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The Future of Audio Amplification

I have recently paired an Audio Research DS225 Class D amplifier with an Audio Research tube preamplifier (SP8 mkii). I cannot believe how wonderful and lifelike my music sounds. The DS225 replaced an Audio Research SD135 Class AB amplifier. Perhaps the SD135 is just not as good as some of the better quality amps that are out there, but it got me thinking that amazingly wonderful sonance can be achieved with a tubed pre and Class D amp. I have a hunch that as more people experience this combination, it will likely catch on and become the future path of many, if not most audiophile systems. It is interesting that Audio Research has been at the forefront of this development.
distortions
atmasphere's avatar
atmasphere
11,772 posts
 
And let me say, what ever you look at, these are both pathetic looking square wave shots, even for an old cheap 1970’s solid state amp to be producing,
This is the link about which this comment is made:

https://www.stereophile.com/images/1212AM1fig02.jpg

Obviously the above quote is false, being based on a Hasty Generalization:

Unless you didn't do the math, that's actually a very respectable waveform; 0.05milliseconds is 20KHz! Its pretty hard for **any** amplifier to make a good **squarewave** at 20KHz- to make it really square you need bandwidth to at least 10x the fundamental frequency.
We can see a bit of peaking in the waveform- probably the result of the phase shift of the filter, which is probably set fairly low to deal with the rather low 400KHz switching frequency; my guess is about 60KHz.

And the amplitude is pretty low, so the residual is easily seen. The residual is a bit high, about 1/2 volt. The link does not specify if the amp is under load, but if it is, then this is an older amp not representative of amps made in the last 5 years; if not under load that's quite decent despite the low switching frequency.







georgehifi's avatar
georgehifi
10,312 posts
 
Listeners having a problem with their mids and highs have a system problem not a Class D amp problem.

They don't have the problem without the Class-D in the system, are you listening to your self, and you call yourself a room tuner. I wouldn't want to guess what you do to counter the mid/high problem.
georgehifi's avatar
georgehifi
10,312 posts
 
Unless you didn’t do the math, that’s actually a very respectable waveform; 0.05milliseconds is 20KHz!
Wrong!!! look at it and think again. It’s Stereophiles, there’s your hint, they’ve NEVER EVER given a Class-D 20khz square wave, as it would look unrecognizable as a square wave.

https://www.stereophile.com/images/1212AM1fig03.jpg
And it’s slewing because of it's own switching noise output filter, https://qph.fs.quoracdn.net/main-qimg-17247bf6b43ad6bca34cf5536ad13758
tweak1
3,645 posts
 
Ric, I found it, but I don't see anything specific about mono v stereo. That said, my last 4 class Ds were monos. Only my current AA PA -1 is stereo. Too bd your amps aren't ready

I have a chance to do a swap with a guy who has the AA monos for my stereo amp +  $$$, but as class D is evolving so quickly, I am concerned that I will not be able to get anywhere near what I am paying, which is 50% off MSRP
michaelgreenaudio's avatar
michaelgreenaudio
1,019 posts
 

"are you listening to your self"

Nope, I'm listening to music and working on folks' systems who have Class A, AB and D. No need to guess George when I'm doing. Oh, and since you mention roomtune, go ahead and type roomtune into a search engine. RoomTune started with me George. How do you think the hobby got the term room tuning. Look it up for yourself in TAS, Stereophile or any other audiophile magazine when they covered "RoomTune" from 1990 on. This is where you insert your snappy put down_________:) But just remember George those magazines have already been printed many years ago. It's call audio history. You don't have to like it, just like you don't have to like Class D amps. You also don't have to like me, but your missing out on a fun audio guy.

http://www.michaelgreenaudio.net/

I think some guys here try to hard to be relevant and it causes them to become the opposite from what the hobby is and is about, the enjoyment of listening to music. I think most here have experience with A, AB and some D. And with that experience a respect is given to all the amp types. I personally think the OP is pretty clear. "the future of audio amplification" It's not a trick question, and it's not a put down for what any may like the most. Trying to tell all of us that we're going to someday see innovation stop, well that's simply not going to happen. I don't care if the next Class is W, innovation is the future.

Michael Green

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