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#48427 - 03/03/02 12:06 AM anybody know the transformer size?
gchon Offline
Deputy Gunslinger

Registered: 06/29/01
Posts: 10
Loc: palos verdes, ca
would like to know how much current this amp would actually produce. Called outlaw, but didnt get an answer. All they could tell me that it contained 2 toroidal transformers.

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#48428 - 03/03/02 12:24 AM Re: anybody know the transformer size?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
Looking for how much current it will draw, or what the output is? The specs say that it has a max power consumption of 1800W (which on a 120V system, would indicate a max current draw of around 15A unless I'm even rustier on my electrical formulas than I think). Is that any help?

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#48429 - 03/04/02 10:50 AM Re: anybody know the transformer size?
Matthew Hill Offline
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Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
I don't understand how it can output 300x7 into 4 ohms and still only draw 1800W. My calculations, assuming 80% efficiency, put it closer to 2600 watts.
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#48430 - 03/04/02 04:52 PM Re: anybody know the transformer size?
Azistoohot Offline
Gunslinger

Registered: 02/06/02
Posts: 47
You're right -- It cannot be rated at 1800 watts and produce 7 channels at 300 watts. Something has to give. Of course, you're really going to have to be cranking a movie (or perhaps DVD-A or SACD) at high volumes to get 300 watts into 7 speakers.

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#48431 - 03/05/02 12:15 AM Re: anybody know the transformer size?
eurorom Offline
Gunslinger

Registered: 03/04/02
Posts: 96
Loc: El Paso Texas
ok.GUYS THE ANSWER IS VERY SIMPLE,48 AMP'S OF CURRENT PEAK.THANK YOU.....SMILE EUROROM TO THE RESCUE.

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#48432 - 03/05/02 09:56 AM Re: anybody know the transformer size?
eurorom Offline
Gunslinger

Registered: 03/04/02
Posts: 96
Loc: El Paso Texas
HI GUYS,I GUESS LAST NIGHT I WAS SLEEPY.BUT HERE WE GO.THE 770 AND 755 REPRESENT A DEPARTURE FROM MANY OF THE OTHER CURRENTLY AVAILABLE AMPLIFIER DESIGNS.THIS DEPARTURE IS THE RESULT OF CAREFUL STUDY OF ALL KNOWN AMPLIFIER TECHNOLOGY,CIRCUITS AND PARTS.I CAN SEE FROM THEIR ILUSTRATIONS,THAT THEIR MAJOR FEATURES OF THE 770 AND 755 ARE THEIR OUTSTANDING ABILITY TO DRIVE VIRTUALLY ANY SPEAKER,REGARLESS OF IMPENDANCE.BY USING APROXIMATELLY TWO 700 WATT TRANSFORMERS ALONG WITH 120,000 MICROFARADS OF FILTER CAPACITANCE.IT IS A WELL DESIGN AMPLIFIER TOPOLOGY USE BY SOME OF THE BEST AMPLIFIER DESIGNERS,EXAMPLE KRELL,McIntosh,CLASEE,LEXICON,AND MANY MORE.HOPE TO HAVE ANSWER YOUR QUESTION. EUROROM

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#48433 - 03/05/02 05:42 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Hey Euro -

Not trying to be a pain, but your caps lock is stuck......

The rating is 7 channels at 300w into 4ohms, continuous, so this isn't a peak figure. I'm guessing the 770 draws over 15 amps (19 maybe???) in this highly artificial scenario.

Assuming 100% efficiency it would still draw 17.5 @ 120 volts.

Although most household circuits are wired with 12 gauge wire and protected by 20 amp breakers (and so could supply this) I'd be surprized if UL approved the 770 for this use - the sort of plug most audio equipment has is a 15 amp rated plug.

| |
o 15 amp x 120 volt

| -
o 20 amp x 120 volt (IIRC)

Any way you cut it - in a real listening setup the total draw over time is going to be a lot less than this figure. Maybe UL looked at that factor - who knows?

Charlie
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#48434 - 03/06/02 12:22 AM Re: anybody know the transformer size?
eurorom Offline
Gunslinger

Registered: 03/04/02
Posts: 96
Loc: El Paso Texas
Ok.the question was How much current this amp would actually produce,not how much current it will draw from the wall.CHARLIE you are correct on the fact that it only draws 15,or at best 19 amps of current.

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#48435 - 03/09/02 12:58 PM Re: anybody know the transformer size?
Surrounded Offline
Gunslinger

Registered: 03/03/02
Posts: 44
Loc: Raymond,NH,USA
Quote"Although most household circuits are wired with 12 gauge wire and protected by 20 amp breakers (and so could supply this) I'd be surprized if UL approved the 770 for this use - the sort of plug most audio equipment has is a 15 amp rated plug."

