Q&A # 165 - February 22, 2000

Staff

Q  My question concerns my reading about the usage of Radio Shack meters in the setup of speakers in a room. What meter are they referring to? What exactly is it used for and how?

A Radio Shack SPL (Sound Pressure Level) meters are used for determining the loudness, in dB, of your speakers. It can be used to measure frequency response (room response, actually), although it is not a precisely calibrated instrument. So, you could use it to balance the volume of all your speakers at your listening position, for example. There are two models. One is analog with a meter that has a needle. The other one has a digital readout. They are both very inexpensive, and a worthwhile investment for home theater enthusiasts.

Q I've still got my Yamaha RX-V990 receiver, and am considering adding a multi-channel power amplifier as recommended. Can I ask your opinion on which setup to go with? Here are my choices: 1) Harman Kardon PA-5800 5 channels, 80 watts per channel, good recommendations including a glowing review in a printed magazine; 2) Audio Source 5.2 Monoblocks. Similar to the Marantz MA series, these are each rated at 100 W @ 8 ohms, 150 W @ 4 ohms, and are stable into 2 ohms. Each has its own power supply. Using three of these would mean that I would route the rear speaker pre-outs of my receiver to the L & R main-in inputs of the 990. I know that having five identical amplifier channels is fashionable now, but is it really necessary for DD/DTS? I don't have a 5.1 source yet, so I'd like to know if I can expect to hear as much information in the surround channels as in the front three. Personally, it's my reasoning that for the same money, more should be invested in the front three channels (both speakers and amplification) than the surrounds, because with any of the movies I go to at the theatre (both DTS and DD), I'm hearing more information from in front of me than behind me. Is my logic flawed, or is it REALLY advantageous to have surround speakers and amplifiers that are identical to the front L, C, and R for home theater?

A You are doing the wise thing by having outboard power amps for the front channels, and using the receiver's amplifiers for the rear. A five-channel outboard power amp is fashionable, but what you are doing is highly economical, since the receiver's power supply will have a much easier time driving just two of the channels. The rear channels are for ambience and certain special effects. The amount of signal is highest in the center, followed by the front left/right, and then the rear left/right. However, I would suggest having the same speakers in the rear. The speakers are much more likely to have a different tonality than the amplifiers when using different models.

Q When watching movies on my home theater system, I have noticed a big difference in sound levels between the dialogue and the action effects. When I set the volume for the dialogue, the action effects are too loud, and I have to turn the volume down and turn it back up when the effects are finished. Is there a setting I can change on my receiver or DVD player to get the levels to be closer together?

A There are two options. One is to go into the receiver's menu settings and adjust the center channel up with respect to the other speakers. The other is to change the dynamic range. Most receivers have this adjustable setting. Using a low dynamic range will allow you to keep the volume at a modest level and be able to hear the dialog without having the action too loud.

Q My main system consist of the following components: Carver CT-17, TFM-35, TFM-55x, TFM-6cb, ALIII speakers, and Nakaminchi MB3. Currently I am bi-amping the AL IIIs. I am using the TFM-55x to power the ribbons and the TFM-35 for the woofers. Is this the most efficient way to power my speakers, or do would you recommend a different way? Currently, the AL IIIs are located in my living room which has a vaulted ceiling. I am using my family room as my home theater. I did not want to spend the amount of money that I spent on the main system, so I started internet shopping for system components to build a system around my Toshiba 32" TV. I started with the JVC-SX-XSW22 surround sound speaker system and tried to integrate it into my main system along with the Toshiba 3109 DVD player. This was okay to start, but it did not give me DD or DTS capability. So I purchased the Technics SA-AX720 and SA-AX720. I am currently in the process of upgrading from the JVC speakers. So far, I have replaced the mains with Infinity Minuette L-MPS and the center has been replaced with a JBL-SVA Center. I am thinking of purchasing two more JBL-SVA Center speaker to use as mains. I thought about just getting the JBL- SVA 1500 mini-towers for the mains, but the specs are identical to the SVA center, and I like the way the SVA center can be angled. You keeping mentioning that it's important to have front and rear speakers matched. How important is this suggestion? I was thinking of mounting and using the Minuettes as rear speakers. In your opinion, what will I be sacrificing if I go with this setup? Or would you recommend adding  JBL-SVA 1500 mini towers to my setup as rear speakers, if so, what will I gain?

A The center has the same specs as the mains probably because it might be the same speaker just with the rear binding posts rotated so you can set the speaker on its side. This is called an LCR speaker, meaning that it can be used across the front in all three positions. Often, the "center" speaker won't even have the binding posts rotated. This is an ideal speaker to use not only in the front, but the rear too. This way, you get the balanced tonality for DD and DTS that I have mentioned before.

