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

Nice to see that curve graph. I have two unrestored Yamahas that I still use, a CR-420 and CR-240, and both have the variable loudness knob. Yeah, that was kind of unique to Yamaha in the 70s and early 80s.
There were a few other manufacturers and models with variable loudness in the '70s, but, yes, only Yamaha made a habit of it.
That habit persisted for quite a while. Indeed, I actually use the loudness on this later (early 1990s), dump-find rascal (RX-570) in our "den" to warm up the rather bass-shy output of some otherwise surprisingly nice-sounding little Fostex loudspeakers.



 
Manufacturer's data for TPA3116, TPA3251 and Tripath TA2020-020, THD+noise, 1KHz c. half-power;

TPA3116 - 0.1%
TA2020-020 - 0.03%
TPA3251 - 0.005%

If these figures are remotely relevant to how good they sound then it shouldn't be a surprise that the TPA3116 doesn't sound any better than the TA2020 (ETA >> implementation , surrounding components and circuitry probably having far more bearing). I have to assume that people being impressed by 'louder' was the reason for the hype around the TPA31xx back in the day.

The TPA3251 (3250 and 3255 are similar) is theoretically, literally almost an order of magnitude better than the TA2020 and so much better than the TPA3116 it isn't funny.

So what the hell, ordering a 'Tilear' TPA3251

Come on half power thd rating says absolutly nothing. First what is half power? 2W, 20 W ,200W ?
Thd under 0.0x at a given power is useless couse nobody can hear. So adding two useless parameters doubles the uselessness. If you think this or that sounds better there is only one way. Thats a blinde test. Yes its a hard way. But the only way to go.
 
There were a few other manufacturers and models with variable loudness in the '70s, but, yes, only Yamaha made a habit of it.
That habit persisted for quite a while. Indeed, I actually use the loudness on this later (early 1990s), dump-find rascal (RX-570) in our "den" to warm up the rather bass-shy output of some otherwise surprisingly nice-sounding little Fostex loudspeakers.



I've always been intrigued by those Fostex drivers, but have never taken the plunge. Kinda have too many speakers as it is...

As to power, I will be interested how our original poster finds the amplification level of the new amp and how it compares to his prior amp. I like my A04 in the bedroom system but it definitely does not play as loud as my other D amps.

My Schiit Gjallarhorn came, using it this AM with some 6-ohm KEFs. Plays loud enough for the workroom and I've only got the volume knob halfway on the preamp. I don't hear any difference from the Fosi V3/Fosi P4 combination I was using over the weekend, but it's a nice looking amp/preamp combination. I would say this little amp is definitely enough power for a medium sized room if used with efficient speakers.
 
Of course this is what in "the old days" we more or less solved by using the loudness circuit. Those varied in quality from manufacturer to manufacturer, but it was a nice way to make a quick adjustment when playing at a lower/background level to boost the bass and treble without fiddling with the tone controls. I still rotate/use a restored Marantz 2216 and Kenwood KA-3500 just for their all-in-one convenience, and I do enjoy having that available. The built in phono preamps sound pretty good, too.

My favorite circuit of that type was in older Onkyo equipment. An old workhorse receiver, the TX-8511, had "selective tone control" that always sounded just right to my ears. Another older Onkyo that I just gave to my older son for his girlfriend's system had an interesting bass boost/slider combination as well as regular tone controls. Same kind of thing, a way to apply quickly a varying level of bass boost.

And of course we can replicate loudness today by having an alternate Equalizer APO preset for a set of speakers when playing low - but that's not as easy as just pushing a button.

Truth is, while I love all my new equipment - you just don't get as much functionality as what got packed into 70s and 80s integrateds and receivers, and for a decent price. Tape dubbing, loudness, four inputs, tone controls, balance adjustment, etc etc. The tradeoff is greater transparency, specs and flat frequency response...
I'm old enough to remember it well - I rather miss the days when you could buy affordable, rock-solid Japanese hifi equipment, beautifully built amps (and cassette decks!). I guess none of us ever thought that production and labour costs in Japan, of all places, would bring it to an end.

