Westlake Audio Loudspeaker Systems - Online Manual

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Creating A Dampened Acoustical Environment For Critical Stereo Listening

The listener's evaluation of speaker performance can be greatly influenced by the general room acoustics, exact placement of *speaker/listener in the room and the *equipment and its interaction with a particular speaker.

Many theories abound about what the listening environment and reproduction technique should be. It is Westlake Audio's design philosophy that the reproducer (speaker) should be as close to a point source as is possible and the environment should not interfere with the observation of this source by the listener.

To accomplish this, the reverberation time (RT60) should not be excessive (.5 seconds or less) and the travel paths controlled (controlled travel path™) to direct reflections away from the listener or attenuate them as much as is practical.

To control reverberation requires that the room will have many objects and/or irregular geometry for diffusion and a considerable volume of absorptive material. It is very hard to have too much low frequency absorption/diffusion and easy to not have enough. The furnishings within the room can provide some of it (stuffed chairs and couches, carpets, drapes and people provide most of it), but often more is required. A point to keep in mind is that some amount of absorption/diffusion must occur in all planes to prevent discrete echoes from developing as the environment is dampened down.

Serious consideration should be given to reflect interference paths to the listening position. These reflections can reduce the apparent mid bass frequency response and lead the listener to conclude that there is too much or a muddy bass sound. The stereo image will also lose definition. These reflections can be coming off the floor, ceiling or walls.
* See separate application notes.
Reflections that originate between the front of the speaker and the listener location are particularly troublesome. They can be located by positioning a small (_ sq. meter) section of mirror on the suspected surface. Any view of the speaker(s) from the listening position(s) must be treated with an absorptive material, i.e. polyester foam, fiberglass or mineral wool. It should be noted that material less than 4" (100mm) thick are ineffective at low frequencies. Also note that the effectiveness of the material can be greatly improved if it is mounted _ to _ meter off of the treated surface. This is especially true if the surface is concrete or plasterboard.

On the floor, carpet, by itself although absorptive, does not stop enough of the L.F. reflection. The mirror should be positioned on the floor to reveal the area in need of additional absorption. A large pillow may be helpful in this area. If the listening room is a control room this reflection may be blocked (or delayed as it travels under or around) by the console if the speakers are wall mounted. If the speakers are near the console meter bay this reflection will probably be more noticeable at mid and high frequencies. Not much can be done in this case except to change the speaker/listener relationship.

In practice, this technique may result in a large amount of treatment being placed on or in the front of walls, on or under the ceiling, on or slightly above the floor. This will also help to reduce the low frequency buildup (long RT60) which may occur due to inadequate absorption at low frequencies. Corners are places where the L.F. sound pressure will be potentially very high. Absorptive materials are particularly effective in or slightly in front of (.5 to 1 meter) the corners.

Set up properly in a well-dampened environment, the Westlake monitors should produce a clean, balanced, well-defined sound stage with excellent center image.

Westlake Audio offers complete acoustical design services.

Mounting of Monitors

The salient point in mounting reference monitors in a wall soffit is to break the hard connection to the structure by using a compliant material such as machine (sponge) rubber (M.R.), felt or insulation itself.

Care must be used to make sure that the isolation material is not bridged (thereby providing a short circuit) by mounting hardware (screws, nails, etc.) in the final installation. The use of over size through holes and rubber grommets under the fastener heads should be used to prevent this. The drivers themselves in our speaker systems are mounted using these type of isolation systems and can be used as an example.

Additionally the stereo (L/R) monitors should be equally offset from room center line (C.L.) (assuming a symmetrical room), at the exact same height, inclination and rotation as well as be the exact ( + 1/16") same distance to the listening position.

Following these guide lines and using short, low loss (Westlake WI or BWI 04) cables connected to a good (or better. Two stereo amps, one on each speaker) low impedance amplifier, and using liberal amounts of absorptive material (for good bass absorption) you should have an outstanding monitor environment.

