Onix Rocket UFW-10 Manuale utente

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UFW-10 Subwoofer Setup Guide

Written by Bossobass

AKA, Dave

Edited by PhenomeNhan

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Table of Content

PREFACE..........................................................................................................3

SUBWOOFER SETUP TIPS AND PROCEDURES................4

TOOLS REQUIRED:....................................................................................................................................4

TERMS:....................................................................................................................................................5

STEP #1: POLARITY TEST...................................................................................................................7

STEP #2: FIRST LEVEL ADJUSTMENT..............................................................................................7

STEP #3: PLACEMENT ........................................................................................................................8

STEP #4: LEVEL ADJUSTMENT .........................................................................................................9

STEP #5: RELATIVE PHASE ADJUSTMENT....................................................................................10

STEP #6: FINAL LEVEL ADJUSTMENT ...........................................................................................11

ADVANCED SETUP SECTION......................................................12

PARAMETRIC EQUALIZATION........................................................................................................12

DUAL SUBWOOFERS -- MONO CONFIGURATION : ........................................................13

Asymmetric Placement Of Dual Subwoofers: Asymmetric...Not symmetric........................................13

DUAL SUBWOOFERS, STEREO CONFIGURATION :........................................................14

PLACEMENT ........................................................................................................................15

DUAL SUBWOOFERS, REBASE ROUTING CONFIGURATION :......................................15

YOU MUST HAVE:...........................................................................................................................15

CONNECTIONS: ..............................................................................................................................16

THIS IS WHAT HAPPENS: ...............................................................................................................16

ADVANTAGES :....................................................................................................................17

FINAL THOUGHTS..............................................................................18

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Preface

The following has been a labor of love for me. Love of the subject (low frequency reproduction in

multi-channel audio systems in the home), and love for Mark Schifter, his vision and watching

him realize that vision from the sidelines (though anyone who meets him never feels like a mere

spectator).

I've also done this because I promised I would. Please go easy on me, as I'm not an educated

person, and I'm sure I've left out plenty. I only hope that someone who is in the shoes we all

have to walk a mile in when we're first introduced to this digital, multi-channel octopus, will

benefit in any small way by the information below.

I also would like to disclaim the facts that some of what I say is biased toward my own thoughts

and some of what I say is downright controversial. I would like for those who read this

rudimentary guide to add input, discoveries and tweaks as they are appropriate, as well as

adding to the TERMS section as people ask about ones that aren't included. I omitted many

terms for this reason.

I also have not included pictures or diagrams...maybe the graphics guys can add that input.

Good Listening, and, by all means...Listen Accurately!

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Subwoofer Setup Tips And Procedures

Tools Required:

1. Radio Shack SPL Meter. Can be obtained at Radioshack:

a. Analog version:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=3

3-4050

b. Digital version:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=3

3-2055

2. 1/12 Octave Sine Wave Test Tone CD. You can generate your own tones or download

some tones that have already been generated for you:

a. http://www.nch.com.au/tonegen/

b. http://www.snapbug.ws/sinewaves/

3. Tape Measure.

4. Frequency Response Graphing Software (optional).

5. A Tripod For Mounting Your RS Meter.

NOTE: All of the following information will assume the following:

1. A Pre/Pro or Receiver is being used to provide Bass Management.

2. All satellites set to 'Small' and subwoofer to 'Yes'.

3. A crossover point of 80 Hz is used.

4. Your subwoofer(s) is/are connected properly to your Pre/Pro or Receiver and your house

electrical system in strict accordance with the Owner's Manual that came with your

subwoofer.

5. All 5 satellite speakers are calibrated from the listening position to a reference level.

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Terms:

1. LFE: Low Frequency Effects, AKA: Low Frequency Enhancement, AKA: The .1 channel.

2. Redirected Bass: This is all information contained in all 5 satellite channels that is below

80 Hz., which is redirected to the SW (subwoofer) output of the Pre/Pro or Receiver.

3. SW Output: This is the output of the Pre/Pro or Receiver that sends a combined, single

signal comprised of the LFE channel and the Redirected Bass from all 5 satellites (or, any

satellite that's set to 'small' in the speaker setup menu) to the subwoofer(s).

