Q&A # 42 - December 16, 1997

Staff

Q I have a pair of Paradigm Monitor 7s. What are the differences between bi-wiring, bi-amping (horizontal, vertical or 2 mono amps/spkr) and how does active bi-amping compare to passive bi-amping? I was also wondering if you could do a review of Golden Audio's SE40s which I have heard are an amazing bang for the buck. I find it very difficult to find reviews on Canadian speakers, e.g., Paradigm, PSB, Mirage, Energy, etc., and although I'm not biased, they always seem to be a better bang for the buck than imported speakers (I live in Canada). I paid $330 Canadian for a pair of B&W 302s and paid $520 for a my Monitor 7s, and the difference is incredible in every aspect, but I'll save the reviews for you guys/gals.

A With bi-wiring, all the speakers in one enclosure are being driven by one amplifier, but instead of the crossover network for the tweeter and woofer being connected together by a bus bar on the back of the enclosure, they are connected together at the speaker terminals on the back of the amplifier, using two sets of speaker cables. It is a controversial technique that may work with some cables, but not all. Bi-amping, on the other hand, works very well. Separate amplifiers are connected to the tweeter and woofer in each enclosure, thus, requiring 4 separate amplifier channels. In the horizontal configuration, two stereo power amplifiers are used, with the left and right channels of one power amplifier driving the left and right tweeters, and the left and right channels of the other power amplifier driving the left and right woofers. In the vertical configuration, the left and right channels of one power amplifier drive the tweeter and woofer of one speaker enclosure, while the left and right channels of the other power amplifier drive the tweeter and woofer of the other speaker enclosure. There are arguments for both configurations. For the vertical configuration, there is not as much drain on the power supply as there would be for the horizontal woofer amplifier (two woofers will need more power than one woofer and one tweeter). However, with the vertical configuration, there is an imbalance of power requirements for the two channels of the stereo amplifier, since the woofer demands much more than the tweeter. Using 4 separate monoblock power amplifiers is probably best, since each has its own power supply.

Active bi-amping is where the crossover is between the preamplifier and the power amplifier, while passive bi-amping just uses the crossover networks in the speaker enclosures. Active is better than passive because, with passive, the crossover networks absorb the energy from the power amplifier that is not being sent to the respective driver. In other words, with the woofer, the inductor(s) in the crossover network absorb high frequency information from the power amplifier, and convert it to heat. With the tweeter, the capacitor(s) in the crossover network absorb low frequency information and convert it to heat. Putting the crossover before the power amplifier allows only high or low frequency information to be sent to the respective power amplifiers, and this is much more efficient. In this case, the crossover networks in the speaker enclosures have to be bypassed. Also, a good active crossover has to be used, with fine adjustments.

We have some (more) Canadian speakers coming for review. The Canadians appear to make very nice products, and they are, indeed, good value.

Q I would like to enter the Dolby Digital world by replacing my receiver with separates. I already have 5 channels of amplification (Acurus 200x3, fronts; and HK Citation 19, 100wpc, rear) and a powered subwoofer. The Lexicon and Meridian processors that you have reviewed sure sound attractive, but at about $4000 without a tuner, are way past my budget. The Rotel RSP980 combo that you reviewed (about $2300 with AC-3 adapter) seemed like a possible choice, but the comments about the lack of "user-friendly" controls make this a bit scary. I think that what I really need is something like the Adcom GTP600 which is a preamp/DS processor/tuner combo (about $1000), except with DD. Are you aware of such a combo on the market in this price range? The '97 Audio Buyers Guide lists a Marantz AV550 for $1000, which seems to have the features that I want, but I can't find any info on this, even on the Marantz home page. Is it not out yet? Another possibility, but more expensive, is the HK Signature 2.0 pre/pro/tuner ($2500). Will you be reviewing any pre/pro/tuner combos in the future? I appreciate any suggestions that you have here. Thanks.

