5 dB louder, because
in a home size room the summation also includes the summation
/ cancellation of various standing waves and reflections;
therefore the summation is uncorrelated.
By using the accurate
phase test above you will AUTOMATICALLY have set both
the PHASE (timing) and LEVEL, since it has
to be both the same level and exactly out-of-phase to
cancel. But remember when you are ALL done with this,
inasmuch as your "system is calibrated, there
is often a huge difference in the bass level and content
between different sources. You may find that DVD's are
more consistent and that music CD's are all over the map.
You can then arbitrarily determine any reference point
you like and work + or - from there; i.e. you might have
to turn your subs UP 3dB to play rock CD's and DOWN 2
dB to play SCI-FI movies. It's up to you. Do not think
because "it's calibrated" you are stuck with
TRACK 1 : Pink Noise 2 minutes
@ -20dBfs The L and R channels are IDENTICAL. Because
the noise is at -20dB below full scale digital, it represents
the same level as "THX" or "Dolby"
"reference" level. That means that when your
system volume is adjusted "normally"
and this is what people typically call reference
level (everyone in the consumer industry
uses a different and arbitrary scale
) you should
get 85dB SPL (slow weighted C of course...) at your sweet
spot chair. Do not do this test before you do the phase
This also means
the CD is CAPABLE of 20dB MORE, which translates to 105dB
SPL. You may use the pink noise for overall SPL measurement.
Since the 2 tracks are identical (they are bit correlated)
if you are playing one channel only and you turn on the
2nd channel the room level should (on paper) sum 6 dB.
However, as mentioned above, because of phase anomalies
and reflections in any given home-sized room, this almost
never happens, but you can expect perhaps a 3, 4, or 5
TRACK 2 through TRACK 17: Tones
(clean sinewaves) @ -1dBfs These tracks are all recorded
1dB below the MAXIMUM POSSIBLE ON THE CD. PLEASE BE VERY
CAREFUL WHEN PLAYING THESE TRACKS. The highest frequencies
are first. (120, then 110, then 100, then 95 etc.) Start
with your system volume very low and move it upward until
the desired result is obtained. The REASON these are recorded
at this level is so you can determine if your subwoofer
(or mains, or headphones, or entire system etc.) is CAPABLE
of playing these frequencies and at these levels.
You can therefore
determine the maximum possible output from your sub and
your entire system and how it is coupling into
your room at each given frequency. YOU are responsible
for the careful and judicious use of these test tones.
It is theoretically possible to damage your speakers,
your amp(s) or your hearing with the careless use of these
test tones or of the Techmaster PEB tracks below. Please
If, when playing
individual bass tones (or the Techmaster PEB tracks, below)
you find various objects, air conditioning grilles, drawer
pulls, art objects, lamps, neighbors, etc. vibrating then
I suggest you get some museum gel to stop their vibration.
It's available here: www.detailsart.com/museumgel.aspx
Tracks 18 and 19
offer a quick and dirty (but not fanatically accurate)
method of getting the sub and the mains at the same level.
You cannot use your SPL meter with the pink noise coming
from your receiver. If you do the phase part above, YOU
DO NOT NEED TO USE THESE 2 TRACKS. These were ORIGINALLY
intended for when everyone was obsessed with Radio Shack
SPL meters and in the olden days there was no phase control,
only an incorrectly labelled phase switch
(it isnt phase; its polarity
) on MOST
brands of subs
and it was a quickie way to set LEVELS.
Notice it has nothing to actually do with phase or timing
- and there is the downside. You might think the levels
are fine but you havent adjusted the phase correctly.
Therefore the test is essentially a waste of time with
more modern subs, but I have included it here anyway.
TRACK 18: HF
PRE-CONTOURED Noise at -20dBfs This High Frequency noise
is pre-contoured to be used with a Radio Shack or similar
SPL meter when setting up a Home Theater receiver which
HAS bass management. Adjust the volume control so this
track is playing through the MAIN SPEAKER(S) at 85dBa
(slow weighted C) at the listening position.
TRACK 19: LF PRE-CONTOURED
Noise at -20dBfs This Low frequency
noise is pre-contoured to be used with a Radio Shack or
similar meter when setting up a Home Theater receiver
which HAS bass management. Leave the volume where it was
in the Track 17 test, above, and play this track. Adjust
the SUBWOOFER level so the meter (set to SLOW WEIGHTED
'C') matches the 85dB as in the test above. By using these
2 tracks, it is not necessary to do any mathematical or
mental conversions... just match the levels at the listening
position. Since the SPL in the room is at 85dB, and the
recording is at -20, that leaves 20 dB headroom for the
Dolby / THX level of 105dB for peaks. Both of these tracks
are only for an approximation and are NOT NECESSARY AT
ALL if you use the sine wave method above, since it is
FAR more accurate.
FREE BONUS TRACKS
20 and 21 - Holly Cole - Please
purchase every Holly Cole CD you can find ! She deserves
it and you will love it. While the recordings themselves
are all superb, they are of a different enough flavor
to keep you on your toes. The bass on Jersey Girl is a
little bit heavy, perhaps 1-1/2 dB or so too much.
