Q&A # 226 - April 24, 2001

Staff

Q I have a TV with S-Video input with no component input and no built in progressive scanning. I am going to be upgrading my DVD player right away. The question is should I buy a DVD player with progressive scanning even if I will not be upgrading my TV? Will the progressive scanning ability of the DVD player be wasted on my TV if I am only hooking it up to S-Video instead of the recommended component inputs? Should I upgrade my TV at the same time?

A I would suggest getting a DVD player with progressive scan output capability. At some point, from your message, you will undoubtedly be getting a new TV. Going from composite video to S-Video makes a large difference. Going from S-Video to interlaced component video makes a smaller difference. But going from interlaced component video to progressive scan component video makes a huge difference. So, all of your new purchases should be with progressive scan component video as the ultimate goal.

Q In one of your articles it is mentioned that 4:3 TVs can only display 330 lines out of the 480 lines of 16:9 DVDs. As you know some of the Sony TVs have a 16:9 mode. Does this mean that if I set the TV to 16:9 mode then all 480 lines will be displayed?

A With a 16:9 TV, all 480 lines would be used to show the movie, as long as the 16:9 DVD is enhanced for 16:9 TVs. The older DVDs that have 16:9 movies on them are not 16:9 enhanced, so you have to zoom in on the image to get it to fill the screen. This is simply expanding the 330 lines of the movie to end up using 480, but the processing results in a loss of sharpness. With the 16:9 enhanced DVD, all 480 lines of the DVD have movie signal on them. The 16:9 TV stretches the image sideways to fill the screen, and as a result, the picture is much sharper. The best setup for current DVDs is with 16:9 enhanced DVDs, a progressive scan DVD player, component video connection to the TV, and the TV being a 16:9 model that can handle progressive scan video. This will give you an image that is amazingly close to film.

Further, yes, all of the source lines will be scanned by those 4:3 TVs with a so called "16:9 Mode", BUT you are using less of the CRT face, and consequently less phosphors, as compared to a 16:9 model. This means either less light output or more blooming (the blurring that occurs when a CRT is driven too hard) on the 4:3 model as compared to a 16:9 set. So even though we are starting to see a crop of HD 4:3 sets with a 16:9 mode for preserving the resolution of 16:9 formatted DVDs, it is still desirable to have a 16:9 set for the best image possible, and a minimum of black space.

Q What would you recommend as the next level of improvement on my current HT system for two-channel music listening? My current system consists of a Yamaha 2092 receiver, Polk RT12 main speakers, Velodyne HGS 10, Audio Source Amp 3 driving main speakers, and Sony DVD/CD player. Certain CDs containing piano music have a ringing sound or edginess on treble, but some CDs are OK so I know it must be due in some part to the recording. However, I have been thinking about using a hybrid amp to drive the main speakers which have tubes on the front stage and MOSFET power transistors, i.e., a Jolida amplifier., which may tone this down. Is this the route to consider or another route such as speakers, DVD/CD player, preamp, etc?

A The reason tubes are used as input stages in some designs is the recognition that the input stage, being a voltage gain stage, shapes the waveform. The output stage, being the stage that supplies the current, is not technically a gain stage, although it is often referred to as one. There are a number of companies that make such amplifiers, such as Lamm Industries, LLano, and the just reviewed Smart Home Theatre 2X150VT. The sound really is spectacular, but it is an expensive engineering task. It is not something you would likely ever find in a mass market product. In your situation, such an amplifier would probably make an improvement, but you still have to deal with the mass market preamplifier in your Yamaha 2092 receiver. Mass market receivers serve the purpose of offering consumers lots of features inexpensively, but compromises have to made, and this often gives a pinched, less musical, and sometimes edgy sound. It occurs with all the mass market manufacturers. So, if you buy the tube/MOSFET hybrid power amplifier, you should also get a good preamplifier to go with it. On the other hand, the Audio Source Amp 3 is a pretty good amplifier. You could probably make a substantial improvement by just getting a better preamplifier and using it with the Amp 3. In the case of Jolida, their hybrid products are integrated amplifiers, with the preamplifier being tube and the power amplifier being MOSFET. That is different than having the input stage of the power amplifier being a tube.

Q 1) I am using an Onkyo 646 for home theater with an ED-301 processor, and will use an Adcom 555 amp for the fronts, Adcom 2345 for the center/surrounds. The 646 gets physically hot using its internal amplifiers; will it run "cooler" with the Adcoms? 2) Is there a way I can use a CD source connected to an Adcom 565 preamp, and connect that to the aforementioned Onkyo 646/Adcom amp system, to get "the best of both worlds" . . . the 5 channel experience through the Onkyo, and higher quality CD sound through the Adcom preamp? 3) what's the solution for using S-VHS output DVD players w/ RCA video input TVs?