A Since you already have some Acurus products, I would suggest waiting until the Acurus ACT-3 is released. It is a dedicated processor with Pro Logic, DD, and from what we understand, DTS, which will be about $1,500. You should not use the presence of an FM/AM tuner as one of the criteria for selection of processors, since a good tuner can always be added as an outboard item. Sometimes manufacturers' web sites don't get updated as often as they should, so you should contact the specific manufacturer or dealer to ask about a certain product that you don't see listed on their site.

Q Just read your Q&A #40...and would like a bit of an elboration of amplifiers. I have two systems: Audio with modest Conrad-Johnson MV-52 amps (EL-34 tubes about 40 watts per side) and an older Conrad-Johnson PV-5 tube preamp. The other is an AV Home theater with a Parasound HCA 1206 and powered subwoofers and active high pass x-over. I don't know if I have ever clipped my home theater system, but it's possible I guess. You mention listening to a gun shot at an intitial 40 watt setting and the need for a large and rapid delievery of current to support the necessary volts. Do you really think we listen to 40 watts very often let alone the transient peaks the advertisers say WE NEED? I ask this because I listen to a variety of music on the lowly tube system. I vertically passively bi-amp, i.e., two stereo amps. I do not know what the current capability is nor the voltage potential is of these simple EL-34 tubes...perhaps you can fathom a guess....nor do I know if they have much of a damping factor (my hunch is that damping factors are silly numbers by-and-large).....But even in loud passages of a symphony or jazz rim shots the amps and speakers do OK, really! So this is a long way around to ask the question: how many watts do we really listen to for most musical/movie material? Let's assume we don't listen at the THX referenced 85dB (too loud IMHO). Let's say, as I do, I set the processor at 75 dB....and I am sitting about 10 feet from the LCR speakers in an average room 14x20x8. Yes I know T-Rex and bombs are loud (105+ dB) Just how many watts are needed, really? Since my tubes have modest current, fair volts and therefore fair watts...why do they sound nice (subjective) and mostly are adequate? Does the notion of the quality of that first watt really hold water? I wonder if I ever really use all the available current in my HCA 1206, especially since they only are asked to reproduce sound from 80 Hz on up and are being augmented by many hundreds of subwoofer watts from multiple subs. I suspect I, like many of us, are guilty of overkill. Am I way off base here?

A What you have brought up here is one of the fundamental reasons why tube audio components are still so popular, and in fact, are enjoying a renaissance. Solid state amplifiers distort with lots of odd-ordered harmonics (third, fifth, etc.), while tube amplifiers distort mainly with even-ordered harmonics (second, fourth, etc.). Odd-ordered harmonics are very irritating to our hearing, while even-ordered harmonics are not. In fact, even-ordered harmonics can actually be pleasing! So, even though your tube amplifiers may be clipping now and then, the harmonics that are generated don't bother you. Also, Conrad Johnson ("CJ") tube components are superb quality.

As to how much power we really "need", this depends on the impedance and sensitivity of the speakers, and what your music loudness preferences are. For two-channel audio systems, using 8 Ohm speakers with a sensitivity of at least 89 dB/w/m, I think that 40 clean watts/channel should be fine for most situations. On average, listening to audio involves about 2 watts - 10 watts/channel. If the speakers are not very sensitive, then more watts are needed. A kettle drum, plucking a harp string, rim shot, etc., require about 20 times this amount for an instant (the leading edge). If the volts and amperes are not there, the dynamics will be lacking, but it is for such a short period of time, you might not really notice it. Only when you compare that with a fast, powerful amplifier, would you hear what has been missing. The tonal quality would be about the same, but the "punch", "slam', or "twang" are added. Of course, there is no free lunch. Big tube amplifiers are incredibly expensive, and secondly, big amplifiers usually have multiple output devices in parallel. There is a general feeling in audio that "simple is better". That is another reason tubes are popular: the circuits are usually simple. Of course, you can go on any of the audio newsgroups and get into an argument about the pros and cons of tubes vs. solid state components. Someone will say that tubes have a "sweeter" sound, and then someone else will say that solid state is more accurate and that tubes are not really high fidelity. The bottom line though, should be what it sounds like to the individual and whether or not it is an enjoyable experience.

