DIGI DISAPPOINTMENT As a Pro Tools user of eight years, I was disappointed with the 5.0 version for reasons that I thought could have been covered in

DIGI DISAPPOINTMENTAs a Pro Tools user of eight years, I was disappointed with the 5.0 version for reasons that I thought could have been covered in your review.

I use Pro Tools for music production, TV and radio spot production, audio sweetening for broadcast productions, and extremely "anal" narration editing that has given me a reputable narration service in this town.

In Version 5, Digidesign redesigned the keyboard shortcuts, which threw me for a loop. I have spent thousands of hours feeling comfortable with Version 4.3, and it worked well for me. My efficient, high-speed editing depended on the fact that I did not need to click on a bar to get the Smart Tool; I used the keyboard shortcut.

I also did not like the graphic interface when I tried to set my preference of insertion control. Why does the scrub control set the insertion differently from the way it worked in 4.3? After many attempts, I could not get the insertion to follow scrub/shuttle and have the insertion not follow Playback.

And finally, I thought that the feature of "stationary playback head" was a plus in theory. Yet, without at least a faster-than-most G3 CPU, the graphic display of this feature was very choppy and not beneficial at all. I'm using and will continue to use my 9600 because of my card slots full of DSP, video and SampleCell for music production. I would like Digidesign to provide a disclaimer that the stationary head will work in a useful manner provided you have the CPU to handle it. I have decided to keep using 4.3 in both my studios, which are used by several other engineers.

Tom KrolTK Audio Inc.Skokie, Ill.

HOW MUCH IS THAT DAW IN THE WINDOW?I liked the article on budget studios ("Building Your System," July 2000 issue), but think it's a mistake to not include the cost of a computer. True, most everyone has one, but most will need to upgrade (older system/slow CPU, not enough memory, not enough hard drive space, no external drive, missing peripherals, etc.). In some cases, it's cheaper to buy a new, stand-alone system; so, in my opinion, the question of buying a computer and necessary software should be compared to the cost of a stand-alone workstation.

One other issue that was not covered: With Mac abandoning the PCI slot on many new models (iMac, iMac dv, iBook, etc.), how are we supposed to interface multiple channels? Firewire isn't getting the support of third-party developers due to Apple's steep licensing fees and political doggery. USB2 is coming up as a viable option, but I'm not aware of audio peripherals for it. In general, I want to record via my computer but feel this is a transitional time for the Mac with OSX threatening to outdate existing software, and new hardware-interface technologies competing with no standard in sight. Thanks for letting me rant.

James PearsonOperations Manager, WKYU-PBSBowling Green, Ky.

MEYER QUESTIONI have a question regarding part of your Technology Spotlight on the Meyer X-10 monitors (June 2000 issue). You wrote, "Meyer engineers took the concept and developed it into Pressure Sensing Active Control (PSAC), which places a pressure sensor - essentially a calibrated condenser microphone - in front of the woofer. The information picked up by the sensor is then sent to the PSAC comparator circuit inserted before the LF power amplifier, which compares the sensor data to the input and puts the two signals in precise alignment."

I'm not sure I understand just how these two signals can be put in precise alignment. Is the input to the amp delayed to align with and then compared to the information from the sensor? If so, what possible corrections could be made since the woofer has already produced the waveforms being analyzed?

Call me ignorant, but I do not understand what possible use this sensor could be since it is, in reality, after any possible point in the chain where a change can be made. In other words, the wave has been physically produced by the woofer and can no longer be altered. Thanks for your time. I generally enjoy and find useful your reviews and articles.

Nick JoyceNP StudiosVia e-mail

MEYER ANSWERThe correctional circuit is not a simple feedback loop, but an advanced control system developed and patented by the University of California at Berkeley. Meyer Sound has licensed this technology for loudspeaker application.

Feedback and control system theory tells us that in order to have a stable system with a feedback loop you have to make sure that the phase shift is less than 180ø in the passband of the system.

When the phase shift is 180 degrees the system will oscillate if there is any gain left in the loop. In power amplifiers with feedback loops delays can be less than a few microseconds; therefore the 180ø point can be in the megahertz range. Some early power amplifiers that had poorly designed feedback loops often oscillated at very high frequencies.

In the case of the X-10, the pressure microphone is about 1 inch in front of the dust cap, deep inside the cone area. This is in the "near field" of the speaker where the pressure wave is being created.

The 180ø frequency due to sound wave propagation to this position is several thousand Hertz, well beyond the operational bandwidth of the low driver, affording the opportunity for control systems to be applied, resulting in significant, appreciable benefits in the net performance of the system.

John MeyerPresident and CEOMeyer Sound