VA rating for the Outlaw power supplies???

Discussion in 'Archived Threads 2001-2004' started by Randy G, Mar 15, 2002.

  1. Randy G

    Randy G Second Unit

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    I've been searching everywhere for the power ratings of the dual torroidal amps in the 770, but even Outlaw's website doesn't mention anything other than to say the 770 draws 1800 amps max. Does anybody know, or should I make an assumption that Outlaw isn't publishing that info for a reason?

    Thanks
     
  2. Randy G

    Randy G Second Unit

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    *bump*
     
  3. Randy G

    Randy G Second Unit

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    *double bump*
     
  4. Kevin T

    Kevin T Screenwriter

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    why don't you call outlaw and ask them directly?

    kevin t
     
  5. Randy G

    Randy G Second Unit

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    I called 2 days ago and sent an email...didn't hear from them, so I just called again. Turns out that they WILL NOT DIVULGE the power rating of the dual torroids in their new 7 channel(770) amp. Many other amp companies have no qualms at all about publishing this rather innocuous info, so it makes me somewhat suspicious as to whether there really IS enough juice in that amp to push all seven channels to their full rated output simultaneously. I've now decided that I won't be purchasing this amp, but your trust issues may differ.
     
  6. Legairre

    Legairre Supporting Actor

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    Randy,

    Do you mean their response was that they don't give out that info or that they never responded? I think they should at least let customers know. This a very important spec for amps. The size of the power supply has a everything to do with whether or not an amp can make it's rated power.
     
  7. Randy G

    Randy G Second Unit

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    Legairre,

    I completely agree with you. Actually, if you check out their Outlaw Asylum, a number of folks have discussed this very issue, and the concensus seems to be that the math doesn't work.

    I called Outlaw 2 days ago and sent them an email as well. I tried again today, and got thru to a tech guy. He said that Outlaw neither publishes nor will disclose that information....too bad.
     
  8. Legairre

    Legairre Supporting Actor

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    Guys,

    I know another company that won't disclose their figures, but they make speakers. Out of decency I won't say the name, but you know who I'm talking about. We all know that the amount of power an amp can deliver is based on several factors, but if the power supplies aren't large enough. Then it will never make it's rated power with ALL channels driven no matter what the other factors are. Several mid-fi amp makers like Sherbourn, Rotel, Parasound, ATI and a few others do well in this area(I know I forgot a few). Unless you have something to hide there's no excuse for refusing to give the size of the power supplies. All the companies I mentioned are proud to give this spec. I don't know of any amp companies that don't give this spec.
     
  9. Russell _T

    Russell _T Supporting Actor

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    This would be a big concern to me. I seem to remember that they admitted that the 1050 did not reach rated power with all channels driven and gave as an excuse that all channels were rarely if ever drawing full power. I would be very disappointed if this were true for the 770. I have waited a year for the 950/770, and would be willing to reconsider if they won't publish these simple specs. What exactly do the Feds require them to publish?

    Russ
     
  10. Russell _T

    Russell _T Supporting Actor

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    Anthony,

    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.

    Russ
     
  11. Sankar

    Sankar Second Unit

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    I had looked up the ratings for the 750 and AT1505 less than a year ago and if memory serves me right, the 750 had 1.6KVA, and the AT1505 had 2KVA. Unfortunately, I'm unable to recall where I had read this information. (I also recall that the Anthem MCA-5 had two 550VAC transformers for a total of 1.1KVA).

    No idea about the 770, though ...
     
  12. Patrick R. Sklenar

    Patrick R. Sklenar Second Unit

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    Okay, I'm a dummy. I honestly don't think I understand what you folks are complaining about. Just how does a "VA rating" relate a power amplifier? Besides asking all of you, I also wrote the following to Outlaw:

     
  13. Legairre

    Legairre Supporting Actor

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    Patrick,
    An amplifier can only produce as much power as it's power supplies can ask for from the outlet. Let's take the Rotel 1095, an amp I'm very familiar with. The 1095 is 200x5 wpc and had been written about in several articles to well exceed 200x5 with all channels driven. Some have reported that it's closer to 240x5wpc with all channels driven. I know your saying "yeah right" so here's a few articles.
    http://www.hometheaterhifi.com/volum...er-1-2000.html
    http://www.rotel.com/pdfs/reviews/rmb1095_audiomag.pdf
    http://www.rotel.com/pdfs/reviews/rm...atre-austr.pdf
    The 1095 could never make 200x5 with just one 1.2 va power supply. The power supply just wouldn't be capable of asking for the 1600 watts the 1095 would require from an outlet to produce 200x5 with all channels driven, so Rotel has put two 1.2va power supplies in the 1095. Will I ever need that much power. I doubt it, but I PAID for it so I should get what I paid for. If I didn't want an amp that could produce the numbers that were advertised I would have bought something else.
    Other amps that either make or EXCEED their rated figure with all channels driven are the Sherbourn 5/1500A, Parasound 2205AT and the ATI 2505. These are just a few amps that do what they advertise.
    The amount of power an amplifier can produce with all channels driven is limited to two main factors. The amount of power it can ask for from an outlet(the size of the power supplies determines this) and the amount of power the outlet can provide. You can really kill this last one by putting a cheap surge protector between the amp and the outlet. A cheap surge protector will limit the amout of
    power the outlet can provide.
    This is why the VA rating means so much. If the power supplies aren't large enough. There's no way the amp will make it's rated power. Sure the outlet could still limit you(this is something you can't control), but why not control the part that you can and get what you paid for by buying an amp that has power supplies that can ask for the power it's rated to deliver.
    Outlaw response to Patrick:
     
  14. RAF

    RAF Lead Actor

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    I must be missing something here. I've been following this discussion and I understand how va rating of a power supply is related to its performance. But if the specifications of the 755 are 200 Watt per channel-all channels driven at .05% from 20 - 20 kHz, which anyone with bench equipment could verify, then what's the problem? If a product, any product, delivers on its specifications then what's the issue?

