Are class H amplifiers "the next big thing"?
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Silver Member Username: CheapskatePost Number: 337 Registered: Mar-04 | i've been seeing super expensive class h halcro amplifiers getting raves for a couple of years by now, but a day or two ago, found out that a $30 battery powered 15wpc amplifier, "sonic impact class T" (H), is also getting a huge following at the other end of the price spectrum. one review featured a modified version of the class t that the reviewer claimed sounds better than any tube amp he's ever heard. are class H amps inherently that good? is their near 90% efficiency levels part of this? has anyone heard any buzz about other class H amps like hypex? |
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Silver Member Username: CheapskatePost Number: 340 Registered: Mar-04 | oops! i think i meant "class D" and not class H. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5718 Registered: May-04 | The Sonic Impact amp was discussed here a few months back. No one could give any input on the amp since it was in a 6-8 week back order situation. Last time I checked, that was still the same hold time. Keep in mind the Sonic Impact amp is only a few small watts. It can, from what the reviewer stated, be sub'd into a system designed for single ended triode amplifiers with speakers of extremely high sensitivity and very simple impedance load. You are not going to hook this up to a pair of 87dB, 4 Ohm speakers and get satisfactory performance. Even with speakers which match the sensitivity/impedance needs of the amp, the design makes it very much like the S.E.T.'s and the Classs D amps in that its output frequency response wil be affected, to a large extent, by the speaker load it is shown. The amp is designed to work into a specified load; when shown a varying impedance, it can have frequency deviations. As I said, the other two types of amps have the same problem, so this is not unique to the Sonic Impact designs. For the most part, the Sonic Impact amplifier remains an unknown since very few have managed to get into the systems of people who will hook it to a decent source and appropriate speakers. As of now, I would say the amp has possibilities just as many other products throughout audio's history have come along for small change and made a big change in the industry. I hasten to add, many of those products that made a splash, never survived in their own wake. |
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Silver Member Username: CheapskatePost Number: 344 Registered: Mar-04 | well i'd like a class t or two myself. one to replace my skateboard smashed 20 year old 20wpc yamaha boombox amp (that still sounds pretty good and has a nice phono preamp) that's driving my PC speakers to have access to my volume on my desktop and another one for a custom sound system for my bicycle instead of messing around with a hypex kit. for a bike system, the class-t is perfect. i'm having alot of trouble with the sony boombox that i bought for the job buzzing at around 100Hz bass tones. without even really pushing my yamaha, i'm getting 1,000 times better sound out of my missions than the boombox. i have just started to notice that alot of class d and h amps are highly rated inclung bel canto and emotiva. at the high end, many have called halcro "the best amplifiers in the world" and with all of the underground buzz around the sonic impacts, it just sounds like their might be something to the new wave of high efficiency amps. i'm thinking that a little bit of DIY with hypex kits could give me "giant killer" sound for the maggies i'll be getting before the year is up if class-d is really better than A/B. FORGET class A and maggies! $10,000 and a livingroom hotplate. LOL |
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Silver Member Username: Frank_abelaBerkshire UK Post Number: 895 Registered: Sep-04 | Class T is a specially derived version of Class D developed by Tripath Technology (www.tripath.com). These amplifiers promise much because they run above 85% efficiency as opposed to the usual 60% for class B and 10% for class A (typically). They also develop high power in small circuits and the efficiency means they develop less heat so again they can be used in more applications than usual, such as automotive applications. There have been / are some higher end digital amplifiers (e.g Chapter Audio, Sony's TDA9000 AV receiver, TacT Audio, Bang & Olufsen's ICEpower technology, Veritas Audio, Yamaha's YSP-1 surround projector had 42 of them!) and they are certainly becoming more prominent as time goes by. It may be that digital amps will be the way forward in future. regards, Frank. |
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Silver Member Username: CheapskatePost Number: 350 Registered: Mar-04 | i THINK that the very well recieved "acoustic reality" amps from europe might be class-D, and a member of the DIY crowd mention UCD-180s (hypex) as among the best "bang for the buck" amps. the thread for that particular amp in a class-d diy specific forum has over 1000 replies. i'd call that a buzz. it looks like me that the technology is starting to become "the standard" at and price point it competes in. those two brands out of 16 total appeared in a "best cheap amp for maggies" thread i posted in another forum. 1 out of 8 people are recommending class-d? there just might be something to the technology i think... especially in portable applications. time will tell. i'm keeping my eyes and ears open. |
