Class D Technology

I have no dog in this discussion/fight/whatever, but FWIW I believe the statement Mr_m is referring to is the following:

Atmasphere 11-3-2016
Right now the technology is to the point where the amps have become practical for mid fi, but they still have a ways to go before they can challenge a good class A transistor amp or a good tube amp. There is no question that this is a technology to be watched.

FWIW I do not interpret that statement as "dismiss[ing] Class D
as nothing more than midfi......."  As I read the statement it does not by any means exclude the possibility that the best present day implementations of class D may be much better than mid-fi, while nevertheless not being as good as what well implemented class A solid state or a good tube amp can presently offer.

Personally I take no position on this, having no experience with class D.  But that is how I interpret Ralph's statement.

Regards,
-- Al

 

Yes, I have read this thread in its entirety. You could not have made it anymore clear. Go back to the beginning of this thread and read your own post. Not a false statement.

Obviously I could have been more clear or this conversation would not be happening!

Al’s got it right. Note where I say ’good’ twice in the statement Al is quoting.

As I have mentioned before, we’ve been playing with Class D for about the last 15 years. While I think they have gotten much better (15 years ago they were a joke) I’ve yet to hear one that keeps up with a ***good*** amplifier of conventional design (note emphasis; FWIW I’m used to listening to some pretty ’good’ amplifiers...). High end audio is pretty variable and I know of amps that are considered high end that I personally don’t think are all that good. I know of one such amp that has balanced inputs yet its CMRR (Common Mode Rejection Ratio) is about 18 which is pretty terrible if not outright criminal.

So I can see the interpretation issue. Most class D amps have specs and sound that are similar to many midfi amps (take a look at a Kenwood car stereo’s specs and compare to many ’high end’ amps and you will see that there’s not a lot of difference). Some don’t; they’re better. And they will continue to improve.

For example the scan frequency is continuing to rise. George makes a pretty big point about this. You can’t scan at 100KHz and get good high end resolution. 250KHz is in fact marginal if you really want to do it right.

As I mentioned before, you can get high power high speed output devices that switch at the speeds needed, but they cost so much right now that the resulting amplifier would be a lot more expensive than a tube amp of the same power would be (tubes are usually the most expensive form of power). So as a result no-one uses devices like that. In fact many designers simply use chip sets so they’re locked into the performance of whatever the semiconductor house provides (who rarely have audiophile interest at heart).

Just to ad to Ralph, why would Technics (SE-R1) strive to develop twice the current going switching frequency, if there was no point to it.
But you pay for this first off development $30k! But the price will come tumbling down when others adopt it. But it also still needs to be higher again.

Cheers George

Whatever Ralph meant the mid-fi comment did make me laugh knowing that the sound I hear from practical Class D amps today (like the ones I own which are neither the least or most expensive) is not mid-fi by any reasonable listening standard.

I suppose mid-fi is in the eye of the observer or the ear of the listener.

Nevertheless respected tube amp makers like Arc and Rogue have been on teh bandwagon for a number of years now knowing Class D is the ticket to get the sound their customers might like with most of the speakers out there today that are not overly  tube amp friendly. My local dealer sells Arc and Rogue (mostly tube amps for many years) and has jumped on teh Class D bandwagon even saying that the Rogue models he sells are the best sounding with the speakers popular with his customers (Magnepan and Sonus Faber).

@mapman I totally agree with the above statement. I'll also point out that Magnepan themselves say on their website to avoid Class D. 

That's why i purchased TOTL Emotiva seperates. I was confident that the dealer where I purchased the Maggies carried and recommended Emotiva as well. It sounded good when I purchased the Maggies.

Fast forward 6 months and I can truly say the Emotiva gear was mid fi. The Rogue gear outclasses in in every way. I don't care that Magnepan says to avoid Class D. They are wrong for making such a blanket statement, and I was wrong for heeding the advice.

I am finally very happy.