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Old 21st August 2005, 07:13 PM   #1
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Default ART sla-2

Why are there no Damping factor specs for these amps ? Is it that bad ? Even my old pioneer lists them in its spec sheet.

This guy is offering to sell me this for 250 bucks. I might take it for my subs just because i am renting it anyway. Until i hear back from peter Daniel. Its not very good for my top end. NO better then my ancient pioneer.

Is there way to measure the factor with a Meterman 37ZR?
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Old 21st August 2005, 07:51 PM   #2
Netlist is offline Netlist  Belgium
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Here's an explanation how to measure damping factor.
I recall reading a recent thread about the pro's and con's of high and low damping factor. No need to tell you that your ears are the final judge and specs are only a commercial necessity.

/Hugo
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Old 21st August 2005, 08:06 PM   #3
anatech is offline anatech  Canada
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Hi Madmike2,
Use the method Netlist linked. Try to stay low in frequency. Many meters are not accurate above 80Hz - sorry, but you normally do this in the midband nearer to 500Hz or so (1KHz is one test freq. standard). You can measure around 100Hz but avoid 60, 120 and 180Hz as you may get ripple effects from the power supply, and use a dummy load. A speaker's impedance is highly variable with frequency, and level to some extent.

A well equipted shop would use something like Dale non-inductive 8R0 250W resistors and a good meter such as an HP 34401A or Fluke 845 (?). There are others. You need a sine wave generator with reasonably low distortion. Do not drive the amp too hard or other issues will become important.

-Chris
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Old 21st August 2005, 09:54 PM   #4
sam9 is offline sam9  United States
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They may not mention it because damping factor may not be such a high priority to their customer base. Quite a few writers have opined that SS amps nearly always have far more than adequate dampimg factors without any special attention by the designer. I'm not necessarily concurring but it is not an uncommon point of view.

There is also an article in the latest edition of "AudioXpress" where the factors contributing to loadspeaker damping are analized. In the article the author concludes that the voice coil/magnet interaction is the dominate factor in damping and that an amplifier's constibution is nearly insignificant. I read this very quickly and have not given it deep thought so I'm not in a position to concurr or object to the conclusion. Nonetheless, if ART shares this conclusion that may be another reason why they don't state it.

In any case you can measure output impedance with a signal source and a DMM. DF is then simple calculation. BTW, it is frequency dependent.
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Old 21st August 2005, 10:04 PM   #5
anatech is offline anatech  Canada
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High damping factor is normally achieved through high feedback levels. This is normal in most SS designs and there was a period where "the higher the better". Damping factors from around 50 to 100 are normal and in average situations (no silly loads) is enough. Hollow state ranges from, say 4 to 18 on average (eight is a good average number). Different sound, but good.

My previous post should have indicated a Fluke 45, not 845. Finger trouble.

-Chris
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Old 21st August 2005, 11:20 PM   #6
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my finger gets me in trouble all the time it just wants to keep giving itself to others while driving walking biking. It is a very giving finger.
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Old 21st August 2005, 11:55 PM   #7
anatech is offline anatech  Canada
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The world needs more giving people such as yourself. My finger has been told to not be so giving. The company name is all over the van! They even took the phone number off. Others should not talk on the cell phone whilst driving.
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Old 22nd August 2005, 01:18 AM   #8
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That finger - I see a lot, is mentally deficient types signalling their IQ! Unity! They seem desirous to communicate their (lack of) intelligence to the world, who am I to stop them?


Cheers,
Greg
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Old 22nd August 2005, 02:40 AM   #9
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Wow amplifierguru , my finger says hi It also wants me to inform you that it has a degree in Criminology 3/4 of a diploma in audio engineering half of one in Stationary Engineering and is now actually trying to complete one in Civil Engineering. But if you will take it i can give you the finger as well, i need it back though as it gets busy during rush hour ala "L.A Stories" the family edition.

^^ all in fun Mods, all in fun

Michael
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Old 22nd August 2005, 02:43 AM   #10
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Not going to bother trying to measure the amp. I am slowly starting to see that there is no point to it what so ever. It either sounds good or it does not. regardless of spec damping factor. for now i am just enjoying what so far sounds good to me ill fiddle more later
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