There are many answers to this seemingly simple question! There are some that say that a low number is just fine - I think that I read on the Gamut website that 25 is sufficient. http://www.gamutaudio.com/faq/details.asp?id=16
There are others that say, a large number is a must - the higher the better - several s.s. amps claim very high damping factors such as 500 or 800 or even 1000.
There are still others that say that DF is a complicated matter & that there is no correct answer that'll satisfy everyone. Since DF is defined as speaker impedance divided by amplifier output impedance & since speaker impedance varies with frequency, DF will also be a function of frequency. In fact, several amplifier's output impedance is also a (different) function of frequency. So, you have a ratio that has both numerator & denominator with 2 totally different functions of frequency. So, the DF curve, is at best, not drawable on a piece of paper when it comes to a real-world operating condition i.e. a particular amp driving a particular speaker UNLESS you know the exact impedance vs. frequency response of both items.
If you do, you have 1 more hurdle - what is the impedance vs. frequency response of your speaker cables? This fellow features in the mix too!
usually, a DF number is spec'd in the manual using 8 Ohms speaker input impedance. However, are any of your speakers 8 Ohms input? If they are, do you really think that they maintain 8 Ohms from 20Hz to 20KHz? what if your speakers are 6 Ohms input? then, is the DF spec'd in the manual any use to you?
So, best is to use your ears to judge if the amp connected to your speakers is providing you the bass response you are looking for. Forget chasing this spec - I believe that it has little info to offer you.
FWIW.
There are others that say, a large number is a must - the higher the better - several s.s. amps claim very high damping factors such as 500 or 800 or even 1000.
There are still others that say that DF is a complicated matter & that there is no correct answer that'll satisfy everyone. Since DF is defined as speaker impedance divided by amplifier output impedance & since speaker impedance varies with frequency, DF will also be a function of frequency. In fact, several amplifier's output impedance is also a (different) function of frequency. So, you have a ratio that has both numerator & denominator with 2 totally different functions of frequency. So, the DF curve, is at best, not drawable on a piece of paper when it comes to a real-world operating condition i.e. a particular amp driving a particular speaker UNLESS you know the exact impedance vs. frequency response of both items.
If you do, you have 1 more hurdle - what is the impedance vs. frequency response of your speaker cables? This fellow features in the mix too!
usually, a DF number is spec'd in the manual using 8 Ohms speaker input impedance. However, are any of your speakers 8 Ohms input? If they are, do you really think that they maintain 8 Ohms from 20Hz to 20KHz? what if your speakers are 6 Ohms input? then, is the DF spec'd in the manual any use to you?
So, best is to use your ears to judge if the amp connected to your speakers is providing you the bass response you are looking for. Forget chasing this spec - I believe that it has little info to offer you.
FWIW.