I belive it would be impossible to produce 300 watts constant to all 7 channels with 15 amps. A standard house is wired with 14 gage wire with a 15 amp breaker and up to 6 outlets per breaker(depends on local codes). I will be running a dedicated line for my 770 I don't see any other way to keep from popping the breaker.

[This message has been edited by Surrounded (edited March 09, 2002).]

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#48436 - 03/10/02 08:03 PM Re: anybody know the transformer size?
eurorom Offline
Gunslinger

Registered: 03/04/02
Posts: 96
Loc: El Paso Texas
Possible it is to run 300watts continuos at 4ohms,the reason being that the amp stores energy.Plus it is almost imposible to run 300watts all 7 channels at any given time.If their is a movie or music that demands it,well then you have your storage ready to come into play.It is always nice to have your dedicated ac line. eurorom

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#48437 - 03/10/02 08:18 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
Originally posted by Surrounded:
[B]A standard house is wired with 14 gage wire with a 15 amp breaker and up to 6 outlets per breaker(depends on local codes)./B]


Maybe in your locality.

In all the houses I've seen in Oregon the lighting is done on 14 gauge with a 15A breaker and outlets are wired with 12 gauge and protected with 20A breakers. Some spec houses might be wired as described (to meet minimum codes) but the custom homes I've seen are not wired that way.

In any case, the outlets are almost always of the 15 amp variety.


Charlie
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Charlie

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#48438 - 03/10/02 08:26 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
Originally posted by eurorom:
Possible it is to run 300watts continuos at 4ohms,the reason being that the amp stores energy. eurorom


OK Yoda. ;-)

AFAIK 'continuous' in the FTC use of the term means essentially forever, so the 'storage' capacity is a moot point.


Charlie
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#48439 - 03/10/02 09:27 PM Re: anybody know the transformer size?
Surrounded Offline
Gunslinger

Registered: 03/03/02
Posts: 44
Loc: Raymond,NH,USA
Charlie I live in NH where the Outlaws are from and the majority of the homes are wired 15 amp 14 gage. You also stated CUSTOM homes I believe thet would be the exception. We only use 12/2 20a for kitchens with a gfi breaker. Which would mean to target the masses you are stuck to 15a max at the outlet.

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#48440 - 03/10/02 10:37 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
Originally posted by Surrounded:
Charlie I live in NH where the Outlaws are from and the majority of the homes are wired 15 amp 14 gage. You also stated CUSTOM homes ..... to target the masses you are stuck to 15a max at the outlet.


I doubt the common practice in their home state was a huge influence, and I also doubt a 90 pound, 7x200 watt home theater amp is really targeted to 'the masses' in any meaningful sense of the phrase.

I've never spent much time in the NE, but in the NW everything except old houses, trailer houses and a few lower end tract houses will have 12gx20a on the outlets. I've seen 14gx15a, but I've never done it or known anyone who would admit to it.

Not that it's bad or wrong - It's just not done much, at least not that I've been around. I suppose if a builder was REALLY tight it would be something, but copper is really cheap.

In any case, the 770 is almost certainly equipped with a 15a plug, so it shouldn't be designed to draw more than that for an extended period. Perhaps it's fused at 15a or maybe UL let it pass due to oversight or the reality (realistic duly cycle) of its' intended use.

I'm really most curious what it's musical power levels, short and longer term, are.

Have a good one,


Charlie
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#48441 - 03/15/02 02:00 PM Re: anybody know the transformer size?
Audiophile Mike Offline
Gunslinger

Registered: 03/14/02
Posts: 16
Hey guys... I'm an electrical engineer and have designed audio power amps so hopefully I can shed some light on the AC power rating versus the power output.

First of all, the most a standard 120 volt household product should be rated to draw is 1800 watts (which is the most you can safely get from a standard 15 amp household circuit). So that likely explains the 1800 watt rating on the back panel (and in the specs).

As for 300w x 7 continuous output, that would indeed require an even greater amount of power from the AC line. Most class AB audio amps are only about 60% - 70% efficient. So if we assume 70%, you have (300x7)/0.7 or a whopping 3000 watts of AC power draw!

This would require the amp to have at least two 1500 VA transformers which is unlikely. It would also cause a lot of AC line "sag" even on a 20 amp 12 guage circuit. Even if you somehow manage to provide 120 volts AC at 25 amps to the line cord, I doubt this amp will product 300 watts x 7 from all channels at once.

Running 200w x 7 out, you would still need about 2000 watts of AC but this is a more realistic number. The amp just might meet that spec (at least on the 3 channels that have a transformer to themselves) if they used 1000va min. transformers. The other 4 channels might have a harder time sharing one transformer.

