I see the 770 is rated at 200 wpc with an 8 ohm load. What is its power output and compatibility with a 4 ohm load? I have a 6.1 setup now with a 1050 + SVS sub powered by a Peavey amp. If I go to a 770 later on, I would like to use the 7th channel for the SVS (which has a 4 ohm driver). My 6 speakers are 8 ohm.

Thanks... KJP

I don't think we'll know that for a while, but you might toss Outlaw an e-mail asking them, as I somehow suspect that the answer is floating around their office somewhere and Scott may have it within reach.

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Gonk

Do let us know if you find out, will you? My Axioms are 4 ohms (actually something like 5.5 ohms) and I'm curious as to how much sound will come from this thing.

I plan on using Thiel 2.3s. They drop down to 2.3 ohms. I wonder if the 770 can handle that kind of load ?

Don't most speakers drop below their "nominal" impedance at some point? I wouldn't be surprised if my Axioms are occasionally below 4 ohms.

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Matthew J. Hill
matt@idsi.net

Thiels are notorious for being hard to drive.

I've had 3.5 in the past which my Rotel 100w would NOT drive. It would shut down.

I no longer have those speakers but really love the 2.3 and don't want to encounter the same problem.

The 2.3 are rated at 4ohms but for must of the range they are around 3ohms according to a review in Stereophile.

The (minimal) specs for the 770 are now posted in the products section of the Outlaw's web site at http://www.outlawaudio.com/products/770.html#

It lists the 770 power output as 300 watts for 4 ohm speakers.

Full list follows:

Power output: 200 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). 300 watts RMS x 7 @ 4 ohms (other conditions same as above)

S/N: 119 dB

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

Damping factor: 850 (10 Hz - 400 Hz)

Input sensitivity/Impedance: 1.43 volts for full output/28 k ohms

Remote Trigger voltage: 3 - 32 volts AC

Power requirements: 115 V 50-60 Hz

Power consumption: 1,800 watts (maximum)

Dimensions (W x H x D): 17.2 x 7.75 x 18 (inches)

Weight: 90 (lbs)

I currently own a Counterpoint SA220 amplifier thats rated at 220 watts @ 8 ohms, at 4 ohms it increases to over 440 watts. I have checked other amps ratings like the Sunfire amps and other high end units, it appears they also for the most part double there wattage going from 8 to 4 ohms.
Outlaws amps appear to only increase their wattage by 50% instead of doubling it according tho the specs for the 750 and now the 770. Are they just conservatively rating the units or is it an inferior design technology (I wopuld be suprised if it was the latter).
Can somebody please shed some light on this subject.

Power consumption = 1,800 watts (maximum)?

We're talking dedicated circuit here. Even then, most home wiring is maxxed at 1800 watts, so toooo much sound can trigger breakers. You should be deaf by then, so you won't hear the music stop :-)

JJ,
An efficient amp should theoretically double its output from 8 ohms to 4 ohms, as I've understood. Less efficient models will have lower output levels.
I'll try to dig up the article. Or the 770 may just be limiting the output.



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Emin

The best an amp can do is double its wattage with each halving of the load. The amplifier topology and the capacity of the transformer all work together to determine the actual wattage. From 200W into 8 ohms to 400W into 4 ohms, the current of the amp must double. Most amps are current limited as the load decreases. Most reach a point of instability as the load goes even lower (i.e. 2 or even 1 ohms). The amount of rated power at 4 ohms compared to 8 ohms gives you an idea of how much current the amp can deliver.

50% more wattage at half the load is not bad, but there are "better" amps out there. Some receivers actually decrease in wattage from 8 ohms to 4 ohms, as they are limited by current and the possibility of overheating.

If you have a low impedance speaker, you can either buy an amp that nearly doubles its power into 4 ohms or just buy an amp with lots more power than you need. That way you won't be pushing it too hard, even with a 4 ohm load.

With the 770, 300W into 4 ohms is still 300W. My amp does 125W into 8 or 200W into 4 - a little better than 50% more power into 4. I also have 4 ohm speakers. I have no problem driving them. I have driven the amp into clipping with the opening of Toy Story when the bass is really pounding and during the depth charges of U571, but never for music.

Any decent amp will drive 4 ohm rated speakers. The question is how loud do you want to be able to go. You can try the 770 and return it if it doesn't have enough volume for you. If a 200W amp doesn't cut it, then you are gonna have to pony up some serious bucks for an even bigger amp - buy the 750 for the other 5 channels and then a 250W or 300W x 2 (into 8 ohm) amp for your mains. The other option is to passively biamp you mains, which would give you higher volumes using 4 amp channels of moderate power. Are the Thiels bi-wire/amp capable Roderick?