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Discussion Starter · #1 ·
Good Morning fellow AVSers

I recently took delivery on an on sale B Stock Outlaw 7900 Amp for $2499. They say it is rated at 300 W per channel x 7. I now don't think my speakers will support this beast. They are all NHT and their specs follow.


Mains are VT2's and the impedence says 6 ohm nominal. They say they require min 50w and maximum 250w

Center is an Audio Center 2, also 6 ohms. The min is 30w, max is rated as 200w

Side surrounds are Super One's and are 8 ohms nominal. They are rated min 25w max 150 watts

Rear surrounds are VS-2's also nominal 8 ohms and a min of 20w and a max or 150 watts.


This will be my seven channels for the amp. I also have a set of NHT Super Zero's as front presence speakers in place but don't know if i will be able to use them, unless somehow I can hook them up to the Yamaha Z-11 Receiver I plan to use as my pre-amp.


I know I should have checked out the speaker specs before ordering the amp, but I didn't and we're past that now. I'm looking for a little advice from many of you on this site that have extensive experience in these matters. Any and all will be greatly appreciated.


As an FYI, I have an electrician coming this Monday to verify I have the required 2 15 amp dedicated circuits to effectively power the Outlaw amp. With regard to it's use, I will primarily be using it for Blu ray disc (80% of its use) that will be played through my recently acquired Oppo 105. I also use a Direct TVbox (15%) and a 300 disc CD changer (5%) in this dedicated theater room.


Thank you again for any suggestions/possible options you can provide. I greatly appreciate it.


Best Regards,

Rob
 

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Quote:
Originally Posted by Bookedup  /t/1496587/new-outlaw-7900-amp-too-much-power-am-i-toast#post_23877455


Good Morning fellow AVSers

I recently took delivery on an on sale B Stock Outlaw 7900 Amp for $2499. They say it is rated at 300 W per channel x 7. I now don't think my speakers will support this beast. They are all NHT and their specs follow.


Mains are VT2's and the impedence says 6 ohm nominal. They say they require min 50w and maximum 250w

Center is an Audio Center 2, also 6 ohms. The min is 30w, max is rated as 200w

Side surrounds are Super One's and are 8 ohms nominal. They are rated min 25w max 150 watts

Rear surrounds are VS-2's also nominal 8 ohms and a min of 20w and a max or 150 watts.


This will be my seven channels for the amp. I also have a set of NHT Super Zero's as front presence speakers in place but don't know if i will be able to use them, unless somehow I can hook them up to the Yamaha Z-11 Receiver I plan to use as my pre-amp.


I know I should have checked out the speaker specs before ordering the amp, but I didn't and we're past that now. I'm looking for a little advice from many of you on this site that have extensive experience in these matters. Any and all will be greatly appreciated.


As an FYI, I have an electrician coming this Monday to verify I have the required 2 15 amp dedicated circuits to effectively power the Outlaw amp. With regard to it's use, I will primarily be using it for Blu ray disc (80% of its use) that will be played through my recently acquired Oppo 105. I also use a Direct TVbox (15%) and a 300 disc CD changer (5%) in this dedicated theater room.


Thank you again for any suggestions/possible options you can provide. I greatly appreciate it.

I'm not all that fearful about any of the issues that seem to be worrying you.


Speaker power ratings are not an exact science, and 200 watt speakers and 300 watt amps, or vice-versa can live long and happy lives together, if you use a little common sense.


Speakers usually sound distressed before they are being hurt. If your ears are sensitive enough to hear your speakers starting to sound sour, and if you don't exceed those limits, then you probably won't hurt them.


Secondly, just because a power amp can make 300 watts doesn't mean that it actually does so. The guy operating the volume control has a lot to do with this. Pretty much everything!


In another thread we were just discussing a survey that tried to estimate how much power people are actually sending to their speakers when they crank 'er up. More than 90 % of the respondents seem to stop cranking around 50 watts. So, you may have wasted your money, but with reasonable use you probably aren't going to hurt either the amps or the speakers.



About the two electrical power circuits - its another thing to not worry about so much. That power amp is not going to start blowing fuses unless you hook up lab grade resistive test loads and push pure sine waves through it. Basically, in home use the two power circuit thing is subtle hype. The idea is to make you think that you've got something wild and different. Not so much in typical use!


