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Old 26th January 2003, 03:25 PM   #1
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Default Damping factor..?????

Damping factor, in terms of impedance..ohms and output, what does a low dampening factor >200, give you versus a high dampening factor >5000
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Old 26th January 2003, 07:47 PM   #2
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Nothing... as 200 is high enough allready as fas as I understand.

/Peter
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Old 26th January 2003, 08:33 PM   #3
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Default Damping

Yipes!!! I'm posting in the Solid State Forum.

Here are a few sources.
A thread from here and two online articles that I think at least bring up some good issues. I would love to hear anyone's informed take on (Frank, John ,....)the articles or Rodd's comment below about the amp absorbing and using the energy which implies that resistive dissapation of stored energy is not the sole electrical damping element (or at least I think it does).

Damping Factor, by Dick Pierce http://www.diyspeakers.net/Articles/...G%20FACTOR.pdf

Tomcik, D.J.; The Missing Link in Speaker Operation, Amplifier Damping and Speaker Performance. http://www.otlamp.com/articles/tomcik/index.html

and a local thread w/ some of our best and brightest:
I must admit I've been musing on Rodd's comment for a while that reads as follows:

Hey Guys,

"Damping Factor" is a way of putting a number on a very dynamic characteristic of an amplifier. The output impedance of an amp is not purely resistive. It is a complex function that has a phase angle and amplitude that varies from instant to instant. The inductive reactance of the drivers voice coil moving through the magnetic gap is also a complex function with phase and amplitude. Energy from the driver will be disipated in the the resistive component of this complex impedance, this is true. But, this is not the only way that the amp will damp the motion of the drivers cone. The amp will absorb and store energy from the driver and use it in the next instant of time depending on the phase and amplitude (which can be negative) relationship between the Rg and the back EMF of the driver.

Rodd Yamashita

The thread is here. Rodd's comment is page 3. info on amplifier damping factor

Cheers:
Craig Ryder
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Old 26th January 2003, 11:09 PM   #4
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Low = 200.

That's very funny.


pass/ - went to hear Stardust Cowboys last night, and sat
next to fiddle player. Wife tried to make him dance.
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Old 27th January 2003, 12:11 AM   #5
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Low = 200 Thats silly.

Stardust Cowboys, Hmm sound like a band I heard at the Espy recently.

Where were they playing?

That must have been amusing, did Mrs Pass have the camera handy?

Just to add to the confusion, Has anyone considered power supply effects on damping factor.

ie between the postive and negative wire exists the amp and power supply. ie the more stored energy available the more power available to drive the speakers ultimately.

Just thinking out loud, if we assume the power supply is a reserve of stored energy, the amount of energy it can hold and maintain is governed the filter bank and level of the supply rails.

Thus higher rail voltage sq's the level of energy and has a great proportional impact on stored energy than adding filter capacitors.

Carver wrote a very intersting article on this subject when he was developing the Phase Linear 700, noted for its control and dynamics, the rails are nearly 100 volts +-, so the stored energy is massive. It also has many parrelled output devices and heeps of feedback, damping is quoted as 1000 to 1.

I while ago I used mine, a Clair Bros 700B to power front of house PA for a band in a pub, the amp they used previously was 150 watts.

The visually ability of the 700b to control the JBL 2226 15'' woofers in the J bins was surprise, the pk to pk excursion was probably 1.5 inches or more at very high velocity on the kick drum.

The punch was felt 2 blocks away! The speakers survived to live another day. The other amp sounded like someone hitting a pillow!

I am inclined to suggest its the power that moves the mountains and gives a subject account of high damping on the cones.

More confusion,

Bigger amps also have higher current output stage per say with many parrelled output devices, funny that they appear to have more control as seen by the above example (real fact)

Thus a piddly amp (say 30 watts) with high feedback could have so called high damping factor on paper, but appear to have less subjective control.

Ian
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Old 27th January 2003, 04:11 AM   #6
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It's an interesting observation that big amps without high
measured damping factors often control the bottom end
very well, and little amps often do not. This all being at
reasonable wattage levels that the small amp can handle
without distortion.

pass/ - listening to Jet Society to chill out
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Old 27th January 2003, 04:36 AM   #7
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Thought you had gone to bed Mr Pass?

The time line makes it confusing ...

Hmm I think we are 19 hours ahead, so it is Monday afternoon and sorry is only 10.30 pm Monday night there, correct?

Ah well I just figured this from experience and observation.

But what is a high damping factor? At the tech college I did my speaker course they said anything over 30-50 was academic. (but we know musles and braun are the real reasons)

But I think it is more important to bass reflex systems, particularly high Q designs where the peak needs damping.

Putting the woofer in the feeback loop would be interesting hey, sorta motional feedback, pity I did not my on eof those Phillips MF speaker when they came out.

Ian
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Old 27th January 2003, 05:19 AM   #8
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Quote:
Originally posted by macka
Hmm I think we are 19 hours ahead, so it is Monday afternoon and sorry is only 10.30 pm Monday night there, correct?
Sunday...

dave
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Old 27th January 2003, 07:20 PM   #9
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Sorry I meant Sunday night not Monday

(the home brew has effected me)

Ian
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Old 28th January 2003, 12:57 AM   #10
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If your 8 ohm woofer has a dc resistance of 7 ohm for example then are you really going to get a damping factor greater than 8/7 = 1.142? If you add in the crossover choke resistance then the wheels really fall off.
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