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Fine Tuning
Downloads (Tuning)
(Bass and Room tuning, SPL graph, room mode calculator)
Download it FREE by clicking below, (Microsoft Excel needed)
SPL Compensator 2 [54kb]
- Explains how to use a Radio Shack SPL meter to record frequency
response.
- Enter in numbers, view adjusted measurements, and compare 3 different
graphs.
- Enter in room dimensions and find out ALL standing waves for that
room.
- Enter in a few numbers and find out how loud your sub is, or will be.
- Find out the audible difference between different amps and peak
loudness.
- Updated 10-14-02 with 3 trial graphs, and average response
graph.
- Updated 11-11-02 with Port Length Calculator and BETA Helmholtz
resonator calculators.
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Related Download Links
Download Sin waves from sweeps, to separate tones
HERE.
Download a tone generator HERE.
Response recorded at ~ 83db
Response recorded near 100db
Example of how SPL can affect frequency response. The red
line has adjusted radio shack numbers while blue is what the meter actually
reads. (These measurements were taken previous to tuning the placement)
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Purpose: To find the perfect location and
setting for my speakers to provide an undistorted clean frequency response
without electronic equalization.
Hypothesis: (Educated Guess) I predict there will be Response dips at
44-51hz, and 70hz. There will be peaks at 80-113hz. These guesses are
based on the calculated standing axial resonances of my room.
Test: Here is a diagram of the theater room (Pics see bottom of page).
Testing is done with a Radio Shack SPL meter (Slow C-weighted on a tripod).
Graphs and compensation can be downloaded below as well as the
calculators/formulas I used. Email me if you want to "real" detailed files
as I would like to conserve space and keep this article brief.
<Click here for the article>
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Tips and Secrets
These are my collection of tips and theories to improve sound. I hope
you will find these points helpful in your quest for perfection. In no
particular order:
- Sweet Spot - The key to a good soundstage is speaker positioning.
If you sit slightly to the left, you'll notice the "singer" may also move
slightly to the left. This is due to the phase and time nature of sound.
In order to hear the full potential of your speakers, I would point the
tweeters directly at the corresponding ear. (Left main to left ear)
If you pictured the tweeters as lasers pointing directly away from the
speaker, you may want the lasers to intersect 1-2 feet behind the head in
order for the tweeters to aim more at different ears. In addition to
setting up the speakers this way, you may also want to sit at a height in
which the tweeter is ear level. The result of this is you are directing
as much sound as you possible can from the speaker to your ear. To some,
this may result in too bright of sound, in which case you may actually enjoy
listening to a speaker "off-axis" or with them not pointing directly at the
listener. By pointing a speaker slightly off axis you can take off that
hint of brightness from a speaker while some speakers may even be designed to
face straight forward due to their good off-axis response. The common
term used for "angling" speakers inwards towards the listener is Toe-in.
- Speaker Placement (Spacing for sound) - Speakers close together
will result in a narrow soundstage. In other words, the separation of
sounds on a "distance" scale may not be big. What some people may also
not realize is that some of the sound "couples" when moving 2 speakers closer
to each other and can result in an added warmth in bass. Some people
believe that by placing the speaker against a wall adds bass but what they
don't realize is that it could be simply making the bass appear boomy (not
accurate, bloated). Most speakers are designed to operate with smooth
response away from walls so by tuning one with a wall can be like simply
adding bass boost. Some people may like this while others may find that
the added bass boost is nothing but reflected sound from the walls and
actually thins out the details. This is why I like to place speakers at
least 12 inches from any walls and if I want to add more warmth, I simply
bring them closer together for "coupling" rather than move them closer to any
walls.
- Speaker Placement (Spacing for imaging) - Think of the two front
speakers as forming a triangle along with the listener. Once you find
the distance between the speakers you can then move the listener forward or
backward for good imaging. A common rule of thumb is to form an
equilateral triangle with all angles equal to 60 degrees. Some people
like to sit a little closer than that so they adjust the side angles from
40-60 degrees. I find that if a speaker gets too spaced apart, the mono
sounds of a vocalist begin to sound too spacious and unfocused. As you
bring the speakers closer together the vocal source should become much more
pinpoint and will allow the listener to locate specific sounds in the
soundstage. Finding the best location may take some playing around and
there certainly is no "right" answer out there. I like to put my
speakers as far apart as possible while maintaining the most precise image
possible.
- Vibrations - Vibrations can be the CD and turntable's worse enemy.
