Q Regarding a NAD 2150 Power amplifier, would it be capable of playing for extended periods of time at maximum volume without clipping ? I would need this amp to run some speakers in a mobile disco. I have found out so far that this amp is 50 W rms. But being somewhat of an audiophile myself, I believe NAD amps have a larger than average voltage. One more thing, what would you recommend buying this amp second hand?

A I think you are asking for trouble using a consumer amp rated at that power for disco. They are not built for that kind of activity. Get a touring amplifier, like Carvin, which has lots of power for low dollars. They are not quite as high fidelity as a consumer hi-fi amp, but will run all night long at full output, and when you play music really loud, there is so much distortion in the speakers, it does not matter what the amp is doing. They have fans built-in and are designed to drive low impedance speakers too.

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Q A friend of mine gave me an old Sony STR-D711 receiver, but there isn't a place on the back to hook up my sub. Is there a way to do this relatively easily?

A Yes, for old receivers without sub pre-out jacks, just use the rec-out jack. It won't be affected by the receiver volume control, but you can do that on the subwoofer rear panel. Also, Paradigm makes a little gem they call the X-10 which streets for about $100 US and $150 Canadian. Called a "Subwoofer Control Unit" it simply goes between receiver and main speakers, giving them a mild 1st order high pass at 60 Hz, and gives you a mono line level output for a subwoofer with level control. Here is a link: http://www.paradigm.ca/Website/SiteParadigmProduct/ParadigmModels/HighPass
SWControlUnits/ControlUnit_Specs.htm.

If you want to go even cheaper, feed the line inputs from a parallel run from the speaker outputs, with an L-Pad in between. I think roughly a 10:1 voltage drop, or 11:1 should be fine for most circumstances. It would look like this for each channel:

+ ----------200 ohm resistor-----------------------Hot Center Pin of RCA
|
Amp Output 20 ohm resistor
|
-
----------------------------------------------------------Ground of RCA

This will simply read the amplifier output signal with minimal and insignificant power drainage, delivering a lower level, low-noise feed to the subwoofer input. It can then be set to the relative level once, and left alone. The end scenario is the same as what you'd find with loudspeakers that have "powered woofers" built-in.
 

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Q I have a Denon AVR-3300 receiver, rated at 105 watts per channel. The sound is not clear enough for me. Would I benefit from bi-amping to get more power?

A Mid-level mass market receivers don't really have the sustaining power that you can get from an outboard amplifier. Rather than bi-amping, I would suggest that you just get a good outboard power amp and use the pre-outs on the receiver to drive it. Something with 200 watts per channel x 7, like the Outlaw Audio 770 that we just reviewed, would be great.

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Q  I have a Panasonic HDTV, the 32HX40, and I was wondering what would be the best DVD player for my TV. I have been looking at the Panasonic RP-82 and the CP72k. Does the RP-82's extra features make it much better than the CP72k? I thought it would be great to have the five changer but ultimately the picture quality makes more of a difference.

A We are just finishing up the Yamaha CX-1 DVD player, which is like an RP-82, but it is a changer rather than a single disc player. It is excellent, like the RP-82 (no chroma bug), and is DVD-A, like the RP-82. We have not tested the CP72k.

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Q I would like to know if I can use a power amp that I've had in my car system to drive a subwoofer for the entertainment system in my house. If so what do I need to do? The amp is a two-channel @ 98 watts rms per channel or 250 watts bridged. I have not decided if I want to use the woofers from my car because I've had a buddy who swapped out his factory woofer and it doesn't sound that good, so maybe he did something wrong.

A It will work, but you need a clean 12 volt DC power supply. If you don't have one, it would be less expensive to just get a touring amp like the Carvin, mentioned above. For just a few hundred dollars ($370), they deliver 700 watts bridged into 8 Ohms. Subwoofer drivers for cars are designed differently, usually with low impedance (4 Ohms) and for small enclosures. Lastly, I just finished the bench tests on the SVS 25-31PCi powered (320 watts) 12" subwoofer, and at $549, it is one of the best subwoofer bargains on the planet. The full review will be published later.

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Q I wish to enable a home theater system to output to a plasma screen and a projector, enabling me to switch between the two outputs. How can this be achieved?

A You would need a component video switcher (I am assuming you are not referring to S-Video). There are several on the market, and you should get one that has a bandwidth of 200 MHz or more.  You could also just get a distribution amplifier, which would probably cost less money, essentially creating a powered Y connector, and then you don't have to bother with switching. You just turn on either or both displays as you need them.

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Q I currently use a Toshiba 2109 DVD player to output to a Faroudja NRS scaler, which feeds an NEC XG 110 CRT projector. With the raves on some higher end DVD players (Arcam for an example) I am wondering if they would have any worthwhile improvement to offer over what I currently have, knowing that the NRS requires interlaced input.

A Although the Faroudja may mask the chroma bug from the 2109, you will still get better color if the player does not have it to begin with. So, select a new player without the chroma bug. None of the Panasonic players has it, nor does the Denon DVD-1600 (single disc player) or the Yamaha CX-1 (multi-disc changer).

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Q  If you add a sub to each of the front channels, will the bass information be overkill, or is this kind of configuration not so crazy as it seems?

A It is not crazy at all, especially if you cross over above 50 Hz where the bass is directional. This gives you stereo subwoofers, and they are terrific. I use three Velodyne HGS-18s. One is for the left front, one for the right front, and one is just for the LFE channel, through which I run an Audio Control Phase Coupled Activator which creates sub-harmonics (half the input frequency). They are all turned down so that each one is just putting out part of the total bass. This results in almost zero distortion, even when the house is shaking on its foundations.

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