Q&A # 111- April 13, 1999

Staff

Q I have four B&W 602s on stands, a B&W CC6, a Yamaha DSP-A1, and a Sunfire subwoofer. I have two questions about setup. Should I select "large" or "small" speakers for the B&Ws on the DSP-A1? Since the Yamaha crosses over at 90 Hz, I'm worried they are not being used to their full potential. What would be the best positioning for the surrounds since they are direct radiating?

A "Large" or "Small" settings on receivers are relative. The 602s are full range, even though they are not floor standing speakers, so I would select "Large". The 90 Hz high-pass is really for the modular speakers that have 4 1/2" woofers. Also, set your subwoofer's low pass at about 50 Hz or 60 Hz. This will prevent your sound from being too heavy in the 80 Hz - 90 Hz range (where it would cause boominess). When and if receivers and processors have digital crossovers so that we can select among numerous low-pass/high-pass combinations, then it could be advisable to high-pass the 602s at about 60 Hz, and low-pass the subwoofer at the same frequency, assuming the digital crossovers have brick wall (infinite slope) capabilities, so that essentially nothing passes above the low-pass and nothing below the high-pass settings. Even some floor standers might benefit from removing everything below 40 Hz, and the power amplifiers would perform better. Then, subwoofers could handle everything below 40 Hz, and the whole system would be very efficient. Place the rear left/right speakers in the same relative position as the front left/right, since digital surround has full spectrum audio in all the channels.

Q I currently own a Panasonic A310 DVD player, and a Lexicon DC-1 processor. I am considering using both of these pieces only for home theater, and buying a new CD Player (Rotel 971 or CAL-10), along with a tube preamp (Quicksilver or Audible Illusions 3A) for serious 2 channel audio (to be used with my existing Rogue 88 tube amp and Vandersteen 2Ce Signatures). Am I going to waste a couple of thousand dollars, because DVD-Audio is just around the corner? Should I wait another 12 months to see what shakes out?

A Pioneer's 24/192 technology (24 bit - 192 kHz sampling) apparently has been approved as a standard in DVD Audio. I think Sony/Philips' SACD technology will also be routine at some point. Both of these are DVD technologies. Within a year or so, there will be high performance players that do a good job with CDs and DVDs available from everyone, including the brands you mentioned. CDs will be phased out because DVDs can hold all types of music, whether it is the conventional two-channel PCM stereo that is on today's CDs, multi-channel DTS, multi-channel Dolby Digital, 24/192, or SACD. DVD is really the next generation CD, not just an additional technology to CD. DVD is going to replace CD. Your Panasonic A310 will not do a very good job with CDs, so you might consider a dedicated CD player that is in the $300 - $500 range. Because all purpose players of high quality from all the manufacturers are so close, I would not spend a great deal ($1,000 or more) on a CD player right now.

Q I recently upgraded to a B&K 4090 pre / Sunfire Cinema Grand from my original Carver Receiver. Anyway, while the B&K / Sunfire combo blows away the Carver in most respects, I noticed that the radio on the B&K was rather poor. The Carver had its own AM antenna (which I use to get local sports broadcasts for the most part) and the screw-on connections to which I attached a cheap-o wire dipole antenna.

When I attached the dipole antenna to the B&K, the reception was very inferior on FM. To date, I haven't been able to get much in the way of AM to the B&K at all --- I haven't tried the expensive antennas yet, but running with what I have hasn't produced much in the way of audible sound.

So, at this point, is it worth trying lots of antennas to see if the powered jobs work? Or does the B&K just not have a very good radio to start with? I'm guessing since I can get a better signal on my clock radio I've had since the mid-80s, we might be talking a poor internal tuner here.

A Tuners in receivers have deteriorated because the average user focuses more on playing CDs, VCR movies, DVD, etc. The digital music stations on satellite and cable are much, much better than any AM or FM transmission. Frankly, the only time I listen to the radio is when I'm in the car. It sounds like your situation is one of reception, so an amplified antenna would probably solve the problem for you.

Q I own Yamaha DSP-A1 and my question is , is there any possibility for the sound coming from the output of this unit to be THX-proccessed?

A Although THX does not make their processing standards public, it appears that the DSP modes on many receivers and processors, including the DSP-A1, allow the same - or similar - processing. The EQ for the center channel to make the dialogue less harsh and more listenable, plus the phase adjustment between the two rear speakers when listening to Pro Logic, are both present in modern receivers, such as the DSP-A1. Plus, the DSP modes are often programmable down to the fine details. The result is that less and less receivers and processors have THX certification. There is no point in paying a THX certification fee for a receiver or processor if the DSP modes duplicate THX functions. However, THX certification for speakers and amplifiers still represents a nice high quality stamp of approval.

Q It's said that progressive scan DVD players are on the horizon. Would an investment in a "reference quality" Sony DVP-S7700, which doesn't offer progressive scan, be a mistake? I've heard the picture quality is so good on the new Sony that it may not be distinguishable from a progressive scan picture. Or would it matter only on a progressive scan TV?

A The availability and potential combination of line doublers, progressive scan DVD players, progressive scan TVs, and film vs. video sources, make a prediction of what the final image on the TV will look like confusing. So, first, I want to point out that progressive scan and line doubling are two different things, but line doubling requires progressive scan in order to work. Secondly, if the source is from a video camera that is interlaced, or from a video signal that comes originally from film, this makes a difference as to how the final image appears. With an interlaced video camera image, progressive scan works best in combination with a line doubler. The line doubler takes the first field (scanning lines 1,3,5,7, etc.) and interpolates the in-between lines to give a computer generated, line doubled, progressive scan, frame. Then it does the same thing with the second field (scan lines 2,4,6,8, etc.). This can help quite a bit with NTSC interlaced video, but with non-interlaced video signals (I can see that some broadcasters are already using these with high speed sports TV programs such as football), progressive scan without line doubling would probably give a better picture than with line doubling, because line doubling makes mathematical assumptions about what its computer thinks is in between the lines. This is especially so because not all line doublers are equal in quality.