With multiple output devices (transistors or tubes), each device is contributing to the sound, and slight differences between the devices can cause distortion. The monoblock power amplifiers (White Audio B-80s) for one of our two audio reference systems have only two output devices (MOSFETs) for each amplifier, one per leg (positive and negative portions of the waveform). They don't have high power for dynamics, but they do have extraordinarily clean sound, and for that audio system, I chose accuracy rather than high power. I mention this because there is no panacea for audio nirvana. We have to choose what is important, sound-wise, and then get the appropriate product.

Q I have a Sony STR-D550Z receiver and all of my speakers are 8 ohm speakers, but my RCA SP2030AW powered subwoofer is rated at 4 ohms. The trouble that I sometimes have is that if the sub doesn't receive enough bass, it will shut off until it receives the signal it needs. When it does come back on, it seems to struggle if the bass is low and I hear somewhat of a deep crackling noise. The sub is set up with the Left and Right speaker outputs to the speaker-level inputs on the sub and then run from the outputs on the sub to the Left and Right front speakers. There is a single RCA input on the sub, but my receiver does not have a sub output. Is there any other way to hook up the sub using the RCA input? And more importantly, would that make a difference or is it the difference in impedance between the speakers and the sub?

A Most receivers have a set of audio recording outputs for connecting to a cassette tape recorder. I would suggest using either the left or right RCA recording output, and connecting that to the RCA input on your subwoofer. It won't have both channels of the low frequency signal, but it probably will sound better than the speaker-level connections you are using now. However, don't connect the left and right RCA recording outputs from the receiver together (i.e., using a "Y" connector to connect left and right together and sending both to the single subwoofer input). If you have an audio cassette recorder in the system, then use a "Y" connector between the receiver and one of the recording inputs on the recorder. One leg of the Y connector is attached to the receiver recording output jack, one would go to the subwoofer RCA input, and the other to the cassette recorder input. You will have to adjust the subwoofer volume separately from the main volume on the receiver, since the recording outputs are not affected by the main volume control.

The impedance of the speaker outputs on the receiver are not 8 Ohms or 4 Ohms. Actually, the output impedance is probably more like 0.01 Ohm or so. I am not sure what the crackling noise is, unless it is something that just occurs when the sub first turns back on, and the power supply capacitors are not fully charged. In any case, I don't think it is something to do with the impedance, but rather that speaker level inputs are not really a very good way to run a subwoofer.

Q I sent a post to you on 12/2/97, re: primarily speaker questions, of which I was eagerly anticipating a response. As I viewed the Dec. 9th Q&A, I noticed there was no mention of my questions. I figure the lack of response was either due to my "long winded" questions, or my expressed disappointment with the Sunfire Sub. Much of the reason I have enjoyed you're publication, is due to my belief that you are a fairly objective organization, and not primarily motivated by advertising dollars?

If your lack of interest was inspired by my "long windedness" here is a shorter version:

I'm looking for the ultimate value in a music first & then home theater speaker system. I have a 20x20 listening room. I like contemporary Jazz and action/adventure movies. The mix of music & theater is about 60/40 music and then theater. I can pick up a PSB speaker package for about $3100, which includes:

(Mains) PSB-Gold i
(Rear's) Stratus Mini
(Center) C-6
(Sub) Stratus 3i

In your experience, are there other speaker systems on the market that I should consider? If so, what & why? Also, in consideration of the above info, what is the best value in an amp & preamp to make them sing?

If any of these requests are "politically incorrect", please feel free to e-mail me directly at: *****

A We have tens of thousands of readers now, with the number growing constantly, and we get lots of questions, most of which we answer privately. The ones that end up here on the public Q&A are of general interest. In any case, just be patient, due to the load of questions.