4. SPL: Sound Pressure Level. This is the unit of measurement used to calibrate the channel

levels of all of the 5.1 channels. SPL is measured in Decibels, which is abbreviated as dB.

5. Subsonic: This is the description used for any sound that is below the threshold of human

hearing, or below approximately 20 Hz.

6. Tight, fast, articulate, etc.: These are adjectives that describe a subwoofer that is capable of

delivering low frequencies on-time with the rest of the system, without any peaks in

response.

7. Boomy, muddy, slow, etc.: These adjectives describe a subwoofer that lacks the capabilities

of the subwoofer described in item #6, and/or is misplaced or badly calibrated, resulting in

peaky response.

8. Polarity: Better described as Absolute Phase. Usually, this adjustment is made by

comparing 0 degrees to 180 degrees. If 2 speakers are 180 degrees 'out of phase', then

there will be gross cancellation of sound waves in the region of audio information that the

2 speakers share the reproduction of. In the case of satellites and a subwoofer, this will

be at and around the crossover point.

9. Relative Phase: Phase is time. It's measured in degrees. If you can visualize a sound

wave that curves upward to it's peak and then downward to its bottom--that is one cycle

of the wave. Since degrees of angle are not curved, there are infinite degrees along this

wave. As the frequency is lowered, the phase changes. Some subwoofer designs change

more drastically than others.

Distance disparity between speakers and subwoofer also changes the time that it takes for

the shared audio information to reach your ear. Because these situations result in infinite

phase differences between speakers and subwoofer, there is no perfect phase setting that

works for all frequencies through the crossover region. This is why it's important to keep

distance to the listening position and infinite phase control in mind when setting up any

subwoofer.

10. Crossover Region: A typical multi-channel audio controller has crossover options that are

based on a Linkwitz/Riley 24 dB per octave network. This means that the subwoofer is

stopped from playing above the crossover point and the satellite is stopped from playing

below the crossover point. This stoppage of the speaker's natural response is not a brick

wall. It is a gradual braking from the crossover point and then beyond that at a rate of 24

dB per octave.

The idea is that across 2 octaves (from the crossover point to one octave below that point

the satellite has a brake applied that ends up being 24 dB lower, and from the crossover

point to one octave above that point the subwoofer has a brake applied that ends up being

24 dB lower, a total region of 2 octaves), the sum of the 2 signals at any point in the

crossover region should sum to unity, or, in other words, result in a frequency response

curve that is a flat line. This 2-octave area of overlap between the satellites and the

subwoofer is the crossover region.

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Overview:

The goal in adding a subwoofer to any multi-channel audio system is to achieve as flat a

frequency response curve as possible, in your particular room, with your particular system,

through the crossover region and to as low as your subwoofer will allow. This is not to say that

there is no room for adjustment from this point to allow for personal taste. Rather, it is the place

to start.

The steps, in order, are:

1. Polarity Test. You never want to lug the subwoofer around the room looking for the spot

where it will sound best if the polarity is reversed.

2. First Volume Calibration. During the placement exercise (pun intended) you'll listen for

bass notes of a music program that are of the same volume (no boomy notes or weak

notes). If the subwoofer isn't at least closely calibrated to begin with, that will occur at

any spot the subwoofer is placed.

3. Placement. As in real estate, location, location, location.

4. Relative Phase Adjustment. One of the more important tweaks to smooth out the frequency

response.

5. Final Volume Level Adjustment. After tweaking all of the above, a final subwoofer volume

level tweak will get you there.

NOTE: I've left out the step of tweaking the crossover slopes of the satellites and the subwoofer.

Although it's a very important tweak, it's beyond the capability of the vast majority of multi-channel

systems, and is a rather involved discussion for a more advanced setup guide than this one is intended

to be.

Calibration discs (Avia, Video Essentials, etc.)