In reality, however, even cranking your favorite bring-down-the-house DVD, the AVERAGE power consumed by the amp is unlikely to exceed 1000 watts even when pushing it to clipping. There will be plenty of power supply reserves to go around. This is how $299 100w x 5 receivers manage to sound as good as they do. On the test bench, with 5 channels driven, they usually only manage 35 - 50 watts/ch.

If you want more continuous power from all channels on 120 volts, you need to look at something like the Sunfire Cinema amps which are more like 90+% efficient thanks to Bob Carver's trickery. Or use 2 or 3 channel amps split up on multiple AC circuits. The big Cinepro amps (which use huge 3600 kva transformers) recommend running them on 240 volts (or a special 30 amp 120 volt circuit) if you want to get anything close to their full output power.

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#48442 - 03/15/02 05:58 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
Originally posted by Audiophile Mike:
.... I doubt this amp will product 300 watts x 7 from all channels at once. ....


Yeah - I understand that. It also raises some interesting questions regarding the specification given and the FTC rules. I hope the Outlaws don't get too much trouble over that....

I'd love to see a time vs. clipping output diagram at 2, 4 and 8 ohms for a real production sample.


Charlie
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#48443 - 03/16/02 04:36 PM Re: anybody know the transformer size?
Azistoohot Offline
Gunslinger

Registered: 02/06/02
Posts: 47
"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)"

My problem is that this statement is misleading. 300x7 is 2100 watts, with 100 percent efficiency. At 120 volts, that's 17.5 amps, which most circuits won't support. Additionally, it's very doubtful that a test would support this assertion.

That doesn't mean that I think the amp is crap. On the contrary, I'd like to hear it. However, this is a misleading statement.

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#48444 - 03/18/02 09:41 AM Re: anybody know the transformer size?
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
Maybe it really will try to suck 20+ amps out of the wall outlet in that circumstance. I wonder what its internal breaker is rated at? If 15A, then yes, the statement is definitely misleading.
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Matthew J. Hill
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#48445 - 03/19/02 08:54 AM Re: anybody know the transformer size?
Azistoohot Offline
Gunslinger

Registered: 02/06/02
Posts: 47
Matthew: It probably does attempt to suck this power out of the wall. However, they also state that "Power consumption: 1,800 watts (maximum)". So, based on this, there's no way for it to produce 2100 watts (300x7). However, there's also little or no way for someone to ever draw that much power unless they have a set of inefficient, low impedance speakers and like to listen really loud.

I have a Creek 30 watt/channel amp that goes as loud as I care to go for two-channel, for both my Mirage (8 ohm) and Linn (4 ohm) speakers. 300 watts would be obscenely loud.

I just don't think that a company should be able to state, on the one hand, that maximum power is limited to 1800 watts, and yet, on the other hand, that the amp has a power output of 300 watts x 7 channels (2100 watts with 100% efficiency). There should be some type of disclaimer. Perhaps if you order the 220V version, you can get it to actually produce 300Wx7?

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#48446 - 03/19/02 09:47 AM Re: anybody know the transformer size?
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
I wonder if the 220v version also states 1800 watts max draw.

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matt@idsi.net
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#48447 - 03/19/02 09:54 AM Re: anybody know the transformer size?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
It might be useful to check out Pat's post on HTF this morning -- he asked the Outlaws about this very subject.

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Gonk
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#48448 - 03/19/02 10:18 AM Re: anybody know the transformer size?
psklenar Offline
Desperado

Registered: 03/01/01
Posts: 479
Loc: Southern New England, USA
I was going to post that here ... guess it's not necessary now.

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#48449 - 03/19/02 10:28 AM Re: anybody know the transformer size?
steves Offline
Desperado

Registered: 06/18/01
Posts: 356
Loc: Oregon
Pat,

Good job! I didn't get it either. Something else that I don't get was this post over at HTF:

Quote:
At $1800.00 the 770 is not inexpensive. The 950 may be the only game in town, but there are several good amps in this price range.


Well, I've been looking, but can't find any manufacturer who offers a SEVEN channel amplifier rated at 200 WATTS per channel for $1800.00. What did I miss?

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#48450 - 03/19/02 10:44 AM Re: anybody know the transformer size?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
I don't know of many seven channel amps at all (B&K has the Reference 7270, but it retails for closer to $3000 -- and it is rated at 7x375W at 4ohms and 1830 watts max power consumption). There are some 5 channel amps that are competitive with the 755 in the sub-$1500 price range (not necessarily with 200W of power, but considered sonically competitive based on the 750), and I think that's what was being referred to at HTF.

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#48451 - 03/19/02 10:57 AM Re: anybody know the transformer size?
psklenar Offline
Desperado

Registered: 03/01/01
Posts: 479
Loc: Southern New England, USA
Steve,

What Gonk said.


Gonk,

Man, are you fast!