You bring up a point worth discussing here, which is the advertising. Obviously, the only source of income for our magazine is advertising dollars, since it is free to the readership. Any editor or staff member at any popular magazine, which has paid advertising, and who says they are not influenced by advertising dollars, are, imho, either liars or idiots (maybe both). Of course advertising dollars are influential, whether subscribers pay or not. I thought long and hard as to how to deal with this problem, since I have to pay money for the webserver and writer costs (it is very expensive). I simply cannot publish the magazine with no income. Since it is free to readers, the only other source is advertising. You may notice that we don't have a lot of ads, and that all advertisers have had at least one product reviewed in Secrets. This is for a reason. I first request a product from a company for review, and then, if the product(s) are of a good quality, I may ask that manufacturer to support the magazine archive (all previous reviews and articles are stored for access by readers at any time) with advertising dollars. We don't ask all companies whose products we have reviewed, and which have good products, to support us with ad dollars, because we want to move slowly and put as much as possible of the income back into the magazine. This way, we are comfortable with the advertising manufacturer supporting the magazine, as we like their products with or without advertising dollars. For companies who submit products that we don't particularly like, we simply don't ask them to support the magazine. That's about as honest a description of our policies that I can give.

The Web is one of the most important revolutions in history, maybe even ranked along with the Agricultural Revolution thousands of years ago, that helped begin civilized societies, and the Industrial Revolution of the 18th century. Perhaps when every nation has unlimited access to the Internet, including all the Third World Countries, there might never be another major war because we will all be able to communicate with one another, and prevent such aggressions. In the meantime, it is a tremendous benefit to the little guys (like us), but a horrifying invention to some of the big establishment organizations. Suddenly, the content provider controls the publishing, rather than the publishing empires, publishing agents, and distributors. Someone with a novel, cook book, essay, self-produced CDs (or even just the basic digital recording available for download), whatever, can put them on the web, with millions of potential customers. The pie doesn't have to be shared with anyone. Not the major publishers, recording companies, radio stations, etc. The content creators will get it all. Billions of dollars are involved, and the establishment does . . . not . . . like . . . this . . . one . . . little . . . bit. The power structure is crumbling. It won't be too long before the bandwidth will be sufficient to put full motion, full screen video with high quality sound on websites, so that, let's say, your old high school or college can connect all their sporting events and other interesting activities through the web. Instead of being restricted to certain games being broadcast on TV, you could log on to your school (or any school, including those not part of the regular broadcast programming) and watch your home team . . . any and every weekend, on the Internet. Garage bands are already putting their music on the web. Eventually, anyone will be able to have their own TV or radio station at minimum cost. Do you think the broadcast industry likes this idea? I forsee lots of people in $2,000 suits crying. If you look at an average printed magazine, count the number of pages devoted to advertising, and compare it to the number of content pages. Ask the magazine what they charge for an advertising page. The web does not have nearly those kinds of costs involved if it is done right. No printing, no paper, no shipping, no returned unsold copies, availability world-wide. Someone once said that freedom of the press is limited to those who own one. Well, now we all own one. Think of how this will improve the quality of what we watch and listen to, because only the good stuff will survive. There are many large companies that love, or will love, the web. Manufacturers in particular. But, as you can see, there are some companies who stand to lose a lot. The consumer wins all around.

Now, as to your question about speakers, if you like PSB, then listen to Paradigm, Energy, and B&W. They will be in a similar price range and tonality. The "best" preamp/power amplifier combination is really a matter of individual perception, but you should probably spend another $3,100 on them, with $1,000 on the preamp and $2,100 on the power amplifier. A Parasound combination would be a good place to start your listening.

Q I know I'm not the only one doing this or maybe I am, but there must be a way to interface my computer with my television and home audio equipment. Basically, I'm in the process of upgrading everything and I would like some way of integrating all three.

