The Effect of Damping Factor in an amplifier

[the record spot]

I was reading up on the tech specs on one of my amps, Sansui's AU-217 on an Australian website, and - as with a few of the amps in the AU range, it's conservatively rated at 30wpc (the Mk II was 40). The site then goes on to say that the Damping Factor of 80 (as per the tech spec) has an impact and hence the wpc rating is probably somewhat higher. I'm interested to know (from a layman's POV) what the DF does to the power output rating as the Wikipedia entry seems to suggest it relates more to an interaction with speaker cone movement?

 

[Craig M.]

never heard of damping factor affecting power output. maybe a low df might sound louder, due to boomier bass.

 

[Andrew Everard]

The site you were reading seems to have got itself in a bit of a twist, trs: the damping factor is purely related to how well the amplifier is able to control the speakers, and has little relationship to maximum output power.

 

[jaxwired]

High damping factors are suppose to be superior, but I'm not sure how it really translates. I've seen some amps with damping factors over 1000. Most have a much lower factor, like around 100. For some reason Naim amps are on the low side.

 

[jockey.wilson]

Damping factor is purely a relationship between the output Impedance of the amp and the Impedance of the load (ie speaker) that the amp sees.

Unless the figure quoted is against a reference (ie 8 Ohm load at say 10 KHz) it means nothing, since the impedance of a speaker is constantly changing with frequency anyway. DF has nothing whatsoever to do with power or loudness...

 

[Andrew Everard]

jockey.wilson:and the Impedance of the load (ie speaker)

Well, the speaker plus the speaker cable, actually...

 

[jockey.wilson]

Andrew Everard:

jockey.wilson:and the Impedance of the load (ie speaker)

Well, the speaker plus the speaker cable, actually...

Picky!!!

But you are, of course, correct...

 

[Anonymous]

I was reading some stuff this morning and read this.

Damping factor. The ratio of the output stage impedance and the speaker system impedance. The ideal amplifier would be a perfect voltage source to the speaker being driven by it. In the real world however, this doesn't happen, but we try and get this ratio as high as possible (so the load variation has as little effect on the output voltage as possible).

How accurate it is, I don't know, but it makes sense.

 

[Frank Harvey]

Damping factor varies depending on frequency anyway, so is a little pointless to quote unless all amps quote like for like. I usually tend to avoid the damping factor thing as most people don't know what it is, and just talk about well an amp can control speakers.

 

[MUSICRAFT]

Craig M.:never heard of damping factor affecting power output. maybe a low df might sound louder, due to boomier bass.

Hi Craig

Your SIA2-150 MK2 has enough damping factor to keep a car under control!

I have been listening to the album Programmed For Love by Bent through the QBD76/SIA-150 MK2/Dynaudio 2/7's and it sounds superb.

Btw, my demo/display SIA2-150 MK2 is very hot. Don't you just love class A biasing!

Thanks for your support.

All the best

Rick @ Musicraft