When I upgraded my theater room to an Atmos setup, I blew most of my budget on the pre-amp (Yamaha CX-A5100) and speakers (DIYSG 1099's + Volt surrounds & Atmos). I didn't want to spend another several thousand dollars on a new 11ch amp at the moment, so I went on the hunt for a high quality budget-priced amp to drive the system temporarily. What I ended up buying turned out to be such a great amp that I decided to keep it for good! And I got it at an absolutely ridiculous price - just $180 delivered!! That was an unusual deal, it looks like you can currently get one for around $350-$450 delivered, which is still an incredible value for what you're getting. Or if you're patient you can wait for a good deal like mine to pop up on eBay. Hell, just last month one lucky person
scored one with a winning bid of just $0.99 w/free local pickup!
The amp I'm talking about is the Crestron CNAMPX-16X60. This is a 16 channel amp made by ATI which was designed for Crestron whole-house audio systems, but it can very much be used in a home theater setup as I'll explain below. This amp was by designed legendary amplifier engineer Morris Kessler, and it was the first ever 16 channel amp to deliver 60W/ch. It uses the exact same amplifier boards and transformers as several other other high-end amps made by ATI - such as the ATI AT2007 (MSRP $3,000), the Crestron CNAMPX-7x200 (MSRP $5,000), and the current bang-for-your buck champ the Monoprice 7x200 (MSRP $1,500). The only difference with those amps is they have 7 two-channel boards which are internally bridged to produce 7 output channels (one channel driving the + and the other channel driving the -), while this amp has 8 two-channel boards with 2 output channels = 16 channels. But, one little known fact about this amp is that ALL channels are bridgeable externally (more on that below), giving you 8 channels of output @ 220W!
The specs on this one-of-a-kind beast are VERY impressive:
Output Power (20Hz-20kHz, all channels driven):
60Wx16 @ 8 ohms, 90Wx16 @ 4 ohms, 220Wx8 bridged @ 8 ohms (NOT 4 ohm stable on bridged channels)
: 3Hz to 50kHz, +0/-3dB
: 20Hz to 20kHz, +0/-0.1dB
Total Harmonic Distortion (THD)
: ≤0.03% at full power
IHF I.M. Distortion
SMPTE I.M. Distortion
: >110dB A-weighted
: >100dB, 20Hz to 20kHz
The phrase "built like a tank" almost doesn't do this amp justice. It weighs nearly 100lbs, has 8 individual amplifier boards - each with their own power supply and held together with dual-braces along the tops to keep everything in place, the amp heatsinks are MASSIVE, as are the two soft-start toroidal transformers, the boards are all glass epoxy coated for protection against the elements (such as humidity, dust), and the speaker terminals are mounted directly to the chassis - rather than being mounted to a board inside the chassis - so you can use the heaviest gauge wire known to man and still not see any terminal sag! I actually tore the whole thing apart and inspected every inch of it out of curiosity, and to clean all the dust out of it, and I was blown away by the quality throughout. I'll post some pics in a reply below.
As shown in the specs above, the output of this amp is 60W @ 8Ohms in single channel mode, but when you bridge two channels it jumps up to 220W @ 8 Ohms. And all 16 channels (8 amp boards) are bridgeable, despite the Crestron manual saying you should only bridge channels 1-4 and 13-16. I'm guessing that is recommended to prevent any chance of overheating, but it's obviously possible to run them all bridged without a problem since the AT2007 and Monoprice 7X200 both have 7 of the same boards running bridged with no overheating issues. And that, my friends, is what makes this such a great Atmos amp: by bridging 10 of the 16 channels you are able to get 5 channels @ 220W (for the L/C/R/SL/SR), with the other other 6 channels @ 60W (for the RSL, RSR, and 4 ceiling Atmos). At first I thought the rear surrounds and Atmos speakers might get overpowered by the mains getting 160W more power, but then I realized they probably don't need as much power since they are located about 8ft closer to my ears. I used an SPL calculator and determined that with my fronts getting 220W @ 16ft and the others getting 60W @ ~8-10ft, the SPL at the listening level will be almost exactly the same! (108.7dB for mains, 109dB for surrounds & Atmos).