I'm thinking that if that little Fosi Audio preamp comes in at a good price I might get one and bypass the volume pot in the TPA3251, which would get back at least some of that connectivity and functionality (certainly such a set-up would be a 'solved problem' for my purposes).
 
you have too many speakers?!? ;)
Well, uh, yeah...not as many as some folks on here, but approximately a baker's dozen...sold two sets this year, so I'm reducing...

Let's see - in play now in the house: KEF Coda 7, KEF Q 15.2, Paradigm Titan v1, Polk Mini Monitor 3, ADS L520, Advent 5002

On the sidelines: Polk Monitor 5jr+, Elac Debut 2.0 B6.2, Infinity RS226, Baby Advent II, ADS L420, PSB R30, Polk Monitor 4

I like to rotate 'em around but I mostly have smaller rooms, so never have needed towers. The ADS L520s are in my main downstairs system and the Advent 5002s are in the basement (very occasional use but they do have a nice deep sound with the 10" woofers).
 
I quite like the ads 520. There's a pair here -- at least I think they're 520s. ;) (actually, turns out they're 570s). I like ads loudspeakers.

The Debut 2.0 B6.2 that were here are gone, though. After a couple of years of playing with them (location, sources/amplification, that sort of thing) I just resigned myself to accepting that I just don't care for the way they sound. :(

I don't think I've ever run either on a PWM amplifier, though -- just to stay even marginally, kinda sorta on-topic. ;)
 
There were a few other manufacturers and models with variable loudness in the '70s, but, yes, only Yamaha made a habit of it.
That habit persisted for quite a while. Indeed, I actually use the loudness on this later (early 1990s), dump-find rascal (RX-570) in our "den" to warm up the rather bass-shy output of some otherwise surprisingly nice-sounding little Fostex loudspeakers.



First thing my mind goes to is limited ventilation in that tight space for the receiver.
 
First thing my mind goes to is limited ventilation in that tight space for the receiver.
It's not quite (!) as bad as it looks, but we do keep the door open on the cabinet when it's running.
It gets warm, but only warm.
It's been living in there for a decade and not complained :)
This time of year, it runs ca. 8-14 hours a day, 7 days a week, playing Holiday music for the holiday season. :) It's a thing my wife and I are somewhat obsessive about :facepalm: We do have... a lot.

The little Fostex "fullrangers" are fairly sensitive and the power requirements from the receiver for background volume music to fill the main living area of the house are fairly low.
 
Come on half power thd rating says absolutly nothing. First what is half power? 2W, 20 W ,200W ?
Thd under 0.0x at a given power is useless couse nobody can hear. So adding two useless parameters doubles the uselessness. If you think this or that sounds better there is only one way. Thats a blinde test. Yes its a hard way. But the only way to go.

Well, "absolutely nothing" might be over-stating it.

Distortion appears to drop to a minimum at about 50% output with all these amps according to the data sheets, and it more or less stays there before they go into clipping (abruptly).

My TA2020 is probably spending most of its time in that optimal range producing single-digit watts (0.03% THD). At the same levels/SPL's the more powerful TPA3116/3118 will be producing more distortion than its 0.1% minimum, which might be as much as 10x the 2020's, and that might be at least part of the reason I didn't find it as good.

The TPA32xx produces less distortion at all levels than the TA2020 (never mind the TPA31xx), which is why I've decided to give a TPA3251 a go.
 
I'm old enough to remember it well - I rather miss the days when you could buy affordable, rock-solid Japanese hifi equipment, beautifully built amps (and cassette decks!). I guess none of us ever thought that production and labour costs in Japan, of all places, would bring it to an end.

I'm thinking that if that little Fosi Audio preamp comes in at a good price I might get one and bypass the volume pot in the TPA3251, which would get back at least some of that connectivity and functionality (certainly such a set-up would be a 'solved problem' for my purposes).
I'll let you know if I hear what they are thinking of in terms of price. They haven't mentioned yet. It's a nice little unit, I have to say. The only thing I mention in my review that I didn't love was that the volume control was a little less sensitive in the early part of its scale - when playing low volumes. But if used in combination with an amp that also has a volume control, it's easy to dial in to just the quiet level you want. The remote works well.

The volume knob on the V3 is a bit more gentle coming up from 0. If the volume on your new amp is like my A04, it should also be OK for you - I think it is still a log pot, but it has a lot more soft level control than the A07. And I'm using a 32v power brick with it...

