There was also Dr. Tripathi's Class T amp for high efficiency speakers. Very low distortion, low noise, low cost and sound quality so good that the big chip brand who acquired the patent for the TA2020 chip deliberately killed it.
I built a Class H amplifier for use on 12volts ... it used a Philips IC with all the necessary circuits built in ... it sounded great ! It delivered 70 watts into 4 ohms
Another good one that has been on my mind recently as well! Thanks Paul! I have a Class H Technics unit stashed away, I believe circa 2001. I should put it back into daily commission for a quick minute and get a feel for it again.
Its a gem. Class H is awesome. You will find a BASH chip on the heatsink inside, who developed the Class H. It has a class D power section, with an AB amplification section. High efficiency, sound of AB. No longer around, but the BASH technology was the pinnicle of audio reproduction at efficient power levels.
Many pro audio amplifiers have a class H topology. QSC is a prime example. Repairing them is a nightmare due to the multiple voltage rails available to the amplifier and the feedback circuit used to switch rails.
Totally unnecessary. The reason they are using multiple rails is because there is a company that owns the actual rights to the real tech called BASH. They use a Class D power section, with a Class AB amplification section. Small parts count, higher efficiency, retains Class AB sound. Nobody wants to pay for the licensing fee, so this is just away around the patent / fee. Open up an old school Technics and you will find a BASH chip on the heatsink, and a VERY low parts count, smaller transformers, etc.
well technology has always been changing.... qsc was in the game early and their power sections have improved over the years. Of course Class d Topology will always win in the efficiency war. Still class AB is used widely in pro audio but digital amplifiers have grown with the industry. Yes Bash does have some IP in the digital amp game but so do others such as ICE and Powersoft.
Here in philippines, class H power amplifiers are famous. They are used in big mobile sound systems and mini sound systems. Many manufacturers here makes class H power amp that can produce over 20,000 watts rms......
Complimenti per il video, posseggo l'amplificatore Pioneer A-70 vintage anno 1983 dynamic power non switching in classe H , 2x120 watt rms su 8 ohm e 2x 320 watt rms su 4 ohm , ha un suono cristallino ,completo e con bassi potenti
Bob Carver used class H in his tfm line of amplifiers. I currently own an AV 705x 5 channel amplifier for home theater. I've had it since 2003, bought it used and it's a workhorse. 125 watts channel 5 channels driven. I can crank that bad boy all day and it only gets warm.
There is still a large market of Class H in the Philippines, there’s this event called Battle of the Sounds, hard-kick bass lovers. All use Class H of 1800W RMS, 2500W rms and 10000W peak.. using 20000Wpeak speakers just for 15” 😅
Interesting, I can imagine a multi-taped power transformer generating several rails, however swapping from one to the next would be tricky, swapping cleanly between the two sides of a class AB, without generating crossover distortion is bad enough, but then stepping through many supply options for the output stage - wow.
Both my Hitachi HMA-8300 class D amps sound great after 40 plus years. I use them as subwoofer driver amps in my system and they do their job well there.
amazing job translating tech talk to understandable explanation! Thank you Paul. Some comments on here surpass the goal, it's not about being over correct, yet is is about making the basics understandable. I very much like the amp being a 'valve' as it effectively just is. See the electrons flowing through the channels of the conductors :)
Hi i'm from the philippines here we still use class h and ab amps although most of them here are used in large PA systems only a few are class d but mostly used in smaller systems
Sorry Paul that's not right here are the definitions of class G and H . Class-G amplifiers (which use "rail switching" to decrease power consumption and increase efficiency) are more efficient than class-AB amplifiers. These amplifiers provide several power rails at different voltages and switch between them as the signal output approaches each level. Thus, the amplifier increases efficiency by reducing the wasted power at the output transistors. Class-G amplifiers are more efficient than class AB but less efficient when compared to class D, however, they do not have the electromagnetic interference effects of class D. Bob Carver's "Magnetic Field Coil "amplifiers were one of the first class G way back in 1978 .. Class-H amplifiers create an infinitely variable (analog) supply rail. They are sometimes referred to as rail trackers. This is done by modulating the supply rails so that the rails are only a few volts larger than the output signal "tracking" it at any given time. The output stage operates at its maximum efficiency all the time. Bob Carvers "tracking Down Converter "power supply amplifier is class H and was one of the first to implement it with his Light Star amp back in 1995.
