Q&A # 144 - October 19, 1999

Staff

Q In reference to the PS Audio P300 review, here are some additional points about changing the AC frequency. A higher AC line frequency will mean that any leakage of main AC components (frequency and harmonics) into an audio component's power supply will be at a higher frequency. Whether or not that's a real issue depends on the rejection properties of the component. A higher frequency may benefit power amplifiers whose power demands may tax the onboard power supply. Bass frequencies are tough on power supplies not only because musical content usually carries more output in these regions, but because low frequencies will tax one rail more than the other for periods of time. Recharging each set of rail capacitors in shorter intervals won't help the really low frequency output, I believe, as the output cycles span multiple charging cycles, probably limited more by the on-board transformer and storage capacitors. However mid-bass transients above the recharging cycle could theoretically benefit from quicker fill-ups, though I suppose one could argue that a larger power supply to begin with would be more appropriate, and I can't say that I would disagree with that. Then again, one could also argue that the same money spent devoted to a better regulated power supply in the components would make more sense as well, but that's difficult to do after the fact, and an AC regenerator allows you to address a multitude of components. One of the real attractive qualities of an AC regulated power supply is that it lowers the effective output impedance of the wall plug. This would do two things. One, is that so long as the power demand is within the output capabilities (mucho money probably for a power amp) a large power amp might be able to deliver greater power than if connected to a conventional (though far cheaper) AC outlet which could sag voltage under a heavy load, limiting voltage at the amplifier. The other neat thing is that garbage thrown back on the AC line by components, particularly power amplifiers, that otherwise potentially contaminates peers on the line, will be shunted by the AC power supply output.

A Thanks for your input.

Q I've only recently found your site, and have been spending days reading everything in it. I had become complacent in sure knowledge of being happy with my home theatre until deciding to move to DVD, which spurred on a few weeks of reading and researching, and ultimately becoming dissatisfied with just about every piece of equipment I had. It had been 10 years since I'd done any real research into home theatre, which explains a lot. I noticed you reviewed two of the receivers I was looking at to replace my aging Pro Logic receiver; the Yamaha RX-V995 and RX-V2095. From reading the reviews, it is very hard to say if the 2095 is actually a better receiver than the 995, though it is $700 more MSRP. The reviews didn't seem to be overly impressed with the amplification in either receiver (or possibly in receivers in general). I was looking for an "all in one" solution to my decoding and amplification needs, with features like DSPs just icing on the cake.

Is the amplifier section of the 2095 any better than on the 995? I can get the 995 for 800 dollars at my local retailer, and was happy about the choice until I read about the weak amp section. Since having a zillion DSPs isn't a factor in my decision making, should I be looking elsewhere in that price range? Or perhaps spend that much on an integrated amp, and if so, which would you recommend? Or would you recommend buying the 995 and perhaps upgrading with an outboard amp later, or even using the Pro Logic receiver I have now for part of the amplification? (The receiver I have now is a Technics 100W main and lesser power to center and rear.) On to subwoofers: I had recently bought a Klipsch KSS-3 powered subwoofer, just before I started learning about the advances in home theatre. It is only a 6 1/2" driver powered by a 50W amplifier. Of course sound-wise it isn't adequate for my main subwoofer, but at the time I was buying the Klipsch name (having heard Klipschorns in my youth I fell in love with all things Klipsch) and the fact that I was buying a demo model marked down 50% to $200. I have been trying to decide what to do next. On paper, Klipsch's KSW-15 looks slightly better than the Velodyne CT-150 reviewed recently here, and at $50 less MSRP. I don't have a local retailer to go listen to either of these; I live in a rural area (I was lucky there was a Yamaha retailer close by, but I haven't even heard those receivers yet, the store was out of both models.)

As for my sad 6 1/2" sub, I still have time to take it back. Should I just get my money back or should I consider hanging onto it as a second sub; perhaps for the rear surrounds? I'll also confess right now I have no idea how to connect that in to add it as a second sub. If this will help, I'm doing this in a 10' x 13' room, concrete floors with thick padding and carpet, with 6" fiberglass insulation and paneling on all four walls, and the only window is on the rear wall. My current speakers include a Klipsch DC-3 center channel and DS-3 rear surrounds (both Reference series) along with that KSS-3 subwoofer and a pair of 12" 3-way Pioneer mains (yes mass market, but upgrading those has to wait). I have a new Echostar 4720 Dish Network satellite receiver with optical digital audio out, and a Toshiba 3109 DVD player, also with optical output. At the moment, this is all going into the Technics receiver mentioned above and a 27" Philips TV. (I plan to upgrade the TV as well later, but that would be a whole extra Q&A on ideas for that). I don't really count the Technics CD changer, the Technics cassette deck (dual mic inputs, I just use it for recording songs I'm in process of writing), and my two hi-fi VHS VCRs (one is a high end Toshiba for video editing). I'm also looking into upgrading all my interconnects (all "came with the unit" quality), but I did run Monster speaker cable for all the speakers (including into the walls when my house was built for the rear surrounds). Frankly, all I've read on interconnects and cables have left me more confused than ever; I know I need to upgrade them, but how much for what I have no idea. Despite my obvious naivety in the field of home theatre knowledge, I've enjoyed reading your site, and will definitely keep up with it from now on.