Yes, it was a lovely time then (70s) too to enjoy audio - hence why I do keep a lot of vintage equipment going, I've just pulled back and gotten a bit more selective. Bought too many things and backups for things a decade ago, still weaning some of that down. With the cassette decks, I don't feel too bad about the reserves, as they just don't make those like they used to. I marvel at how well my lower-level Nak decks keep running - they are amazingly resilient if they just get some use at least once or twice a year...
 
Looks like I almost certaiinly need more than 19.5 volts for the TPA3251, it would work but apparently the 12V convertor (for the preamp stage) on these amps is optimised for the 'recommended' supply and they get noisy if it's much lower. Now eyeing the Farnell catalogue for 32V c. 5-6A supplies, they pretty much start around the £60-70 mark, more than the amp. I'd be rather less comfortable leaving it powered on permanently like I do the TA2020 and its 13.5V, but maybe OK with a medical grade PSU?
 
Just to re-iterate;

has anyone else ever found that their audio rigs, while kicking-ass at 'realistic' SPL's, are just flat, un-detailed and boring when they try and listen at levels that don't make crockery rattle and antagonise their neighbours?

I can't believe I'm the only one.
Yes, I used to feel the same way as well. |Much less so now though because my main criteria for choosing between audio components for the last many years has been how they sound at pretty low levels, which is admittedly harder than just turning the volume up.
 
I just have a suspicion that the cheap D-amp chips from TI and the like don't scale particularly well, or at least they have a range of output levels where they work best that's proportionate to their rated output or supply voltage.

Admittedly my experience is limited, but when I tried out some TPA3118's back in the late 2010's which everyone said were a major upgrade from the TA2020 ... they weren't - they could go louder but none of them were anything like as good as the Indeed TA2020 I've gone back to at 'calm' or 'late night' volume levels. And I've got a box of PSU's, the largest being 19.5V which will give me all the SPL's I need but won't power a TPA3255.

I don't want or need an amp any louder the TA2020, it would just be nice to have a bit more headroom for non-brickwalled recordings.
If you want to be an oddball and stay with something old, small and musical you might, if using digital inputs, try one of the little STA326 chip based amps such as the Alientek D8 which I much preferred to those Ti chips. On the other hand something modern like the Fosi V3 monos can deliver stupid amounts of power but also doesn't lose anything to those old Tripaths or STA chips for low level musicality either - so we don't have to continue being dinosaurs :)
 
Well, "absolutely nothing" might be over-stating it.

Distortion appears to drop to a minimum at about 50% output with all these amps according to the data sheets, and it more or less stays there before they go into clipping (abruptly).

My TA2020 is probably spending most of its time in that optimal range producing single-digit watts (0.03% THD). At the same levels/SPL's the more powerful TPA3116/3118 will be producing more distortion than its 0.1% minimum, which might be as much as 10x the 2020's, and that might be at least part of the reason I didn't find it as good.

The TPA32xx produces less distortion at all levels than the TA2020 (never mind the TPA31xx), which is why I've decided to give a TPA3251 a go.

See you want a lot from others.1)Reading the Data sheets of 3 chips that are usually not of much use couse the implimitation counts. We dont know that specific implementation.
2) Knowing at what Watt you listen?

but ok lets forget this. The hard part comes.
Imagine that a person can heare for sure a thd difference of 0.1 to smaller than 0.1. Thats very hard for me to imagine this. Did you ever test this?

Dont think the tpa3251 is a bad chip. But the reasoning? Mhhh??

Btw. have a nice christmas!
 
Yes, I used to feel the same way as well. |Much less so now though because my main criteria for choosing between audio components for the last many years has been how they sound at pretty low levels, which is admittedly harder than just turning the volume up.
An indicator to me that things are right is not getting the urge to keep cranking SPL's up, whether in-room or though 'phones. For example I once sold a Creek headphone amp because a quick A/B'ing (with HD580's) convinced me the headphone-out on the Rotel integrated was good enough - the result was constantly turning up the volume and then losing interest in listening through 'phones.

