note that all links open into a new page or tab
/ Setup CD Version 2.7.2
LR -20dB 2 min
LR -1dB 1 min.
||110 Hz LR
-1dB 1 min.
||100 Hz LR
-1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 2 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Hz LR -1dB 1 min.
Noise -20dB 1 min.
Noise -20dB 1 min.
Don't Smoke In Bed
LR -20dB 4 min.
LR 180 degrees out of phase -20dB 4 min.
||80 Hz SINE WAVE BLIP test
LR 60 sec
0dB FULL LEVEL ! One blip every 2 sec.
track... !!!! little bass and dynamic snippets of audio
fun and surprises updated Nov 2015.
/ Setup CD V 2.7.2
Sine wave test tones are at -1dBfs !
Read the instructions !
a tiny shameless plug...
As per last weeks discussion regarding my experiences
with your surround system calibration technique/subwoofer alignment:
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
on a quest to re-calibrate every system Ive ever installed
using the Soundoctor method!
Owner | Chief Technician
Mogul Media Systems LLC
instructions have been greatly expanded for this latest
If you'd like to cleanly
print this out here's a PDF: Soundoctor_Test_CD_v2-7-2.pdf
10 pages, 236k
The PDF also has the WHITE NOISE section added.
Thank you for ordering this
TEST CD ! (yes, there's an order button at the bottom of the
You are in for a unique
audio experience. This CD represents more than 30 years research
into the best methodology for the easiest and most comprehensive
subwoofer integration and system alignment, including speaker
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 that)
f) Sub integration with Home Theater / Surround system (if you
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
Find the section where he says YOUR ROOM IS LYING TO YOU.
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 4-dimensional grid. EVERY frequency has peaks and nulls
at EVERY DIFFERENT SPOT in your room. Scary, isnt it?
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
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
) 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 response
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 place.
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
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
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
summed 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 in-phase.
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 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
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/home-audio-electronics-subwoofer-crossovers
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 cabinet.
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 that setting.
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 dB increase.
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
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 carefully enough.
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
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
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 still valid!
TRACK 25: White Noise, LR 4 min @-20dBfs.
Both channels are sample-accurate / identical.
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 side.
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. 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 domain.
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 be interesting.
FREE BONUS TRACK 28
- 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 PayPal.
Thank you for your interest in this
test CD !
If there's a space on the order page, I'd love for you to tell
me where you heard about the CD ! Thanks !
page is www.soundoctor.com/testcd and was last updated on
July 4, 2018