A In general, mass market receiver amplifiers are made to handle modest listening activities. They really don't do very well when cranked up to high volumes with action movies. The manufacturers are perfectly capable of building heavy duty amplifiers, but then they would not be mass market products affordable by all. The 995 is the top model in Yamaha's strictly mass-market line, and the 2095 is on the edge of high performance, while the DSP-A1 is a high performance model. The amplifier in the 2095 is a step better than the 995, but since you downplay the need for DSP modes, I would suggest that you get the 995 and use your old Technics to drive the rear channels. This will take a load off the 995's amplifier section. The KSS-3 subwoofer will be essentially useless in a digital surround world. Take it back and get the larger 15" sub. I have not listened to Klipsch subs in a while so I can't comment on them, but the Velodyne CT-150 is one of the best subs I have ever heard in the < $1,000 range. Your Monster speaker cables are fine, but I would suggest upgrading the interconnects to at least the Radio Shack Gold Patch type. They are not very expensive. The interconnects that come in the boxes with mass market hi-fi equipment are inadequate.

Q I have a Yamaha RX-V795 receiver, a pair of Tannoy R2 main speakers, Infinity CC3 center speaker and Boston VRS micros as surround speakers. My problem is the Tannoy speakers are 6 Ohms while the rest of the speakers are 8 Ohms. How do I select the speaker impedance setting at the back of the Yamaha receiver?

A You can use the 8 Ohm setting. Because the speakers are all different brands, you will probably need to carefully adjust the volume of the front L/R vs. Center vs. Rear.

Q I would like your opinion on the Infinity Overture 3 speakers. I can  purchase them on-line for $1300/pair. Are their better speakers than these in this price range?

A As I recall, the Overture 3s had a bunch of 6" powered woofers with a down-firing port. An advantage of powered woofers is that you can use their equalization and limiting circuits in order to get more bass output than the cabinet, drivers, and efficiency level would normally allow. On that model, I believe you could adjust the bass output to complement both personal taste and room acoustics. On the other hand, you could do the same with an outboard EQ. The disadvantage of built-in powered woofers is that you can't use true active bi-amping, since the upper range drivers use a passive crossover, and the bass amp takes its signal from a full-range speaker-level input. That's not a big deal for the speaker, but it doesn't save the full-range outboard amp or receiver that much effort. Even though the woofers don't draw substantial current from the upstream full-range amplifier, since it's still applying a full-range voltage swing at the loudspeaker terminals, neither does the extra amplifier increase the total dynamic range. I've had an opportunity to listen to that speaker in a variety of situations, and I have to say it's pretty good. Detail is decent, but its real strengths are in that most receivers can drive it easily, as it doesn't require too much in terms of current. Because of the limiting circuits for the woofers, it can play relatively loud. To answer the original question as directly as I can, whether or not you can get better speakers at the price depends on what you mean. If you're talking about going into a dealer showroom and paying retail for floor-standing speakers that can give the same low-end extension, dynamic range, and sound quality, then the answer is no, because you are not paying retail. On the other hand, if you're looking over the used market, there are a variety of speakers that will give them an all-around run for the money, and depending on how you weight the criteria, could offer far more. For an Infinity example, if you're willing to give up the efficiency, tonal flexibility, and amplifier-friendly nature of the Overture 3s, you might be able to find a pair of Infinity Renaissance 80s for the same price or less, which used the same midrange and treble ribbon drivers as both the $14,000 IRS Epsilons, and $7,000 IRS Sigmas. In terms of sonic transparency, the Renaissance 80s would hands down whale on the Overture 3s. Then again, even on the used market, you'd still have to throw down at least another $800-$1,000 or so on a stereo amplifier (an older Aragon 4004 would do nicely) to get them up and going (if you haven't already) since they absolutely gobble power. Which is the better speaker? The one that suits your needs. Tough question. At $1,300, I think you're doing alright, but I wouldn't suggest going for it unless you've already heard them and like them, and/or have a return privilege.