I've tripped plenty of circuit breakers with power amps - my test bench is wired for 230 volts and 30 amps so when I take out a breaker, its not your typical household 120 volt 15 amp circuit. I can tell you exactly what I'm doing when that happens:


(1) Hook the amp being tested up to my 1 KW+ rated (each) 1% 2 ohm test load resistors. This load is composed of 4 8 ohm 250 watt non-inductive 1% power resistors made by Dale.

(2) Crank the amp up to full rated power which might be a kilowatt or two.

(3) Let the whole thing simmer for a while.


If I put on my audiophile hat. hooked up speakers, and listened to music I'd probably be drawing 5% or less of what happens during some of my lab tests. Instead of 30 amps at 230 volts we're talking 3 amps at 120 volts. The dual power cord thingie on your new power amp only makes sense for lab tests with steady pure sine waves cranked all the way up.


So, this shiny new toy you got may have you a little spooked, but remember its just a machine and you have been given total dominance over it. If by nobody else, me! ;-) Just tell that amp that Arny Krueger empowered you over it, and you will both be OK. And so will your speakers! ;-)
 

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What Arny said.


How about some real life examples. I still have my older Outlaw amp rated at 200w x 7 channels. For a long time it also powered some NHT Super Ones. Never had a problem. Even at their medium efficiency rating I never had the need to crank it all the way up. So a decade later, never even blew a tweeter. Consider some ratings as useful while others fall into the CYA category.


As for the two dedicated 20 amp circuits, well wouldn't you know it, I have an opinion on that too. Under certain conditions my Outlaw amp is capable of supplying 300 watts per channel, yet the wise people at Outlaw included a 14 gauge cord, although quite short. Without knowing the circuitry inside your amp, me thinks if the 120 volts went to a slow blow fuse protected bus ahead of the PS, that a SINGLE 12 gauge cord would do nicely. But then it must be a fully dedicated 20 amp circuit, just in case your speakers are inefficient. Also I suspect because of economy of scale, two 14 gauge cords with 15 amp plugs, might even cost less than a single 12 gauge cord with a 20 amp plug. Plus receptacles capable of accepting a 20 amp plug are not common in the residential world.


As a side note, there were times when my system had both the Outlaw amp and a Sunfire True Sub on the same circuit!!! One time at a high end stereo store, prior to purchase, they let me check out the Sunfire with my Fluke MM and an amp adapter. Yikes! During transient spikes the math confirmed that thing was indeed putting out 2700 watts from it's candy bar size amp in an 11" cube with no ventilation. I'll take one please. But the key here is transients. That's why the cords aren't bigger.


One more thing, I wasn't in the residential world, but again without knowing how everything is wired internally in your amp, make sure your electrician doesn't put that second dedicated circuit on any available circuit. It needs to be on the same phase or POOF.
 

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Discussion Starter · #4 ·
Thanks to both of you gents for your informative responses. Looks like I might not have as much to worry about, as I had thought. The power cords supplied are 14 AWG w/Gnd. I believe I'll need both, as I recall reading that one would only power a few of the channels and not all 7. I don't understand how they would divide 7 channels evenly into 2 but I'll go ahead and make sure I have two. On the same wall with the amp, I also have dual 800 watt SVS subs and I'd rather not take any chances, so, I'll have the electrician do the math and see what is required. As mentioned, I'll have to be careful with the volume control, as I do like it loud! My next upgrade is going to be new main speakers up front and I'll most likely move the VT2's to rear surround duty. I haven't even started to consider what make/model I might want up front but probably something that is power hungry, maybe an electrostat. Thanks again for all your sound advice!


Rob
 

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Discussion Starter · #5 ·
Hi Patrick,

Can you please explain your last statement to me a little more? The one about the second dedicated circuit being on the same phase as the first? I really need to understand this before the electrician shows up early tomorrow morning.


Thanks again,

Rob
 

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The 7900 manual uses inexact wording dealing with the issue about different phases for the two dedicated circuits. Saying "separate dedicated circuits" doesn't address "same or opposite phases.


