2 Ohm Speakers and Class D amplifiers

[Mojo Warrior]

Class D amplification is popular and tends to handle 2 Ohm speaker loads better than most A/B amps. Some amp manufacturers, such as Crown, spec their amps at 2 Ohms. Recently, innovative speaker designers (e.g. Tekton) are introducing high end speakers optimized for 2 Ohms. Many currently available speakers impedance drops below 4 Ohms.

I find this development intriguing. It appears that they exploiting the ability of Class D amps in advancing speaker design. Obviously, a properly designed Class D amp can deliver more power into 2 Ohms vs 4 or 8 Ohms. I am not a speaker designer but maybe there advantages on this side of the equation, as well. Especially when it involves the design of the crossover in a speaker with multiple drivers.

My question to the forum is: should ASR begin measuring the performance of Class D amplifiers with 2 Ohm loads, going forward ?

 

[Head_Unit]

The impedance/resistance of the speaker is in the denominator of the loudspeaker efficiency equation. That does NOT mean a 4Ω is twice as efficient as an 8Ω etc, because to lower the impedance generally means fewer turns of wire in the magnetic gap, reducing BL product which is in the numerator. But in some vague sense it is wasted resistance burning up power; if the voice coil was a zero ohm superconductor the speakers could actually be as efficient as Klipsch and Zu and etc claim . Hence we get speaker impedance creeping lower over time, and the high price of something like a 10Ω Devore O/96.

Personally I dislike this trend, as losses and heat tend to be proportional to the square of the current, a big lesson I learned from a chief amplifier engineer relaxed up by a lot of sake. That was regarding AB amps, I'd *think* it would apply to Class D or G or whatever but cannot say for sure.

In autosound, 4Ω has long been dominant due to historical difficulties in getting high voltage drive, in particular from simple power supplies. I long thought it would make more sense to have 8Ω or even 16Ω drivers with amplifiers designed for higher voltage. Then the amps could run cooler, and there would be far less strain on the battery and alternator. However the winds of history were against this, and only Rockford Fosgate had the market power to make that successful however I suppose they never thought of it.

As for "My question to the forum is: should ASR begin measuring the performance of Class D amplifiers with 2 Ohm loads, going forward ?" well @Mojo Warrior despite all I just said my vote is YES ABSOLUTELY @amirm should test at 2Ω. It would provide an interesting window into performance, short of testing into semi-inductive and semi-capacitive loads. And for car products, 8Ω and 4Ω tests are a bit ludicrous-better than nothing, but like measuring only 16Ω and 8Ω for home amps.

 

[JSmith]

My question to the forum is: should ASR begin measuring the performance of Class D amplifiers with 2 Ohm loads, going forward ?

Hypex Nilai500DIY Amplifier Review

This is a review and detailed measurements of the Hypex Nilai500DIY class D amplifier module with PS500DIY power supply. Parts were provided by the company and member @Rick Sykora was kind enough to assemble it: As indicated, the single channel amplifier is on the left and the power supply on...

www.audiosciencereview.com

JSmith

 

[Head_Unit]

Ha ha, I believe the intent of the original question was for stereo amps