I bought the Indeed after trying out the infamous Lepai for a giggle (also got a couple of SMSL's which were meh, and briefly tried an Amptastic in an effort to better the Indeed - it was as good but not better). It was quite memorable firing it up the first time (at that time with an Asus Xonar Essence STX), what was going to be a shuffle through tracks ended up being the first album I cued up, Talk Talk's Spirit Of Eden, from beginning to end, it was that good. ETA >> this was while I was trying to de-clutter my whole PC/media player system back in 2012 and it ended up replacing my Rotel RA820BX4.
 
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Looks like I almost certaiinly need more than 19.5 volts for the TPA3251, it would work but apparently the 12V convertor (for the preamp stage) on these amps is optimised for the 'recommended' supply and they get noisy if it's much lower. Now eyeing the Farnell catalogue for 32V c. 5-6A supplies, they pretty much start around the £60-70 mark, more than the amp. I'd be rather less comfortable leaving it powered on permanently like I do the TA2020 and its 13.5V, but maybe OK with a medical grade PSU?
Didn't know that about the preamp stage, but I think you are probably right. I think 32v with 5-6 amps is a good power point for these amps. 32v ok as well.

I think a medical grade supply type PSU is safer to leave on, if you have some sort of casing for it and/or good protection for the wire leads... What is your reason for leaving the amp on all the time? Folks here go back and forth on that issue... I understand the off/on lifespan point of view. As for me, I power a system on in the morning generally and turn off when I am done for the day with it, but I don't leave running all the time. I've had only one brick problem with the D amps, a 24v 5a supply for one of my SMSL SA-50's from years ago - it developed a squealing sound, but didn't overheat, but I retired it nevertheless. The latest power bricks that came from Fosi and Aiyima have presented no problems thus far.

The whole SPL/watts race on these amps is just kind of silly marketing in my view...each of the makers trying to emphasize what they think will push the most units. Same with the op-amp swappability. These are very good little amps for the 50wpc - 75 wpc normal type of listening, for people really wanting to play at 110db they should be spending up and buying a Hyex or Purifi amp, or a modern Class AB amp. They are still good products for most listeners, hype on the specs aside.

I agree with those on the board who continue to point out that the power ratings for them are overstated, but I differ in that I think that does not make them toys or junk. Will they last as long as an old 1970s class AB amp? Probably not, but we don't know. We're likely to get more use out of each amp than the lifespan of our cell phones, at least.
 
There's a point where you can expect too much at once for very little money. Power, quality, longevity, customer support, all at once? Maybe it's worth a consideration going a step up, save some money, get a basic Hypex poweramp or AB Yamaha integrated for 500 moneys for example, and be done with it for years.

I perfectly understand a low money situation, but there's a point where an investment is very much worth it in terms of cost over time, with continued satisfaction. I'd say 500 moneys (€$£) is exactly that point.
 
There's a point where you can expect too much at once for very little money. Power, quality, longevity, customer support, all at once? Maybe it's worth a consideration going a step up, save some money, get a basic Hypex poweramp or AB Yamaha integrated for 500 moneys for example, and be done with it for years.

I perfectly understand a low money situation, but there's a point where an investment is very much worth it in terms of cost over time, with continued satisfaction. I'd say 500 moneys (€$£) is exactly that point.
I guess as much as anything it's the always-on capability these D-amps have, 'idling' they draw a couple of watts at the wall. As I mentioned earlier, for almost a couple of decades I've been leaving my PC and most peripherals powered on 24/7, practically 24/365, and in that time never had a hardware failure of any kind, even of HDD's - I have a couple of pairs of 500GB and 1TB that ran in RAID 0 continuously from c. 2012 until 2020 (you can see the hours in the SMART data) and they don't even have any reallocated sectors, in fact I'll occasionally plug one of them to a SATA hot-swap bay to use as a scratch disc. Power and thermal cycling is what will usually cause failures IMV.
 
With all this talk about the relative power, cost and value of chip-amps, we must keep in mind that truly high-power stereo Hypex amps are available today for ~$700 that give 380 watts into 8 ohms, which can power essentially any speaker.

What a wonderful time! Chip-amps give us 50 -100 watts (8R) for under $300, and ~doubling that cost gives you all the power you would ever need. :cool:
 
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