Q I currently have a Yamaha DSP-A1 with a 7-channel configuration. I have two older main speakers, Jamo SL-180, and for front and rear I have 4 Carlsson bipolar speakers mounted on the walls, and a Carlsson center speaker. I also have a Yamaha YST-SW300 powered subwoofer. The Jamos are rated at 8 Ohms, and the rest (except subwoofer) at 6 Ohms. When watching DVD or HT the voice-match is just awful and the sound is just not good enough. I have disconnected the center channel and am using the mains instead. It was a sound improvement, but the loss in HT effect is not acceptable. Can you recommend speakers to go with the Jamos? I want to keep them because they are great for music. The Carlsson speakers sound cold and hollow compared to the Jamos. Usually I don't have a lot of volume because of my family trying to sleep. Sometimes the auto-power on the subwoofer doesn't work. Is this because of the low volume? Can this be adjusted without increasing the volume?

A The center channel is very, very important. Since you like the Jamo sound, you should probably go for a Jamo center, perhaps their Center 200. Auto-on circuits have a problem with low volume. In the case of using your sub late at night, just use the manual on control. Other than that, you might try adjusting the subwoofer output level on the DSP-A1 up and the input volume control on the subwoofer down, or the other way around, to see if that affects the subwoofer switching on at low volume.

Q Since home theater is an explosive growth area, what is your opinion on buying stock in publicly owned audio/video companies?

A Well, let me tell you how I go about buying and selling stock. I pick the companies I am interested in and watch them every day, usually looking at how the price changes several times a day, over a period of a month or so, and having taken a look at how the price has changed over the last 12 months, as well as over the last several years. You can set up a news page on your browser that will automatically give you all kinds of information, updated, every time you open that page (the stock prices given are usually about 20 minutes old). I watch the pattern of up and down cycles, and if it looks interesting, I log onto my on-line account, get a real-time quote, then buy, sell, or do nothing.

I never buy stock based on someone saying that such and such is a good buy in some publication or TV program. In my opinion, these people are not going to be giving you their real stock tips. They would be nuts to do this. What they assume is that you are nuts enough to take their suggestion and buy the stock. Then guess what they do a day or so after they publish their suggestion? They sell that stock because their suggestion has caused more people to buy the stock and the price has gone up.

Here (see above) are some graphs of a stock plotted as price over time, for 3 years, 1 year, 3 months, and 1 day. Notice that there are peaks and valleys visible in each of those intervals. Depending on when I want to get in and out of a stock, the appropriate graph is consulted, but I always look at each of them in any case. Day traders look at the daily history of ups and downs, and try to anticipate what the graph will look like at some point ahead in time during the day, and buy or sell accordingly when they think the graph is about to turn upward or downward. Their idea is to own nothing at the end of the day.

The Internet has been a disaster for the big investment guys. Now, the little guy has access to the same info that they do, and the little guy can buy and sell just as fast as they do, especially with the availability of real-time quotes to everyone. Rather than play into their hands and buying based on published recommendations, I prefer to do my own research and make decisions based on common sense. I like to put the profits into my pockets instead of theirs. I use these techniques regardless of whether it is an A/V company, dump truck company, or whatever. Rather than just buying into A/V in general, I would look for a company that has shown consistent growth over a several year period. Not every A/V company out there will be successful. But the bottom line is that I always do research and never buy on a whim. Keep in mind that this is not a recommendation for you to get into or out of the stock market or to follow my methods.

Q (1) In your review of the PS Audio P300, you said that the Panasonic LD-10 and audio dropouts problems were fixed by using the respective PLCs. However, you did not mention if you were running the LD-10 off of batteries or AC. If AC, I would expect that the LD-10 would do badly with a "wall wart". Why? Because the equipment, in this case the LD-10, was designed to run off of batteries as its primary source. Putting a high quality PLC into the LD-10's supply path should allow the wall wart supply to work much better because it will have an easier time providing well regulated output.

(2) Primarily, to the above, would be an improved noise floor, although measurements are never given which show this. If indeed the noise floor is improved as much as is implied in PLC reviews, it should be easily measurable at the amplifier output.

(3) More mystifying to me, is an improvement in imaging or "soundstaging". To be quite frank, this completely baffles me. The AC mains power supplies both channels and any fluctualtions in voltage will affect both channels equally. In other words, current demands by the equipment which are reflected back to the mains will affect both channels equally and should not affect channel separation which is the main determinant of the imaging quality of a piece of electronic equipment. So, how exactly does a PLC affect imaging on equipment with power supplies designed to contemporary standards?

(4) It might affect a video image, but does the PLC affect audio? While I see lots of claims and anecdotal evidence I see very little information in terms of blind tests or lab measurements of the output of audio components which are used with a PLC and without.

