Q&A # 204 - October 31, 2000

Staff

Q That's it! Your new benchmark reviews push you guys over the top. Secrets is now the best A/V publication in the world, and I'm not going to renew any of my printed hi-fi magazine subscriptions. Why should I pay money for something that is second best?

A OK, OK, take it easy. Relax. Life is good. Spend the money on a couple of nice dinners with your wife.

Q I have an AMC 3050 stereo amplifier, Rotel CD player, and a pair of B&W 602 S2 speakers. I want to expand the system for "home cinema" purposes, but don't want to get rid of the AMC amplifier. So, I thought about buying a receiver like the Onkyo 575X, Yamaha RX-V596, or Denon 1801, plus B&W 601 surround speakers and CC6 centre. Could I connect the front speakers pre-out of the receiver to the aux input of my AMC (in order to maintain my original stereo configuration), and when I play DVDs, hear the front speakers through the AMC and the rest of the channels from the receiver? Is this correct? Is this possible? Is this a good (in terms of sound quality) solution?

A Yes, that is exactly the configuration you should use. It will not only give you the front left/right sound through the AMC, but will allow the receiver to perform better with the center channel and rear left/right channels.

Q (1) I want to turn On/Off my power-amp EAD PM500 with my DC2. What type of trigger cable do I have to use? Where can I buy this cable (Radio Shack?) (2) I connect my DC2 to a Panamax 1000+ line conditioner, and I want also to turn On/Off the Panamax by DC2 (trigger). The Panamax has a power cord to connect to a receiver (12V or 120V) to permit turning On/Off the Panamax when I turn On/Off the receiver. Can I do that with the DC2?


A Trigger plugs are usually 1/8" mini plugs, or 3.5 mm, tip-sleeve connections, like a small headphone plug, but with only two conductors instead of three. Check the manuals of your equipment to make sure that the connectors are correct, and the voltage out of the DC 2 is appropriate for the trigger input of the EAD.

If your DC 2 has a twelve volt trigger output, and the Panamax has a twelve volt input, wire the voltage accordingly, positive to positive, ground to ground. If you're talking about the power cord that's supposed to go into receivers' convenience outlet, what you're going to need is a Xantech AC-1. It's a voltage-switched AC outlet. Run the trigger out, so that the tip of the mini plug goes to the connection labeled +, and the sleeve goes to the -.

Q My questions concern the crossovers and directionality of the bass in this setup. (1) The receiver is set to crossover at 80 Hz by default to the Velodyne. If bass is directional to around 50 Hz or so, and my SuperOnes can produce to 57 Hz, will some material be going to the sub that was meant to be "audibly directional" material going to one of the other 5 channels? This is assuming I use the "large" setting in the receiver setup. If I use the "small" setting for the SuperOnes, won't this make it even worse because highly directional material goes to the sub that should be going to the SuperOnes? (2) And of these 3 settings: Small, Large, and THX, just what is the receiver expecting from the THX setting? Full range all around? (3) Basically, without investing in a whole new system, is there a way with my setup to eliminate this problem? I guess it's not really a problem but it bothers me to know that directional sound, which is an extremely important aspect of home theater, may not be going where it was intended.


A (1) First off, 80 Hz is not highly directional. With a wavelength greater than thirteen feet, it's pretty near omni-directional unless you've got a speaker with a 14 foot front baffle. The issue you're dealing with is, is whether 80 Hz content is localizable. Just ever so slightly. I've got a couple of subs running with a 4th order L/R crossover at 80 Hz, and if properly calibrated, the blend is pretty convincing. However, in my experience, most people skip the calibration part, turn the subwoofer up too high, resulting in not only boomy bass, but more content coming from the subwoofer above 80 Hz (user, for example, has the sub output 12 dB higher than the rest of the system, so content at 160 Hz that was previously 24 dB below reference due to the crossover is now only 12 dB below), which is certainly localizable. So, if you can actually calibrate your levels, I think setting your speakers to "Small" and using the 80 Hz crossover can work fine, with the benefit of using less amplifier power from your receiver, and lowering distortion from both the amplifiers and the speakers, possibly at the expense of less mid-bass output, which for all we know, might be better. Or, if you wanted to run the SuperOnes as "Large" speakers, if the Velodyne has an adjustable crossover itself, you could pull down the crossover frequency by using the onboard crossover, and setting it to 60 Hz or so. (2)  No. THX mandates an 80 Hz, second order, Butterworth alignment high-pass filter in the electronics, and a 4th order Linkwitz/Riley low-pass filter with the sub. If the system is using THX-certified speakers, this should result in a splice between all channels and the sub which results in a 4th order, Linkwitz/Riley alignment. (3) Try both of the above, stay with whatever you like, and stop worrying so you can enjoy the system, and maybe even some movies!

