The Truth about Modern Class D

I have heard this amp touted as the best amplifier ever made. By contemporary standards it is not horribly expensive, but it is also not cheap. Through most of it’s range it was absolutely beautiful. I listened for a long time because the system sounded so good, although the soundstage was ridiculously huge, as were the speakers, so I blame them for that. If the harsh notes had happened only once or twice, I would have blamed the recordings, but I heard it again and again. I was actually left with great hope for Class D, but this isn’t the amp. I have moved to all Class A amps, I assume I am sensitive to switching distortion and Class A has no switching distortion. Class D also has no switching distortion, but there is a lot of signal manipulation going on in a Class D amp, maybe too much. This amp uses the much touted Gallium Nitride transistors, and is indeed state of the art. http://gan-fet.com/2014/02/13/rock-solid/#more-204

I am just waiting for Ralph to announce his new class D amp, hoping to try or get an early prototype, owning his AB tube amps and him betting on class D I'm sure that would be something to have. We will see. He is been pretty quiet (not like others touting whatever they sell) 

Hey @jdl57 - I have heard the effects you are talking about in a number of hotel rooms. It was poor room acoustics.

IMO, one should examine the cable/speaker impedance curve when choosing ANY amplifier. Class-D can be more sensitive due to the low pass filter.

It is true that knowing both behaviors is important, however Class D output impedance is well within the range of high quality Class A/B amps with feedback.

The Class D amps I am most familiar with have lower output impedance than most tube amps, but probably not as low as some beasts like the Codas or Sander’s with their 30 transistors per output channel. :)

Keep in mind a lot of linear amps have a low pass filter on the output to prevent oscillation. Then there is the Technics amp which actually measures the speaker impedance and compensates for it with DSP. Pretty nifty.

Best,
E

My experience with Ric Schultz’s EVS 1200 with barely 75 hours is; it is vastly superior to my previous class D amps 2 different W4S (~ 8 years ago), Emerald Physics 100.2 SEs (3 years ago), Audio Alchemy DPA-1 which I just sold to keep the 1200, and PS Audio M700s, which sounded like the DPA-1 with 2.5xs the power, which my room demands (MSRP $2999). The EVS uses 2 of the newest 600w IcePower modules, which he then does a number of tweaks to, plus other cool tweaks an Italian chassis: $2200,

If interested, I have  thread on Agon

It is true that knowing both behaviors is important, however Class D output impedance is well within the range of high quality Class A/B amps with feedback.

The Class-D output filter is RLC with the speaker providing the R. However, the speaker is not just R, but also has LC components. Like all things audio, the designer has to make choices. Regardless of how well designed the amplifier is, there will be loads with which it will not mate well.

Add in loudspeakers with crappy phase response and things could get ugly in hurry.

I think of it like putting an Indy engine in my motorhome. It's got boatloads of power, just in the wrong area. Put my motorhome engine in an Indy car and it will come dead last in 500 miles, but first in 5000.