Problem is: Paul assumes that all his subscribers are stupid enough not to go in deeper technical details. If it's not so, then Paul has very shallow technical knowledge and that's what I suspect about him. He is first of all a salesman.
Yes, Paul described class G , not Class H. But I though the Carver Mag Field design was class H where he used a primary AC thyristor power supply to modulate the rail voltage. Very basically putting a light dimmer on the power transformer primary. This is a crude switch mode power supply in that a thyristor or Triac is a switch that chops up the AC sine wave. You could build class H with a modulated linear power supply but then what would be the point. You would just be moving the inefficiency to the power supply versus the amp.
@@andydelle4509 Carver used the "magnetic field" term on more than one design, and they are actually quite different implementations. In my opinion, he was rather notorious for not divulging any detail about how his designs actually worked, instead using rather general top-level descriptions that tended to disguise the inherent "Achilles heels." One design used the thyristor in combination with a power transformer that operated in saturation. Another didn't have the thyristor stage, but did use a bank of switching FETs to modulate the supply rail over a wide range. Of course the latter design gives the supply rails much better agility for tracking the audio signal. He also produced some Class G designs, such as a receiver equipped with both +/-40V and +/-60V rails, with power transistors which switched between them as needed.
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An indian amplifier maker named ahuja still makes class ab & class h amplifiers for dj and pa. They have amps ranging from 30w rms to like 15kw rms. And really expensive cuz it comes with a big fat transformer and toshiba 2sc5200 bjt & typically makes their circuit capable of twice the rated power.. I have a 45w one and they r using dual 150w capable transistor for a 45w rms amp and it delvers more than rated. And has very little distortion & sounds amazing. I was a bit worred about their quality cuz the price was cheaper than car headunits & so i was expecting fake numbers & poor quality but after getting it & taking it apart i am genuinely impressed by the quality of components and its all assembled by hand and tied up well.
Yes, class H is still been today, more so for RF amplifier where you very good linearity with good efficiency, this why I am using class HQ in my newer RF designs. That way I can get the linearity with class Q at the same time I control the supply rail in class H for the efficiency, so I get best all round performance possible.
QSC budget PA amps are class H. The cheapest being their GX series and their PLX series being a step up from the GX series. I switched from a Technics AAA amp that I bought in the late 1980s to a QSC GX5 that I bought more than a decade ago. Mainly because my Technics puts out something like 110 watts and my QSC puts out 500 watts. Because I went from a pair of JBL L100 (12" woofer) bookshelf speakers to a pair of JBL MP415 (15" woofer) bookshelf-sized PA speakers about 20 years ago maybe longer. JBL MP415 28.3" H x 18.2" W x 15.1" D JBL L100 23.5" H x 14.25" W x 13.625" D (I Googled the dimensions of the MP415 and the L100 because it's easier and because I sold my L100 speakers.) It was going to be a temporary solution. But to me, the QSC amp sounds just as good as the Technics amp. So I've never upgraded my PA amp to a hi-fi amp.
I own a Sony S master bookshelf stereo that supposedly has a G/H amp in it. This is a fairly new unit, I believe around 2013. It's an IC, not discrete components. It has what looks like a standard audio amp IC, then has another large IC that is the power supply controller. From what I read there isn't necessarily a delay to ramp up supply voltage/current since the feedback from the amp IC is what controls the power supply chip. The ramp up/down is instantaneous relative to the signal input. The specs I found online rate the amp chip at something ridiculous like 80w RMS per channel assuming it is fed with a large enough power supply. In the small form factor of mine I believe it's more like 20 per channel. It sounds fine but definitely not comparable to a true A/B design
I'm a bit confused because if Class H has been supplanted by Class D, then why does the Benchmark AH2 100 watt per channel perform so superlatively in terms of measurements and sound quality? I haven't heard them myself, but it is frequently lauded as good or better than any high end amplifier. Also it seems that most high end and ultra high end amplifiers, I've looked into are still mostly Class AB.
Seems like a lot more can go wrong. Less wire, less trouble. My ears never cared about class anyway. Thanks for the in depth explanation. Someone gave me a Panasonic receiver and I noticed Class H on the face, that's what brought me here. Doesn't sound any better than any of my 70s Sansuis.
I have a class H amp 1800w x2 8ohms 2400w x2 4ohms loaded with 4 1200w max power crown jack hammer speakers. 2 speakers per channel. I have two of it which means i got 8 speakers for bass only. It is hooked in a modified L36 box. And im happy coz the amp doesn't heat that much even in a full volume. But i usually play it at 1 o'clock to 3 o'clock volume position only for safety.
