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outboard amp hooked to a intergrated receiver?
#4450 07/19/02 03:29 AM
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I have an Onkyo 787 receiver and a pair of m-80's and a vp-150 and a pair of bookshelfs for the rears with a rear center.for h/t everything works fine but for two channel the m-80's push the Onkyo too hard and if I"m not carefull I can set off the auto protect.has anyone here hooked up an outboard amp to a h/t receiver,and if so did it work fine? I'd like to slowly slip into seperates but I like the Onkyo and I'd like to absorb the cost over a long period of time.besides I want to buy a pair of qs8's soon.

Re: outboard amp hooked to a intergrated receiver?
#4451 07/19/02 04:54 AM
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Something's wrong there Murph! I have an Onkyo 797 pushing a pair of M60 type speakers. To say there's no problem is an understatement. The M80s are even more efficient. (Are they 4 ohm speakers? If they are, you have to set your receiver to accommodate them or I think you may burn those channels).

I use an outboard Denon PMA500V 2 channel 85wpc amp for channels 6+7.

Good luck


Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.
Re: outboard amp hooked to a intergrated receiver?
#4452 07/19/02 06:13 AM
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Since the 787 has a quite powerful amp section and the M80s are very efficient, it's surprising that you're having trouble. Of course there's no problem with connecting the pre-outs to an external amp, but I wonder if power is really the problem. Yes, the M80s are rated at 4 ohms and Onkyo says don't go under 6ohms, but that really shouldn't cause trouble. Possibly in two-channel do you have the volume so high that you're simply asking too much of the equipment(and your ears)?

A long-shot : the 787 has a ventilating fan to help prevent overheating. Listening closely, can you hear it running at times, or is it possibly not operating?


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Enjoy the music, not the equipment.


Re: outboard amp hooked to a intergrated receiver?
#4453 07/19/02 11:42 AM
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the Onkyo 787 dosen't have a ohm switch and I can trip the protect mode off quite easily if not carefull.I've set the volume controll down under the "refrence" level and my listening room is a little on the large side.after hours of movie or tv watching I stuck my head in there and listened for the fan but never heard it.how else can you check for that?also,the speakers I replaced with the m-80's never set the auto-protect mode off and they were 4 ohm but then they never sounded as good as the m-80's

Re: outboard amp hooked to a intergrated receiver?
#4454 07/19/02 03:50 PM
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Hi Murphyman,

I posted some time ago about the cost compromises HT receiver manufacturers make in order to include lots of features and underprice the competition: case in point--the Onkyo cooling fan. Instead of extensive heat sinking (costly), to cool the output transistors, Onkyo has been using cooling fans in recent years. The Onkyo I had ran very hot--far hotter than other receivers I've reviewed (Pioneer, Yamaha, Denon, etc.), and its fan never kicked in either. Be sure the 797 is really well ventilated, and if the warranty is still on it, have a service center check the fan's thermostatic control. Put your hand on top when you've been running it for an hour or so. Warm is fine; hot is not.

The impedance curve of your other speakers may have been quite different than the M80's curve. It depends on what frequency the curve dips to 4 ohms. But I suspect what's happening is that you are pushing the 797 too hard (big room), the output transistors heat up, and the 797's protection circuitry kicks in and shuts it down. Many of these receivers don't deliver anything near what they claim when you run them in the multichannel mode. So go easy or get a bigger power amp with a proper output section that's rated for 4-ohm loads, one with extensive heat sinking (it will be heavy).

Regards,


Alan Lofft,
Axiom Resident Expert (Retired)
Re: outboard amp hooked to a intergrated receiver?
#4455 07/19/02 10:15 PM
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I have an old sony receiver that heats up so hot you could burn you're hand but my onkyo runs nice and cool but I can't hear the fan run.but maybe it's really quiet and thats a good thing.I picked up an adcom amp from ebay and hopefully it will work out fine.

Re: outboard amp hooked to a intergrated receiver?
#4456 07/26/02 08:26 PM
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just an update on the amp issue.I pluged in an Adcom gfa-555 with kimber pbj's to the onkyo and the sound and performance is astounding!I even turned it up to try to get the distortion lights to flicker and it got scary loud and clear with barely a flicker of the lights.these m80's are MONSTERS and ate up every bit of the 325 watts/ch.just one question,dose anyone leave their amp on all the time and would it shorten the life of the amp if you did so?


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