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email: pat@sklenar.info ---===--- home page: Grumpy's Lair
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#48452 - 03/19/02 11:35 AM Re: anybody know the transformer size?
steves Offline
Desperado

Registered: 06/18/01
Posts: 356
Loc: Oregon
Pat, Gonk'

Thanks for your reply. I looked at the spec's shown on their web site for the 7270 and it was interesting to note power ratings are listed as: at 8 ohms,200W @1 kHz and at 4 ohms it is 375W @ 1kHz. Seems the Outlaws were right-at least in this case (as indicated in your original post at HTF)! Thanks again.

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#48453 - 03/20/02 01:28 AM Re: anybody know the transformer size?
eurorom Offline
Gunslinger

Registered: 03/04/02
Posts: 96
Loc: El Paso Texas
CHARLIE FTC rules cont....for ever?

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#48454 - 03/21/02 11:12 PM Re: anybody know the transformer size?
rcaudio Offline
Gunslinger

Registered: 11/19/01
Posts: 81
I think Outlaws response to this issue is accurate enough. What is the issue? Do you think the 750/755/770 will not actually deliver their rated power?
P=V^2/2R
Power is RMS, volts are peak and R is in ohms. Buy my hand the 750 delivers 51.3 volts peak into an 8 ohm load. Peak current is 6.4A. All 5 channels driven gives you 32A peak. Peak volts times peak amps give you peak power; 1644W. I believe that I read that the 750 has a 1650 VA transformer. Judging from the 4 ohm performance this is conservative.
The 750 delivers 44.7 volts peak, 11.2 Amps into 4 ohms; all channels driven for a total of 2500 W peak. If it can do this and not catch fire I think we're OK. I don't think fire has been a big issue, at least with the 750.
Hopefully the material you listen to has an average 50% duty cycle, DC just doesn't sound that interesting. If the amps are 50% efficient and considering 50% duty cycle the VA ratings make sense.
IMHO unless the amps don't deliver on their spec this is a moot issue. Wait for a test if you really doubt Outlaws ratings on the 755/770. I'm sure the 750 was tested; did it not deliver full power?

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#48455 - 03/25/02 02:19 AM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
[QUOTE]Originally posted by rcaudio:
I think Outlaws response to this issue is accurate enough. What is the issue? Do you think the 750/755/770 will not actually deliver their rated power?
P=V^2/2R
Power is RMS, volts are peak and R is in ohms.


Um.... How can you compute root mean square watts from peak volts?

Basicly I think the issue is whether the 770 can really deliver 2100 watts to 7 speakers CONTINUOUSLY while drawing 1800 watts from the outlet. This would seem to be a neat trick.

I have little doubt it can do it (and probably more) for brief moments and I'm pretty sure it can more than deliver the goods on real program material. That's not at issue.

I can't think of any MUSICAL or HT application where I would have a source that required a symetrical high level sustained signal from all channels. But this (highly artificial) scenario seems to have made its way into the specs.


Charlie
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#48456 - 03/25/02 09:35 AM Re: anybody know the transformer size?
Azistoohot Offline
Gunslinger

Registered: 02/06/02
Posts: 47
The problem isn't that the amp won't sound good or won't be satisfactory, as 99.9999% of people will never experience a lack of power or clipping with this amp. Even 100 watts per channel into 4 ohms for 7 speakers is way more wattage than most people need. The problem is that the specifications say that the amp can produce a continuous 300 watts per channel for all 7 channels into 4 ohms. This simply is not possible based on an admitted limitation of 1800 watts through the transformers.

The issue is simply incorrect specifications. There should be an asterisk that says something to the effect of "* amplifier power is limited to input voltage and current. With a 120V and 15A circuit, this amp will produce X watts per channel into 4 ohms, all 7 channels driven 20-20kHz." Where X is less than 300 watts.

For me, when a company makes a statement that I know is not true, I lose some faith in the company. Is it a big deal? Not really, but it does make me wonder.

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#48457 - 03/25/02 12:30 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
Originally posted by Azistoohot:
The problem isn't that the amp won't sound good or won't be satisfactory, ....

For me, when a company makes a statement that I know is not true, I lose some faith in the company. Is it a big deal? Not really, but it does make me wonder.


Yep. I suspect that rather than a deliberate effort at deception this is a case of a simple mistake, and as you say I don't really see that it's significant from a practical viewpoint, although it does IMO need to be clairified and/or corrected.

In HTF there is a quote where what appears to be one of the Outlaw engineers kinda seems to denigrate this thread or one like it, calling the participants 'armchair engineers'. I find this a bit disturbing when all we're basicly pointing out is that perpetual motion is, in fact, still unattainable.


