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Choosing the Right Amp

 

New member
Username: Peter56

Post Number: 5
Registered: Oct-05
The display board died for the old amp and is unavailable. The old system worked great but I never turned it up all the way.

Old amp = 130 watt per ch. minimum RMS, both channels driven at 8 ohms from 20Hz to 20,000 KH with no more than 0.008% total harmonic distortion. CD snl 100. The old amp also had a crappy third ch with with 5 watts.

Then below it says 125 watts.

Speaker setup = a total of 340 watts at 8 ohms in the living room. 2 1987 Realistic Optimus 900 base reflex 100 watt ea. With 12 in woofers, 4 midrange, 2.5 in tweeter. 2 Optimus â€"21 70 watts ea. acoustic with 10 in woofers, 3 in tweeters.

I am running 2 100 watt and 2 70 watt house speakers in the living room + 2 smaller speakers in the kitchen. The setup is stereo and no surround or sub woofers. I would like to be able to control the volume level on each channel separately. It would be nice to be able to do some kind of wireless sound in my upstairs office and bedroom. I presently live in a 2 bedroom apartment but am planning on a 3 bedroom house with a garage and basement + a deck in the near future and would like to put sound everywhere from this amp.

My first question is what is the correct amount of wattage to drive 340 watts of speakers across 2 channels?

Next, why is the total harmonic distortion so much worse on a new piece of equipment vs what the Kenwood KRV-126R I purchased in 1986 had?

The amp I am considering as a Onkyo TX-NR828 7.2-Channel Wireless Network A/V Receiver $999.00

Onkyo TX-NR828
http://us.onkyo.com/Products/model.php?m=TX-NR828&class=Receiver&source=prodClas s

Specs are: 130 watts minimum continues power per ch, 8 ohms loads, 2 ch driven from 20Hz to 20kHz with max total harmonic distortion of 0.08%, snl 106

similar amps:
http://us.onkyo.com/Products/prod_class.php?class=Receiver&source=globalnav

Money is not a concern but having something that will last and/or will be easy and cheep to fix down the road is.
http://us.onkyo.com/Products/model.php?m=TX-NR828&class=Receiver&source=prodClas shttp://us.onkyo.com/Products/prod_class.php?class=Receiver&source=globalnav
 

Gold Member
Username: Magfan

USA

Post Number: 3047
Registered: Oct-07
Speaker 'watts' is a near-bogus specification. If you are LISTENING at all, it is difficult to wreck a speaker with too much power. Not saying it can't be done, but speakers fed too much power WILL have audible signs of distress.
That being said, you can and should look at the speaker impedance AND sensitivity to get some idea about how much power is appropriate.

I wouldn't worry or place to much 'stock' in a change in measured distortion from .008% TO .08%. Measurement technique may have changed and certain amplifier design features......like feedback....which you generally shouldn't be concerned with.....effect this number. Bottom line? Speakers SWAMP that number as a general rule, having MUCH higher distortion than the upstream electronics.

HT receivers are NOT the way I'd go if I wanted something 'that will last and/or will be easy and cheep to fix down the road'. That particular technology changes fairly quickly and manufacturers are always on to the 'next new thing'. Are they up to HDMI 5 yet? Even 2 or 3 year old HT receivers are problematic at 'fix it' time. Some parts are proprietary and if a weak link, may become unavailable sooner than later.

The Other HT receiver hangup? While is might be 130x2, that power rating drops like a rock when presented with more speakers. It might only be 60x5 or thereabouts. AND, low impedance speakers....those rated at 4 ohms or even higher (6 and sometimes 8 ohms) if such speakers have a big 'DIP' in impedance. Most HT receivers will run Very Hot when presented with such a load. Some will perhaps malfunction or go into 'protection' and stop until cooled. Using such a receiver in a restricted space.......is asking for problems.

