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Switching/D-class amps and their supposed improvements over the years;

Mark S.

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I can remember when the Texas Instruments TPA31xx series chips arrived in the mid-2010's and people exclaimed that they were so much better than the Tripath TA20xx that it was a no-brainer to chuck out your Tripaths and get hold of the latter former.

A few short years later the TI TPA32xx series arrived and ... who cares about those "old" TPA31xx amps anymore? Chuck them out and get the newer ones.

Really?

I still have an Indeed TA2020 (the best of several I tried) which, to me, remains unmatched in creating space, detail and dynamics at (I would guess) sub-90dB levels in my listening space, an apartment in a converted Victorian building with nearly 3 feet of rock wool between floors and substantial masonry between me and the dwelling next door, IOW at levels which allow me to remain on good terms with my neighbours.

So my question is; APART from the "realistic" or wedding/bar mitzvah party SPL's which the newer chips can summon, in what ways have have D-class amps actually improved in the last 20 years?
 
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I'm seeing 3 things.
1) more power. You can get 200-500wpc at 8 ohms. Where as with a/b amps you are typically looking at 80-180wpc at 8 ohms.
2) cost. they are now relatively affordable and you can find great measuring and performing amps in the sub $2000 range for 2ch
3) linear frequency response. They have solve the problem where the frequency response and thd would change change with frequency coloring the sound.
 
When I say the old TA2020 is "unmatched", I mean compared to a couple of TPA3118/3116's I tried, but more importantly to the Rotel RA820BX4 (a pristine example) I'd been using for a few years previously back in the day, an amp which was very well-regarded for its resolution at low volume. It wasn't even close in terms of the 'space' created around the speakers. And no, this was NOT a matter of "rising treble" in the TA2020 or some such.
 
I'm seeing 3 things.
1) more power. You can get 200-500wpc at 8 ohms. Where as with a/b amps you are typically looking at 80-180wpc at 8 ohms.
2) cost. they are now relatively affordable and you can find great measuring and performing amps in the sub $2000 range for 2ch
3) linear frequency response. They have solve the problem where the frequency response and thd would change change with frequency coloring the sound.
1) I don't need more power
2) I paid c. £30 for the Indeed TA2020 (without PSU) as I recall
3) dunno
 

Amps haven’t evolved that much even from the very beginning beyond what @Beershaun mentioned in his post.
 
I would be quite surprised if that cheap little low power amp can compete with newer designs in terms of noise/distortion, nevermind power. And it almost certainly has the serious load dependency that all early class D designs suffered from (and many still do today without PFFB).

However, if it is working fine for you and you don't notice any improvement in your setup with your listening habits with newer equipment, no one says you have to upgrade. There's a difference between whether there have been improvements, which there have, and whether those improvements are relevant for your situation.

It doesn't actually look like you've compared to any modern designs, though? That Rotel you mentioned is from the early 90s from what I can see. In any case, with modern electronics you generally will have a hard time telling any of them apart since they generally do their job of getting the signal from the source to the speaker without audible noise or distortion affecting the signal.
 
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I would be quite surprised if that cheap little low power amp can compete with newer designs in terms of noise/distortion, nevermind power. And it almost certainly has the serious load dependency that all early class D designs suffered from (and many still do today without PFFB).

However, if it is working fine for you and you don't notice any improvement in your setup with your listening habits, no one says you have to upgrade. There's a difference between whether there have been improvements, which there have, and whether those improvements are relevant for your situation.
Quite so, but I'd be interested in an amp with more headroom than the TA2020 but keeps 'the magic' at the watts/SPL's in question.

The impression I get is that D-amps haven't scaled that well from the Lilliputian early designs which had resolution at very low levels thanks to the absence of the two-transistor crossover of B-class, IOW they emulated low-power A-class/single-ended amps
 
On the other hand, the prices would make this a pretty cheap experiment for you. Buy a Fosi V3, or an Aiyima A07 MAX, or the latest PFFB-based ones, and give it a try in your home. If you don't like it, return it or sell it off.

I still have and sometimes use a 10-year old SMSL SA-50, which I think had a 7492 chip in it. It plays LOUD with only a 24v5a power brick. And still sounds just fine to my 66 year old ears.

But the newer amps do sound really good. The two I mentioned above have tapered volume pots/control, rather than log, which to my mind is one of their best features. Much easier to dial in low to mid volume range than with the log pots.

Fosi is releasing a new, nice matching 3-input RCA preamp with tone controls soon, which I am beta testing for them. It makes a nice paring with the V3 amp and includes a good remote.
 
On the other hand, the prices would make this a pretty cheap experiment for you. Buy a Fosi V3, or an Aiyima A07 MAX, or the latest PFFB-based ones, and give it a try in your home. If you don't like it, return it or sell it off.

I still have and sometimes use a 10-year old SMSL SA-50, which I think had a 7492 chip in it. It plays LOUD with only a 24v5a power brick. And still sounds just fine to my 66 year old ears.

