Q&A # 23 - August 5, 1997
Staff
Q My circa 1973 Marantz 2245 receiver is ailing, and needs to be replaced. My sources are a Beogram 5000 turntable and a Yamaha CDC
705 changer. My speakers are B&W DM602is. I have around $2,000 to
spend on a preamplifier and power amplifier, and was considering
among the following: Preamp: 1) Rotel RC980BX or RC 995 (the former
has remote), 2) Adcom GFP555II, 3) Conrad-Johnson PV10A. I am not
crazy about the lack of control on the CJ (am I crazy for wanting
balance controls?), but otherwise liked what I heard. Power amp: 1)
Rotel RB990BX, (200 W.ch), 2) Adcom GFA5500 (200 w/ch).
Any preferences? Other suggestions? Is it worth spending a
disproportionate amount on the preamp? Any suggestions for speaker
hookup beyond the lampcord I am now using?
A Since you are obviously a vinyl fan, I would suggest the CJ-10A, with the phono equalization stage (obviously). For the power amp, I would suggest the Adcom. It has MOSFET output devices that will blend well with your LPs and tube preamp, and will also tame any harshness from CDs. Speaker hookup can be expensive. However, just about any of the commercial audio cables will be better than zipcord. Try the Nordost Flatline 2-Flat. It is reasonably priced, and we like it a lot.
Q I have a Sherwood RV5030 Pro Logic Amp and I wish to connect a subwoofer to it. It doesn't have a sub-out, but it does have a line-out from each of the centre, left & right, and rear pre-amps. I understand I could use the left &
right line-outs for the sub, but they are currenty linked to the main amps
with U-links. Can I remove the U-links and replace them with Y-links, i.e.,
so I can tap off for the subwooer, and will that adversely affect the sound
quality or level going to the main amps?
A Yes, Y connectors between the preamp and power amps will do the job for you. We have done that many times with no adverse effects on the sound. If you were to connect a preamp channel output to three power amps (two Y connectors in tandem), that would cause some high frequency rolloff, but one preamp channel to two power amps (one for your main speaker amplifier, the other to the subwoofer) is fine. Do this for both of the front right/left channels of the preamp.
Q I would like to improve the bass in my current home theater system (primarily for movie special effects). The audio components in my
system are Rotel RSP 980 for the processor and Rotel RB 985 for
amplification. The speaker are B&W 603 mains, DS6 Surrounds, CC6 Center and
AS6 for the subwoofer.
My question is this: Would adding a second AS6 subwoofer significantly
improve the bass or should I replace my current sub with one that has more
power and is capable of handling a lower frequency response?
A The 603s have pretty good bass to begin with, and although the AS6 would complement bookshelf speakers, it does not improve things that much alongside the 603s. I would suggest getting a more powerful sub. To maintain a reasonable budget with respect to your other components, you should have a listen to the Sunfire Subwoofer. For more money, the Velodyne F-1500 and M&K MX-5000 are killers. Those, and the new Velodyne F-1800 are my (JEJ) favorite thunder machines. The Mirage BPSS-210 is the cleanest sub I have heard, but it is does not have the punch that the others do. Since you have a processor connected to a five-channel power amp, try using a Y connector to split the output of the center channel from the preamp, with one leg going to the center channel power amp on the RB-985, and the other to the B&W AS6. This will give you some added bass to the center channel, where most of the action occurs. Most center channel speakers don't put out much below 50 Hz or so.
Q I plan to upgrade my surround channels with dipole speakers for better ambience in Pro Logic application (as many reviewers said).
However, my "AV room" (or rather AV-corner) lacks a side wall. Mounting on the
celling will not be a good option because of the high ceiling. Can the
dipole be mounted on the rear wall? I came across advice on the web (but
can't recall where I read it) that said to switch the Left and Right dipole
speakers (i.e., left speaker mounts on the right side and vice versa). What
is your recommendation?
A Dipoles give a more ambient, diffuse sound, because the lower frequencies are cancelled at the sides. By aiming the speakers sideways, with respece to where you are sitting, the sound is made to bounce off walls before it gets to you, rather than coming direct from the speakers. If you don't have a side wall, then indeed, put them on the rear wall. You may have to adjust their position so that they sound equal in loudness, since one will be pointing at an open wall, while the other points at the solid side wall. I would not recommend reversing (right to left, left to right) the connections though. The rear speakers in Pro Logic are mono. Secondly, if you go to digital surround (AC-3, DTS), the rear sounds would be coming from the wrong sides.