Several solutions present themselves. A 'distribution' system consisting of impedance matching transformers and amplification is ONE such. Jan may chime in with how such a system can work for you....or some information tips.
I like WIRELESS speakers, and a 'server' solution. You can connect several of these in a wireless manner.
Audio Engine makes a wireless hookup system to their POWERED speakers.
I heard Vanatoo at the recent THE show in Newport Beach, CA. and they also make wireless speakers with a built in DAC. They sounded FINE to my ears.
The advantage of a speaker with built in amps is that the amps better be well-matched to the speaker, it saves wiring, and you have less 'stuff' strewn about.

Ultimate cost may be higher than simply getting the HT receiver, but you can also approach it as modules....adding a zone as money permits.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17774
Registered: May-04
.

"My first question is what is the correct amount of wattage to drive 340 watts of speakers across 2 channels?"


There is no single answer to this question. The most basic answer, IMO, is there is a significant difference between "wattage" and "power". A sizeable portion of what is put into a loudspeaker as electrical watts will be lost in the transduction into acoustic watts. The average consumer loudspeaker is only about 2% efficient at this process. As efficiency rises, the need for watts and power decreases. There are numerous threads in this forum which discuss this topic if you'd like further clarification.

Music material will dictate to some extent how much power will be required in any situation. Bass frequencies and dynamic peaks require much more of everything a system has to offer than do high frequencies and sustained wavefronts. Buying wattage alone is a somewhat foolhardy proposition as acoustic output increases expotentially with watage increases, which means higher power seldom results in actual average levels increasing. Higher power provides more reserves to protect against damage due to too little power. If that seems like gobbledegook, this too has been explained in many, many threads located in the archives of the forum.




"Next, why is the total harmonic distortion so much worse on a new piece of equipment vs what the Kenwood KRV-126R I purchased in 1986 had?"



IMO one of the worst mistakes you can make in consumer audio is to conflate specifications and measurements with sound quality. This, in essence, is why your older amplifier was spec'd at lower total harmonic distortion. The "average" buyer sees only what the manufacturer wishes to show them and, like the slight of hand artist, distraction is the key to a successful performance or a sale against equally poor choices. The typical manner employed for the reduction of THD has deleterious effects on sound quality. Yet, depending on the acuity of the listener, low THD specs can serve as a placebo which placates the buyer into believing they have something of value when, in fact, they do not.

My advice regarding audio specs has always been to largely ignore all specs other than HxWxD plus weight to make sure what you buy fits on the shelf you have picked out for it. Otherwise, specs are a fool's game and, who wants to be labeled a fool? The equipment should match the priorities of the buyer/user and no more. The buyer/user's task is to assemble a set of worthwhile priorities which will serve to guide them towards an acceptable solution to their search.



"Money is not a concern but having something that will last and/or will be easy and cheep to fix down the road is."


Then I would say get away as fast as you possibly can from more mass market BS. Mass market manufacturers are in the business of selling gear, not maintaining or repairing gear. They have zero interest in you, the customer, once you've handed over your cash for their new item. They have remained in business mostly by a continuous deception based upon how much crap they can pile into a box and then shove its controls into a hand held remote. 90% of what you are being sold in the average $1k mass market receiver is BS you will never use. So, why buy it in the first place?



While no manufacturer can stay in business for long if they are only maintaining decades old merchandise, the high end audio manufacturers tend to take an entirely different view of their clients. Most view the client as another music lover, equipment lover, etc scornful of the way in which the mass market treats their products and customers. Many of the classic high end manufacturers of the last half century have components which are still satisfying their clientelle after decades of service. This doesn't come cheap but, if money is truly no object as you claim, then your best bet is to seek out the independent audio retailers in your area and do some talking and listening.

If you are, as it would appear, someone who has never auditioned fine audio equipment, you will have many treats and surprises awaiting you. You have many things to learn and far, far more to unlearn. Listen to the dealers with an open mind. They will earn their profits in a way no big box store can.

Where do you live? What independent audio shops are in your area?




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