If you carefully adjust your system then you should perceive
this. If the bass seems WAY too heavy, or not heavy enough,
then I will venture a guess that either or both the phase
relationships and the levels of your subs are not set
Don't Smoke in
Bed tests the limit of the plain ol' 16 bit process. Her
voice should be FLAWLESS and yet the sibilants on many
/ some systems might sound flawed - yet the CD is actually
clean and the waveforms are pristine. This is a fabulous
test track to A-B different connections, i.e. compare
the analog vs the coaxial digital, or RCA vs Balanced
connections, vs whatever else your player has for outputs,
and choose the cleanest. Her website is here: www.hollycole.com
. While you're looking for Holly Cole recordings also
try and find any of the now out of print Techmaster PEB
CD's. You won't be sorry.
FREE BONUS TEST TRACKS
22, 23, 24 - Techmaster PEB
Newtown Records and Techmaster PEB were at the heart of
the Bass Revolution, which started in Florida in the early
90s (!!!). Their work remains at the top of every
list: engineering, musicality, style, quality, production.
Track 24 is the Ultimate Bass test. If your system cannot
play this at 105 dB it is either set up incorrectly or
you need JL Audio Subwoofers! (and you need them
correctly set up
)You can damage ANY brand of sub
or main speakers with these tracks if abused. Be careful!
Guess what: these
tracks are from 1993 and are completely analog. And are
TRACK 25: White
Noise, LR 4 min @-20dBfs. Both channels are sample-accurate
TRACK 26: White
Noise, LR, 180 degrees Out of Phase, 4 min @-20dBfs.
For use with HDMI connections, where you can't use "Y"
cords, or if you CAN'T get at your actual speaker connections,
or perhaps you have bi-wired mains and it's just way too
much trouble to reverse the polarity of one Left or Right
To use these, see
my WHITE NOISE test section, HERE: www.soundoctor.com/testcd/whitenoise.htm
TRACK 27: The
BLIP test. This test is quite unique. It presents one
BLIP every 2 seconds. That BLIP is 1/2 a cycle of an
80 Hz sinewave, only going in the positive direction,
at 0dBFS. It has a duration of 6.5 msec. Therefore that
waveform looks like this:
1 "BLIP" signal
Notice the BLIP
is POSITIVE-GOING (only) and the top of the sine wave
is exactly at 100%, therefore this represents full possible
level (modulation) on the TEST CD, i.e. 0dBfs. When you
play this BLIP Test, the "end result" of the
phase of your system, sometimes called absolute polarity,
should make the Low Frequency cones move OUTWARD. This
is also a fascinating, superb, and rather severe test
to determine the delay time of the subwoofer relative
to the rest of your system. As carefully outlined in my
SUBS white paper, if your sub is 360 degrees (or even
720 degrees) late, you cannot measure it with a frequency-measuring
device, and you will think the frequency response is flat
but the impulse response will be smeared. That is the
most important reason why measuring in the frequency domain
is largely a waste of time, unless you FIRST fix the time
Since this signal
is at 80 Hz, and your crossover is set to 80 Hz, you should
be able to hear this signal from either/both your mains
and your sub(s). Therefore if you turn the volume down
on the sub(s), you can use this test to determine absolute
timing of other parts of the system. This will "rough
in" speaker distance timing, and then you can use
the WHITE NOISE test (below, and on the white noise page,
here: www.soundoctor.com/testcd/whitenoise.htm), to really
fine tune. Yes this blip test is a very obscure test.
Ideally, with this
POSITIVE-GOING waveform, your low freq speaker cones and
sub should move OUT of the cabinet towards you. This gives
you the correct absolute polarity air pressure
wave just as if it was coming from the front head of a
kick drum, for example. Be aware that some / many records
have gone through the entire recording / mixing / mastering
process and have the WRONG polarity. Its interesting,
but dont obsess about it too much
Do not be
dismayed if you are totally confused by this track. Those
of you enamored with audiophile headphones will find the
comparison of this track on headphones vs speakers to
FREE BONUS TRACKS
28 - 36 a surprise or multiple surprises each time.
Fun bass, sample music, and dynamic snippets...
This TEST CD is
$18 USD and it comes with full printed instructions. This
price INCLUDES shipping and handling, no matter
where you are, worldwide. The CD will be sent
1st Class Mail. Please click the button below to pay with
After the big robbery,
the new preprinted blank Test CD's have arrived
and all the delayed ones ordered have gone out as
of Thursday, 10/28. New orders will go out immediately.
Thank you for understanding.
Thank you for your interest
in this test CD !
If there's a space on the
I'd love for you to tell me where you heard about the
Please be aware
of 5 things:
1) That because
of the Covid situation, trips to the post office
will be a little less frequent, and,
2) Because of
the political post office mess, if you DON'T
receive the CD in a timely manner (that means just
a few days) please email me directly to let me know.
3) Your information
will never be sold or shared - I only have
your info for direct communication with you, such
4) You can always
email me directly for 1:1 assistance.
|5) Here comes
the clincher... IF you are on ATT email,
they block me because since it says 'doctor'
in the email address they think I am selling
drugs on the internet.
SO IF you have a question or an issue, you
must send me an email with your phone number
and I will call YOU.
Yep - hot off the press... every
CD is manually burned, one at a time.
page is www.soundoctor.com/testcd and was last updated on
November 28, 2021