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#48305 - 02/25/02 12:51 PM Re: 770 and 4 ohm loads?
Azistoohot Offline
Gunslinger

Registered: 02/06/02
Posts: 47
I don't believe that Thiels are biwireable/biampable. Supposedly they sound great, when driven by a great amp and supporting electronics. They supposedly don't sound nearly as good when driven by bad amps and electronics.

I am currently using an Onkyo receiver to drive three 4 ohm Linn speakers and two 8 ohm Mirage speakers. Even though the receiver manual has a warning to not use speakers with less than 6 ohms, I've had no problems. The Onkyo, however, isn't very musical (however, I'm comparing a $600 receiver with my friend's $5000+ Proceed separates driving the same speakers). It's much better for movies than music.

I'm going to either try the Outlaw 950/770 combination or, if I don't like the Outlaw combo, buy used Proceed gear. Another option is to use a 2-channel proceed amp (for the front Linns and stereo) but then use the Outlaw 950 and maybe the 750 amp.

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#48306 - 02/25/02 07:20 PM Re: 770 and 4 ohm loads?
Roderick S Offline
Deputy Gunslinger

Registered: 02/18/02
Posts: 7
No the Thiels are not capable of being bi-amped......

The specs for the 770 look promising. I will give it a try....

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#48307 - 02/27/02 12:32 PM Re: 770 and 4 ohm loads?
tkirchen Offline
Deputy Gunslinger

Registered: 02/27/02
Posts: 12
Question? Does anyone know if the 770 is stabile into 4ohm loads. I realize it is not out yet so the answer is likely to be no. All of my speakers are 4ohm.

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Troy
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#48308 - 02/27/02 12:45 PM Re: 770 and 4 ohm loads?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
The 770 isn't available yet, but Outlaw did post specs for it recently (see this link ) and they do list it as capable of 300W per channel at a 4 ohm load, so I would assume that it is stable there. If you're really not sure about the 770 being able to handle your speakers, fire an e-mail off to Outlaw -- they're good about answering questions like that.

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Gonk
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#48309 - 03/05/02 10:07 AM Re: 770 and 4 ohm loads?
eurorom Offline
Gunslinger

Registered: 03/04/02
Posts: 96
Loc: El Paso Texas
HI GUYS,THE 770 SHOULD BE ABLE,IT IS ABLE TO DRIVE ANY SPEAKER OR LOAD TO 1ohm,REMEMBER 300watts AT 4ohms CONTINOUS,BUT SHOULD BE,WOULD BE ABLE TO HIT OVER 400 watts,at any given time.....eurorom.

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#48310 - 03/09/02 01:44 PM Re: 770 and 4 ohm loads?
Surrounded Offline
Gunslinger

Registered: 03/03/02
Posts: 44
Loc: Raymond,NH,USA
Quote:
Originally posted by JJ:
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.


Correct me if Im wrong but your talking about a two channel amp. When you start putting 7 amps in one box you are still limited to the 15 amp outlet on the wall. I believe if you look at even the high end multi channel amps they won't double the wattage when the load is halved. Some I have seen rate the wattage the same at 4 ohms. I belive most mfgrs. if honest would give you a rating based on a transient using energy stored in the capacitors. As far as Sunfire is concerned they use a entirely diffrent approach. Where most amps are running at full idle Carver uses a tracking down converter which allows the amp to keep the idle just above the input signal. which consumes much less power and requires minimal heat sinks. But the Sunfire amps are not as clean as conventional designs. Come to think of it if you have electric heat you could disconnect the line from it and connect it to your 770 and let this puppy heat your home theater.

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#48311 - 03/15/02 02:21 PM Re: 770 and 4 ohm loads?
Audiophile Mike Offline
Gunslinger

Registered: 03/14/02
Posts: 16
You might want to see my post in the Transformer Size thread. I'm willing to bet the 770 cannot manage 300w x 7 continuous power with all 7 channels driven at once. This would require over 3000 watts of AC line draw. Of course, there aren't any other 7 channels amps I know of that can manage that feat either.

If you can run a 220 volt circuit, a big Cinepro amp will easily outpower the 770 but it's also about 3 times the price. Likewise, the Sunfire Cinema amps are more efficient so they can manage more power on a typical 120 volt circuit but they don't make a 7 channel model and some question their sound and reliability.

If all your speakers are 4 ohm models (or inefficient/difficult to drive), and you like it loud, I'd seriously consider using TWO power amps running on two dedicated AC circuits. You can only get so much power out of one 15 amp power cord.

As for the power doubling when you go from 8 ohms to 4 ohms that's usually somewhat a game of specsmanship. A perfect amplifier would indeed behave that way, but even the amps that are rated to do it, don't really test that way. An amp rated for 200w/ch at 8 ohms and 400w/ch at 4 ohms (like the Sunfire Cinema Grand) will in reality usually put out like 250 - 300w/ch into 8 ohms and say 405w/ch in 4 ohms. So while it meets the spec, it only does so because they (oddly) adjust the 8 ohm rating downward to make it appear like a "perfect" amp.

As applejelly posted, the 770 is respectable with its 50% increase into 4 ohms. The catch is, I doubt it can do it with all channels driven. But that's not really the amp's fault as much as what you get from a single 120 volt wall outlet and a shared power supply.

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#48312 - 03/21/02 08:20 PM Re: 770 and 4 ohm loads?
gmiles Offline
Deputy Gunslinger

Registered: 03/21/02
Posts: 3
Loc: Montgomery, AL
Power question. I just built a home theater and put a dedicated 30amp circuit in my wiring closet, with only a 20 amp plug. Is the power cord on the 770 going to limit me to 15 amps anyway? or can I substitute a nema 20amp plug... and does it matter as it's limited to 1800 watts anyhow? confused. How many amps does the 770 pull under it's maximum load.

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#48313 - 04/11/02 12:14 AM Re: 770 and 4 ohm loads?
stiletto Offline
Gunslinger

Registered: 02/20/02
Posts: 38
Loc: Winter Springs, FL, USA
I am guessing from the spec saying 1800 Watts that they put a transformer in there that will handle 15 amps. This would give them about 1800 watts. It would be hard to drive all 7 channels at once at maximum output using music or movies. I am guessing if you do that for sustained periods of time you are going to have a melt down or a thermal shutdown. 300 watts is a lot of power for a speaker and if you need more than 7 channels at a little under 300 watts you will definately have a hearing problem in the near future. I would also wadger a guess that while running normal music and movies the 770 would be capable of handling well over 300 watt transients , but doesn't have the caps to keep it running for sustained operation. I can't imagine the capacitance required for 1800 watts sustained! Would be some monster caps.

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#48314 - 04/11/02 09:42 AM Re: 770 and 4 ohm loads?
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
Does anybody know how much capicatance the 770 and 755 have per channel? IIRC, the 750 had 20,000 uF, but I haven't seen any figures listed for the newer models.

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Matthew J. Hill
matt@idsi.net
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Matthew J. Hill
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