Charlie


[Fixed a typo]


[This message has been edited by charlie (edited March 25, 2002).]
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#48458 - 03/25/02 01:39 PM Re: anybody know the transformer size?
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
I noticed that in the manual, the maximum draw is indicated to be the same, 1800 watts, for both the 755 and 770. Interesting...

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matt@idsi.net
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#48459 - 03/25/02 03:18 PM Re: anybody know the transformer size?
morphsci Offline
Gunslinger

Registered: 02/15/02
Posts: 243
Loc: Charleston, IL, USA
Guys, this phenomena is not limited to the Outlaw amps. The Rotel RMB-1095 is rated at 5 X 330 W @ 4 Ohms. It is listed as 1600 W max. power consumption (1200 W on net but that is a misprint). It seems unlikely that Outlaw would get into trouble over this from anybody since it seems to be common practice.

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#48460 - 03/25/02 04:16 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
I tried that one once too - "But dad, everyones doing it...."

Didn't work for me.

I suspect the original poster was laboring under a misconception that somehow the VA of the amp was of concern, and we've pretty much strayed way off that line of thinking.

The 770 looks good, I just hate to see something this unimportant get all blown out of proportion. Better to fix it and move on.


Charlie
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#48461 - 03/25/02 04:25 PM Re: anybody know the transformer size?
Azistoohot Offline
Gunslinger

Registered: 02/06/02
Posts: 47
Charlie, is HTF hometheaterforum? I'll take on the Outlaw engineers! This is simple math -- you only need the equation V=IR or P=VI. You don't even need to know the efficiency of the amplifier or anything at all about the design of the amplifier.

I do know that many companies also follow this practice, but it's still not right.

I also know that power doesn't equate to sound quality -- my Creek 30watt per channel sounds better than my 100+ watt per channel Onkyo (in two channel mode), even though the Creek isn't supposed to drive 4 ohm speakers. I have no doubt that this amp sounds pretty good, especially for the price range. I just would like some realistic specs, because people who don't know anything are going to say "the outlaw amp is better because it's rate to produce 300 watts into 7 channels," when the amp can't do this (continuous power, driving 4 ohms, that is). We have to wait until someone actually tests it to see what the real specs are. Then, we have to wait until someone tests a competitor.

As long as this amp isn't like some of the receivers that are rated at 100wpc into 5 channels but that only test to 45wpc into 5 channels @ 8ohms.

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#48462 - 03/25/02 04:54 PM Re: anybody know the transformer size?
Matthew Hill Offline
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Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
As someone else has previously pointed out, this rating is probably not with a duty cycle of 100%. I'd have to guess that amplifier power outputs probably have some "standard" duty cycle that they're rated at.

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matt@idsi.net
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#48463 - 03/25/02 05:28 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
The FTC regulates this. Here is the newest set of amendments I could find. The federal government has this rule for a good reason.

http://www.ftc.gov/os/2000/12/amplifierrulefrn.pdf

Charlie
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#48464 - 03/25/02 06:34 PM Re: anybody know the transformer size?
steves Offline
Desperado

Registered: 06/18/01
Posts: 356
Loc: Oregon
Quote:
Azistoohot said:

With a 120V and 15A circuit, this amp will produce X watts per channel into 4 ohms, all 7 channels driven 20-20kHz." Where X is less than 300 watts.


Outlaw recommends, at a minimum, a 20 amp circuit be provided for these new amplifiers.

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#48465 - 03/25/02 06:52 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
If the unit connects with a plug that is of a design for 15 amp service this would seem to be an issue. A 20 amp plug won't fit into a 15 amp recepticle.


Charlie
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#48466 - 03/25/02 07:30 PM Re: anybody know the transformer size?
steves Offline
Desperado

Registered: 06/18/01
Posts: 356
Loc: Oregon
Quote:
A 20 amp plug won't fit into a 15 amp recepticle.


I'm sorry, but this I don't understand.

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#48467 - 03/25/02 07:36 PM Re: anybody know the transformer size?
JasonA Offline
Gunslinger

Registered: 01/17/02
Posts: 84
Loc: Marion, Iowa
Quote:
Originally posted by charlie:
The FTC regulates this. Here is the newest set of amendments I could find. The federal government has this rule for a good reason.

http://www.ftc.gov/os/2000/12/amplifierrulefrn.pdf

Charlie


I emailed Dennis Murphy, who's name appears in this document. Here is his reply:

Quote:

I do enforce the FTC rule, and I also am
the happy owner of an Outlaw 1050. It would not seem to me that the new Outlaw
could produce 7 channels of 300-watt power at 4 ohms continuously in the home.
(That's a personal opinion, not a legal ruling, and it's subject to rebuttal.)
But you should know that the Rule does not really apply unambiguously to
multichannel amplifiers of this type. The Rule requires that all "associated"
channels be driven to full power simultaneously during the FTC rating test.
That part was written in 1974 when the only real "multichannel" amps were
stereo. For those, "associated" channels clearly meant left and right. But
which of the 7 Outlaw channels are "associated"? The Rule doesn't give a clear
answer, and we are not insisting at present that home theater amps be rated with
all channels driven simultaneously. The industry just announced a voluntary
standard, which we are studying. So--it's possible that Outlaw's 4-ohm spec
is a little misleading, but at the same time they would not be violating the
rule just because the unit could not put out all that power simultaneously.