@@FSXgta I know you're commenting tongue in cheek... however, fwiw; A 20 amp circuit can pass 7-8 times the rated 20amp trip amount, .. for up to a second or more. It will allow up to 3x the rated amount for up to 10sec or so. And most importantly, the same 20amp circuit, can allow up to 1.5-2times the rated amount for a period extending as long as 30 seconds. That's over 100amps for around 1-2 seconds, about 60amps for around 10 seconds, and the circuit will allow 30-40amps for as long as 30 seconds! From a 20a breaker.
I lol'd when you said class D came along. I was just saying that to myself. It's getting even more interesting now with super hf drive waves and super fast circuitry. I often describe the method of class D as one of those hairdryers facing upward with the ping-pong ball floating on the air stream above. If you hold the dryer on full, the ball will float as high as it is able. Pulse the dryer and the ball will float lower. The shorter the pulses.. the lower the ball will float xx
I now feel dumber for having read all that. What was the dam point you're making? Sorry I'm not trying to be an a**, I was just waiting to hear why you were laughing and I never saw the reason.
@@kohnfutner9637 My point was "class H isn't as prevalent anymore as a topology due to the progression of the class D".. I was merely mirroring what Paul stated and offering up my explanation method of pwm that i use when someone asks about the difference between the class's. My jaunty class D 'method explanation' was added after my agreeing with paul... due to observing Paul, explaining the other class's with his hands. Why the snarky reply? I feel that your 'stated' diminishing intelligence and resemblance to a hind end should not be exacerbated by any passing comments I have made about class H amplifier topology. Xx
Until you apply watts and ohm to that mix,, A/b amps tend tend use the 1st 50watts or and use b stage to use higher watts whether you use 8ohm or 4 ohms loads which can be 65-80 watts at 8ohm and 90-180 watts at 4 ohm.. Sadly as great emotivas amps are until thewhite paper comes out for 3, 2 and 1 ohms we have no clue whether the speakers we use will work I own jensen speakers rated at 6ohms so expect if i was to power them with emotiva amps I would expect the power rating to dip into 2ohms load which could peak at 1000-1500 watts..
Was this class G? The Kenwood KA-9X integrated amplifier was 120 wpc and had a split power rail. 35 VDC and 75 VDC. Also used the Sigma Drive which was a sort of servo feedback loop which had sensing wires that ran back to the speaker terminals on the loud speaker itself, and provided negative feedback to signal to the amplifier. Kenwood ditched the Sigma Drive due to errors in hooking up the wires blowing outputs, too many warranty repairs.
@@andydelle4509 Check here: www.electronics-tutorials.ws/amplifier/amplifier-classes.html. I could come up with some classes: "Class V" for a servo amplifier with a speaker feedback mechanism. "Class U" for a current amplifier (some products exist). "Class M" for digital multi-voice coil drive (multi-drive class D).
Class S is a funny way of saying the ADC is the driver as well. These classes are based on power delivery vs supply consumption. There is also a concept called power added efficiency which focuses on using the power from the input signal rather than the supply.
Yes, there is Class Q, that is used for Radio Frequency (RF) amplifiers, but Class D or I work far better in audio applications, this is why there are many class and combination of classes that can work together to meet a wide range of applications.
Hi season's greetings from the UK can I ask if a class H power module be replaced with a class D module on my Technics SH-EH780 or am I talking rubbish only I think mine is misbehaving thank you ! 👍🎄😁
Wearing shorts isn't necessarily tied to climate or geographical area. I'm an outdoor shorts guy 12 months a year, with the exception of the most bitter cold, sub zero windy extremes of January. I walk our dog multiple times a day, and in the winter to keep an eye on her comfort, I wear shorts and sandals to help gauge her level of comfort ... if not she'd go full tilt right into frost bite ... simply wanting to please. She's a Pit, with barely any hair, she'll wear a coat, but not those damn footies, ... hence my approach. You get used to it.
Emotiva does use class H. I prefer A/B, but class D can sound very good indeed these days. PS Audio is one of the best at class D amplification ( Sprout and Stellar series).
In a class A amplifier, the output transistors conduct 100% of the time as they follow the input signal, amplifying it along the way. In a class AB amplifier, one transistor amplifies the positive half of the signal and another transistor amplifies the negative half of the signal. There is always crossover distortion as the signal crosses over from one transistor to the other, but it is much more efficient than class A because the transistors don't have to handle the full power supply voltage. Each transistor only handles half the total voltage. Class H amplifiers suffer from high frequency switching distortion since the signal is switched on and off at high frequency. Because of this, they are best used for sub-woofer applications only.