Speaker Muffs - Foam Baffle Extensions

The Evolution
Loudspeaker design is an evolutionary process. Incremental improvements in sound quality are achieved by paying close attention to the details; and to the laws of physics as they relate to sound reproduction.

In our 25 year history we have introduced some proprietary design concepts that have challenged the industry norm. Now... another evolution in sound... the Westlake Audio Speaker Muff.

The Physics
The Speaker Muff is a foam baffle extension which increases the area of the front baffle. As the size of the baffle increases it takes longer for the sound/energy to reach the cabinet edge.

Normally some of the cabinet edge reflections are reflected back to the listener; competingwith the direct energy radiating from the speaker. By moving the edge reflections out in time their amplitude is decreased and are therefore lessaudible.

The Benefits
The distortion caused by cabinet edge reflection is reduced; the listener hearsmore of the direct sound from the speaker. This has a "smoothing effect" on the frequency response; and localization within the sound stage dramatically increases. Also the larger baffle area focuses more energy towards the listener and creates a perceived increase in bass response.

Ease of Use
The Speaker Muffs are placed on  the loudspeaker/monitor so that the front surface of the foam is flush with the front baffle of the speaker. The foam is precision wire cut for each model which allows for a pressure-type fit. No Adhesives are necessary.

Product: HR-X 4-Way, 2 Channel Active Crossover
Applicable Systems: HR-1, HR-7, SM-1
Subject: System Hum and Noise

The HR-X active crossover when installed in a system will be connected directly to a minimum of 5 other pieces  of electronic equipment in addition to the A.C. wall outlet. This presumes  a quad amplified system using stereo amplifiers. In the case of separate  mono blocks, nine items are directly connected.

This being the case, coupled with the fact that the drivers in these systems typically have sensitivities well in excess of 100dB/W/m, the potential  for audible system noise and hum is great. To realize the full sonic potential of these systems demands that the installer focus his attention to the  detail of how the wiring is installed.

A point well worth remembering about the HRX unit itself is that it was  designed to produce the lowest noise floor possible. To accomplish this  a number of physical characteristics are inherent to itís design.  One is the chassis construction. Three magnetically separate compartments have been formed, welded, and heat-treated (annealed) using Hi-Mu 80.  It is soft, which is a characteristic of high permeability materials,  and accounts for itís slightly uneven look. However itís performance  is unequaled where electromagnetic shielding is concerned. This creates a virtual black hole (magnetically speaking) for the medium density (42 ICís), highly sensitive signal electronics cards to sit in.

The center position contains the dual power supplies for the left and  right channels. The shielding in this case reduces the intensity of any  radiated magnetic field from the power supply to the signal cards or nearby audio electronics. In itís dual nature the power supply provides total isolation of the right to left channels as only the power cord is common. This provides an ideal left to right crosstalk specification, essentially that of two separate crossovers, limited only by the installation wiring, or other component specifications.

At the rear of the unit is a 3 position terminal strip which provides  electrical access to the chassis (center terminal) and left and right audio grounds respectively. Lowest noise (mainly hum) may be achieved  with the chassis connection open or connected to the system audio ground, or lacking this, to the left or right, or both left and right terminals. Some experimentation may be required to find the combination most suitable  to a particular installation. Many high quality power amplifiers (or pre-amps) provide user selectable connection from chassis to audio common. It is usually best to start by opening the audio to chassis links on all equipment  and listen to the hum and noise present in the output of the speaker system.

By observing the hum change as particular  links are installed the best combination (for lowest noise) can be empirically  determined. Often it will be with all but one link removed. That link is usually the chassis to left or right (but not both) link at the HR-X  crossover in the case of a quad amplified system using stereo amplifiers (particularly if the amplifiers are used h.f. / h.f left / right in one  amplifier). In this case connecting a 2nd jumper from both left and right produces a ground loop as the left and right is already connected in the amplifier chassis.
In the case of left and right signals not on a common chassis (mono blocks or stereo amps not sharing left and right signals), a link from the HR-X  chassis to left and right may produce the lowest noise.

