Expanding the Class D Conversation: How Would You Characterize Their Differences?

provide a profile of an ideal speaker to match up with his Class D monos. What would an ideal speaker profile spec [or range] look like?

@decooney That depends on the class D. Amps of the non self-oscillating variety probably should not be connected to ESLs since they might go into oscillation due to an interaction with the filter choke at the output of the amp. Self-oscillating amps like ours, Orchard, Hypex or Purifi do not have this problem. 

I don’t really care what the amp is; all amps have less distortion when driving an easier load and yes, you can hear that difference in distortion (smoother and more detailed with less distortion...). Speakers of lower efficiency often have thermal compression problems that are less or non-existent with more efficient speakers (ESLs being an exception since they don’t have a voice coil).

So I’m of the opinion, based on experience, that if you want the best out of your amplifier investment, that you should avoid lower impedance and lower efficiency speakers on general terms. 

You don’t lose any resolution with higher efficiency. You just get a more dynamic presentation. 

Like most other solid state amps our class D is fine with 4 Ohm speakers. But also with any 4 Ohm speaker, your speaker cables will be more critical and it will be a good idea to keep them short! This is the reason we made monoblocks and have a balanced connection, so you can minimize speaker and interconnect cable interaction with the sound of the system.  

Finally, people ask us all the time if we will make a more powerful amp. We just might, but I’d like to point out a simple math issue. If you can’t make your speaker fly with 100 Watts, you won’t do it with 200 Watts either. You’re going to need an amp that makes 10X more power (1000 Watts if 8 Ohms, 2000 Watts if 4 Ohms) because you need a 10dB increase in power for the presentation to sound twice as loud. IMO such speakers are impractical.

To understand this better, a 3dB increase in volume requires double the power. That increase is barely noticeable to the ear. 6dB is more easily noticed and requires a 4x increase in power.  For the most part, the bigger you make an amp the harder it is to make it sound like real music. 

So you do yourself a big favor by working with speakers that are easier to drive.

When you don't have a hammer, you avoid nails 🙂

@devinplombier That is less than generous. Ralph has always been straight with us. 

The problem with more efficient  speakers is they tend to also be bigger and heavier ie not practical for most. 
 

Some like Fritz are designed to be easier to drive yet not necessarily efficient. 

I’ve found good quality Class D amps help me out a lot by being very efficient at driving a broader variety of speakers well.

@markmuse wrote:

Ralph has always been straight with us.

Absolutely, and I always enjoy his contributions even in those times when we don’t share the same point of view.

My comment wasn’t directed at him, but rather at the speakers-my amps-can’t-drive-shouldn’t-exist crowd.

I firmly believe that if there is a single hifi component that should be chosen strictly on the basis of their end sound, it is the speakers. And if it just so happens that your choice likes to wallow in one-ohm territory, the correct response is to buy amps that are comfortable driving one-ohm loads.

Hope this clarifies things a bit 😃