A39 - It is often assumed that excessive amounts of power are required to drive a dipole woofer, because of the necessary 6 dB/oct acoustic roll-off equalization and additional boost required for drivers with Qts below 0.5. In fact, equalization does not change the power requirement. It is a driver's cone excursion for generating a desired SPL which determines how much output voltage and current an amplifier must be able to provide.

A28 - The shorter you make D, the distance between front and rear openings of the PHOENIX and H-frame woofers, the higher the frequency for which the rear wave adds in phase to the front wave, and the unequalized dipole output reaches its first 6 dB peak. Unfortunately, there is a resonance that comes into play before this peak. The cabinet structure between the driver cone and the cabinet opening forms an acoustic transmission line.

A30 - A dipole placed in a room corner should provide minimal excitation of room modes or resonances. The corner is a region of maximum sound pressure and it is well known that a typical monopole woofer in this location will couple optimally to all room modes. A monopole woofer would be a high impedance pressure source in the high impedance region of all wave modes (Z = p/v) and be optimally adapted to support them.

A34 - The low frequency roll-off of a woofer and its associated group delay are optimal, from what I have observed, when they follow the response of a 2nd order highpass filter with Q = 0.5. When a driver is mounted in a dipole W-frame or H-frame its mechanical resonance frequency Fs decreases to Fd, due to air mass loading, and Qts increases by a similar percentage to Qtd. For example, a driver with very strong motor, Fs = 18 Hz and Qts = 0.2 might have Fd = 16 Hz and Qtd = 0.

Not much. At Fs it takes maybe around 5 W to drive a 12" unit to full excursion in free air. It takes just a little bit more in the open baffle cabinet because of the air mass loading. More power is needed as frequency goes up. I have found - by monitoring the p-p voltage across the woofer terminals - that each woofer channel is easily served by a 50 W amplifier.

Troubleshooting - I get an error message "Unable to create video window" when I try to play movies.

A31 - Yes, there is, from a sound reflection and also from a standing wave point of view. Both are a consequence of the figure-of-eight or cos(angle) free-space polar response of a dipole with its opposite phase front and rear radiation and very low output at 90 degrees off-axis. Assume the dipole speaker is placed at the same distance from the front wall as the listener has to the wall behind him.

In England, people drive on the left side of the road and steering wheels are on the right side of the vehicle. However, in UFO's version of 1980s England, both of these have been reversed. Although I am not aware of an official explanation for this, it seems likely that UFO's creators were simply going along with what was being predicted at the time, which was that England would switch their driving system sometime in the near future.

I give a formula in Ref. 2 and in Design Models A1 that relates the sound pressure level from a driver on an open baffle to the SPL from the same driver in an acoustically small closed box, assuming that both have the same cone excursion. frequency Fequal the SPL is the same for either driver arrangement. The open baffle driver output decreases at 6 dB/oct below this frequency relative to the closed box.

Yes, usually damage to your power steering pump will happen within relatively few miles if you continue to drive with little or no fluid in your power steering reservoir.

A25 - A rear firing tweeter for the PHOENIX would increase the speaker's high frequency 4p acoustic output by 3 dB for an even more uniform power response. In earlier designs I actually used such a tweeter. Because of the physical size and separation of the two tweeters - in terms of wavelength - it is impossible to obtain a simple cos(a) polar response.

A39. There is no easy way for us to answer this question. First, we do not have much experience aboard other boats to compare. Second, this is a very relative question. Boats move, and they can move a lot. For some people this is no problem, for others it is a major problem. In our opinion, if you have trouble aboard boats, a different kind of boat (size, type, etc.) will not really help you that much. It is like riding roller coasters, some people cannot do it.

Joni drives an adapted van which has no steering wheel. She drives her van pretty much the same way she steers her power wheelchair. She also has a panel of push buttons that operate power windows, radio, air conditioning, etc. She worked very hard to develop enough shoulder strength to be able to control the vehicle.

Kirk's old Exodus demo's have been seen floating around, he has also recorded a track with Les Claypool and Mike Bordin set for possible future release (by Primus?), he has produced demo's for Death Angel, he has recorded solo's for Pushead's band Septic Death, you can also find him on the Spawn soundtrack playing guitar on the Orbital song called "Satan" (along with the re-mix of For Whom The Bell Tolls).

We are very cognizant that pain control is very important for the patient's well being. Medications are provided to control the level of pain. The typical patient, however, requires only Tylenol and occasional Tylenol with Codeine for control of pain.

The moveable mass racket provides better power and control because it reduces the twist for off-center-hits.

Approximately $100 to $200 for a case with power supply, plus the cost of the hard drive, plus the cost of the SCSI-TV. Buy a tape drive that is recommended by your backup software. We have tested ARCHIVE and TEAC tape drives using "AmiBack" backup software.