New amps underpowered?

I dont want to go overboard with equipment since as you say 4k could be a mid-way between 2k and 8k

I think an oppo and a new amp will be good enough ;)
 
Another thing to do is check the power supply value for both your current amp and the new one you are looking at as this will give a more accurate figure for the total power output they will give. ....

This is the point I was going to make. The REAL power can never exceed the Power Supply rating. It is not uncommon for a AV Receiver to claim 100w/ch for a total of 700w, yet it will only have a 400w or 500w power supply. Yes, when you driver two channels, you can get much higher power, maybe even 200w/ch, but when you try to drive 7 channels heavily, the power drops to 72w/ch. That is just a fact of life.

Now, they aren't really cheating because the Surround Channels are not driven any where near as heavily as the Front and Center Channels. They carry the real weight, and take the real power load.

According to the owner's manual of the Onkyo TX0NR818, the power is -

(North American)
135 watts minimum continuous power per
channel, 8 ohm loads, 2 channels driven
from 20 Hz to 20 kHz, with a maximum
total harmonic distortion of 0.08% (FTC)


FTC is a solid and real unambiguous power rating to a standard speaker impedance load full spectrum with minute factional Total Harmonic Distortion.

So, 135w x 7 channels is 945w total. However, to the best of my ability to determine, the power supply is 730w. Meaning with all channels driven, the single channel power can never exceed 104w/ch. Though that information is not clear and direct, it took a degree of interpretation.

In other parts of the world, for what ever reason, they fudge the power rating by making them -

(Others)
7 ch × 180 W at 6 ohms, 1 kHz, 1 ch driven
of 1% (IEC)


Notice NOT to a standard Load, NOT full spectrum, and NOT to minute fractional THD, and we really don't know how many channels they are driving. It could be just one channel. In short, that is an inflated power rating.

As to your original amp, the Onkyo TX SA 805, unless you still have the owner's manual, and unless it gives clear specification, we can't really know what the true power was of this amp.

But do keep in mind, a GOOD 50w/ch stereo will likely drive speakers better than a 100w/ch AV amp. Plus, once you get up near 100 real watts, the quality of the amp means more than the power. In a more expensive amp, you are not buying power, but clarity and drive capability. A strong high current 100w is a lot better than a weak modest current capability 100w amp.

Quality buys you clarity, not power.

All AV Receivers have enough power, so concentrate on the quality of the amp, and the power supply. Many Consumer grade AV amps are not 4 ohm rated. That is, they need speakers of 6 ohms or 8 ohms. If the front three are 4 ohms, because of higher current draw, they are going to have a hard time keeping up.

Also, because they are cramming so many amps into such a small space, cooling can also be an issue; more power consumed means more heat. But there is sometimes a limit to how fast that heat can be dissipated. If you are driving all channels hard, to low impedance loads, your amp might overheat and shut down. In this case, it is a combination of cooling ability and the power supplies ability to supply high current demands.

Also keep in mind that some amp maker rate their power will ALL Channels driven, meaning that those lower power ratings reflect Real Power delivered under any and all circumstances.

If you are serious about REAL power, then plan on spending some REAL money on a bank of discrete Stereo Power amps and a AV Processor/Pre-Amp.

Short of that, focus on amps that are noted for having high current, high powered power supply, and generally high quality amp components.

Just a few thoughts on the subject.

Steve/bluewizard
 
Last edited:
@ steve

I must admit that is a very detailed analysis and I am impressed. Some how I used to compare the total wattage with per channel output and determine the factual output.

However how do you determine amps having high quality amp components. Could you quote a few of these or rather name a few amps in $1,000 to $1,500 range?
 
Price and brand reputation are the best indicator of quality, and can we assume when you want prices on various suggested amp, you are talking about AV Receivers, and not stereo amps?

Right now in consumer graded amps, I think I favor either Denon or Marantz. Yamaha would run a close second. On the higher end, Onkyo might be just fine. While they are consistently acknowledge as great Movie amps, some complain that they fall down on the quality of music. However, amps like Marantz are consistently rated as good music amp.

In a recent review in Home Cinema Magazine, they gave the Marantz SR7007 very high rankings. Price currently at about £1299. The next model smaller the Marantz SR6007 also receiver a very good review (£899). The Marantz SR7007 is rated as a Home Cinema TOP PICK -

"...Marantz continues to be one of the performance champs of the A/V Receiver catagory. The SR7007 expertly conjures musical magic and cinematic excitement. ...well worth the price.

A similar Denon model would be the Denon AVR4311 for a similar £1299.

In a Yamaha at the same price (£1299) consider the Yamaha RXA3010.

Look carefully at the Marantz SR7007, very up to date, very high feature set, 3k/4k ready, 3D, DLNA audio streaming over computer network, etc...

Marantz UK | SR7007

Though many of these advanced features are common on the lasted higher end amps.

Once you cross the £1000 threshold you are into a new class of amps. Expect any trusted brand over £1000 to sound very good.

