Class D is just Dandy!

@merrillaudio,

Thank you you for taking the time to share great insight on Class D amplification. A bit of clarification on couple of things, in your comments, 

"Class D tends to be fast, unless slowed intentionally or with a tube"  - Are you referring to mating Class D with a tube preamp/Linestage?

In reference to above comment, the end user should be able to reduce "Coherency Distortion" issues with a tube pre as pointed out in your Synergy 2 paragraph, right? 

I have been experimenting with Tube/Class D amps in a bi-amping setup with Tube preamp. It hasn't been easy as I intentionally chose not to add any external crossover or gain switch in the signal path.

I do feel I am very close to the attaining that perfect synergy of Tube's lush mid range and Class D's prodigious slam in the low end.

Cheers!  

@lalitk I've a tube pre used in conjunction with my class D monoblocks. I absolutely love this combo. Beautiful, lush detail with loads of power and control. 

If you don't mind me asking, how the heck are you going to bi amp without a crossover? I do hope you get there..

Just about a month after getting my first class D, I now have two. I love the Primare I32; but it has no acceptable option for headphones. So I got a little Topping TP30 Mk2 which accepts input from the I32's Pre-out and has headphone and speaker outs. I can connect conventional headphones in the conventional way and my Stax electrets to the speaker terminals. It works and sounds quite nice, except the I32 does not have a speakers on/off switch, since it only has one set of outputs. I need a quick, convenient way to disconnect the main speakers, which are bi-wired and a PITA to connect via bare wire, without compromising the 12G speaker wire. As much as I wanted to avoid bananas, I ordered some stackable ones yesterday.

Hi @merrillaudio

Welcome. I'd like to ask you a few questions about what you pointed out.

However as with all transistors, there is a lag between the command to switch and the actual full switch. This is call the dead time. This has been reduced over the years with faster transistors and also limited with feedback. But it is fast. Hence the apparent speed of Class D also.

Sorry, could you be mistaking "switching time" with "dead time?"

As I understand, you are talking about switching time. How long to go fron on to off, or vice-versa.

I think "dead-time" is a little different. As I understood, the problem with bi-polar PWM amplifiers (uses + and - V at the transistors) is that you must NOT have the positive and negative sides on at the same time. This affects both efficiency and distortion. I link Wikipedia and a B&O brochure discussing it. (The PDF is a little easier to get).

https://granitedevices.com/wiki/Dead-time_distortion

http://www.icepower.bang-olufsen.com/files/solutions/iceedge_brochure_final_20150624.pdf

By the way, this issue with multiple transistors being on at the same time plagued Carver for many years. :) but in his case, he was switching among multiple voltages of the same polarity. Eventually it was solved by reducing the switching speed.

Best,

E

FYI,

Found some good references re: Damping factor and speaker sound quality and posted here:

https://forum.audiogon.com/discussions/measurements-clearly-explained

Best,


E