6 replies to this topic

[con]

OK to start

Damping Factor (DF) is the amount that the load(speaker/sub) reacts with the amp.
Impedence changes the DF, at 1ohm DF is much lower than at 4ohm
Typical value is ">200" for "good amps" (eg. soundstream)

Now
Does the DF affect the sound quality very much?
Is the DF more important for ported boxes as sealed boxes are more predictable?
why is 200 the "magic number" why dont they say 250 300 etc?

One more thing
The CALIBER CA2000D+ has a DF of 80 (min 65, measured 88.8)
is this why it is so cheap?

[ November 04, 2003, 01:48: Message edited by: Con ]

[Bassaholic]

Its damping factor, not dampening.

The damping factor is simply the load impedance divided by the output impedance of the amplfier.

BUT the impedance changes - it rises due to inductance (and as the coil heats up...), and rises especially at resonance. It is actually the difference in damping factor that is most audible and it will effect the frequency response.

What is the magic number you ask? Well since all speakers will have different amounts of impedance rise, its hard to pin down a number, but it is generally accepted that as long as the system damping factor is above 25, it should be inaudible. (by system damping factor, I mean taking into account any series resistance - the speaker wire resistance is actually part of the output impedance.

It has little to do with sealed or ported boxes.. (well in actual fact, since there will be an impedance trough at the ports resonant frequency, therefore the impedance over the operating bandwidth may actually be lower, therefore you may actually get away with a LOWER damping factor.)

[ November 04, 2003, 00:01: Message edited by: Bassaholic ]

[con]

Dampening - oops my bad

Bassaholic You Said

Quote

It is actually the difference in damping factor that is most audible and it will effect the frequency response.

So if your amp DF was 25 with a 1ohm load then output impedance is 0.04
then at resonance the load is 6ohm DF is 150

isnt 25 to 150 a big difference?

yes i do agree with the ported having lower impedance at tuning so the amp could provide more power at that frequency in theory than to a sealed box

[NUTTTR]

I ran a D2 @ 1 ohm, supposedly VERY low damping factor (as in below 20) and only really noticed it was a little more boomy, however, running the US amps, supposedly over 2000 @ 2 ohm, it doesn't really sound that much different, not as boomy tho
Aaron

[the[K]id]

As bassa said, once it is over 25, the difference is totally inaudible. The speakers will affect the sound far more at this point than any change (25-100 produces something like a 0.001% change in sound, I may look it up if I ever go back to a uni library)

[suparoo]

dampining factor does play a large part, but im not sure about minor changes in it if there noticable.

Eg one of my ClassA amps has a DF of only 4
compare it to one of my newer FET amps with DF's over 200
and yeah, the higher the dampening factor, the tighter and faster the bass is.
the classA with a DF of 4 the bass is alot softer and slower, bass notes are literaly slower

[Winno]

I was talking to the service manager for Alpine and Infinity (NZ)last week about this very topic and he said that DF is lowered as impedance drops.
Bridging also lowers the DF (halves it).
This, depending on the situation, could result in a subtle change in sound quality possibly for the worse.

BUT he said that as the impedance drops and/or you bridge into the load, more power is able to be developed which helps things "sound better" again.

In a nutshell, he summed things up by saying that what you may lose in one area, would be gained differently in another and vice versa.

The trick is to find for your situation which one is better. This will be based on your needs, system wise and also on personnal preferences.