Isolating them with pads or small stress balls can certainly help, but there
are also other ways to prevent vibrations. Bass is essentially moving
air and can be quite violent in the corners of a room which is why you should
place equipment where the bass gets strong. The wall behind the listener
is also bad as it is susceptible to the direct sound of the speakers as well
as being in a high bass area.
- Acoustic Treatments - Absorbing or diffusing sound can almost
certainly help a reflective room. If the wall behind the listener is
within 4-6 feet, this could result in a lot of reflected sound off the back
wall to compete with the direct sounds of the speaker. A solution to
this is to absorb or reflect sound at locations such as the side walls,
ceiling, and back wall. A common place for such treatments are in the
"mirror" locations. If you picture the side wall as a mirror, then
picture looking into that mirror from the listener position. The
location on the wall where you see the reflection of the tweeter is where
you'd place the acoustic panel. Some houses have objects with high
reflective surfaces such as coffee tables or tile floors. These can also
degrade the sound quality which can be solved by covering them with a rug or
towel.
- Lighting - The purpose of light is to see. While listening to
music it is sometimes much easier to focus on the sound when the light is
decreased in the room. You're senses may also become more tuned to
hearing which can result in an overall improvement in enjoyment. Playing
music at night makes it even better since the power line is cleaner, the
ambient noise outside is quieter, and the room can get darker. Another
time I like to listen to music is early in the morning. You're ears have
rested and have heard nothing but silence throughout the night. One more
tip is if you notice a lot of glowing LEDs on the television and equipment you
can simply block those out with a small dab of kneadable eraser. I found
that the knead erasers come off clean and can block 100% of the LED's light.
- Volume - Keep that volume control in hand since different music
often calls for different volumes. I found that even my own mood
determines what I'll enjoy the music at so I can't even write down "reference"
volumes on some of the CDs I have. However, once you can find the right
volume, it can make that much of a difference in the enjoyment of music.
- Bass Equalization - First off let me say to NEVER boost a frequency
to fill in a gap in the response. Always decrease the volume to
equalize. Reason is it requires more than 10 times the power to increase
sound 10 decibels and even then the sound may still be too low. Reason
for this is because there are cancellations that are occurring due to the bass
frequencies that interact with the room. With precise parametric
equalization and measurements, one can equalize the bass quite well. I
suggest using fine increments to isolate the problems such as 1/10th octave
increments or better. Using one of those graphic equalizers to try and
solve bass problems is useless as they are wide range and not designed for
such detail.
- Speaker Break in - I recommend 50 hours for the average commercial
speaker, and as long as 200 hours for some of the more picky loud speakers.
As for amps, preamps and source components, I haven't been too convinced that
break in makes that big of a difference but what you can do for breaking these
in is to use an 8 ohm wire wound resistor that simulates the resistance of a
loudspeaker and wire it between the positive/negative tips of the receiver.
As for breaking in speakers, If you put one speaker out of phase and make them
both face each other, the result will be a dramatic decrease in bass and mids
due to the speakers canceling each other out. The tweeters will
still probably be loud but it's still a lot quieter than breaking in speakers
LOUD while setup normally.
- Is Bass Omni directional? - You'll probably hear many people
that will use this statement to back up their decision to go with one sub in a
corner. I on the other hand am a firm believer in stereo subs.
Here are some reasons why one sub isn't enough: Direct and reflect bass
will arrive at each stereo microphone at slightly different times.
Therefore, stereo subs can play these time related notes in each channel.
Bass provides a good sense of space due to the different timing of how bass
reflects of walls and ceilings. Our brain picks up these spatial "cues"
of bass and interprets them to make the performance more real. With a
mono sub you get no "bass stage" and the sounds can even begin to sound like
they are shifted closer to where the sub is. Reason for this shift is
because the subwoofer has a crossover and tapers down the loudness as it plays
higher frequencies (to seamlessly blend with the mains). This taper
involves a sub playing frequencies that can be localized which then affects
the overall sound stage. Also, if you've ever listened to two speakers
with one out of phase you'll hear an odd cancellation of sound. Now
imagine bass as having tendencies to sound in/out of phase during recordings
to give spatial cues for room a size. What happens with a mono sub is
the in/out of phase bass gets combined to mono and gets canceled out into
nothing. The listener of a mono sub can not experience the same kind of
sound as a person with stereo subs. Stereo subs are capable of playing
"out of phase" with each other while a mono subs can not. Now remember
that for 5.1 movies the LFE track IS a mono source so this only applies to
stereo 2 channel formats.
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