140wpc into 8 ohms: enough for Contour 1.3SEs?


Hi --

New here. I have a Hafler DH-220 modded by Jim Ott at Nothwest Audio Labs to provide power in excess of 140 watts per channel into 8 ohms. Will this be enough power for a pair of Dynaudio Contour 1.3SE speakers (a likely near-future purchase)?

Thanks in advace,
Carl
carlsaff

Showing 3 responses by sean

I'm sure that the amp will drive the speakers, but whether or not it will do it with finesse and authority at high volumes or during complex passages will remain to be seen. My experience with Dynaudio's is that they need as much power as you can foist upon them. Then again, if you are in a small room, you'll need less power regardless of what speaker you use. Sean
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Panny: While i basically agree with your statement pertaining to "quality over quantity", there are many commone reasons why that simply doesn't work.

First: If you are driving the amp quite hard on a regular basis, most amps will tend to "fall apart" sonically. Delicacy, fluidity, detail, separation of instruments and notes, etc... all tend to get lost in the shuffle.

Second: If the amp is being pushed hard enough to be driven into clipping, sound will surely suffer. This is not to mention that damage to both the amp and speakers could result.

Third: Many low powered amps of very high quality are biased quite richly i.e. they stay in Class A longer than a bigger amp that switches into Class B sooner. This will generate quite a bit of heat. Judging from what i've seen in most installations, the lack of air-flow around such amps is an invitation to pre-mature failure and / or increased trips to the repair shop.

As such, you have to figure all the factors into the equation. As a general rule, i would prefer a richly biased high power amp to achieve both the low level sonics and maintain the dynamic headroom that i find necessary to keep things sounding "clean and cohesive".

Carlsaff: If you like the sound of your modified Hafler, try looking into a modified DH-500 or, probably more appropriately, an Acoustat TNT 200. Sean
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Bare in mind that most speakers become LESS efficient as more power is pumped into them. That does not mean that volume goes down as you put more power into them, but that power is lost in greater quantity due to thermal losses as you drive them harder. In effect, you run into what is basically non-linear dynamic compression. Combine this with the fact that many amps have a hard time dealing with increased current demands, their power supplies begin to sag and reflected EMF is increased as you drive a speaker harder. As such, one is typically best off finding the most sensitive speakers they can find that are suitable to the application. By doing so, you'll be pulling less power from the amp, so it runs with less stress and sounds better. At the same time, the speakers aren't being fed as much power, so they don't heat up as much and go into thermal / dynamic compression as rapidly or as often.

Having said that, i haven't found a lot of highly efficient speakers that i really like to listen to on a long term basis. I'm sure that there are others out there that share this dilemma, but then again, there are some folks that find low sensitivity more of a drawback. That is why there are so many different speakers and designs out there : ) Sean
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PS... Driving in a convertible with the top down on the highway, piloting a motorcycle with stock mufflers and no helmet or driving a "Jeep" type vehicle with bigger tires in suburban areas typically clocks in at about 90 dB's. Taking a Jeep on the highway with "off-road" type tires can be amazingly loud due to the amount of air that gets trapped in the treads. The motorcycle doesn't seem as loud as most of the sound is projected behind it, but the wind whipping by your ears definitely has a similar effect.