@@k5dbx Actually, EVERY amplifier manufacturer does that, but with a switcher, the switching freq. is too high to be very effective. That is why switchers are only good for base. All their specs show this. Only analog amps show 0.01% THD or less and this is from negative feedback that has been used since day one of audio amp design.
@@k5dbx Increasing application of negative feedback can only approach the zero distortion ideal, while ZDR actually permits crossing the zero distortion line and creating negative distortion, making it theoretically possible to completely eliminate distortion. "THEORETICALLY" Feed forward amplifiers actually add unwanted distortion. Zero Distortion Rule performs its distortion cancellation at the amplifier's inputs thereby eliminating the power problem. This was the second technique that many analog amps started using 50 years ago to cancel distortion. And since the feed forward circuit is essentially concerned only with low-level signal, it cannot add any distortion of its own. Looks like ZDR took what we have known for many years and used it. AWESOME! So, how much THD does the Yamaha ZDR Amp actually have???? And, thank you for your replies.
@@k5dbx That is TRULY INCREDIBLE, both THD and dynamic power...(and 2 ohm loads) that you need with 1812 Overture cannons and cymbals...very impressive. Glad to see someone paid attention and used modern techniques for audio. Thanks so much for sharing.
Invotone A2400 works with class H power supply. It can be seen via oscilloscope with power supply and signal shown simultaneously. Up to some voltage level it uses flat voltage supply, and over this voltage level it modulates voltage supply. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-QT3a7y8-62E.htmlm30s
So Class H is basically Class A with variable DC supply rail(s) at a voltage just enough to provide headroom. Like it. The fidelity of class A without the excessive heat.
Class D can sound comparable to class AB, but it will cost more than class AB since it has less power consumption. Consider Marantz PM-10 as an example of high level class D.
Interesting about Class H. It does seem it would be difficult to vary the power supply output fast enough to avoid issues when big demanding musical peaks arrive. Class D and it's use of PWM seems rather similar on a conceptual level to fuel injection in engines. The injectors are on/off, their "on time" determines how much fuel the engine receives, the pressure at the injector rail is always the same. Combined with vastly better processor power running it, fuel injection reacts very quickly and accurately now, it is even able to spray several events per power stroke in an engine, which has greatly smoothed and eliminated the "rattle" from diesel engines. I think Class D has followed along a similar path. Early examples deserved the bad rap it got, but lately Class D can give us quite a bit of power in an economical package, or a ton of accurate power in a more expensive package, both are a win for everyone. I still favor a big meaty Class A/B amp over Class D unless driving a subwoofer, but that is probably more just out of habit. Part of this hobby is enjoying the equipment one has, simply for what it is.
Technics Class Z LOL kidding lol all this PSB maybe one day when my Arcam Delta 60 Intergrated packs it in maybe I'll get a little Sprout nothing too fancy after I get over the loss of my Arcam which I baught used about 7 years ago maybe
Yes Mike. I had a listen to the SA20 in Richer Sounds, and loved it. It brings the sound out into the room. So I bought one. The SA30 came out later, but that's out of my price range. Go and have a listen.
That's not what happened. BASH is the underlying tech to class H+. If you open a Technics amplifier it will have a BASH IC which requires a liscensing fee. The entire "liscensing fee" debacle eventually destroyed BASH / Class H... and BASH technologies went under because nobody wanted to pay the fee, and just designed class AB instead. I believe you may be able to still liscense the tech through remanents of the company, but nobody does because they don't want to pay to have the IC built, and the tech licensed. Class D was developed to get around the patents. It doesn't have to be a tricky circuit, you just use a class D power section, with a class AB amplification section, which is what BASH was. Done.
Class I uses two Class D outputs offset by 180° to each other, this is done by a phase shift network on the input stage. By the amount of interest here I plan do an article on all classes of amplifiers covering: A, B, C, D, E, F, G, H, I, P & Q, and how they all relate to each other.
My Arcam is a class G amp. This is proprietary to their brand. But I wonder if there will ever be innovations in amplification that become more popular than the use of class AB or that sound better than class A
@@ameldaquirk3965 I was told that Arcams’ class G technology was patented, it may be that their version of class G is, and not class G as a whole. I am referring to my SA20 if anyone is curious