Just thought some of you might be interested. I believe a standard for rating multi-channel amps would work something like running the front 2 or 3 channels at full power, and the remaining channels at 1/8th or 1/3rd power. This presents more of a real world scenario than a "continuous, all channels driven" spec.

Jason

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#48468 - 03/25/02 08:25 PM Re: anybody know the transformer size?
morphsci Offline
Gunslinger

Registered: 02/15/02
Posts: 243
Loc: Charleston, IL, USA
Quote:
I tried that one once too - "But dad, everyones doing it...."


Sorry Charlie. I think you misunderstood. My statement was that the rule, as is now clear, is probably a little more complex and outdated. My point, was that it is very unlikely that numerous companies would use this terminology and not get called on it if it really was illegal. Now deceptive .... thats a 'hole 'nuther kettle of fish. (another tuna reference).

[This message has been edited by morphsci (edited March 25, 2002).]

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#48469 - 03/25/02 10:50 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
I'm curious if Jason made it clear to Mr. Murphy that the 770 spec clearly states 'all channels driven'. As for the rest - yes, the FTC discussion was pretty clear that they were still getting up to speed on the new multi-channel stuff.

The doc I cited seems pretty clear that 'associated channels' would be any that are driven within the same frequency range, but I'm sure the FTC is probably still pondering.


Charlie
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Charlie

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#48470 - 03/25/02 11:02 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
Originally posted by steves:

I'm sorry, but this I don't understand.


It's hard to explain without pictures, but they are different shapes. If you go here:

http://www.hubbell-wiring.com/new/hub9811.pdf

You can see on page 2 a 15 amp receptacle on the left, a 20 amp on the right. The 20 amp is designed to accept either a 15 or 20 amp plug.

I could be wrong, but I suspect a device with a 15 amp plug shouldn't draw more than 15 amps over the long haul, discounting surges and so forth.


Charlie
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#48471 - 03/25/02 11:28 PM Re: anybody know the transformer size?
rcaudio Offline
Gunslinger

Registered: 11/19/01
Posts: 81
Quote:
Originally posted by charlie:
[QUOTE]Originally posted by rcaudio:
[b]I think Outlaws response to this issue is accurate enough. What is the issue? Do you think the 750/755/770 will not actually deliver their rated power?
P=V^2/2R
Power is RMS, volts are peak and R is in ohms.


Um.... How can you compute root mean square watts from peak volts?

Basicly I think the issue is whether the 770 can really deliver 2100 watts to 7 speakers CONTINUOUSLY while drawing 1800 watts from the outlet. This would seem to be a neat trick.

I can't think of any MUSICAL or HT application where I would have a source that required a symetrical high level sustained signal from all channels. But this (highly artificial) scenario seems to have made its way into the specs.


Charlie[/B]


How else would you calculate RMS power. It's simple Ohm's law.
Learn to design your own amps. You can start here;
http://www.diyaudio.com/

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#48472 - 03/26/02 12:55 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
I suppose it depends on what you mean by 'peak'.

Take music out of it for a moment and lets talk power distribution. In a DC circuit watts is simply voltage multiplied by amperage. It gets more complex in AC due to phase angles and so forth which can make VA not equal watts, but in a resistive circuit (like a test load) RMS is computed the same as DC IIRC. So RMS volts times RMS amps would result in RMS watts, or AC watts that heat the same as DC watts would, not the AC watts as measured instantaniously at the peak of the AC waveform.

If you are talking about 'peak' as in musical peak then that's a whole different thing and isn't really germane to my point.

In any case the line input and speaker output are BOTH AC and both obey the same laws. You can't put in 1800 watts and get out 2100, that is the crux of the issue.


Charlie
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Charlie

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#48473 - 03/26/02 02:32 PM Re: anybody know the transformer size?
rcaudio Offline
Gunslinger

Registered: 11/19/01
Posts: 81
Peak means peak. Any EE would know what peak means. RMS only applies to sinusoidal waveforms. RMS Voltage is computed by Vpeak
times square root of 2, RMS current is calculated by Amps(I peak) times the square root of 2. The rest is simple Ohm's law. Check your EE textbooks.
No one can use program material to spec a power amp. Sinusoidal waveforms are always used therefor any reference to program
material is completely irrelevant in this discussion.
Peak power may very well be applicable since transformers are rated with Volt Amps. Also, my calculation seemed to match what Outlaw
indicated in their post. As a telecom engineer I've never speced parts for a commercial audio amp and don't know what standard practices are used in the process.
As a DIY audio designer I've always went for overkill since I'm not designing to a price point. In my 450 Watt sub amp I used peak power and a 80% derating, the transformer is a 550 VA unit. This is a bit small but I've never had a problem (you can't be that picky with surplus parts). What do you use in your designs Charlie, I'd really like to know.

