Class D amplifiers

[opnly bafld]

Damping

Butler Audio

Floyd Toole

https://diyaudioprojects.com/Technical/Papers/Damping-Damping-Factor-and-Damn-Nonsense-Floyd-Toole.pdf

 

[RVT1K]

Anything over 200 appears superfluous.View attachment 3869647

This is really interesting. What does Rg stand for?

But look at the scale, the worst case for the theoretical DF of 10 is better than +/- 1dB. I know most electronics have essentially flat frequency responses -in the audio range- but speakers never get that close. The difference seems insignificant to me..am I missing something?

And just because this thread had me wondering, I looked up the rated damping factor for my Adcom GFA555 II's and it 800 or better from 20Hz to 20kHz.

 

[Lux Man]

I am interested in thoughts about the output damping factor on these amps. Almost no manufacturers publish this information. It makes me think that they must have high output impedance. Am I wrong? You can probably tell I am drawn in some by the low price of these amps. I sent a request to support@Fosi and got a reply that indicated that they did not know what a damping factor might be.

You are worried about damping factor? You should be far more concerned with living next to the edge of the earth- the UP! Can you see it from your front porch? Gosh that must be nerve racking...

 

[Lux Man]

I grew up there. Best place in the world for a kid to grow up. Endless woods, trout streams, lakes, ski hills, and no fences for snowmobiling.

I use the Fosi MC351 but just for the TV system.

 

[whoaru99]

But look at the scale, the worst case for the theoretical DF of 10 is better than +/- 1dB. I know most electronics have essentially flat frequency responses -in the audio range- but speakers never get that close. The difference seems insignificant to me..am I missing something?

Not IMO.

I belive Rg represents the amp's output impedance that gives the DF listed, relative to 8 ohms. E.g. 8 ohm nominal load / Rg 0.8 = DF 10, 8 ohm nominal / Rg 0.08 = DF 100.

 

[RVT1K]

I understand science seldom sways one from their anecdotes/opinions/beliefs but just in case anyone is interested in a read. It's sorta long and really needs to be a complete read not just a first paragraph or two thing.

Damping Factor: Effects On System Response

Much ballyhoo surrounds the concept of "damping factor." It's been suggested that it accounts for the alleged "dramatic differences" in sound between tube and solid state amplifiers. The claim is

www.audioholics.com

The link has been posted in past threads but stuff just tends to get buried by time/new threads.

Spoiler: there is something to DF, but not really what most people think.

That was an interesting read and I found this to be particularly interesting:

However, these data do not support the assertion often made for the advantages of extremely high damping factors. Even given, again, the very conservative argument that ±0.1 dB deviation in frequency response is audible, that still suggests that damping factors in excess of 50 will not lead to audible improvements, all else being equal. And, as before, these deviations must be considered in the context of normal response variations due to manufacturing tolerances and environmental changes.

And, as you suggested, there are other factors to consider like load variation.

 

[krautmaster]

... That is great UncleAng. The perfect graph that I would like to see. That settles it, I will go for the Crown amps at DF 200. The 50 reading like the Folsi Ve does looks awful...

Looking at the graph closely, a damping factor of 10 and 20 are indeed awful, while 50 is not too bad (only 0.2 db at its worst), and 100 and up are excellent.