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Bronze Member Username: SubiedriverPost Number: 45 Registered: Apr-05 | New edition of Forbes magazine has a story about Sonic Impact (maker of T-Amp) and Tripath, the maker of the chip in that amp. Story also mentions Red Wine Audio, which uses guts of T-Amp to make high-end amps called Clari-T. Go to Forbes.com and do a search for "Sonic Impact." I have 2 of the Sonic Impact T-Amps and have hooked them up to somewhat decent equipment (B&W speakers, KEF speakers) and fed uncompressed files from iPod. Sounded good to me but I'm no expert. Apparently most Class D amps produce too much distortion and are only good for subwoofers. Tripath founder, Adya Tripathi, found a way to pulse signals at much higher rates than typical Class D amps do. This somehow reduces distortion, Tripath claims. The $3 chip in the T-Amp uses the same architecture that more powerful Tripath chips use; those chips end up in amps from Audio Research and Bel Canto which sell for up to $10,000. The T-Amp chip is a model 2024 chip which powers tiny speakers in plasma TVs from Sharp, Sanyo and Samsung. Tripath showed the chip to Sonic Impact which decided to make a battery powered amp for kids to take to the beach. They had no idea it would catch on with audiophiles. Now Sonic Impact is building higher-end amps using Tripath chips. Price will be $150 for 15-watt amp and $300 for a 50-watter due out next year. It's all in the Forbes article so enjoy. |
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Silver Member Username: DiabloFylde Coast, England Post Number: 243 Registered: Dec-04 | I recall reading some rave reviews of the $30 Sonic Impact T-Amp some time ago, but being sceptical about such things, paid little attention. Maybe I was wrong? The chips are now used in some well-reviewed expensive stuff. I've been reading a few threads on DiyAudio.com recently and there seem to be plenty of satisfied users on there, many who prefer them to amps like Naim and 300Bs. So I've ordered a couple of different types from AutoCostruire ,the Fenice20a and the 2020 kit. With the kit where you can vary the gain and also adjust for the speaker impedance by using different component values. It should be interesting to hear how they compare to my existing amps. Will probably use one to make a headphone amp - they are supposed to be very good in this role. Regards, diablo |
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Silver Member Username: CheapskatePost Number: 353 Registered: Mar-04 | i wouldn't really trust forbes as "the last word" in high end audio. LOL. yes... the "red rose" is the modified class-t that i'd read about. the reviewer for that $450, i think, version of the amp claimed that they preferred it's sound over any tube amp they've ever heard. class-d CAN be done wrong, and i've seen it mentioned a few times, but what many consider to be "the best amp in the world", halcro, is in fact a class-d amp. not only that, but these following manufacturers are all making highly regarded class-d amps, but they're keeping the technology on a low profile... probably to stem the eventual flooding of the market with class-d amps that offer amazing bang for the buck: Halcro Toccata Industry: TacT Millennium Bel Canto Design: Tripath Millennium Jeff Rowland PS Audio: HCA 2 eVo and Flying Mole: Mole DAD-M100 not only that, but panasonic has already released two class-d recievers that have a minor cult following, and i just read that samsung has released "the most powerful reciever in the world" which is class-d. i'd love to get my hands on an onkyo, denon or yamaha class-d reciever if they ever release one. THEN i'll be able to switch to magnepans without spending obscene amounts of money to accomodate their snobbish amp matching requirements. LOL class-d is still a 'best kept secret' by the makers that got there first. it's crfeeping into the market for sure. altec lansing, i believe, is already selling class-d "boombox docks" for ipods. |
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Unregistered guest | > The Sonic Impact amp was discussed here a few > months back. No one could give any input on the > amp since it was in a 6-8 week back order > situation. Last time I checked, that was still > the same hold time.[/quote] Actually, PE has had them for qute some time now... http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-952 > Keep in mind the Sonic Impact amp is only a few > small watts. It can, from what the reviewer > stated, be sub'd into a system designed for > single ended triode amplifiers with speakers of > extremely high sensitivity and very simple > impedance load. You are not going to hook this > up to a pair of 87dB, 4 Ohm speakers and get > satisfactory performance. This all depends on your system goals. If using as a computer system, they get plenty loud enough for most, even with the lesser efficiency speakers. Or for small rooms or apartments, they work fine. For instance, I have heard them on a pair of fullrange speakers I have built that are right at about 85dB and with a modded T-amp running them, they sounded great and got up around the 95dB mark or so (experienced quesstimate) without to much problem. For most folks, thi sis plenty loud for average listening. Here are few fun links about this little amp... http://mywebpages.comcast.net/ampbox/page2.html http://www.redwineaudio.com/index.html http://www.6moons.com/audioreviews/sonicimpact/t.html http://www.michael.mardis.com/sonic/start.html http://www.pacifier.com/~gpimm/sonic-impact.htm These little amps are actually very well recieved from those who have spent the measly $30 or so for one. Just my thoughts... Noidster |
