CurtPalme.com Home Theater Forum

[stereodave70]

I've been looking at upgrading to at least 300 watts to my mains. 120 watts from my receiver just doesn't drive the new mains well. Last year's upgrade was the Klipsch reference system; rf63, rc64, rs62. It all sounds great for movies, but I want more from music. I was looking at outlaw audio 7900 power amp at 300watts per channel. The guys in the outlaw saloon say that outlaw rates there amp's wattage very moderately. This amp weighs in at 145 lbs and requires 2 15 amp circuits to run full power. And there is also the price tag. Also have considered Crown power amps, the XLS 1500 or maybe even the 2500 just to drive the mains. What I'm confused about though is the difference between the types of power. Why is the HT gear so much heavier or how can pro gear be so much more powerful.....seriously!!! 10 lbs for 440w x 2 vs 145 lbs for 300w x 7 ? What do you guys think? I know some of you guys are using the pro gear stuff, is any one using the Outlaw stuff?
Thanks
Dave

[Curt Palme]

One of the main things is that you need to make sure that everyone is talking RMS Watts when rating their wattages.

Even the pro companies are now BSing, claiming 4000 watts from a 15 amp outlet that only puts out 1800 watts tops.

I much prefer pro gear to the consumer stuff.

THe rating you post above, 300w X 7 is bull****. That will be some rating like 'Instantaneous Peak Power' or some crap like that.

Keep in mind as well that 3db requires double the power, and 3db isn't much. Try sliding all sliders on a graphic eq up by 3db. That's twice the volume, but it's only a slight perceptive change in volume. So while gobs of power is great for headroom, you need to make sure your speakers can take it, and that you've got the clean AC power to source what the amp is looking for.

Klipsch should be really efficient, maybe you're going deaf?

[Curt Palme]

One of the main things is that you need to make sure that everyone is talking RMS Watts when rating their wattages.

Even the pro companies are now BSing, claiming 4000 watts from a 15 amp outlet that only puts out 1800 watts tops.

I much prefer pro gear to the consumer stuff.

THe rating you post above, 300w X 7 is bull****. That will be some rating like 'Instantaneous Peak Power' or some crap like that.

Keep in mind as well that 3db requires double the power, and 3db isn't much. Try sliding all sliders on a graphic eq up by 3db. That's twice the volume, but it's only a slight perceptive change in volume. So while gobs of power is great for headroom, you need to make sure your speakers can take it, and that you've got the clean AC power to source what the amp is looking for.

Klipsch should be really efficient, maybe you're going deaf?

[stereodave70]

The guys at Outlaw are very proud ($$$) of this amp. Every thing I look at I look for the RMS rating, if it doesn't say "RMS" then it probably is bragging about peak. Even Velodyne brags about having 3000watt amps on their DD-series subs, but in fact are only 1250 watts RMS. Here are the specs for the Outlaw Audio 7900 power amp. Remember this amp requires 2 separate 15 amp circuits.


Specifications

Power output: 300 watts RMS x 7 (all channels driven simultaneously into 8 ohms from 20 Hz to 20 kHz with less than 0.05% total harmonic distortion).

Signal to Noise: >120dB below rated FTCfull bandwidth power

Power Bandwidth: 5 Hz - over 100 kHz (+0/-3 dB)

Crosstalk: Greater than -100 dB from 20 Hz to 20 KHz

Intermodulation Distortion: Less than .02% from 250mV to full rated FTC power

Voltage gain: XLR 28dB, RCA 28dB.

Slew rate: 50 Volts/microsecond

Remote Trigger voltage: 3 - 24 volts DC

Power requirements: 2x 115 V 50-60 Hz

Power consumption: 2x 1,440 watts (maximum)

Dimensions (W x H x D): 17.2 x 9.5 with feet x 19.5 (inches)

Weight: 145 (lbs)

[kal]

One thing to keep in mind about pro audio gear is that tyipcally how much noise it makes isn't an issue in pro environments.

For example, it's not uncommon to have a fan in pro power amps that can be heard reasonably well while consumer stuff will either use convection cooling or very quiet fans which means you often need to use *massive* (heavy) heat sinks without fans. That adds weight and costs more. The pro guys will simply add another fan or speed up the fan.

Kal

[kal]

One thing to keep in mind about pro audio gear is that tyipcally how much noise it makes isn't an issue in pro environments.

For example, it's not uncommon to have a fan in pro power amps that can be heard reasonably well while consumer stuff will either use convection cooling or very quiet fans which means you often need to use *massive* (heavy) heat sinks without fans. That adds weight and costs more. The pro guys will simply add another fan or speed up the fan.

Kal

[Boilermaker]

Power ratings by themselves are not that meaningful in real world situations. Power ratings (whichever type) are measured by heating up resistors which have a linear value at all frequencies of 8 ohms. Speakers (with very few exceptions) are very non-linear and many times dip below 4 ohms or less.

If the power supply is robust enough, the heat sinks big enough and enough output transistors, an amplifier rated at 200 watts @ 8 ohms should provide 400 watts at 4 ohms and maybe even 800 watts at 2 ohms.

If an amplifier company does not rate the output power at 4 ohms or perhaps even 2 ohms, I would be suspicious. (normally commercial amps do well here).

I would much prefer a 100 watt amplifier that will double all the way to 2 ohms to a 300 watt amplifier that craps out and current limits at low impedance values. The well designed 100 watt amp will actually supply more power to your speakers than the 300 watt amp that was designed to have an impressive ftc power rating.

I would e-mail Outlaw for this information before I pulled the trigger.


Bob

[kal]

[kal]

[kal]

FWIW, something like an Outlaw 7900 at 145lbs is going to be an absolute bitch to move around and set up because of the 145 lb weight.

Consider getting separate amps, like a 5 channel and a 2 channel, or possibly 7 mono amps. Or even a 3 channel for the fronts and then a smaller (less powerful) 5-channel for the rears and leave one unused. Having one channel unused is fine and gives more power to the others, unless it's a completely discrete design with capacitance and a separate transformer per channel (true monoblock design).

I'm 5-channel: I run a 3x200W amp on the fronts and a 2x100W amp on the rears. Note that I have a larger amp for the front where (IMHO) it matters more for movie soundtracks.

Kal

[kal]

FWIW, something like an Outlaw 7900 at 145lbs is going to be an absolute bitch to move around and set up because of the 145 lb weight.

Consider getting separate amps, like a 5 channel and a 2 channel, or possibly 7 mono amps. Or even a 3 channel for the fronts and then a smaller (less powerful) 5-channel for the rears and leave one unused. Having one channel unused is fine and gives more power to the others, unless it's a completely discrete design with capacitance and a separate transformer per channel (true monoblock design).

I'm 5-channel: I run a 3x200W amp on the fronts and a 2x100W amp on the rears. Note that I have a larger amp for the front where (IMHO) it matters more for movie soundtracks.

Kal

[stereodave70]

The Emotiva XPA-2 and 5 both look very impressive. I thought 300 watts to the rear and sides was a bit unnecessary, just extra cost and weight. Will the sides and rears be able to keep up with the mains?, and what should I expect from the "auto" calibrater? Will there be a huge lack of side and rear fill for movies?

[dturco]

[Spanky Ham]

You might want to check the amp testing thread over at AVS. My buddy Chasw tested a lot of amps.

[dvh99]

http://www.aussieamplifiers.com/modules.htm

have a look at them, they sell different modules.

another australian company with some great products.

http://www.aksaonline.com/buying/buying_price.html