    I'm interested in clean power for my needs and what I'm hearing from my 755 sounds damn good to me. I also realize that I probably will never ever approach all 5 channels fully driven so there is plenty of headroom to me (even using 4 ohm speakers).

    These comments are not being made to be a smartass or anything like that. I honestly don't see an issue here. If an amplifier's specifications only listed power supply VA ratings and not Watts/channel then I might understand comments such as, "There's no way a amplifier with a VA rating of XXX could produce XXXX Watts per channel-all channels driven at XXX THD for 20-20 kHz." However, the specifications of the 755 and the 770 clearly state their Watts/channel performance parameters in terms that are meaningful and helpful to me. If they deliver. Fine. If not, then I move on to the next candidate. Unlike the current pre/pro situation the amplifier market has many, many more options for the potential (no pun intended) customer to consider. Not every amp will please everybody.

    I repeat, what am I overlooking here?

    Thank you.
     
  15. Legairre

    Legairre Supporting Actor

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    Patrick,
    I forgot to mention something. If you look the following 200 wpc amps and the size of their power supplies you can see that the 770 has a small power supply, if you go by Outlaws calculations. The real size of the 770's power supplies could be more or less, but for now all we have to go on are Outlaw's calculations.
    Parasound 2205AT(220x5 wpc) total power supply, 2.0 kva. Kva per channel = 400 kva.
    Sherbourn 5/1500A(200x5 wpc) total power supply, 2.0 kva. Kva per channel = 400 kva.
    Rotel 1095(200x5 wpc) total power supply, 2.0 kva. Kva per channel = 480 kva.
    Outlaw 770(200x7 wpc) total calculated by Outlaw power supply, 1.85 kva. Kva per channel = 264 kva.
    Just look at the kva per channel. All the other amps have at least 400 kva available to each channel, but the 770 only has 264 kva available per channel. Far less than the other amps.
    In actuality ONLY the Sherbourn has a true 400kva per channel available, because it's a monoblock design with 5 independent 400 kva power supplies. The others all share 2 power supplies. There are advatages and diadvantages to such a design, but thats another discussion.
     
  16. Legairre

    Legairre Supporting Actor

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    RAF,

    I don't think your missing anything at all. We're all just discussing whether or not a product can actually make it's rated power. I agree that the sound is what counts, but the amount of power an amp can produce can effect the sound depending on the speakers your driving. We all look at specs in amps, pre/pros and other equipment. If I'm buying an amp to drive some Paradigm Studio 100(which many say need a min of 200wpc to sound really good) then I'd only buy an amp that could truely produce 200wpc for my fronts.

    I agree if a product doesn't fit you needs move on. We're not hammering Outlaw. We're just having a discussion. The title of the thread was "VA rating for the Outlaw power supplies???", so that's what we're discussing. No offense to anyone is intended.
     
  17. JimN

    JimN Stunt Coordinator

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    Not to throw a monkey wrench in here but the Rotel site lists a power consumption of 1200 Watts for the 1095 but the Outlaw site lists a power consumption of 1800 Watts for the 755. How does this relate to power output, efficiency and transformer VA? Also I believe you need to check your units above, how can a total of 2.0 kVA for 5 channels result in 400 kVA per channel?
     
  18. Legairre

    Legairre Supporting Actor

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    Jim,
    Manufacturers list their kva ratings in tenths and 1000s, This is a direct comment from Rotel. Hense the 2.0 kva. 2000 kva amps or 400kva x 5 = 2.0 or 2000.
    I've written Rotel in the past as several other people on HTF have and Rotel says the the 1095 consumes closer to 1600 watts. I wrote them because I noticed a discrepency in their figures. On their site they say 1200, but in the manual it says 800. So I wrote them and they said that actual figure is closer to 1600.
    Here's a copy of their response. If you'd like a copy of the entire email conversation just let me know I'll post it here.
     
  19. Randy G

    Randy G Second Unit

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    I'm sure Legairre meant to say 400 VA per channel instead of 400 kVA per channel.
     
  20. Patrick R. Sklenar

    Patrick R. Sklenar Second Unit

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    Legairre,
    Okay, so according to your list the Outlaw has fewer "KVa per channel" than the others. I recall from my college physics classes that:
    P=E*I is Watts (power) = Volts times Amps (current)
    E=I*R is Volts = Amps times Ohms (resistance)
    the latter being one way to write what is known as Ohms Law.
    So just what are KVa's? One Thousand Volt-Amps? So ... you calculated 264KVa's, but I think you mean "264Va" (i.e.; no "K" or "1000"). So if you're saying that's V*A, then that means that P = 264 VA or 264 watts which is 32% more than the 200 watts the unit is rated for. Unless I'm really missing the boat, it would seem to me that you just proved that the Outlaw amps are a third more powerful than they are actually rated?
    Jim,
    2.0KVa divided by 5 would equal 400 "Va" which I'm suspeting really should be "VA".
     

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