Q My selection process for a complete system continues, but I'm pretty well set on the Aragon 8008BB and 8008/3 combo as to the soundstage. For the speakers, I still like the M&Ks, but I heard and was very impressed with the Aerial 7Bs (although a full system from Aerial ain't cheap). One speaker that seems to have a lot going for it is the RBH Signature series. I read your review of the MC series, and was wondering if you've heard the Signatures? They look like a pretty good buy too (those guys in Utah are "different").

A The Aerial line is, in my experience, very good. I've heard the 10Ts do some wonderful things. I think that in terms of sound quality, stressing in my humble opinion, they probably run neck in neck, with the M&Ks having an advantage in the performance/dollar category. On the other hand, the Aerial line offers a build quality and craftsmanship that M&K doesn't quite go after, in terms of how the cabinets are joined and finished. The M&Ks, do offer some very nice cherry veneers, but it also bumps the price up as well, which is why they probably haven't focused on the more cosmetically driven market. I do believe that build quality in itself does have the primary value worth paying for, but what you are getting with the Aerials are sound and looks. I'd consider my money well-spent on either.

Speaking in terms of the 10Ts, they are very clean and honest loudspeakers in terms of distortion and frequency response, something which attracted me to M&Ks in the first place. The tonality may be slightly different, as well as the imaging characteristics, but this will vary from room to room. If you get the chance, take the final round of contestants home with a good week to play and trade. Obviously, this requires an accommodating dealer, and if you find one, treat them nicely, because even if their price is a few hundred higher than the guy down the street, or on the internet for that matter, the service is valuable.

The M&Ks are more plain, requiring more of the recordings to render depth, but also are able to differentiate nuances very well in that regard because of it, whether it be artificial or natural. The Aerials bring the performance more into the room while still maintaining a bit of the window into the performance compared to dipolar speakers, which very much puts the performance in the room entirely, including the original acoustics.

The M&K THX-oriented satellites, by limiting their vertical dispersion, can snap an image into focus much more readily because they try to avoid the room. The side-effect is that the presentation sometimes may seem less realistic, more like a dubbing stage, simply because not only of the limitations of recording, but the methods of most recorded material.  And, if you're using the vertical dispersion to limit reflections, the vertical angle must be pretty exact to get not only good frequency response, but a good sonic image. Of course, with the MPS-2510s, you can open up the vertical dispersion as well, and take the enhancements of ceiling reflections.

Like the M&Ks, the Aerials use moderately higher order crossovers to lower distortion at the expense of phase response, air-core inductors for more linear dynamic output at the expense of a small loss of efficiency, and are pretty accurate in terms of tonality. I would be pleased to own a set of Aerials. If I had extra money, and extra space, I probably would own a few brands of loudspeakers. I'm very happy with my M&Ks, but every loudspeaker possesses a different set of strengths and compromises. If they were well-engineered, the compromises were intentional and carefully chosen for a purpose.

If you have any tweaky audiophile "guru" friends, they would probably like you to get the Aerials. The sheer craftsmanship, and more 2-channel orientation, makes them fit more easily within the classical "high-end" paradigm. If you don't give a hoot about "qualified" opinions, ignore this paragraph.

In a dedicated 2-channel environment, if you were to stack up MPS-2510s with stereo subs against another excellent pair of floor-standing speakers, like the 10Ts, and probably 7Bs, and assuming proper calibration and setup of both, aside from the fact that M&Ks would obviously have the advantage in the low bass department, I think it would pretty much be a wash that came down to simple preference. It's like listening to two story-tellers that tell the same story, impart the same basic facts, but choose different phrasing.