With video coming from film, progressive scan makes marginal improvement because the film frame is stationary even though the two fields that make up each frame are collected 1/60th of a second apart (with interlaced video cameras taking pictures of moving subjects, there is partial non-alignment of the two fields that make up a complete frame, since the subect has moved slightly between the collection of field 1 and field 2). Although many DVDs are stored in progressive scan, not all of them are (perhaps in the near future, all the new ones will be though). For progressive scan viewing without line doubling, a progressive scan signal can be fed directly out of a progressive scan DVD player. But, for DVDs whose movies are not stored as progressive scan data, the first field of a frame is stored, then combined with the second field, and then the frame is fed as a progressive scan signal to the progressive scan TV (I am making some assumptions here that I may have to revise once I get all this new technology actually in my hands to test). Most of the new TVs will probably not give you the option of doing progressive scan/line doubling or progressive scan alone as choices. The TVs will probably just detect the signal type and do its thing.

If you don't plan to buy a progressive scan TV or HDTV within about 3 years, then the 7700 should be fine. However, even if you do plan to get a progressive scan TV or HDTV soon, the DVD movie does not have motion artifacts between fields like interlaced video signals do anyway, and HDTVs will have built-in line doubling, so the 7700 will still be fine. For the future, I am hoping we will have progressive scan sources (the DVD itself, VCR tapes, DSS programs, etc.), progressive scan transmission to the TV from DVD players, VCRs, and DSS receivers, and progressive scan displays, with the option of line doubling if we want to use it with interlaced sources. Downconversion or upconversion between various resolutions should also be optional rather than occurring automatically. In other words, the display should have user selectable options. I don't think we will see this for a while, because it would confuse most mass market consumers.

Q My receiver (Marantz SR 96) is equipped with 6 channel direct input jacks and pre out/main in jacks. The 6 channnel input jacks are to be used with an outboard 5.1 channel decoder, but what about the pre out/main in jacks?

A Pre-outs are used with outboard power amplifiers, and usually, there are some u-shaped jumpers that connect the main pre-outs to the main pre-ins that have to be removed when you have an outboard five channel power amplifier. With older receivers, the rear channels had less power than the fronts, so you could buy a three channel power amplifier, and connect the front left/center/right pre-outs to the power amplifier, and connect the rear left/right pre-outs to the main pre-ins (the front speaker binding posts on the receiver have to be connected to the rear speakers in this case). This would give more power to the rear channels, and you would only have to buy a three channel power amplifier instead of a five channel power amplifier. Most new receivers have equal power in all channels due to the needs of digital surround, so main pre-ins are not as useful as they once were. However, If you want to use a five channel EQ, such as the AudioControl Bijou, then you need the pre-outs and pre-ins for all channels, even if you have DD and DTS decoding built-in and you don't want to use an outboard power amplifier. In the future, all necessary EQ will probably be part of the built-in DSP.

Q I just purchased a new projection television and would like to use the ISF certified cables by Monster Cable. Problem - the TV does not have gold connectors. I read that gold goes to gold...gold to nongold increases oxidation. Any truth?

A When certain dissimilar metals are placed into contact under specific conditions, they can actually generate a small current. However, I don't think this is a problem with gold to tin-coated copper jacks. Oxidation will occur on the tin jacks regardless, and it is irrespective of the gold. With the gold and tin, you just have one half as much oxidation to deal with (it only occurs on the tin). I am more concerned about the impedance of the connectors. With digital data, it is very important. Right now, RCA coax cables can have an impedance of as low as 25 Ohms, and the connections should be 75 Ohms. That can produce a very unsatisfactory sound when those coax cables are used with a CD transport to DAC connection. Once we go to all digital connections, the cables will be critical. However, it will also be much easier to connect things, since only one cable will be necessary between all the components.

Q I recently listened to a pair of Boston Acoustics VR970 and they sounded great. They have a 1 inch aluminum tweeter sandwiched vertically between two 4 1/2" copolymer midranges. The bass is handled by a built-in 100 watt 10" subwoofer with a 12" passive radiator (side firing). Musically this seems to make a lot of sense, but with sub positioning being a crucial aspect, how would this fill a room? With a television in between, would it be better to have the subs firing outward or inward? My room is about 14' x
20' with an open stairwell to the left of the left main speaker. Would an outward firing sub cause problems by radiating the bass through this wide opening? The right speaker would have about 5 feet of room before it encounters a wall. This proposed system would be used for 70% music 30% HT. Am I better off going with a 2 way tower and separate sub (using up valuable floor space)?

A The position of the subwoofer is not so important as long as you don't put it too close to the wall (no closer than about 2 feet). You should face them so that they give you the best mid and high frequency sound. The low frequencies will simply fall into place. As to outward or inward, position them so that the side firing driver has the most room between it an any wall, cabinet, or large piece of furniture. However, the opportunity to try the positioning both ways should be taken. Likely, one will just appeal to you more than the other, and obviously, that is the one to use, regardless of what object is next to them.

© Copyright 1999 Secrets of Home Theater & High Fidelity
Return to Q&A Index.