Steve/bluewizard
 
Last edited:
why not just take the pre outs to a bigger external power amp
these should be enough mono to 7 channels 500 to 1500watts
1.5kw not big enough move into a cinema


M2 SERIES AMPLIFIERS from D-SONIC
 
Last edited:
I recently ordered an Onkyo TX-NR818 receiver. All 5 of my speakers are cheap Sony bookshelf speakers rated at 8 ohms and 100 watts max. If I play lossless blu-ray audio at reference volume will I risk blowing out my speakers? I bought this receiver solely because it has Audyssey XT32 room calibration. I need to know if I should look for a different receiver if there's a good chance of blowing my speakers out, but whatever receiver I get MUST have Audyssey XT32 room correction. I'm not willing to settle for anything less. New speakers aren't in the budget and I don't have room for anything bigger than a bookshelf sized speaker.
 
I recently ordered an Onkyo TX-NR818 receiver. All 5 of my speakers are cheap Sony bookshelf speakers rated at 8 ohms and 100 watts max. If I play lossless blu-ray audio at reference volume will I risk blowing out my speakers? I bought this receiver solely because it has Audyssey XT32 room calibration. I need to know if I should look for a different receiver if there's a good chance of blowing my speakers out, but whatever receiver I get MUST have Audyssey XT32 room correction. I'm not willing to settle for anything less. New speakers aren't in the budget and I don't have room for anything bigger than a bookshelf sized speaker.

It would ultimately depend on your room size and the distance you are sat from the speakers as to whether you'd blow them, but it is doubtful that you would even if outputtting at reference level, especially given that you say or suggest your room is small?

I would suggest the amp too high end for use with your speakers. I'd suggest you look much further down than the 818 or consider much better speakers. Maybe compromise and buy a lower end/cheaper amp, but also replace the speakers as well? There's little point in spending large sums of money on an amp if the speakers are not up to portraying the benefits of doing so.

Speaker size isn't the factor that determines quality. You can spend as much on bookshelf size speakers as you can spend on floorstanders and there are many bookshelf speakers out there that exceed the performance you'll get from cheaper floorstanders. "Never mind the quality, feel the width" doesn't ring true where speakers are concerned. Neither will Audyssey make a silk purse out of sows ears.
 
Last edited:
I currently have a Denon AVR-591 receiver rated at 75 watts per channel when five 8 ohm speakers are being driven. I know the Onkyo is rated at 135 watts per channel when two 8 ohm speakers are being driven. With the Onkyo, what is its power rating with five channels being driven? How much less power gets delivered by the Onkyo when driving five speakers vs two? I'm just wondering if my Denon receiver can drive these speakers with no distortion at reference volume then will the Onkyo TX-NR818 be OK too? BTW, I sit about 7ft away from my speakers.
 
I currently have a Denon AVR-591 receiver rated at 75 watts per channel when five 8 ohm speakers are being driven. I know the Onkyo is rated at 135 watts per channel when two 8 ohm speakers are being driven. With the Onkyo, what is its power rating with five channels being driven? How much less power gets delivered by the Onkyo when driving five speakers vs two? I'm just wondering if my Denon receiver can drive these speakers with no distortion at reference volume then will the Onkyo TX-NR818 be OK too? BTW, I sit about 7ft away from my speakers.

As I suggested, I see no problem powering these speakers and doubt you'll blow them. You need to exceed the 75db or 85db (excluding +10db for the LFE channel) relative reference level to which most AV amps are calibrated to and constantly play audio at those levels to blow your speakers. What are the speakers rated in terms of their sensitivity? This will give you some indication as to how much power they will need in order to reach reference levels. The higher the sensitivity then the easier speakers are to drive. The sensitivity tells you the SPL you can expect per watt as measured 1m from a speaker. I think it very doubtful that you'll constantly need more than 100 watts to obtain reference levels within your listening room.

I still think you are wasting your money on this amp though if not willing to accompany it with more appropriate speakers. In many respects the speakers are more important than the amp and you should be spending more on them than the amp powering them.

By the way, wattage is relative to the volume and not a measure of such. The wattage rating of the amp is the maximum it can potentially provide and not an indication of what it will continually output while in use. The amp will not continually output 135watts to your speakers and you will not need to have the amp do so in order to attain reference levels within your listening room. The power required to attain the levels with the Sony speakers will be the same as it was with the Denon amp.


EDITED to avoid confusion
 
Last edited:
Thank you for your reply. I'm glad I at least don't have to worry about breaking something. My Sony speakers sound better than the Bose 301 Series IV bookshelf speakers. In fact, according to Sony my speakers were specifically designed for use with receivers that can convert DSD directly to analog. The speakers have a frequency response of 80hz-50KHz. I have a Definitive Tech Pro Sub 1000 subwoofer. Considering my room is a completely untreated room I think Audyssey XT32 will do a much better job than the 6 position MultEQ. Especially with smoothing out bass.
 
Play nice boys, I appreciate you're trying to offer help but you're getting a little too heated now.

No more bickering please! :nono:
 
EDITED post edited due to lack of content with which to associate it.
 
Last edited:
The post is still incorrect. I don't have to like it, but I guess I just have to accept that a high post count does mean everything around here. Noted. :rolleyes:
 

The latest video from AVForums

TV Buying Guide - Which TV Is Best For You?
Subscribe to our YouTube channel
Back
Top Bottom