damping factor

[wasabichondro]

I know numbers are not everything, but I was wondering why Classe doesn't spec the damping factor for their amplifiers? Is it called something else on their spec?

[1oldguy]

Fair question.Curious about that myself.

[AV-OCD]

Found a review on the CA-2100 integrated that plots the damping factor vs frequency. Classe has nothing to be ashamed of here with a damping factor of 1800 below 300Hz (where it is most important).

Damping factor vs. frequency is shown in chart 4 and is of an extremely high value at low frequencies, and as is so typical of many solid-state amplifiers being high up to about 500kHz and then rolling off with frequency.

Considering that this is just a small integrated amp by Classe, I think it is safe to say that Classe's other amps in the Delta line would do just as well if not better.

Full review here:

http://www.soundstage.com/equipment/classe_delta_ca2100.htm

[Srrndhound]

I have a CA-201 amp, and it specs output impedance at 0.017 ohms. That will remain constant with any load, whereas damping factor varies with the load. It's thus better to spec the way Classe does.

For an 8-ohm load, this is a damping factor of 470. But when you add 0.02 ohms for 10' of 12 ga wire, damping factor at the speaker terminals drops to 216.

Hmm, I see that the newer amps don't even mention output impedance. Probably because the higher it is, the more it is swamped by the speaker wire.

[mjb]

I know numbers are not everything, but I was wondering why Classe doesn't spec the damping factor for their amplifiers? Is it called something else on their spec?

Classe probably don't specify it because most don't know what it is, and the rest realise with modern circuit design, coming out with a big number isn't very difficult. Its often overrated. Does a DF800 amp sound better than a DF400? Maybe, but probably not because of the DF400 difference.

[AV-OCD]

Roger -

Where do you stand on the belief that anything above a damping factor of 50 is just gravy?

I'm neutral on the matter.

[Srrndhound]

Roger -

Where do you stand on the belief that anything above a damping factor of 50 is just gravy?

I'm neutral on the matter.

I'd say that's right. Even if you have a very high damping factor, it does not automatically translate to better control of woofers. That is limited by the motor design. If you put a short across the speaker terminals, does the woofer still ring when tapped? If so, then the amp cannot do anything further about it.

[AV-OCD]

I'd say that's right. Even if you have a very high damping factor, it does not automatically translate to better control of woofers. That is limited by the motor design. If you put a short across the speaker terminals, does the woofer still ring when tapped? If so, then the amp cannot do anything further about it.

That sounds like an interesting test. Forgive my ignorance, but would placing a piece of wire across the speaker terminals while the amp is connected cause the type of short you are talking about? And would doing so damage the amp or the speaker?

[Srrndhound]

That sounds like an interesting test. Forgive my ignorance, but would placing a piece of wire across the speaker terminals while the amp is connected cause the type of short you are talking about? And would doing so damage the amp or the speaker?

:E It would! No, I mean to disconnect the amp and replace it with a dead short--hence simulating the ultimate in damping factor.

[AV-OCD]

That did sound like a risky thing to do. ops:

How does one cause a dead short?

How about a 9V battery?

[Srrndhound]

That did sound like a risky thing to do. ops:

How does one cause a dead short?

How about a 9V battery?

After one removes the speaker wire :W, place a jumper across the + and - speaker terminals. There is no need to pass current thru the voicecoil to see the damping effect. On top of that, the internal resistance of a 9V battery is rather high.

[AV-OCD]

As a further display of my ignorance of how electrical circuits work, how does shorting a circuit that has no current flowing through do anything?

[Srrndhound]

As a further display of my ignorance of how electrical circuits work, how does shorting a circuit that has no current flowing through do anything?

The current will flow as soon as the cone is tapped (moved). The voicecoil is moving within the magnetic field, and that generates current. You will find that the cone moves more easily without the short, but resists moving with the short in place.

[jbreezy5]

A higher damping factor does make an audible difference. It also leads to improved woofer control as well (this is actually visible).

You can determine the damping factor of your amp by dividing the nominal impedance of the speaker by the output impedance of your amp.

Srrndhnds example: 8/.017 = 470

Damping factor allows an amp to reject EMF (electromotive force) which is the electrical backwave from the speaker, through the wire, to the amp. The ability of the amp to reject the electrical backwave translates as better cone control helping to keep it within its excursion limits on large bass transients.

The damping factor is less of an issue with surround sound systems that roll-off the surround speakers early and leave the sub w/built-in amp to cover the bass.

If you're a two-channel person, it matters more, especially w/full-range speakers, even on music. It's not necessarily bad to have a low damping factor (most tube amplification does); sonically it can translate to a warmer sounding bass; a high damping factor usually translates to a tighter, punchier bass.

-JBreezy-

[AV-OCD]

The current will flow as soon as the cone is tapped (moved). The voicecoil is moving within the magnetic field, and that generates current. You will find that the cone moves more easily without the short, but resists moving with the short in place.

Aha. That makes complete sense now.

Thanks much!