A (1) An excellent and valid point. One might also suggest that since even the pure AC will cause the unregulated AC/DC adapter to generate a ripple component on its output if it's given a load with any draw, that it would make more sense to regulate the DC power supply of the component itself. If the LD-10 was designed to run off of batteries, the designers might have considered the batteries a relatively regulated power supply in itself, and not thought the cost of including a regulated AC/DC converter worthy of consideration. One might also point out that it would make more sense to heavily regulate the power supplies of all components themselves than regulate the AC before regulating it again at the DC level. On the other hand, once you have your components, it's a bit late, and a PLC or UPS that implements true sine wave regeneration can address a multitude of components after the fact.

(2) We can try to do the best we can, and from a static view, it would be very easy, perhaps even without measuring equipment, simply by putting your ear to the speaker and seeing how close you have to get before any background noise is audible. Stacey noted that he didn't hear much if any difference in that situation. However, some products will introduce more noise from the AC power source only with a high-level signal, as it then causes a greater drain on the rectified AC (DC portion) which then in turn allows more of an AC component to reach the active devices, part of which will be ripple, and some of which will be noise brought in on the AC.

(3) Soundstaging is a very vague word that encompasses perceived spatial attributes. Part of spatial attributes of stereo recordings are picking up ambient reflections for depth cues, usually at a relatively low level. I can't say with any certainty if this was the case, but it seems plausible that if the noise background were lowered in the presence of a signal, it could reduce masking of this reverberant information and enhance the perception of sounds in relation to their acoustic space. You do bring up a very good point, though, in that it would be difficult for noise to affect the inter-channel amplitude/relative delay, from which we derive directional information. Then again, even though people can be very sensitive instruments, they're not precise or linear by design. Often human perception uses one kind of information that influences the interpretation of another.

(4) I don't think there's any question that power supply regulation can affect audio. The extreme case of audio drop-outs with the LD-10 is an example that it certainly can. The real question is whether or not specific types of power supply regulation (such as a PLC) affect the performance of specific components in a manner that is audible. It would certainly be good to use a scientific approach with all reviews, and we're making incremental steps to getting there. Perhaps in the future, as we grow, we will implement those procedures. It takes a lot of people though.

Q Will music be DTS encoded or just Home Theater? I recently purchased a Yamaha receiver that has Dolby Digital but not DTS. I have 60 days to trade up to one with DTS, but I'm really not interested in home theater all that much. So for music, will I be missing anything? Also, I have some really old, but great sounding ADS 200 4 Ohm speakers that I've thought of using for the rear channels. My main speakers are Phase Technology PC-100s, and are rated at 8 ohms. The impedance selector switch on the receiver makes two provisions. The spec states that in the upper position, if you use one pair of main speakers, the impedance of each speaker must be 4 Ohms or higher. For two pairs of main speakers, the impedance of each speaker must be 8 Ohms or higher. The center must be 6 Ohms or higher, the rear 6 Ohms or higher. The lower position states 8 Ohms for one pair of mains, 16 for two pairs of mains, 8 for center and 8 for rear. How can I test the speakers to determine their actual impedance? Digital Ohm meter? Since I'm rated for 4 Ohms in the front and am using 8s and am rated at 6 Ohms in the rear but am using 4s, can I push it to the limits a little, if I don't push it too loud? The ratings are (4+6)/2 = 5, my actual is (8+4)/2 = 6. Is this an acceptable way to calculate it or are the channels more discrete than that? What about if I change the digital settings for speaker size, i.e. small front, small rear? I run the fronts small anyway because they tend to compete on the low end with the Klipsch KSW-12 I have on the sub channel. If the actual impedance (from test above) is higher than the rating, can I assume everything is conservative and go for it?.

A Try a little more fiber in your diet and relax. It is not that complicated. The amplifiers in your receiver are good enough that you can use the setting for one set of speakers and 8 Ohms. Your 4 Ohm loads are in the rear, and although digital surround is full range in all channels, the rear does not get all that much with most films. However, you will probably have to adjust the volume in the rear down a bit, depending on their sensitivity. As to DTS, there are lots of CDs out there that have DTS music on them. It is not just a DVD movie thing. However, DVD Audio, which is the next big music technology on the near horizon, will have 5.1 audio too, and at higher bit rates, allowing uncompressed audio, which will probably sound fantastic. The DVD Audio players will have the decoding built-in, and all you will need is a set of 5.1 analog input jacks on your receiver. Depending on which version of the receiver you have (US and European versions differ), you might consider the future need of a set of 5.1 analog inputs when deciding whether or not to keep your current one or to get a different one.

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