But the newer amps do sound really good. The two I mentioned above have tapered volume pots/control, rather than log, which to my mind is one of their best features. Much easier to dial in low to mid volume range than with the log pots.

Fosi is releasing a new, nice matching 3-input RCA preamp with tone controls soon, which I am beta testing for them. It makes a nice paring with the V3 amp and includes a good remote.
I'm sort of hoping to find an amp all these years later to match the TA2020 at the levels I usually listen but which I might be able to head-bang to when the neighbours are away.
 
That's an odd thing to say. ETA >> what words would you use to describe good sound from a hifi?
It's the source of those descriptions from an amp that are odd. Not necessarily your subjective experience. Those are more functions of the recording and speakers/room.
 
It's the source of those descriptions from an amp that are odd. Not necessarily your subjective experience. Those are more functions of the recording and speakers/room.
Certainly. I'm not rich enough to be an audiophile or even enthusiast, but these are the speakers I've used over the last 10 years or so;

- Wharfedale Diamond 9.0 (original series with die-cast speaker baskets)
- Q Acoustics 2020
- Roth Oli RA1
- JBL Control 1 Pro (ahem - no thanks)
- Another pair of Diamond 9.0's, post c. 2018 after Wharfedale's oddly un-remarked on bait-and-switch in substituting moulded plastic speaker baskets for the aluminium ones (0.5kg lighter per speaker)

The listening space has remained pretty much the same, and it's admittedly small enough to make power requirements somewhat moot, but I'm probably in the majority in that respect.

I'm now back with the Roths (the Wharfedales and JBL's are in the wardrobe).
 
Forgot about the NAD-badged KEF's I got at a charity/thrift shop, late 1980's AFAIK, restored and re-capped them, stripped the tweeters to replace the ferro-fluid (it had vanished leaving some goo behind). They actually sounded rather good, sold them to a friend in need for a song.
 
OnlCertainly. I'm not rich enough to be an audiophile or even enthusiast, but these are the speakers I've used over the last 10 years or so;

- Wharfedale Diamond 9.0 (original series with die-cast speaker baskets)
- Q Acoustics 2020
- Roth Oli RA1
- JBL Control 1 Pro (ahem - no thanks)
- Another pair of Diamond 9.0's, post c. 2018 after Wharfedale's oddly un-remarked on bait-and-switch in substituting moulded plastic speaker baskets for the aluminium ones (0.5kg lighter per speaker)

The listening space has remained pretty much the same, and it's admittedly small enough to make power requirements somewhat moot, but I'm probably in the majority in that respect.

I'm now back with the Roths (the Wharfedales and JBL's are in the wardrobe).
Don't have to be rich to be an audiophile, as all the term means is you're basically an enthusiast of accurate audio playback. If you're involved in other aspects of production, maybe something else could be in play. Generally you want the best speakers you can get for your use/space IMO. I've got a variety of JBL stuff myself.
 
I guess the basic thing I'm trying to ascertain is which of the current crop of D-amps (under maybe £100) is known to work well at low power/SPL's, which over the years I've found to be one of the biggest variables (with Olde Worlde A/B integrated's in particular). As I've said, the TA2020 I'm using is just superb at low levels and although I rarely have the need for more power, a few more dB of headroom would be nice to have for older, un-brickwalled recordings.

I've been looking into fully-built TPA3250/3251-based amps (I have a couple of good Sony 19.5V PSU's I grafted 5.5x2.1mm barrels onto I'd like to use and they wouldn't power TPA3255's as far as I can tell) but they seem to have disappeared (there was an Aiyima A04 and another IIRC from SMSL, but no longer made).
 
I've been looking into fully-built TPA3250/3251-based amps (I have a couple of good Sony 19.5V PSU's I grafted 5.5x2.1mm barrels onto I'd like to use and they wouldn't power TPA3255's as far as I can tell) but they seem to have disappeared (there was an Aiyima A04 and another IIRC from SMSL, but no longer made).

I think 3e Audio is coming out with some 3251-based amps, A5 line?

 
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Yes, those new 3e ones look good. But on a budget, either the Fosi V3 and Aiyima A07 MAX are also good & high-value "all in one" choices. The volume control at softer levels is very good on each of them. Most of the treble rise that gets so much attention here is over 10,000hz which is near the threshold of my hearing anyway - and many speakers tame that anyway, I believe.

A 36v 6a power supply is my preferred brick for these, they still can go plenty loud and that power level doesn't push the amps too hard.

The new Fosi preamp, or another preamp in the chain, can of course assist with volume.

I am waiting on a Schiit Gjallarhorn class AB amp, I finally broke down and bought one to pair with a Saga 2 preamp. Those two units are about $630 all told. Will be interesting to see if I feel gives any difference from the various D amps I own. Kind of an expensive experiment, but I was intrigued by the application to my nearfield setup, where I definitely don't need a lot of power.

You've got a lot of options - I think you could improve your sound just a bit, but everyone's audio perceptions are unique...
 
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