If it's alright, I'm going to get into a more general discussion of full-range vs. sat/sub. Both can be done with very good results, but have different requirements.

In a pragmatic perspective, the floor-standing system would not require any effort to properly integrate the low bass, because it is a single system without options in terms of output, crossover, or placement. So, if the user had no idea, or inclination, to know what he or she were doing, or had a false preconception on how things "should" be done, (i.e., the speakers were definitely going to go in a specific location come hell or high water), the full-range speaker would be far better off.

OTOH, Perhaps the low bass response is less than stellar when the loudspeakers are placed in the location of choice, perhaps for reasons of optimum stereo imaging (which if you're not talking about at least properly time-aligning each channel either by physical proximity, electronic delay or both, is a lost cause), for decorative concerns, or both. This is often the case.

A sub/sat system allows the user to compromise one aspect (the integration of low-bass to higher frequency content) to improve another (bass response accuracy in itself). If done carefully, the compromise in integration can be very minor, if noticeable at all, sometimes actually benefiting the perceived mesh due to smoother room response, and the benefits along other aspects can be substantial.

Add to that the fact that you can apply room compensation via EQ to a subwoofer without compromising the quality of the signal feeding the more sensitive portion of the audible spectrum, since it's on a separate amplifier. I'm currently using an AudioControl Rialto exclusively for the 1/3 octave EQ and 24 dB/octave Linkwitz/Riley crossover for my pair of subs to compensate for room effects, massaging the output to provide a flatter, more even room response, and I'm much happier for it. Performance in that regard by my former full-range loudspeakers, even though they themselves have terrific bass quality, would have been simply impossible in my current listening situation.

You could, of course, supplement the bass response of the larger speakers with a subwoofer or two, which isn't a bad idea under any circumstance so long as it's a good subwoofer, but then you're making the same sacrifice in integration, without the benefit of the higher-frequency speakers being specifically designed not only to integrate with a subwoofer, but to focus their performance objectives above 80 Hz.

The THX crossover configuration, as implemented by many surround processors, was specifically specified as a 4th order, L/R crossover at 80 Hz low-pass, with a 2nd order, Butterworth high-pass at 80 Hz. Why? Because THX also specifies that the satellites have a response equivalent to a 2nd order, Butterworth high-pass at 80 Hz. If you take the effect of a 2nd order, Butterworth alignment at 80 Hz high-pass filter on the electrical signal, and combine it with the identical acoustic alignment of the satellite,
you get, guess what, a 4th order, Linkwitz/Riley high-pass characteristic at 80 Hz. That's why EVERY properly implemented LCR set of speakers roll-off at about 80 Hz, and more importantly, use a sealed alignment.

Now, that's not to say that the THX method is the only viable way to get great sound. You CAN get a very good integration of subwoofers with full-range speakers not designed specifically to complement a subwoofer, but it usually requires moving the crossover frequency down to the less audible range of 50 Hz or so, increasing the output demands on the speaker, and lessening the placement flexibility advantages of the subwoofer. In other rooms, when I've had my full-range loudspeakers, I've done so with very good results.

From the aspect of a 5.1 channel application, I think that the subwoofer/satellites systems have a practical advantage, hands down, in that you can easily provide an identical center channel. A non-identical center channel is in any case, a compromise. It may be a graceful compromise if specifically designed to match the left and right, and if you prefer the sonic characteristics of a particular model of loudspeaker, it may be a compromise worth making, but it's still a compromise, even if the center channel uses identical drivers.

A non-identical speaker has the potential to pose problems in terms of tonality, inter-aural time delay, and directionality due to possible differences in drivers, driver array (physical layout on the baffle), crossover slope, phase responses, and subsequent dispersion differences, all of which detract from the ability of an LCR array to seamlessly disappear into each other. It's hard enough to deal with the fact that a center channel will likely be placed in a different environment than the left and right (on top of a television, perhaps at a different height, with a different relationship to room boundaries).

