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
I used a Mark Levinson 27.5 which is 100 WPC and it sounded great. with the 1.3SEs
Having more watts helps in headroom and you always can do better.I think power is over rated as I would rather have a good 50w ampo than a 500 w amp that does not do the presentation as well.

Right now I am using a Panasonic receiver that is not as good for bringing things in the foreground out as well as my Passive Controller and Modified B&K amp out.

I would like to have that ML amp also.BTW I love it when people ask if 100w amps will be enough for driving horns like Klipsch.

I do not use Dynaudio's BTW I have NEAR M50III's with updated drivers and XO's.

good luck!
www.nearsota.com
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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Hi Sean:

I am reading your responses with great interest and the opportunity to learn. Hopefully, you will indulge my questions.

Some background:
In my second system, which I use for 2 channel HT purposes, I have a NAD 320CEE (50 wpc) integrated amp which powers a pair of Acoustic Research 302 speakers (3 way; 10 inch; 85 db sensitivity; 35 min to 250 max recommended wpc). (Note: These speakers were AR's attempt to introduce a modern era version of a 60's AR classic. The 302's were the modern era AR5's.) My listening room is 15' X 10' X 8.5' and the speakers are each placed horizontally, on shelves inside two standalone bookcases (one speaker per bookcase and then, the two bookcases are butted together) about 5.5' high. In terms of placement inside the bookcase, if you were to look at the speakers, the woofers "kiss" and the tweeters are the furthest apart. About 8 inches of space separate the speakers, of which 3 inches are the solid pine bookcase walls.

I live in a pre-war apartment building (plaster walls; wooden floors & joists) so sound travels up & down. I am fairly considerate (lots of cranky neighbors) and so the system volume is usually pretty polite for music (volume control at 8 o'clock position ) and less polite (10 o'clock ) for movies. If the music were at the 10 o'clock position, it would be pretty loud and at 12 noon, it is not pleasant in the room.

Question(s):

Is my understanding of the math that governs the power/volume relationship correct?

1. If I understand the math that governs volume ... to get a noticeable (3db) increase in volume, you must double the wattage. Using my speaker's specs, would this mean then that ... 35 wpc gets me 85 db and I would max out my NAD to get to 88db as that would require 70 wpc. (Yes/No/Not Quite?).

I pulled a list of SPL comparisons from a power equipment site and based on this, my guess is that I am normally using less than 4 or 5 watts and am at a level of less than 80db.

dB Common Sound

140 ... Threshold of pain
135 ... Siren at 100 feet
130 ... Jet plane at 50 feet
120 ... Auto horn at 3 feet or rock & roll bar
105 ... Chain saw
100 ... Heavy city traffic
80 ... Inside a car at 50 mph or inside a busy office
70 ... Vacuum cleaner
60 ... Normal speech
50 ... Private office
45 ... Living room, suburban area
35 ... Soft whisper
25 ... Bedroom at night

In the case of Carlsaff & his Dynaudios:

30 watts has him at 86db; 60 watts has him at 89db; 120 watts would have him at 92db. (Yes/No/Not Quite?)

Many thanks, Rich
Rich, Your understanding of the application of the math is incorrect. It takes 1 watt to drive these speakers to 86dba - now start doing your multiples. I think you will find that 120 watts should produce about 106dba.