I know more about computers than the other two topics. I've talked to audio and video experts, but they don't know much about computers, so I'm hoping you guys can give me some good insights into going about this.

What I basically want to do is purchase a DVD ROM for my computer and be able to send the video and audio to my home units. I would like also to control all my units with my computer, if it's possible. I know of interface cards that will enable you to view your computer picture on your television, but will this give me the video quality normally associated with having a stand-alone DVD player? And also, since most DVD ROMs have AC-3 capability, is there a way to send my audio to my speakers and maintain comparable sound quality without noise?

A First is the money no object solution. Only a select few will actually be able to afford this method. Wish I were one, but I can dream. Snell & Wilcox make a box called the Interpolator. This box requires a PC and a data or graphics grade projector. It is the best integration I have ever seen, and can be yours at a mere $30,000 for the box (this price does not include projector or PC!) The second, also out of this world cost, is the Faroudja Picture Plus. Instead of using a projector, they use your PC monitor. Again $30,000!

Now for more down to earth stuff for mortals like myself. You can use a PC-to-TV converter, but you lose a lot of quality going this route. With an internal DVD-ROM drive in your PC, you can get DVD on your PC. There are a couple of models that also offer Video outputs that will go to your TV from your DVD-ROM. These DVD-ROM kits, like the one from Creative Labs, come with a Dolby Digital decoder. This can be used with your PC to build a mini theater.

The current problem with DVD-ROM on PCs is that they do not support Windows NT (32 bit native, no 16 bit fixes). A lot of users will not mind because they are still on Windows 95 and will probably move to Windows 98 in the future. But the future of PC computing is Windows NT, so there is much work to be done. I expect to see drivers that allow them to work under NT soon, but they will probably only support accessing like a current CD-ROM drive. The ability to actually watch a DVD movie under NT is still some time away. Until support for NT becomes a reality I will not purchase a DVD-ROM drive for my own use.

As far as controlling your home theater with your PC, some audio electronics have 9-pin serial ports on the back just for this purpose. (Currently only a handful of high-end manufactures are doing this.) The ones who are really taking advantage of this are in the home automation arena.

Q I recently purchased a Mitsubishi 40" television and have the following problem. Whenever the DVD player or VCR is used in pan and scan format (not letterbox), there is a bending of the picture at the top of the screen. This bending, flagging, skewing is not present when the signal comes from the DSS or off the air antenna. It is present in the top 1-2 inches of the screen and is about like a clock showing five minutes till eleven instead of straight up twelve noon.

We have tried four different DVD players (three Toshiba and one Mits), and the problem is still present. The service people are unable to correct it by adjusting the Automatic Gain Control (AGC). The AGC has settings of 00 and 01. A setting of 00 corrects the VCR skewing but makes the DVD skew worse. I took the player into the store and they did the same thing on a projection Mits. However, projection Mits have an AGC setting of 02 which corrected the problem.

To complicate matters, this is present in all Warner Brothers DVDs (I tried eleven) and not in the MGM ones. Mitsubishi technical assistance and customer support reps have not been helpful. One service rep said it is a common problem. The service technicians agree that it is not acceptable but that they don't know how to fix it. They suspect that Mits doesn't want to admit a problem or doesn't know what to do.

Do you have any suggestions? Is this a possibly incompatibility between the copy protection on DVDs (Warner) and Mits as a manufacturer?

A I (SLS) have seen this problem with VHS. We have 37" Mitsubishi computer monitors at work in all of the conference rooms, and they show the bending at the top on VHS.

I have not seen this happen with DVD or LD. Have you been able to try a Columbia title? These all have copy protection, and it would be an interesting test. Macrovision tends to constantly change the contrast from dark to bright.

On the other hand, I (JEJ) have seen this problem with LD using a Mitsubishi 35" monitor. But I only noticed it with the letterbox movies. Any other readers notice this problem with Mitsubishi or other brands of TVs, as well as with various video sources?

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