Eric, thanks for the incredibly quick response! You've thought of things that hadn't occurred to me, and I'm grateful for the additional wisdom.

tca, some dB versus power calculations might help. If five watts is background, say 70 dB, 20 watts (you meant 20, not 2, right?) is four times as much, or six dB more, so it's only 76 dB! 60 watts is three times that amount of power, or about 4 dB more, or 80 dB! The reality is that background (70 dB) is, say, one watt, sorta loud at 80 dB is about 10 watts, and louder than comfortable, 90 dB, is a hundred watts.


The amount of power going to each speaker does depend on whether you use a switcher or not. As Eric points out, the switcher puts a resistor in series with the whole bunch of speakers to ensure that the amp never sees too low of an impedance. But as Eric also points out, even if that resistor gobbles up half of the power going to the speakers, that'll only be 3 dB, which sounds like going down one step on the master volume. For practical purposes of ballparking what you're doing, then, you can just divide the amp power by the number of speakers. It's harder to get that most of the time a listening level you can talk over is in the neighborhood of a watt of power!

oex, it hadn't occurred to me that the second zone amps aren't really built to power a half dozen sets of speakers, but after reading about this over the last couple of months, I'm never going to hook up more than two pair to any second zone amp again. (The used Sonamp 260 is a great idea.) I've just been involved in searching out an amp for this purpose, and most such amps are around $700. That pricing alone backs up the idea that second zone amps shouldn't be used for multi-room setups: if the guys who build amps made for this kind of thing have to charge $700 for an amp that will do it well, how can a small part of a $500 to $1000 A/V receiver possibly be built to perform the same?

Fred, you're right about current controlling the loudspeaker. Here's where that protection resistance in the switcher is a bad thing: it limits the current that can get directly to the speaker, lessening control over movement of the cone. For more controversy and disagreement about what this means, if anything, search this site for "damping factor." Impedance matching VCs don't do this; they transform the impedance rather than adding a resistor to an impedance. So when you use that $1000 pair of speakers, the switch box impairs current to the speakers, affecting fidelity, and volume controls insert reactances and can't linearly handle high power, affecting fidelity. Those $1000 speakers deserve their own amp. This is exactly where you'd use twelve channels of amplification with preamp level volume control instead of one bigass power amp divided up into six rooms with switch boxes and/or VCs between the amp and the speakers. The performance of those expensive speakers suffers if they aren't powered in the (usually) more expensive manner of having their own power amps.

So if, for example, if I run line out of the home theater a/v receiver to the customer's old 125 watt marantz a/v amp, and then run this to the 6-way speaker selector, out to six rooms with non impedance vc's, each room should have ballpark of 20 watts or so, which should be more than enough to each room? Customer is not willing to spend more money right now on a dedicated 12 channel amp, or any other amp for that matter, and I, like you, after reading this post am leary of using the zone 2 on the main a/v receiver to power 6 rooms, 2 of which are outdoor locations which need more power.

Thanks Eric & Fred.

Current, or headroom are so important! I remember selling High Current - High Headroom recievers (but with much lower wattage ratings) against low headroom low current receivers - but with ridiculously high wattage ratings.

I pretty much pass on using the zone two outputs... and will just sustitute a seperate amp or receiver to minimise headaches.

Same for outdoor speakers, or High End... I usually always try to utilise a seperate amp for those, since they usually require more horsepower than the inside speakers.

Yes.

That might never be necessary. If this is going to develop into a multizone system when the budget allows it, then you'll eventually need the multichannel amp. If this is just a two-zone system and that Marantz is a beefy product, it might be all he'll ever need.

Yeah, but is there some reason you couldn't use the Zone 2 amp in your receiver for two of the rooms and the external amp for the rest? I don't even know if that is a preferable approach. I'm suggesting it because it's possible. If there were eight rooms I'd put two on the Zone 2 internal amp and six on the external amp.

Whether you use matching volume controls or switcher plus non-matching controls is another choice to make, and all the posts above suggest that there isn't a clear-cut reason to choose one approach. If you had eight rooms and didn't want to use the internal Zone 2 amp, well, there aren't any eight-position switchers, so you'd have to use impedance matching volume controls. But theory is less clear than what your layout might force you to do.

Here is another dilemma.. If you connect a line out from the main home theater a/v receiver to an amp, then to a 6 way speaker selector to provide sound thoughout the home, then you can only listen to what is currently on the main home theater a/v receiver! If you want to watch a movie in the theater room, and listen to other music in all other rooms, you can't. This is assuming the amp you are using has no other inputs for components. What if, however, you take either the pre-out of zone 2 on the main a/v receiver, or the actual left/right speaker outs of zone 2 from the main a/v receiver, and then connect this to the amp? I am guessing that this will allow you to safely play zone 2, which can be another source, amplified throughout the whole home. And, if you would also like to listen to the same thing in the theater room, all you have to do is switch to that input on the main zone. Is this the way most of you handle this situation when you don't have a dedicated multi-zone amp?