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Bronze Member Username: SubiedriverPost Number: 47 Registered: Apr-05 | I hooked a T-amp to a pair of B&W floorstanders, 90db sensitivity rating, and the sound was surprisingly good. Granted it's a small living room and I wasn't trying to blow out the windows with Metallica. We listened to some female vocals, Patricia Barber and Norah Jones. Very nice. Then again these are good recordings so maybe we were giving the amp a leg up. |
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Silver Member Username: CheapskatePost Number: 359 Registered: Mar-04 | i'm looking into sonic impact for next year's custom bicycle system. the sony boombox that i bought for kicks isn't a match for my missions with my 20wpc yamaha boombox amp, which is big and heavy. obviously the sonic impact isn't practical for the average HOME system, but high efficiency speaker SET fans are used to low power (as little as 2wpc). most powered PC speakers are already in this range. the sonic impact is one cheap way to use a pair of shielded minimonitors that might be collecting dust (like my M71s were) for computer use. when i start doing desktop music... it's nice to know that i'll have decent monitors. the point i'm making is that at EVERY price point, class-d (aka class-t, ice power, tripath & digital switching) amps are getting rave reviews. as it stands now, i'm seriously thinking of getting a panasonic $300 100wpc X6 XR70 reciever which is class-d because it's absolutely the cheapest way to do home theater with the magnepan MMGs that i've been dying to get in my home. the class-d panasonics are also getting a little bit of a buzz, and i've already read a couple testimonials from people happy with panny/maggie setups. i've already read the 6 moons review for the sonic impact, and another one about the red rose hotrod edition, but i'll check those other links out too. i'm most interested in class-d for great sound at resonable prices. EVERYTHING i've read about class-d models has been positive so far. reviewers are really liking this gear no matter what it's selling for. |
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Silver Member Username: CheapskatePost Number: 360 Registered: Mar-04 | heck... for the price that the class-t is selling for, i might even buy two to biamp my bikebox! now, if i only knew where to find info on line level electronic or passive crossovers. thanks for the SI info. the next thing might be people bridging them for mono. a prebuilt amp sure is more convenient for DIY than an incomplete hypex kit. i don't think they make lower power modules anyways. |
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Bronze Member Username: SubiedriverPost Number: 48 Registered: Apr-05 | check out nuforce, another co. making switching amps and getting rave reviews. Reference8 is the name of amp I think. |
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Silver Member Username: CheapskatePost Number: 362 Registered: Mar-04 | well, they're out of my price range, but it just adds to what i've been noticing. EVERY review i've read for class-d amps has been favorable so far. those nuforces sure do look nice. |
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Bronze Member Username: LovegasolineNYC Post Number: 54 Registered: Jul-05 | Budget, Thanks for the post. I read through nearly all the supporting materials referenced on this thread and what tweakers have done with it. The concept of a $30 amp is mindstunning...it's fascinating to read reviews where blind auditions yield provocatively earth shattering results...from the $30 pumper. OTOH, it's also fascinating to read about the tweakers having at it...and slowly, slowly...the money invested into the projects rise and rise as more demands are made upon it. Along with those frequency graphs, I'd like to see a graph of money-to-performance gain as designers and DIYers embrace and expand upon the basic technology. Anyway, fascinating all around. |
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Silver Member Username: CheapskatePost Number: 363 Registered: Mar-04 | it's just "solid technology". every review i've read has been positive. that's it... i'm buying a panasonic SA-XR55 or XR70. in fact, i've already written panny's number down (their website is useless) to ask what the difference is between the 2. they're both similarly rated and priced. panasonic, it turns out has been doing class-d since at least '03! seeing no-one else has joined in yet, i'm not going to hold my breath waiting. i'm going to take the plunge to get amplification that fussy maggies will work with. once i get it, i'll post a mini review in recievers. i like my onkyo just fine, but it's only 55wpc and terrified of 4 ohm loads. LOL i've read at least a couple of reviews of people using various 100wpc pannys to great effect. one XR50 user claims the sound is somewhere between tubes and solid state. this might spell the end of power hungry A/B solid state amps with the possible exception of class-a. i tell you, this is a pretty good time to be a hifi nut. |
