Q&A # 209 - November 30, 2000

Staff

Q I was surprised to learn that the first Technicolor movies were actually shot with black and white film. How did it work?

A Yes, Three Strip Technicolor^�, for old movies such as "Gone with the Wind" and "The Wizard of Oz", was a process that used three strips of black and white film in the same camera, each filtered in such a way that it would record only the red, green, or blue portion of the image. The three film strip images were then transferred to three film positives, with gelatin relief maps representing the image after the silver was removed, and then the three relief maps were soaked in yellow, cyan, or magenta dye, and the dyes were transferred to one single clear film strip for projection. The technique is also called Dye Transfer. It was a fantastic process but very expensive, and the cameras were huge. Here is a link that describes the process in more detail http://home.att.net/~B-P.TRUSCIO/TECHTECH.htm. Also, here is a link that lists all the color film processes http://www.comp.brad.ac.uk/research/GIP/colour.html.

Q My Sunfire Theater Grand II has less bass in DD and DTS than in plain stereo or Pro Logic. When I play a DVD, there is more output from the sub in Pro Logic than there is in DD for the same disc. I have calibrated the levels with a Radio Shack meter and have the preamp set to small speakers on all five channels and have it set at 80 Hz to send the bass to my M&K MX-125 subwoofer. I have found that if I boost the level about 8 dB to the sub that the bass is much better. But when listening to stereo music, I have to turn the boost back down again to 0 dB for proper bass levels. Is this normal with pre amp processors?

A Because DD and DTS are totally digital until amplification, and Pro Logic is an analog process decoded from only two channels, it is normal for there to be some differences in final channel loudness between the DD/DTS and Pro Logic. Not necessarily, but it does not surprise me. First, the player has to condense the 5.1 channels down to two, and then the receiver extracts information from those two channels to give five. It is possible that the bass is already being given a little boost in your processor when it is in Pro Logic mode. I would suggest just turning the bass up or down when switching modes, using the volume control on the subwoofer, rather than adjusting it with the menu in your processor. This will be simpler.

Q I have a 32" TV and I've been looking for the recommended optimum height placement. A friend of mine said to place it so that the center of the TV is about the sitting eye level. Is this accurate?

A Yes, that is right on the money. However, I would not risk putting it on anything unstable just to get it exactly at that position.

Q I have a question regarding my speaker setup that I hope you could help me with. I have a Kenwood VR-306 receiver and Energy e:XL series speakers. The mains are e:XL 28P, the center e:XL-C, and the rears e:XL-Rs. I bought the Kenwood a while ago and bought the Energy speakers just recently. When I purchased the speakers, the salesman said that a separate subwoofer isn't necessary as each main has a subwoofer in it. Here is my setup. I run all the 5.1 analog connections (center, sub, left, right, surrounds) from my DVD player to the receiver. I hooked up the speakers with speaker wire (center, left, right and surrounds), but not the subwoofer out. Since I can't hook it up to the speakers, I set subwoofer to NO on the receiver. Now, when I watch DVDs in Dolby Digital 5.1, I don't hear the 'punch' in bass compared to when I watch it in Dolby Pro Logic. The bass in DPL is MUCH more noticeable and deeper than in 5.1. Is there another way of connecting or setting up my equipment to get that 'punch' in 5.1?

A See question # 2 above. As I mentioned, differences in bass output between DD/DTS and Pro Logic are not unusual. The remedy is just to crank the bass up with the subwoofer volume control when watching movies in DD or DTS. I frequently have to adjust the amount of bass even just between different movies on DVD, all in Dolby Digital. It is not a big deal, and that is why each channel has its own adjustable volume control. Having to turn up the center or the rear channels, or turn up the bass, turn it down, etc., is a pain in the tush, but that is one of the prices for having all the channels.

Q How do I make my own speaker stands? I have pair of B&W 602 S2, so I would like to build stands for these babes. Can you give me some scheme of the stands, because I have general Idea of how the stands should look, but I have a problem with connecting the pipe with bottom and top plate using screws.

A I would suggest using PVC pipe, i.e., the kind that is sold at hardware stores for garden watering systems. They also sell plates that attach to the pipes on the end, and will let you screw the plate to something such as the flat board on which your speakers will sit. Fill the pipes with clean sand before mounting them. You could drill holes in the bottom plate to push three 1/2" PVC pipes through, with the tops supporting the top plate for the speaker, putting a cap on the bottom ends of the pipes, and using those three pipes as legs (a tripod). Felt pads on the bottom of the pipes will dampen the stand with respect to the floor. Make the top plate slightly smaller than the bottom of the speaker, so that there is no shelf for sound coming out of the speaker to bounce off of.

Q If my front and center channel are using Audax drivers, should the rear channels be the same, or can I use another type of driver like Focals?

A As long as the speakers all sound neutral, any driver will be fine. Getting them to be neutral is the hard part.

Q I have recently purchased a powered subwoofer for my home theater, and would like some pointers on how to set it up in a room, and how to balance the controls out properly. These include gain, phase, and crossover frequency.

A There is no real formula for adjusting gain because preferences for bass vary so widely. It is not like cranking the mid-range which would make voices sound very unnatural. Some people like a lot of pounding bass, and others use small speakers with no subwoofer and are completely happy. However, after bringing a new subwoofer home, especially if never having owned one before, there is a tendency to turn the bass up too loud. Heavy deep bass can be fatiguing, so after the novelty has worn off, turn it down so that you don't think, "Wow, listen to that bass," when watching every movie. The bass should be there, but not draw attention to itself. As to phase, I listen to classical music and have someone adjust the phase while I sit in the listening position. Crossover frequency should be about 5 Hz - 10 Hz below the low frequency specification of your main speakers, with the receiver's bass management set to "Large" for the mains. If you are using small speakers, and have the management set to "Small", so that the receiver uses a crossover of about 90 Hz, then set the sub to about 85 Hz. This takes into account the rolloff of the receiver, the speakers, and the subwoofer.

Q I have a Denon AVR-3200 A/V receiver that is rated at 85 watts into each of its five channels.� It has preamp outputs for the center, front L/R, and subwoofer.� I've already attached a Definitive PF15TL subwoofer (325 watts).� I have an old Carver cube amp sitting in the box that has 200 watts/channel into two channels (or 400 watts into one channel).� I'm  thinking that my home theater might get additional punch if I attach the Carver amp.� The question I have is whether I should have the Carver amp power only the center speaker (which does most of the work usually) or both the L/R speakers, which will help spread out the power of the Carver and potentially allow the receiver to concentrate on fewer channels.

A Because 85 watts per channel is just barely enough, and because, as you mentioned, the center channel does most of the work, I would suggest using the Carver Cube to power just the center. If your center speaker is 8 Ohms nominal, then you can bridge the Carver easily, but if your center speaker is a 4 Ohm load, then use just one of the Carver channels to drive it. Bridging an amplifier reduces its ability to handle low impedances.

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