That doesn't make full-range speakers themselves inherently a compromise with 5.1, mind you. Stacey Spears has three, identical, Meridian DSP5500s, all standing vertical, for his LCR array, and I think the results are pretty incredible. In his situation though, the projection screen allows one of the DSP5000s to sit vertically on the floor underneath the screen.

Q I have a 12 year old Pioneer PDM-730 6 disc CD player that has developed a skipping "problem". It seems to get progressively worse toward the end of CDs and happens on all but a few CDs (the DDD ones seem better???). It is a peculiar problem that suddenly started happening 3 days ago. Could it be a dusty laser lens? (The Pioneer plays CDs upside down to limit dust accumulation on the lens.) Nevertheless, assuming it may be a dusty lens, are there cleaners out there that are of any value that would slip in the door of this and my car CD players or should I take it apart and use camera lens cleaner?

Assuming I'd need to take it in for repair, and in that everything seems to cost $100+ to fix these days, is it worth fixing or should I look at replacing it with a DVD player? I've not caught the DVD video bug yet (all I have is a 15 year old 25" TV), but I am very interested in DVD-Audio. I've not jumped in because the standards seem to be still a moving target as the record companies look to retain control. Are the standards settled yet or is my timing bad? I would also want a changer with at least 1-6 disc cartridge capability. Can you recommend a DVD changer player with optical fiber output? I have a Yamaha RXV-595 which has Dolby Digital 5.1 capability but doesn't have DTS or coax input.

A I suspect this is a mechanical problem rather than a lens problem, but you can try to clean the lens by using one of the automatic cleaners that can be purchased at most music stores. Don't take your player apart though. Use the cleaners that consist of CDs with a spot to apply liquid. You put the CD in, and it cleans the lens automatically. Because of the age of your player, I would suggest getting a new one rather than spending $100 on fixing it. DVD-Audio players have started arriving, but not cartridge systems. It will take about a year to get those, and also, the price for DVD-A players will come down by then as well. Your 595 does have DTS DACs though, so it will handle DTS bitstreams from the digital connection out of your DVD player, and the new players of mid and high price have Toslink optical jacks on the rear panel, along with coaxial digital jacks (RCA).

Q I have a Kenwood VR-309 (100w x 5 + .1) digital receiver and some Kenwood 100w speakers. I was playing them too loud, and I believe I have burned out the voice coil of my subwoofer. It sounds completely unnatural, and there is an odd vibration. Anyway, I figure I probably have to replace this subwoofer (if not tell me how to fix it!) Please tell me the best subwoofers around $300 Ii know that's low but please try. My second question is, since most subwoofers are active (as opposed to passive), my receiver wasn't really powering my subwoofer, right? Does that mean I can buy a subwoofer that exceeds 100w?

A For a replacement subwoofer, something like the Paradigm PDR-8 or PDR-10 would do the job, but if you really like to play loud bass, you should wait until you can afford something larger, with a 15" driver and several hundred watts of power built-in. Since the receiver does not drive your subwoofer, as you mentioned, you can get a subwoofer with as much power built-in as you want.

Q How do I set up the levels on Dolby Pro Logic, Hall, Theater 1, and Theater two? What factors should I consider?. The effect level is used for what? When do I have Pro Logic and the above together, and what are the advantages?

A Although Pro Logic and the other modes you mentioned use the same process of decoding from a two-channel stereo signal, "Hall" is called a DSP mode. The various DSP modes add ambience (reverberation) to one or more of the channels, and the Effect Level will vary the amount of reverberation added. You may even find one mode that eliminates the center channel. Pro Logic does not add reverberation to any of the channels. Theater 1 and Theater 2 might be added to Pro Logic as enhancements, depending on the receiver, or they might just be DSP modes all in themselves. If they are enhancements, the LED front panel will say Pro Logic - Theater 1 rather than just Theater 1. You can get enhancements to DD and DTS too. The front panel would say Dolby Digital - Theater 1 if so. As to the advantages, it will depend on your tastes. Usually some of the DSP modes will sound artificial, but one or two will sound good to a specific listener.

� Copyright 2000 Secrets of Home Theater & High Fidelity
Return to Q&A Index.