I did notice that Pass Labs 125W 5 channel amp has a maximum power spec of 600 W. The Pass amp is much more expensive and
conservative design than an Outlaw amp (or any of the other cheap amps, Rotel, ATI, B&K ect) and appears to be rated in the same manner as far as power dissipation is concerned.

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#48474 - 03/26/02 02:41 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
RC,

That's all really cool. In interests of keeping it simple, do you agree or disagree that any device that draws 1 watt max average over time cannot output 2 watts average over time?

This is, in a nutshell, my point. Anything beyond that is needless complication.

The 770 is spec'd to draw AT MOST 1800 watts, yet is also spec'd to put out 2100 watts in some cases.

This might be of interest:
http://www1.tpgi.com.au/users/tps-seti/baloney.html


Charlie

PS - RMS can apply to any waveform - sine is easier to compute and most commonly used. To compute RMS (1) square the waveform function (2) average over time (3) take the square root.

[This message has been edited by charlie (edited March 26, 2002).]
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#48475 - 03/26/02 04:48 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Here's an interesting thought experiment:

(1) Build a 2100 watt monoblock amp that draws 1800 watts.
(2) Drive it to max output with a 60hz sine wave. A voltage reduced version of the power line is ideal.
(3) Use a transformer to bring the output RMS voltage to 120 volts.
(4) Sell the excess 300 watts to the power company, repeat 1-4, plugging each new amp into the output of the last one.
(5) Retire, move to Tahiti.


Charlie
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Charlie

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#48476 - 03/26/02 10:13 PM Re: anybody know the transformer size?
rcaudio Offline
Gunslinger

Registered: 11/19/01
Posts: 81
QUOTE]Originally posted by Charlie:
RC,

The 770 is spec'd to draw AT MOST 1800 watts, yet is also spec'd to put out 2100 watts in some cases.
PS - ROMS can apply to any waveform - sine is easier to compute and most commonly used. To compute ROMS (1) square the waveform function (2) average over time (3) take the square root.

[This message has been edited by Charlie (edited March 26, 2002).]
[/QUOTE]

Yes, that is the true definition of RMS. This proves you knew exactly what I meant by peak. But I like being corrected in this manner.
I can't disagree with the figures we have here but I don't think they apply directly. This is what bugs me;
Pass Labs designs and manufacture ultra high end amps. I just don't see any reason for them to fudge on the specs, they doesn't advertise so there is no point. Since the amp is rated at 125W per channel all channels driven and yet dissipates only 600 watts something isn't right, just as you point out about the model 770. I think, and I'm speculating, that the 600 watts refers to the power the amp itself dissipates and not the total power which would be at least 1200 watts for the Pass amp.
In any case the Outlaw amp looks like a very good product. The heat sinks are big and judging from the weight the transformers are plenty big enough. It's not going to have the head room of an amp like the Pass Labs unit, but the Outlaw costs much less.
What got me to post is when someone on that other forum wrote that they weren't going to buy the 950/770 if Outlaw didn't come clean and release proprietary information. I hope that individual passes on the 950 so someone else can move up on the list.

BTW my dog is a perpetual motion machine and I don't expect I'll make a cent from him.

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#48477 - 03/27/02 01:57 AM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
RC,

I think we're pretty much on the same page. I have no doubt that the 770 is a fine amp and in real world use will far surpass what the specs imply as far as performance. If someone passes on this device because of an engineering choice they are most likely not even qualified to critique (as I am not) then I say consider the source. There are some customers it's better not to have.

On the other hand, even though it's quite heavy I doubt the 770 is carrying a load of fissionable materials for a supplemental power source. I just don't believe the 770 is as productive as your dog!


Charlie
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#48478 - 03/27/02 10:14 AM Re: anybody know the transformer size?
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
Charlie: you never know. We've been surprised by the Outlaws before!

Personally I think it's got a hamster in it.