GETTING THE AMP UP AND RUNNING:
The first question many people have about this amp - and this is probably what scares a lot of people away from using it for home theater use - is how to run it without being connected to a Crestron system. It's actually VERY simple. All you need to do is provide 24V power to the Crestnet port via an external power adapter. You can use any old laptop charger or wall wart that puts out 24V with at least 1A. First you cut off the plug end, then take the green 4-pin terminal that goes to the Crestnet port and connect the positive (center wire) to the top post marked 24V, and then the negative (outer wire) goes to the bottom port marked G. If your amp didn't come with the green phoenix connector you can buy one on eBay for a few bucks. Once you plug that in you'll see a green light come on indicating that the Crestnet card is getting power, then you just hit the red bypass button and the Crestnet card inside will be bypassed allowing you to use it like a regular amp. Once you've done that you can power the amp on & off via the front switch or a switching power conditioner, but you MUST leave that 24V on at all times. If the 24V ever loses power you'll need to hit the bypass button again when power is restored. I plugged mine into the "always on" outlet on my power conditioner so I'll never need to hit that red bypass button again. It only uses 12W of power to run the Crestnet board so we're talking maybe $1/mo to leave that power on 24/7.
BRIDGING THE AMP:
One very important thing that I figured out with this amp is you DO NOT NEED the special Crestron CNXBRMO bridging module listed in the user manual to bridge this amp! All you need to do is provide two out-of-phase RCA signals to each channel, which can be done nothing nothing more than a $5 XLR/RCA y-cable if your pre-amp has XLR outputs. But even if it doesn't, you still don't need the hard-to-find Crestron bridging module, there is a much easier and cheaper option.
If you DO have XLR outputs, all you need is 5 female XLR-to-dual RCA y-cables. I bought these
on eBay for a total of $16 delivered, but they're a tight fit at just 1.5ft long. If your amp and receiver are further away, I found these 1.5m (3ft) cables
for just a few bucks more. All you do to bridge the channels is plug the XLR end into your pre-amp, connect the two RCA ends to two channels on the same amp (i.e. 1&2,3&4, etc), and then connect the + speaker wire to the + of the top channel, and the - speaker wire to the + of the bottom channel, and you're now getting 220W over a bridged connection!
Now if you DO NOT have XLR outputs on your pre-amp, then you will need one additional thing - a Henry Matchbox device. They can be bought on eBay for around $30-$40 delivered, sometimes even cheaper if you can find a multi-pack (I once saw a 5-pack sell for just $50!). Each unit will provide 2 XLR outputs which will give you 2 bridged channels, so you'll need 3 of those boxes to get the 5 bridged channels that you need. The way it works with those boxes is you use the RCA output of your receiver, connected to the RCA input of the Matchbox, the use the above-mentioned XLR-to-RCA splitter cable from the output of that box to the back of the Crestron amp. Then connect the speakers to both + terminals as described above. Using this method adds another $100-$120 to the cost of the setup, but you should still be able to keep it under $500.
So there you have it - an audiophile-grade 11ch Atmos amp on a budget! With the cables (and the Matchbox units if necessary) you're looking at somewhere in the range of $300-$500 total, depending on what kind of deal you get on the amp. That is a ridiculous bargain compared to something like the 11ch Yamaha MX-A5000 amp which costs $2,500 and only puts out 150W/ch to the mains (8 ohms, 2ch driven), and nowhere NEAR that much with all channels driven since the amp maxes out at 650W (and that's total power consumption, not output power, so with a 75% efficiency of a Class G amp you're talking more like 455W which is just 41W x 11 with all channels driven!). Or if you go the Monoprice 7x200 route you would get 7 channels at 200W rather than just 5, but then you still need to power the additional 4 channels which would cost another couple hundred for a good quality 4ch amp, so you'd be close to $2,000 for that setup. This is less than 1/4 the price for basically the same exact amp, and it's an all-in-one solution.
I ended up being so impressed with this amp that I actually just bought another one, and I'm going to bridge 5 channels on the first amp and 6 channels on the other for all 11 channels @ 220W with all channels driven. Probably completely unnecessary, but I scored an equally ridiculous deal on the second one at just $165 delivered. So my 2,400W 11ch amp setup will end up costing a whopping $380 out the door....and I'll still have 10 channels left over, which I'm going to use to power my whole-house speaker system that I'm getting ready to install.