Most current 7.1 AVR's have a seperate pre amp/source selector for zone 2 that operates independent from the main zone. Most also have discreet on/off and source selection remote codes for true independent operation. Some don't, like Harman Kardon. While they supply 2 remotes(the second labeled "Zone 2") the power, source and volume codes work the main zone only, unless you send them to the "zone 2" IR input on the back using a not supplied IR sensor.
While I agree that the best solution for house audio is a 12 channel amp, what is the difference between a Dennon 3808 with 130w/ch,or a 2808 with 110w/ch and a single separate amp with the same output?

phil,

are you saying what's the difference between using zone 2 that has 130 watts and an external amp that has 130 watts?

Don't understand your question really. But a person on a budget would be wise to buy the 2808 and spend the spare $400 on an external amp.

Check the current draw on a dedicated external amp and compare it to the current draw on your prospective receiver and you may understand why the external amp is capable of driving more than 1 pair of speakers per channel effectively. For example, Denon 3808 rates at 7.2A. A 2-channel 100 watt amp will rate anywhere from 5.5A-8A depending on your flavor.

tca, before you wrote this, I was sure that everyone was talking about taking a Zone 2 output, NOT a line out from the main receiver as you proposed. When you say what if, gee, it's almost as if you've discovered that there's a Zone 2 output and are saying "hey, what if we use this, guys?"


Well, if you did that, you wouldn't be doing what ANY of us are talking about, and I thought that included you!

The Zone 2 line outputs are the thing to use. And they call them Zone 2 because they can choose things different from Zone 1, which is the Home Theater Zone. I know, I know, nobody can find the term "Zone 1" in a manual, but if they have a Zone 2, the main section has to be Zone 1.


Now you're with us (which I thought you were all along). But I just reread your previous posts and I see you don't specify whether the output you're taking is from the main zone or the second zone. I ASS UMEd you were talking second zone. After all, the original poster says 2nd zone on the fourth line of the first post.

I wouldn't take the second zone output from its speaker terminals, though. That won't hurt the A/V receiver. The issue is that if the second zone amp can put out 100 watts into 8 ohms, it can put out 28 volts at maximum volume, with some very low noise level. You can indeed take this signal an run it into a power amp, and as long as you never go above about a volt, you won't overdrive the amp. But there's that pesky noise level to deal with. If you take the amp output and drop it using a resistive network by a factor of, let's say ten, then the maximum that will go into the power amp will be 2.8 volts. That's still enough to way overdrive that amp, but in the process of dropping the zone 2 amp's output level, you've also dropped the noise by a factor of ten. If you don't know how to design a resistive network to do this, just use the freakin' RCA jacks that they put on the unit for this purpose. Only put a power amp output into a different power amp's input if you know how to safely scale the signal for voltage and impedance.

So, if I understand this correctly, the 3808 will be better than some and worse than other 2 channel amps if the 3808 is running ONLY zone 2. If the main zone is also being used it will be worse, the difference being in the capacity of the power supply circuit.

ZMass left out a detail that kept me from understanding his point for quite a while.

He's saying that seven channels of Denon draw 7.2 amps from the wall while two channels of separate power amp draw more than five amps. That totally implies that the separate power amp will have more output current than the Denon. But the Denon is drawing 864 watts while the power amp draws 660 - 960 watts for two channels. That might make the Denon look efficient or heroic while the power amp looks profligate. There's a device out there that sucks almost a toaster's worth of power out of the wall to deliver only 200 watts of power? I'll be a class A amp isn't even that inefficient.

All I can say is, there's so much unsaid and assumed about those numbers that I'd rather not argue them, even if they're true.

I've been through this recently, finding that amps in the 2x100 watt range all center on about a $700 price tag. Here's another approach: those amps are better built and more stable than the zone 2 amps in a receiver in more or less the same price range because
a) the receiver has to deliver more watts and do more things, therefore less money can actually get put into a beefy design, parts and power for just those two channels, and
b) separate power amps are not ALL overpriced -- it's not possible to bring out a product and price it way over its value. Prices on these would have fallen due to competition. My experience in this industry is that you get what you pay for* so it's reasonably safe to assume that a whole class of product at a particular price has a price representative of its real value based on what's in it.

*This does not, of course, go for products that are advertised so heavily that you can say they have "a story," or that little rhymes (no highs, no lows, etc.) have been written about. Those things are overpriced because some people go for a good story and a high price. And those things are overpriced across the brand. You don't find several brands of the same type of item being overpriced.

Expect better performance from a separate two-channel power amp than from two channels of an A/V receiver.

Oh, yeah, the separate amp also will be better ventilated, thus tending to last longer between fatal explosions.

I need to read through this thread several more dozen times to understand all the details, but suffice it to say, I'll be powering the zone 2 out with something. I'll probably end up using a 12 year old Denon AVR 2000 to power the 7 other speaker pairs.

This forum is truly fantastic. Thanks everyone!

I'll post my final specs when available, after my CI and I have a pow-wow.