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I need more power!


OneTinyIrken
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I am looking to build a 9.2 home theatre system with the following speakers:

 

4x R-620F (100W continuous, 400 peak)
4x R-41SA (50W continuous, 100 peak)
2x R-51M (85W continuous, 340 peak)

1x R-34C (100W continuous, 400 peak)

2x R-120SW (200W continuous, 400 peak)

 

Now, the receiver I'm looking at is the Denon (AVRX4700H); it says it outputs 125W per channel, but the back of it says 710W.  If it can only output 710W continuous, what would you recommend I get so I can bump up the power output to the 1270 continuous watts required?  I'd prefer to be able to output at least 1500W, but I'd like a cost-effective solution.

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@OneTinyIrken,

 

Welcome to the forum.

 

I would not get too caught up in the power specs thing, they can be very confusing to the average consumer.

 

If the Denon 4700 specs at 125w/ch@8ohms(20Hz to 20kHz) at 0.05% THD, then it will have plenty of juice to drive your whole system in the average size room at "normal" levels.

If you still feel it somewhat inadequate, then just add a stereo amp for your mains or 3 channel amp to drive your LCR.  Amp power is cheap on the used market.

 

Bill

 

 

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The published specs on AVRs (Audio Visual Receivers) can be misleading.  Back in the Seventies, published specs on the existing 2-channel stereos were getting really dubious, with things like Peak Music Power, for example, which gave unrealistic numbers, but may have helped sell receivers to naïve buyers.

 

Luckily, the FCC stepped in, and required the manufacturers to test and publish useful and relatively accurate power ratings, like “power with both channels driven, 20 Hz-20,000 Hz at under 1% THD”.  That was great, but then AVRs arrived, and they don’t fall into the same legal category as the 2-channel receivers, so with weak laws we once again  get ratings like “power at 1 kHz, with 1 channel driven, and THD of 10%”.  Even the better AVRs may only have the spec for when 2 channels are driven, with the actual output per channel with all channels driven being very hard to find.

 

Many receiver manufacturers seemed to settle on 100 watts per channel, just adding channels in the higher models (maybe starting at basic 5.1 units, and getting up to 9.2.4 in the top AVRs, maybe because it was simple to explain and understand.  However, just because an AV receiver puts out 100 watts into one or two channels, you can’t simply multiply the power output by the number of channels.  100 watts driving just 2 channels does not mean 100 watts per channel when driving 7 channels.  The power per channel with all channels driven could be around 50 watts, or maybe even less.

 

All the channels in the vast majority of AVRs are sharing a single power supply, and that’s where the bottleneck is.  Sure, they could use a bigger power supply, but then the AVR would cost more than the apparently equivalent models from the other brands, maybe making it less attractive to most uninformed buyers.

 

OneTinyIrken, that 710 watt number on the back of your receiver indicates the maximum power it could consume, not the power it could output.  Keep in mind that the Class AB amplifiers used in nearly all AVRs are only about 30% efficient, so the output would be less than the input, maybe by a lot.  Don’t worry, nearly everybody has to deal with this, and we do wind up with really good-sounding systems in spite of it all.

 

On the bright side, Klipsch speakers are more efficient than most other brands, due to their use of horns mostly, and often don’t need huge amounts of power to sound good.  1500 watts is a crazy amount of power for a home system, especially with Klipsch speakers.  I’d get a good-sounding, good-quality receiver and see how you like it.  If you decide you need more power, you can add an external power amp for your Main Left and Main Right speakers, or maybe even a 3-channel amp for your 3 front channels.

 

Keep reading and learning, and you’ll soon be able to put together an effective system that didn’t cost the Moon and sounds great.  Welcome to the Forum!

 

 

 

 

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I have a Denon x4300h, well until I sell it, for HT and 2 channel music. I was (sadly no longer) using 5 Martin Logan speakers... 3 of which were 6 and 4 ohms and no where near the efficiency of Klipsch speakers. The Denon would run out of steam for all the reasons @Islander noted. The solution was 2 power amps as @willland noted. I used a Parasound A23 for L/R and a cheap chip amp for C. This helped a lot but you have to fiddle with levels on each amp, and you loose some integration benefits, remote control functions depending on the amps you add etc. But you won’t run out of steam!

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If I had known... back in the day when I bought the AVR, I should have bought an Oppo BDP 105, and the Luxman R-117 I have now, along with say an Akai AM-2950 or 2.  Each vintage receiver then can run 2 channels and never run out of "power" and you get much better sound out of any one of them.  The one benefit of the Luxman is ... a remote control including volume! 

 

I've run this setup albeit with Oppo BDP 103, using the Luxman to run the front L/R and for music.  It also has Pre-out, which is important if you want the subs to run off the same "volume" control.  I'm currently using the small chip amp to run a very cheap (FREE) center channel until I get to my final setup.  I don't think I'm using 10% of the volume knobs.

 

@OneTinyIrken, hope this helps.  Basically, get a couple of power amps, connect the preout from the Denon to your power amps for the L/C/R and off you go.  It works great.  The Denon will control the volume, just be sure that the power amps don't smoke your speakers depending on their output and volume control setting!  You won't need more than 100 watts for the power amps.  There's lots of discussions on the forums for power amps.  Good luck.

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Power amps that are worth it are not cheap, this opens another can of worms. I got caught in the wormhole! Majority of my power amps go to lcr. I added more speakers so I got amps, so there are no dead spots in the room, or run at lower 4ohms, to keep from running more wire. 4 ft  apart in height.

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4 hours ago, Big mac said:

Power amps that are worth it are not cheap

Not really true IMO.

 

I have owned more than 25 outboard amps(Acurus, B&K, Sunfire, Anthem, Adcom, Denon) from monoblocks to 7 channels, and never paid more than $500.00 for any of them.  Never had failure that was not cheap to fix.  As a matter of fact, only one channel failure and I bought it knowing about it.  If I am not mistaken, it was a $100.00 output transistor repair.  

 

Bill

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