I have little experience with these setup discs so I can't offer an opinion as to which is preferred,

or why. I have Chesky's setup disc and actually found it annoying. If you have or have interest

in any of these setup discs, search the forum and pose the questions you may have. I'm sure

you'll get the answers you're looking for and end up with an acceptable method for level

calibration.

I use the calibration tones in my Pre/Pro in conjunction with the RS SPL meter (digital version)

set up on a tripod at the listening position, at ear height (when seated). I have found this

method of level calibration to be very acceptable.

I've recently found an easy way to verify this method, and it's described as an option to try

under LEVEL ADJUSTMENT, below.

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STEP #1: POLARITY TEST

1. Set your subwoofer near either the front left or the front right satellite.

2. Set your RS meter at the listening position (ear high) when seated.

3. Set the Phase Control of your sub to 0 degrees.

4. Reduce the master volume on your Pre/Pro or Receiver to approximately -10 dB.

5. Play an 80 Hz test tone, using your test tone CD, with the FL, FR and subwoofer on.

6. Note the SPL reading.

7. Switch the Phase Control to 180 degrees and repeat the process.

8. Use the Phase Setting that yielded the highest output.

STEP #2: FIRST LEVEL ADJUSTMENT

1. Set the subwoofer level in your Pre/Pro or Receiver's channel calibration menu to -5 from

0 (reference).

2. Set the subwoofer(s) amplifier gain control to approximately one o'clock.

3. Use the Pre/Pro or Receiver calibration menu to calibrate the subwoofer level and use the

subwoofer amplifier gain control (add gain or reduce gain at the subwoofer amplifier) to

arrive at a reading on the RS meter that's the same as the level you use to calibrate the

mains.

4. The reason for the -5 pre-amp setting is to assure that the pre-amp doesn't send a clipped

signal the subwoofer amplifier.

5. In the final subwoofer level tweaks, the preamp subwoofer channel trim can be adjusted

via the remote control.

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STEP #3: PLACEMENT

The goal here is to find the placement spot that offers the smoothest frequency response (not

necessarily the loudest) in your room.

NOTE: Placement also includes the placement of you yourself, in the room. Avoid a primary listening

position that is in the center of the room and that is up against any wall in the room.

The conventional wisdom appears to be that the corner is the best place to start. This is

because the corner of most any room will boost low frequency output, more as the frequency

gets lower. It's also said to excite the highest number of room modes, resulting in the

smoothest overall response. I've often read the recommendation of corner placement, then

parametric EQ to flatten out peaks in response.

I have experienced the highest output from corner loading a subwoofer, but have personally

rarely experienced the smoothest overall response with a subwoofer placed in a corner. I

personally have found that if I hug a wall and slide the subwoofer away from the corner (For

example, assuming the sub is in the front right corner, either hug the front wall and slide the sub

toward the left wall, or hug the right wall and slide the sub toward the rear wall), anywhere from

2' to 4' feet out, it yields a flatter response. You can also move the sub toward the middle of the

room, away from the wall, after you've slid it away from a corner. This will also get the

subwoofer closer to the mains in distance to the listening position, as the corner is the farthest

distance from the listening position in most rooms and cases.

The closer a subwoofer is to the distance of your mains from the listening position, the more

in phase it will be. In other words, the direct radiated sound from both will arrive at your ears

closer to the same time, which yields a less time smeared, tighter sound.

This is the part of the setup of a subwoofer that requires the most time and effort. You

should use a source disc that has a wide range of bass lines in the music. I use jazz that

contains vocals and an upright bass (I always loved how those guys run the neck in walking bass

lines). This will give an idea how the subwoofer is doing, overall, in any given position in the

room, as opposed to a source that drones on using only 2 or 3 notes in the bass line.

The point is that there is variety of bass notes, all the way up to the lower vocal range. Pick

a passage that seems to represent this description and loop it so it repeats as you try different

locations and fine-tune a particular location. Listen for notes that jump out (are too loud in

relation to the rest of the notes) or are too quiet and move the sub in small increments (6"-12"

for the rough placement and 1"-2" at a time to fine tune the placement) until the bass sounds

most even from note to note.