Q 1) I presently have a 5-year old Yamaha 5-disc changer with coax outs. I am planning on getting the Marantz SR-8000 A/V receiver. Where am I going to get the best sound: by going RCA out from the CD player into the receiver and using the CD's DAC or going digital coax out and using the receiver's DAC? Is the receiver's DAC more general purpose, and thus not specialized for CDs or is the fact that my CD player is older and the DAC technology older going to affect things? I know you're thinking of saying trust your ears, etc., but I would like a cold hard objective answer. 2) The Marantz SR-7000 is essentially the same as the SR-8000 aside from a better remote, negligibly more power, and one more digital out. The other major difference according to them is that they're using 'audiophile' quality parts in the SR-8000. Is the SR-7000 at $800 a better bang for the buck in your opinion than the SR-8000 at $1200 for a 75% music/25% HT setup?

A First of all, both your "RCA" out and the "coax" out you mention are RCA coaxial jacks to be used with RCA coaxial cables. The difference is that the analog RCA jack and cable can get away with having less than 75 Ohms impedance, while the RCA digital coaxial jack and cable MUST be 75 Ohms to have the best results. Since you are going for music more than movies, I would suggest getting the 8000. The increased bit of power and higher quality parts will give you a better sound. Your five-year old DAC in the player may very well be just fine. If you went to one of the really new 96 kHz upsampling outboard DACs, you could get some improvement, but it is very likely that the DAC in your player will give you just as good a sound as the one in your new receiver.

Q I was hoping that you could briefly discuss and explain the physical difference between balanced cables, single ended cables, and standard cables. Also, as I understand it, balanced cables will provide the greatest noise reduction if you have balanced components. I understand that this benefit will not be realized if the components are not balanced. If using components which are not balanced, is there a dis-benefit to using balanced cables (other than cost)? Would one be better off using single ended or standard cables instead (again, other than cost)? FYI, I am specifically interested in cables terminated with RCA connectors and not XLR.

A Single-ended cables and jacks are the same as RCA. Single-ended is just a fancier term. They refer to having two conductors, one hot and other other the ground. XLR balanced connections and cables have three conductors, two hot (each has the signal inverted with respect to the other), and the third being ground. By using a balanced cable with an unbalanced amplifier, you are referring to those amplifiers that have unbalanced circuitry, but have balanced inputs and/or output jacks. The balanced jacks are little modules that convert the unbalanced signal to balanced at the output. If you don't have a hum problem, and have an unbalanced amplifier with the balanced jacks, use the RCA jacks instead. If you have a balanced amplifier, then use balanced cables. Single-ended also has another meaning, which refers to a specific amplifier design that has one tube or transistor (or tubes or transistors in series) that amplify the signal. This is opposed to the majority of amplifier designs that are push-pull, meaning that there are at least two tubes or transistors amplifying the signal, with one tube (or transistor) amplifying the + portion of the signal waveform, and the other tube (or transistor) amplifying the - portion of the signal waveform.

Q I can tell that my question is small in comparison to the big time stuff you talk about on this site, but I must admit that I am an amateur at all of this! Please excuse my ignorance. My question is this: I have a lot of the components described in your website for a good home theatre system, but don't have a stereo television. Obviously, my sound quality has improved by running everything through the new receiver and multiple speakers, but will it improve more by adding a good stereo television? If so, give me some input on a good 25 to 30 inch stereo television to purchase. Thanks for your patience for us beginners!

A No question is small. Every bit of info we can discuss here helps the entire readership. The stereo nature of a TV won't affect your sound system per se, but if you were using only over-the-air broadcasts (an antenna), then the stereo TV would be necessary to get a stereo audio signal out to your receiver to decode into Pro Logic or otherwise have stereo audio with TV programs. However, most of us have satellite or cable these days, and it is not necessary to have a stereo TV, unless you don't have an A/V receiver (which you obviously have). Lastly, it would be almost impossible to buy a new TV of any large size (25"  - 30" included) and not have it be a stereo TV. So, you don't really have a problem. Just get whatever TV that suits you. It will work fine with your system regardless.

Q I have a pair of 701 Bose speakers and a Sony DB930 receiver. I have heard that you should use the same brand center speaker, but I am not to sure I want a Bose center. I'm sure there are better centers out there. Do you have any suggestions for center and rear speakers? I do like the 701s very much.

A For a center channel speaker, choose one that is as neutral as possible. The center reproduces the voices, and any unusual tonality will be really noticeable. I would suggest the B&W CC6.

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