A point to keep in mind about the system is that when grounds are linked at multiple locations a ground loop exists. As such, the potential for  the loop to cause A.C. hum to appear in the outputs of the electronics exists. Whether you will hear it or not depends on the environment, amplifier  gain / type of input and whether or not any portion of the loop is exposed  to an A.C. magnetic field that is strong enough to cause a voltage large  enough to be heard. Because of this phenomenon, high gain power amplifiers  (I.E. Over 26dB of gain) will be more sensitive to this condition than  medium to low gain (26dB or less) amplifiers.

In the case of stereo amplifiers where audio common shares two channels, the input leads to each half of the amplifier may form a loop when connected to one channel of the crossover as the active crossover outputs (H.F.  , M.F. , M.B. , L.F.) share a common audio ground. To minimize the loop effect, run the two interconnect cables in close proximity to each other and away from the power amplifier chassis where the transformer / A.C. line cord field may be strong. Also route them away from speaker cables,  which should be twisted to minimize their effect, which (will not be apparent with out signal present) although is not hum or noise per say, is equally destructive. The same effect can be experienced with multi-channel amplifiers even if all channels are on the right or left side (I.E. One multi-channel amplifier @ left, separate one @ right).

HELPFUL TIP: It can be a bit frustrating to trouble shoot a complex system of this sort. Often the amplifiers and or electronics are not located where you, the technician or customer, can easily hear what the results of your changes of grounding or cable positioning is producing. The hum  level is low, and worse than that, if you move about physically, the room  nodes can produce an increase and decrease of apparent hum levels with  just slight head movement. What to do?
Use a pair of high sensitivity, comfortable headphones, wired through  an extension cord/adapter that will plug into the power amplifier outputs (usually a dual banana plug, but sometimes spades or clip leads are required).  Send this mono signal to both left and right ears. As you move the connection from amp channel to amp channel, youíll be listening to the various outputs, I.E. L.F., M.B., M.H., H.F., etc. This will allow you to get  instant feedback of how you are doing, whatís working better or worse, while maintaining a constant distance from sound source to ear.
Westlake Audio 2001

Protecting Signal Integrity  in the Monitor Chain Through
Good Cable and Connector Maintenance Cable connections are extremely important. To assure good connections please note the following:

1) When it comes to good signal flow through connectors, cleanliness is  absolutely necessary.

A.) At the speaker/amp connections the banana connection is extremely  problematic. The female part of the connection is constantly being eroded  by the penetration and abrasions of the male part. Typically the male is sharp and scrapes off the female surface plating particularly if itís  gold, which is soft. So periodic cleaning of both the male and female parts of the banana plug is mandatory if performance results are to be consistent. Cleaning the parts with a wooden shank cotton tip applicator  is recommended using alcohol, MEK or other wetting agent. The cotton tip  must be fully inserted, by rotating into the female part while swabbing 360į of the male part surface is adequate. If upon removal of the tip of the cotton applicator from the female, it looks gray or black, the  connection was dirty, indicating contaminated signal conditions prior  to cleaning. However the lack of visible contaminants does not necessarily indicate good signal conditions since these contaminants can be invisible to the naked eye. Knowing the connection has been cleaned prior to insertion is recommended.

B.) The lower part (where the spade lugs go) of the dual banana (Lc Series)  and the barrier strip connections (BBSM & Reference Series) are much less problematic, owing to the larger surface area and very high contact  pressure that the mechanical advantage offered by the screw design, can afford. However, periodic inspection and/or cleaning of the spade lugs and or mating connector surfaces should be done. Periodically visual inspection  of the spade lug surface should be made (preferably with a 3 to 8x inspection loop) to determine if surface scaring is decreasing the available contact area and thus limiting the signal flow. If so, replacement spade lugs  and/or cable assemblies should be obtained and put into service.