When you feel you've reached the best spot of those that are acceptable as a final resting

place for your subwoofer, then it's time to chart the response. With your meter at the listening

position and only the subwoofer playing, play the test tone disc and record the results. Apply the

correction numbers that are available to correct the inaccuracies of the RS meter at lower

frequencies and graph the results (There are links to software that will automatically apply the

correction factors and plot your graph. A search or request for a link in the forum will yield

results, I'm sure).

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Step 3 continued:

You can tweak the placement from there and see if you can improve your response graph

before moving on to the next step.

NOTE: Use caution when playing sine wave test tones through your subwoofer. They can damage

your subwoofer by overheating the driver's voice coil if the volume is too high. Set the master volume

to yield average readings of around 80 dB at 40 Hz for the sweep. If you start at 10 Hz (well below

human hearing and the capability of most subwoofers) you may feel the need to raise the master

volume, so start by playing a 40 Hz tone and adjust the master volume to 80 dB, then proceed with the

entire sweep.

Set the meter at the listening position and set it to 'C' weight and 'slow'. Start the meter's range at it's

lowest setting at the beginning of the sweep and notch the range up as the frequency of the tones rises

(the volume of the tones will increase as the frequencies rise to the frequency range of the capability of

the subwoofer).

STEP #4: LEVEL ADJUSTMENT

1. Use the calibration menu in the Pre/Pro or receiver setup menu and use the on board

calibration tones of your preamp to adjust the subwoofer level (or a setup disc, if you

prefer) and remember to set the master volume to '0' before you begin this step.

2. Many people like to 'run the subwoofer hot', that is, louder than it should be. This is a

personal preference, but not an option at this point in setup. You're looking for the

reference setup for your subwoofer. You can always change the level later, but you'll have

the reference settings to fall back on if you aim for the flattest in-room response during

setup.

3. The goal here is to level the volume of the subwoofer to the satellites to as close a degree

as possible, given your limited measurement tool (sorry, Tandy).

NOTE: Most people whose opinions I respect believe that the RS meter is approximately, on average, 2

dB off when using the rumble tone pink noise calibration tone. This would mean that if, for example,

your satellites are calibrated using 75 dB as the reference volume with the tones you're using to

calibrate, you would calibrate your subwoofer level to read 73 dB.

I tend to agree with this assessment as the proper method at this point in the setup procedure.

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STEP #5: RELATIVE PHASE ADJUSTMENT

Since the polarity is already properly set from step #1, it's time to fine-tune the relative phase

between the satellites and subwoofer.

NOTE: We will assume that the phase control is set at 0 degrees for this description. If it's set at 180

degrees, just work backward from 180 toward 0 instead of from 0 toward 180. Also, remember to turn

that master volume down to the same, lower level that you used to make your frequency response

graph in step #3.

1. With the phase control set at 0 degrees, the satellites and subwoofer all on and using the

final frequency response graph from step #3 as a starting point, advance the phase

control knob to approximately 20 degrees above 0 degrees (0 + 20 degrees) and run

another sweep and chart the graph.

2. Advance the phase control another 20 degrees (0 + 40 degrees) and run another sweep

and chart the graph.

3. Advance the phase control another 20 degrees (0 + 60 degrees) and run yet another

sweep and chart the graph.

4. Use a different color for each graph and notate what setting of phase was used for each

color.

5. You now have frequency response graphs for 0 degrees, 0 + 20 degrees, 0 + 40 degrees

and 0 + 60 degrees.

6. Look carefully at each graph to determine which graph has the overall flattest line, using

the (+/-) from the flat line method.

7. That would be where to set the phase control and leave it. Only if the 0 + 60 degrees

setting is the best graph should you continue to run further sweeps (0 + 80 degrees,

etc.,) to make sure the next higher phase setting is not better than what you have to this

point.

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