Q I've heard that some DVD players cannot digitally output 96 kHz sampling rates and actually convert them to 48 kHz. I'm wondering what the deal is with 96 and 48 and 44.1 and the differences, sonically, between
them. CDs, as far as I know, are 44.1. DSS had 48, and I don't know about
DVDs. Should I worry that my Pioneer DV-500 DVD player cannot output 96 or
is it no big deal? The question basically is, is sampling rate important?
A There are a couple of DVD players that will play 96 kHz 20 bit sound. However, there is no software library yet. There are many DACs that will handle 48 kHz bitsreams, since that sampling rate has been around quite a while. The higher the sampling rate, up to about 500 kHz (we believe), the better the sound, even though the theory has been that 44.1 kHz was sufficient for CDs. I have never completely subscribed to the principle that the minimum of 2 samples for the highest frequency that you want to decode (44.1 kHz sampling for 20 kHz music), is good enough for great sound. To me, going with the minimum technology doesn't cut it. However, when CDs were introduced, there was only so much room on the disc to have an hour of stereo music. But now it is time to move on. DVDs have 48 kHz, plus the compressed bitrates for AC-3 and DTS. A sampling frequency of 96 kHz is coming for the next generation of CD/DVD audio (in part because 96 kHz is what the studio recorders use, except for HDCD which uses higher), but for now, your present equipment will handle all the software that is out there.
Q I have a 35" Mitsubishi TV which has S-video and composite inputs. I also have a JVC SVHS VCR. Plugging into the S-Video input disables the composite input. How can I handle multiple inputs, some of which are S-Video and others
which are composite? The TV instructions say nothing on this. I have to
unplug the S-Video cable to get the composite input to work.
A You will have to plug one source into one input, i.e., SVHS into Video
1, Laser into Video 2, DVD into Video 3. If you do not have enough
connections on the TV you might look into getting a video switcher. Be
careful using either a video switcher or even a receiver to switch video. If
the internal path does not have enough bandwidth, you will end up hurting
the signal, i.e., if the bandwidth of your switcher is 4 MHz, and you are
passing DVD through which has a bandwidth of 6 MHz, you are going to clip
the info above 4 MHz. All of the fine detail in the picture resides in the
higher frequency area.
Q I can buy a pair of used 8' Transparent Music Wave speaker cables for $95 (the list is $250, I think). Do you think this is worth it with a Parasound HCA-860 and Definitive Technology BP-8 main speakers? I wouldn't normally
even consider cables as expensive as Transparent, but these are in real nice
condition as far as used cables go.
A Good cables can make a difference in the sound. However, it is very important to match the cables with the rest of your system. Cables that tend to be laid back in the high frequencies would not match well with amps and speakers that are also laid back. Other cables might be somewhat forward in the mids or highs. If the amp was forward, then the sound could be harsh, particularly with CDs. Purists will say that you should not have to "tune" your system with cables. I agree. You shouldn't have to, but the real world is a tough place, and all conductors are filters. The conductors inside the amp, as well as the ones outside. It is hard to predict how a set of cables will sound. You should try them out first, and if you like the results, then buy them.
Q Thanks for maintaining this great site! My question regards the best way to upgrade my system for DVDs, AC3 and DTS.
I currently have a Yamaha RX-V850 surround receiver that I boost with an
Acurus 3x200 W power amp for the front and center channels. The
simplest option seems to be to replace my receiver with a new receiver
with built in AC-3, and keep the current configuration. I expect that
the power to the rear channels would be less than to the front channels for
most receivers (probably about 100 W for most AV receivers). From some of
the letters that I have read, am I correct that many of the new AC-3
receivers are not compatible with DTS?
Another option would be to buy a separate processor and a new 2 channel
power amp to drive the front channels (probably about 200 W). This would
also require buying a tuner for radio listening. Can you recommend a
reasonably priced quality processor/amp/tuner combo?
Will the second option offer a substantial improvement over the first? I
know that the second option will be more expensive than the first. Can you
recommend components for option 2 that would be significantly better than
option 1, but that will not lead me into bankruptcy or divorce?
A Separate A/V processors are indeed better than receivers, but they are about 5 times the price, and I certainly would not want to contribute to a divorce. The Yamaha RX-V992 has AC-3 built in, and yes, most of the receivers with built-in AC-3 are not compatible with DTS, because they don't have a set of 5.1 input jacks to accept outboard decoder signals. However, MSB Technology is able to add the DTS decoder card to most receivers, for $700, which is the cost of an outboard DTS decoder anyway. So, as long as the receiver has pre-out jacks for your outboard power amplifiers, get whichever one (receiver) suits your tastes (the Yamaha 992 would be excellent). Get an Acurus 200 x 2 for the rear channels, the DTS decoder card from MSB, and you are in business.
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Secrets of Home Theater & High Fidelity
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