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

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#48479 - 03/28/02 07:22 AM Re: anybody know the transformer size?
gene avallon Offline
Gunslinger

Registered: 02/02/02
Posts: 18
Loc: attleboro ma.
next time your in home deopt look at a 20 amp male plug and compare it to the one on your toaster.
gene

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#48480 - 04/28/02 11:55 AM Re: anybody know the transformer size?
Kabillyhop Offline
Deputy Gunslinger

Registered: 04/28/02
Posts: 5
Loc: Markham, ON, Canada
Lets say you are listening to music at an average comfortable listening level of lets say 5 watts, and a drum is kicked producing a producing a sound that is "twice" as loud as the average. This requires your amplifier to provide 10 times more power or 50 watts to reproduce the sound without clipping. A sound twice as loud as the drum would require 500 watts. Twice the "loudness" is about 10 dB louder, requiring about 10 times the power.

My point is that no one will ever want to listen to music (or HT) on their 770 at a continuous power level of 300W/channel. Not only would it be deafening, but the amp would not be able to recreate the dynamic range (the difference in volume between loud and quiet passages). No sound could be louder than the average.

The reason we want amps with lots of power, and the reason they sound so good, is that they have so much dynamic range. And it is also important that they have this power available to all channels simultaneously with close to zero harmonic distortion. This means it can handle virtually all material you can throw at it and still sound good up to its rated power.

As an earlier poster indicated and was incorrectly shot down, the amplifier uses stored power to deliver to the peak requirements. It is not important that an amp can deliver to its maximum output continuously, however, as some on this thread seem to be expecting, i.e. to require more than 1800W AC power. To suggest that Outlaw is being less than honest with their specs if it can't do this is silly. Cut them some slack!

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#48481 - 04/30/02 10:27 AM Re: anybody know the transformer size?
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
Anybody seen the manual for the CL-2500 MCA amplifier? It claims 500 watts per each of five channels, for a total of 2500 watts output. But, page 15 of the manual indicates it has a 15-amp plug.

http://www.calaudio.com/mcamanual.pdf

Looking at page 17 of the manual, though, its internal fuse is listed at 20 amps. Additionally, it's power consumption is listed at 3.5 amps idle, 32 amps all channels 50% active, 46 amps all channels active at 100%. Apparently the internal fuse is designed NOT to blow until 100% power has been maintained for 15+ seconds.

Interesting, is it not?

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

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#48482 - 04/30/02 03:26 PM Re: anybody know the transformer size?
Azistoohot Offline
Gunslinger

Registered: 02/06/02
Posts: 47
I think 46 amps would burn up the wiring in the house where I am. The electrical system isn't the best in houses that are 40 years old.

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#48483 - 04/30/02 03:34 PM Re: anybody know the transformer size?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
Azistoohot -- I can relate to that! When I boughy my house (built in '54), it still had the original 60A service. Can we say "undersized"? I actually had to have the seller install a main disconnect.

------------------
gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review
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#48484 - 05/03/02 05:51 PM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
Originally posted by Kabillyhop:
Lets say you are listening to music ....

My point is that no one will ever want to listen to music (or HT) on their 770 at a continuous power level of 300W/channel....

It is not important that an amp can deliver to its maximum output continuously, however, as some on this thread seem to be expecting, i.e. to require more than 1800W AC power. To suggest that Outlaw is being less than honest with their specs if it can't do this is silly. Cut them some slack!


Well, I have no problem except the Outlaw spec sheet clearly says 300 watts x 7 channels, all driven continously, so what does that mean in your book?


Charlie


[This message has been edited by charlie (edited May 03, 2002).]
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#48485 - 10/22/02 01:05 PM Re: anybody know the transformer size?
truthseeker Offline
Gunslinger

Registered: 06/12/01
Posts: 37
Loc: Il
I received an email from the Outlaws stating that the torroids in the 770 are "slightly larger" than in the 755, but when trying to post it here, it was erased...twice.

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#48486 - 10/22/02 02:11 PM Re: anybody know the transformer size?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
Are you sure you refreshed your browser? I see two posts from you about toroid size in your previous thread , plus this post.

------------------
gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review
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gonk
HT Basics | HDMI FAQ | Pics | Remote Files | Art Show
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#48487 - 10/25/02 12:52 AM Re: anybody know the transformer size?
truthseeker Offline
Gunslinger

Registered: 06/12/01
Posts: 37
Loc: Il
Gonk,

You are correct! I must now apologize for my premature paranoia. Now I gotta figure out how to delete the above post.

R.

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#48488 - 10/25/02 01:02 AM Re: anybody know the transformer size?
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Wow - I never expected this dinosaur to come back from the dead. Kind of interesting discussion though, on the basis of advertised specs vs. actual physical limitations in light of how the 950 seems to also miss it's specs...
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Charlie

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#48489 - 10/25/02 04:13 PM Re: anybody know the transformer size?
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
Hmm, yeah, nobody discussed in the context of the 950's hiss problems before... interesting...

Perhaps it's simply the word "continuous" that we're hung up on. I wonder if the FCC has some kind of standard definition of "continuous" that indicates 50% on 50% off, 70% on 30% off, etc.

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