Looking for a 2 channel amp @ 300W RMS

Discussion in 'AV Receivers' started by Tuan Le, Oct 11, 2003.

  1. Tuan Le

    Tuan Le Agent

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    Hi guys,

    I am looking for a 2-channel amp @ 300-500W RMS. Is there any decent one out there at around $1000? This amp will be used to power my Polk Audio RTI150 front main speakers, rated at 500W/Channel.

    Currently these two RTI150's are being powered by the Onkyo TX-SR800 receiver. It is very annoying, the receiver keep on getting shut off because of overload. I hope it will do a better job powering the rear surrounds and the center channel after I move the RTI150 off to a separate amp.

    Any help you can give me will be greatly appreciated.

    Thanks
    -Tuan
     
  2. Tuan Le

    Tuan Le Agent

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    What do you guys think of the Adcom GFA-5802?

    Thanks
     
  3. Jason Brent

    Jason Brent Second Unit

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    You'll probably have to go used to get close to that price. I've been looking at the Rotel 1090 (380 x 2) and there were a few at audiogon.com for around $1200, I think.
     
  4. James W. Johnson

    James W. Johnson Screenwriter

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  5. Tom Grooms

    Tom Grooms Second Unit

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    Agreed, At 91db you wont want more than 200 Watts in your price range. Look for a used McCormack DNA 1 or the Belles 150A Hotrod amp. Both of these (IMO) maximize Bang for the buck in the under $1K category
     
  6. Heath_E

    Heath_E Stunt Coordinator

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    Doesn't anybody else find it strange that a good quality 100w/channel receiver pushing 91db, 8 ohm speakers keeps shutting down? Something is wrong there.

    BTW, I agree that 200w/channel would be more than enough, considering the 100w/channel you already have really should do it with those speakers.
     
  7. Aaron Gilbert

    Aaron Gilbert Second Unit

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    Heath,

    Yes, I for one find it strange that 100w is not enough for 91dB speakers. There are two possibilities -

    1) The room is simply gargantuan and the listeners sit 20+ feet away from the speakers, or

    2) The listeners don't mind losing their hearing.

    100w will give you over 110dB, a sound pressure level at which you should not listen for more than 15-30 minutes a day.

    Are these Polks really low impedance? Even if they are though, I was under the impression that Onkyo was a brand which doesn't have problem with low impedance speakers.

    Now, if one just wants more headroom, fair enough. But it seems odd to me that a receiver would be shutting down as a result of a musical peak, as opposed to an abnormally high continuous power output.

    I know this doesn't answer your amp recommendation, but in my experience a receiver should not be shutting down at any sane level unless it's defective or simply cannot handle the speakers in use.



    Aaron Gilbert
     
  8. Heath_E

    Heath_E Stunt Coordinator

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    Nominal impedance on his speakers is 8 ohms. I actually used to have an Onkyo 787, Polk setup with absolutely no problems, even at insane levels.

    Tuan, that thing needs to be looked at.

    BTW, by no means am I trying to talk you out of a seperate amp. But, I think your receiver has a problem that should be attended to regardless.
     
  9. MichaelDDD

    MichaelDDD Supporting Actor

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    I find the "shutdown" problem intriguing as well.

    1. Possibly the connections are shorted at one/both ends?

    2. Possibly he's using very small gauge speaker wire?

    3. Possibly a staple/nail in carpet strip is shorting out the wire somewhere?

    #3 happened to me. I had wire running under carpet and along the baseboards. I stepped on the carpet to tack it back down and the wire had fallen on top of the carpet strip. Nail punctured thru both conductors with predictable results.
     
  10. Andy_A

    Andy_A Second Unit

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    yes, you indeed have a problem with your receiver if it shuts off all the time. A seperate amp is nice, but you should get your receiver fixed first. You can get a great stereo amp for $1000. Take a look at this one: http://www.psaudio.com/products/hca_overview.asp You can find it used for around $1100. Good luck
     
  11. JerryCulp

    JerryCulp Stunt Coordinator

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    It does seem odd to me. I have the Ht-510 that comes in the Onkyo 760 HTIB and it drives my RTi-150's to 90db pretty easily. Even with only 16 guage wire. OTOH, I havent run them for a long time that way.

    Could heat be a problem? Not enough breathing room for the amp?

    I've had that on our Onkyo ProLogic reciever that has other components stacked on it. After 45 minutes at loud levels it starts shutting down.
     