A (1) Yes, the Onkyo will run cool when using the Adcom amplifiers, assuming you don't have some other speakers connected to the Onkyo. (2) If you want to take full advantage of using the Adcom preamplifier, you will need to use the bypass function though it. Connect the front left/right pre-out of the Onkyo to an input on the Adcom, then use the bypass function when you are watching 5.1 movies and turn off the bypass when playing CDs. (Connect the CD player's two-channel analog outputs to the Adcom.) (3) Buy an S-Video to composite video converter for using the S-Video output on your DVD player with a TV that has only an RCA composite video input. They are inexpensive, but keep in mind you will be throwing out a lot of the DVD image quality. Here is a link to a converter: http://www.svideotorca.com/svideorcafm1.html.

Q This has been bugging me: On the back of my subwoofer it has a knob for "low  pass frequency" that goes from 20 Hz to 220 Hz. What should this be set at, or what is a good suggestion for regular use? There is also a switch that says  "phase" and goes between 0 degrees and 180 degrees. What should this be set  to, or what is a suggestion for regular use? Lastly, what is the best placement for a subwoofer? At its current position, it sends less bass to me, and more to other spots like corners. I have carpet, which likes to soak  up bass, and a downfiring 12" powered subwoofer. Thanks!

A If you have the little modular speakers, set the crossover to about 80 Hz. If you have large bookshelf speakers, set it to about 50 Hz - 60 Hz, and if you have full range floor-standing speakers, set it to about 40 Hz. The phase switch has to be tested in each environment, and this relates to where it is in your room. Put the subwoofer as close to where you normally sit as possible. Then put on a good bass-generating movie like "True Lies" and walk around the room to see where you get the best bass. Then, move the subwoofer to that position. Next, put on the movie again, and have your friend switch between the two phase settings while you sit in the listening position. Leave it at the position that pleases you most. Carpet won't really soak up that much bass. They work better for high frequencies. The carpet would help reduce vibration of the floor however.

Q I recently started gathering components to set up my home theater system. I am not in a position to spend too much right now. I picked up an Infinity Minuette L-MPS speaker pair and an HK AVR45 receiver at Ubid. I would like to add a center channel because I noticed I lose some dialogue when I play DVD movies with the optical connection to the receiver. The HK manual recommends having the same brand speakers in the front. Could you guide me regarding this?

A This will all depend on how neutral your Minuette speakers are. Use one of them in the center to see if the voices sound natural. If they do, then get an Infinity center channel speaker in the same model range. Otherwise, it would probably be better to just look for a center channel speaker that is neutral in sound. I would rather have a center channel sound that is neutral, next to some different brand speakers that are not neutral, than everything the same brand and model range, but a nasal or chesty sounding center.

Q I am thinking about getting a CD jukebox with an optical output so that I can bypass its circuitry in preference for the receiver's DAC and circuitry. Will a receiver with a 96khz/24bit DAC be able to upsample and provide better sound over cheaper DACs in the CD player? How can I find out if a receiver has better circuitry or not, since it is rarely advertised or specified?

A First, let's differentiate between oversampling and upsampling. Oversampling has been around since the beginning of CD players. They started out with 2X oversampling, and now they are up around 16X. Oversampling can create samples filled with zeros and is primarily for the purpose of getting noise out of the audible band. It lets the DAC's filters have an easier time doing their job. Upsampling takes the original samples and creates new ones, using mathematical algorithms, with actual numbers. The new samples replace the old ones and can be not only higher frequency (96 kHz) but longer word length too (24 bit). The algorithms attempt to determine what the signal might have been if it had been recorded at 96/24. Of course, having original 96/24 recordings would be best, but to take advantage of today's 96/24 DACs, the engineers have designed upsamplers. The DAC "thinks" that the incoming signal is an actual 96/24 recording and does its job accordingly. So, oversampling reduces noise, and upsampling makes the sound more musical (assuming it does a good job). But, your receiver may not employ upsampling even though it could have oversampling. The DAC in your receiver might be better than the one in the player. It might be indistinguishable. It might also be worse. Using an outboard DAC is something that has been in vogue for awhile, but there are lots of high performance CD players with great DACs built-in. You will just have to compare the two DAC configurations to see which one you like best.

Q Please expound on the subject of surround delay. The how's and why's. Is there any inexpensive instrument that you can use to properly calibrate surround sound delay?

A Delay in various channels is for the purpose of making sure the sound reaches your ears from all the channels at the correct time. Delay can be added to the center and to the rears. Although there are formulas for using delay that are in the receiver instruction manuals, I always just use my ears. If I can hear an artificial sounding echo between the front and rear, then it is time to adjust the delay. You could have a situation where, with no delay, you hear the echo, and then you add some delay. The echo disappears. Then you add more delay, and some echo returns. Use the setting that has no echo. Turn the delay all the way up to the maximum to hear what the artificial echo sounds like, so that you will be able to recognize it at lower levels.

� Copyright 2001 Secrets of Home Theater & High Fidelity
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