Damping Factor - Interesting article

I posted this link on the Class D thread. A few questions into the interview Bruno Putzey talks about DF.

Does the high damping factor of class D amplifiers negatively affect the subjective sound quality of some types of speakers 

https://audiophilestyle.com/ca/bits-and-bytes/purifi-audio-and-the-audiophile-style-readers-qa-with-...

No offence to Bruno, but he doesn't sound like a very deep expert on transducers, but this is a critical point:

Crossover filters are simply designed with the assumption of a voltage source. It’s a matter of standardisation. Otherwise how this particular speaker sounds when connected to that particular amp becomes rather unpredictable.

It is one of the reasons active speakers have design flexibility that simply don't exist in traditional amp/speaker combinations.

How low? For electrical damping of 8ohm speaker difference between DF=10 and DF=100 will be like 6.8ohm vs 6.08ohm (assuming 6ohm as resistance of 8ohm coil). It is about 12% difference in breaking current.

Not to steal Atmasphere's thunder especially when I stuck my foot in my mouth yesterday, with current drive for speakers, impedance is infinite, but ideally you want a trade-off, so to atmasphere's point, you can use a combination of voltage and current feedback to achieve something close to constant power irrespective of impedance, but for that to work, you need drivers that match that characteristic.

It is possible to make amplifier like that, but I found only car amp that delivers constant power:

https://www.crutchfield.com/S-W0uT7l6IaIv/learn/amplifier-power-labs.html#:~:text=Constant%20Power&text=Normally%2C%20an%20amplifier%20will%20change,impedance%20changes%20happen%20during%20play.

@kijanki  @roberttdid was referring to the idea of an amplifier that operates as a power source rather than a voltage source.

Otherwise how this particular speaker sounds when connected to that particular amp becomes rather unpredictable.

Regarding Bruno's comment from the link above, speakers designed to operate in the Power Paradigm usually have level controls for the midrange and tweeter, as the voltage response of the amplifier is an unknown. If you look on speakers made in the 1950s these controls are fairly common. They are not there to help set up the speaker in a given room!

@atmasphere  That's how they describe this car amp:

Speakers and subwoofers change their impedances depending on what frequency note is playing. Normally, an amplifier will change its output power according to what impedance it senses. The Constant Power circuitry Rockford Fosgate developed changes all that, allowing the amp to put out exactly the same power no matter what impedance changes happen during play.

The constant power delivery doesn't necessarily mean it is maximum power (maximum power is delivered only when load impedance is the same as the source impedance).