Opposite phases means the two hot (black) wires will have about a 240 volt potential difference inside the amp. Fine if the amp is designed for that, disaster if not.


While dedicated circuits on the same phase don't have that problem there is one caveat. You need to be sure your electrician isn't tempted to use a 12/3 nm cable for the two circuits using a common neutral. In this case it needs to be two separate 12/2 nm cables. If a 12/3 were to be used, the neutral would be severely overloaded.


In the "opposite phases" case with a 12/3 cable the common neutral would see out of phase loads with the total never exceeding the highest of the two.


i just realized I've been talking about 12 gauge, my preference, when in fact 14 gauge would work in your case, but everything else still applies.


I understand this stuff and I couldn't ascertain from Outlaw's manual if you should use same or opposite phases. It is definitely one or the other.


If this is all mumbo jumbo to you then I would have your electrician talk to the right person at Outlaw and probably not Scott.
 

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Discussion Starter · #7 ·
Many thanks Patrick. my electrician is on site and i have a call into Outlaw. I am confused, so I do need help. Maybe my electrician will understand.


Thanks again,

Rob
 

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Comment: "More than 90 % of the respondents seem to stop cranking around 50 watts. So, you may have wasted your money, but with reasonable use you probably aren't going to hurt either the amps or the speakers."


What is the inference here? That you only need a 50 watt or 75 watt per channel receiver? What about separates? The power of a separate amplifier (separation) is not needed? Is it a waste of money to buy anything over 50 watts per channel?
 

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Have your electricican read my post #6. He needs to understand that.


Oh, those Super Zeroes are the ones I would be most concerned about overpowering.
 

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Quote:
Originally Posted by Ricoflashback  /t/1496587/new-outlaw-7900-amp-too-much-power-am-i-toast#post_23882899


Comment: "More than 90 % of the respondents seem to stop cranking around 50 watts. So, you may have wasted your money, but with reasonable use you probably aren't going to hurt either the amps or the speakers."


What is the inference here? That you only need a 50 watt or 75 watt per channel receiver?

No inference required to establish that more than 90% of the respondents to a particular survey need only a 50 or 75 watt receiver. It is a fact.
Quote:
What about separates?

I've got a bunch in my store room and an AVR in the listening room.
Quote:
The power of a separate amplifier (separation) is not needed? Is it a waste of money to buy anything over 50 watts per channel?

In many cases those statements appear to be true.
 

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Quote:
Originally Posted by Patrick Collins  /t/1496587/new-outlaw-7900-amp-too-much-power-am-i-toast#post_23877778



One more thing, I wasn't in the residential world, but again without knowing how everything is wired internally in your amp, make sure your electrician doesn't put that second dedicated circuit on any available circuit. It needs to be on the same phase or POOF.

I don't think so. I'm an EE and I asked myself, "Who would design a product that would take out a household circuit with such an odd requirement?" My answer was: "I'd build it with 2 separate power transformers, each with its own rectifier block, and it wouldn't make a difference what phases the two power cords were plugged into". This could cost nothing since 2X bigger rectifier blocks can cost 2X more money due to economies of scale.


I checked the user's manual and found that there are indeed two separate power transformers. I see no such caveats in the user manual which would be the place to put it. No fools, Outlaw!
 

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The UL label on that amp probably has a wattage rating higher than 80% of a 20 amp circuit ergo the double circuit. They could have just as easily used a single 30 amp 120 volt cord, but then probably scared away even more potential customers.


Arny, are you saying you sometimes trip the 230 volt 30 amp two pole breaker? Yikes. What are you testing that wouldn't blow it's own internal fuse or breaker first?


The geek in me would love to see some of your tests.
 

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If I was designing this size of amp from scratch I would lean towards one large power supply and one 30 amp cord and circuit. In either case the home owner has to add a circuit.


With two power supplies I wonder, like the OP, if they are built at a 3 ch./4ch. ratio or if one PS is underutilized.
 

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Discussion Starter · #14 ·
The manual says in fact one side handles 3 channels and the other circuit handles 4. Just FYI. Thanks for all the help gents. I greatly appreciate it. The electrician is gone, the grass is mowed, and it's now time to wire everything back up!
 
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