C.) The signal XLR cables and connectors should also receive periodic  inspection and cleaning for the same reason as the banana connectors (scraping  of contact plating) although the low level of current flow combined with low contact pressure makes these connectors sensitive to even dust/dirt  and hand oils. Rarely will the connection quality show up in the line  level or frequency response measurements, however low level signals (as in audio) will suffer degradation (i.e. poor sound) if these connections  are not kept clean. The cleaning operation here is again with a wetted wooden stick cotton tip applicator. However in this case the cotton tip  end can only be used on the male connector pins. Owing to the small diameter of the female contact pin, something else must be done. We have found the back end of the round, wooden applicator is usually about the size  of the contact diameter or slightly smaller. Dipping the stick end (as opposed to the cotton end) into the wetting solution of choice and then  inserting and reinserting into the female XLR contact can produce a cleaning action of the contact. While it is tempting to twist/rotate the applicator  while it is in the female contact, care must be taken not to cause the stick to bind, thus possibly damaging the contact, which would necessitate  replacement of the XLR itself. Alternately a round wooden toothpick can be employed if the applicator stick diameter is too large. Although wire contact cleaning brushes are available, they often donít produce  a good result with the exception of heavily corroded or oxidized contacts.  The advantage that the wood has is that it is porous, thus allowing the  wetting agent to be carried into the contact and the contamination particles  to be absorbed into the stick and thus removed. You can do several contacts with one stick by just snipping of the used end (1/2Ē) at each insertion  and re-wetting.

2) The mechanical integrity of your cables should be periodically assessed.

A.) Visual Inspection: As previously mentioned the spades can be become  so badly scored that only extraordinary pressure will over come the small contact area that scoring produces.

B.) Look at and note the feel of the banana plugs. The male part of the  banana is a spring contact. Like any spring it can weaken over time, especially  if left plugged into a mating female. So itís best not to plug them  end to end when not in use. If the spring has been weakened, and you are  counting on high performance, it is best to replace it. A weakened male  banana, plugged into a mating female banana that does not allow full penetration of the male part is a very problematic condition that should be avoided.

C.) Banana plugs with set screw terminations are extremely problematic.  It is not a question of ďis the set screw tight, or it will loosenĒ  ? But just when it will loosen and will it be noticed before it causes  a problem? The set screw type banana can be used, but diligent retightening and checking must be employed and is usually just an accident waiting to happen, this is especially true in situations of daily use where it is regularly plugged in and out. In addition to the problem of constantly  loosening up, there is the issue of to tin or not to tin a stranded wire. Itís tempting to not tin, as after tinning the wire is bigger and  more difficult to push into the hole and get the set screw engaged in itís thread pattern. However untinned leaves the question: Are all conductors engaged and working? At the start, if real good set screw tension;  maybe yes. But one flexing and the set screw may loosen. Who knows; probably not all of the conductors are active (or at least to the full share of the load). This is why we solder connections in our Westlake Audio speaker cable assemblies. This is also why we recommend solderable dual bananas  for critical applications, especially where lotís of mechanical action is present. Unfortunately these parts arenít as readily available, cost more, and are bigger and thus not easy to handle. But we do find them more bulletproof as far as intermittency is concerned, particularly  if both pins (total 4) on each side are employed so that tugging on the wire wonít produce a rotation on the swedged solder pins.

Electrical Assessment:

A.) A quality ohm meter (digital preferably) can be employed to see that both conductors are equally well terminated, before, during and after flexing.

B.) The test measurement should be stable over several successive tests, before, during and after flexing. If your set-up fails this test, maintenance  or replacement is recommended.
We recommend this application note be kept handy as a checklist for cable  and connector maintenance. Hopefully it will help keep your equipment  working to itís full potential.

Good Luck and Good Listening!

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