  12. mark rush

    mark rush Stunt Coordinator

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    you will need to at least double your power to notice an increase in sound, high watt amps cost big time money, if you have to have 400 watts per channel look at Cinepro, are Classe, Rotel is another a sunfire series 2 will perform well, but something for around a 1000 bucks your choice is limited, you would have good results with a B&K reference 2220 it puts out a strong 220watts per channel, and you can run it down in a 4 ohm load for 350 a channel, good luck
     
  13. Joe Tilley

    Joe Tilley Supporting Actor

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    I don't know if you would wont to or not but why not run two PE plate amps for just the woofer section on them. You would end up with 250watts to just the bottom three woofers & it would be pretty cheep to boot. I took my PE amp into work the other day & tryed it set up like this with one of the displays we had & it sounded pretty sweet. The only down side is the fact that the amp has a crossover on it but for what I tryed out I just turned it all the way up. At least this way all your Onkyo has to power is the single woffer & tweeter.
    BTW those towers can really put out some pretty decent bass hooked up like that. We run the set we have on a H/K 525 & they sound really good with just that but there is a pretty good difference in performance with the PE amp on them.
    Just a thought...
     
  14. Tuan Le

    Tuan Le Agent

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    Guys,

    First I would like to thank all of you that have responded. I appreciate it very much. [​IMG] To answer few questions above, I am running 14-gauge wires. They are still on top of the carpet. And I have double-checked to make sure they are not shorted anywhere. The connections on the speakers and receiver are very tight.

    I am pretty confident that my Onkyo receiver isn't defective. It is playing fine with music. I only run into the "shut-down" issues during the home-theater mode. My guess would be that the receiver is not rated at 100W per channel, with all 5 (or 7) channels being driven at the same time.

    Additionally...according to few guys over at the Polk Audio forums, it sounds like the RTI150's is very power hungry and a separate will be needed to really make good use of them. After reading all the responses, I think I am going to go with the bi-amp route.

    The only decision left is whether I should get a 2-channel amps for the RTI150's only, or might as well get the 3-channel so that I can bi-amp the center channel also. The center channel is going to be Polk Audio CSI40 (rated at 250W).

    Has anyone here used the Outlaw 200 M-Block amps before? I would greatly appreciate your feedback on them. I will look into getting 2 of them if I decide to bi-amp the two RTI150's only. However, if I decide to bi-amp the center channel as well then I will look into the Adcom GFA-5503 3-channel amp (200W X 3 at 8-ohm). Your feedback on this Adcom amp would be greatly appreicated also. [​IMG]

    Cheers
    -Tuan
     
  15. Mark Russ

    Mark Russ Second Unit

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    Guys, there are several people with those speakers who have had AVRs in the 100 watt per channel range with shutdown issues. When set to large, those speakers have a total of 6 6 1/2 inch passive woofer drivers that eat a lot of power. I suspect they dip down well below 8 ohms for at least brief periods, if not sustained. For the 150s to truly shine to all of their capabilities, I would say they need at least 300 watts per channel, although a 200 watt amp will probably do the job. If you have 300 or more watts with those puppies, you don't need a sub with them!
     
  16. JerryCulp

    JerryCulp Stunt Coordinator

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    Tuan, are you using them as "large"? How long does it take to shut down the amp?

    I've run mine at reference or very near for an entire movie, but that was with the sub x'd over at 80hz.
    You have what should be a large upgrade in reciever over what I have.

    I think I'd be talking with Onkyo about this if it was me.
     
  17. Yogi

    Yogi Screenwriter

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    A Parasound 3500 (350x2) or the Rotel 1090(380x2) would be on my top list. Both can be had for a little over 1K on the used market. You will never look back after you have them in your system.
     
  18. Andy_A

    Andy_A Second Unit

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    the outlaw monoblocks look to be excellent amps. I would get in on the promotion they're running right now, which is 5 blocks for the price of 4 ($1124). This would be an awesome setup because you could run 2 monoblocks per speaker and then one for the center channel. You would also have some room to experiment, like running 2 amps for the fronts and 2 for the back speakers, essentially running a five channel amp. The Polks would sound great being run by two monoblocks each, though!
     
  19. Mark Russ

    Mark Russ Second Unit

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    Jerry, that's a good point. They shouldn't cause any shutdown issues when high passed like that. However, in that case, what's the point of even having the 150s in the first place? You are taking away their strongest feature, and that's a criminal waste of woofage.
    There are several good amp options. I'm running mine passively bi-amped with an Adcom 5500 (200 full bandwidth rated watts per channel) powering the woofers, and an
    adcom 5400 (125 full bandwidth rated watts per) driving the tweets/mids. The gain on these two amps is the exact same, so there's no issues to bi-amp them together.
     
  20. JerryCulp

    JerryCulp Stunt Coordinator

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    What made me wonder about the x-over is he said it was in "home theater mode", and typically you use a sub for HT. The 150's have good bass, but not wall shaking bass like a good sub can do.

    I wonder if the shutdown is because of the LFE track pushing the 150's down below what they can really do.
    Do speakers start drawing more current/watts when they are asked to play lower than they really can?

    I got the 150's for music, in 2-channel, I bypass the sub, as you would expect (unless I get lazy). I typically dont drive them hard like I do with movies and have not had a shutdown or any clipping.
     

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