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Gold Member Username: T_bomb25Dayton, Ohio United States Post Number: 1010 Registered: Jun-05 | Yes Yes the T- Amp review in 6moons was quite gratifying for a amp of that price to perform like that.Parts Express is 12 miles away from my doorstep Ill be paying them a visit today for sure.I seen the review about 2 months ago,and while amazed I kind of turned the other cheek,I guess from a bit of arrogance,but im gonna investgate them seriously now.After hearing the Halcro and it was quite amazing and very competative in the superamp arena,likewise for the Bel Canto,and the PSA Audio HCA-2.Eddie is quite fond of his new Panny,I know I said I didnt have any experiance with the digital amps,but I dont think a breif listen to class D qualifys as being experianced with it when all of us have spent our entire lives listening to class A,A/B and tube amps.To really get a strong idea on how well a class D or T amps sounds we have to spend ample time with it,and get acustomed to their sound qualities,so now im gonna take it upon myself to do so. |
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Silver Member Username: CheapskatePost Number: 365 Registered: Mar-04 | i'll definately post a review of the XR55 or XR70 when i get it (compared to my onkyo) and a full report when i get maggies after that. from everything i've read (there's actually a class d thread going on at the asylum right now in the planar forum) there's nothing you can get that's better than $550 maggies and $230 panasonic for the price. i'm looking foreward to being able to embarass $5000+ systems. LOL |
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Silver Member Username: CheapskatePost Number: 368 Registered: Mar-04 | WOW! i just saw a 100wpc JVC surround reciever that uses class D selling for a street price of $130! i'll still go with the panny. panasonic is known to be reliable, and when i was trying to return a junk DVD at best buy, i saw 3 returned boxes... all of them were JVC gear, and i know that my own JVC VCR has never worked 100% right. it needed service right out of the box because it wouldn't play paramount tapes. i'd rather pay $100 more for proven panasonic gear. i might be cheap... but i'd rather spend more for something that won't break right away. reading in a consumer review too, the JVC forgets all of it's settings when you power down. what's my point? class-d is going to offer quality power for less than A/B. if i wasn't so eager to get maggies... i'd be tempted to wait a model year to see who else joins the big power in little box trend. a really cool thing about class-d too is that it's better for the environment... less materials used in construction, and around 1/2 the power used. how cool is that? |
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Bronze Member Username: LovegasolineNYC Post Number: 61 Registered: Jul-05 | With that little Sonic Impact running on DC, what do you think the potential is for these low power demand digital amps to pack big power in a completely portable or mobile system? What is happening at the technical avant guard on the speaker front? Are there powered speakers or supremely efficient speakers that can mate with the class-T for a mobile/portable application? |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5825 Registered: May-04 | Sonic Impact sells a package of a different Class D amp with small flat panel speakers intended as a portable system. You can find it at Target. |
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Silver Member Username: CheapskatePost Number: 369 Registered: Mar-04 | darn PDF documents!!! i was in the middle of a reply, when i tried to view a texas instruments 20w class d amplifier that turned out to just be a chip. i had named (not looking it up again) a sony "1 bit digital amplifier" powered speaker, and a couple altec lansing units. the one i was thinking of in particular was the "inmotion" ipod dock that looks to feature 4 hifonics miniature "full range" drivers. class-d is perfect for portable applications being nearly twice as efficient as a/b. i even read a mention about the application being used in camcorders to extend battery life. not only is class-d great for it's efficiency and sound quality, but i think in the long run, it might even be cheaper to produce as gear no longer needs giant expensive power supplies or costly heat sinks. as to the sonic impact flat panel speakers... i read somewhere that they buzz at volume. i imagine they're nothing more than their "stick on" drivers that are designed to stick to flat surfaces and turn them into speaker drivers stuck to sheets of plastic. i'd like to use two class-ts in biamp mode for my portable application (possibly with larger d cells and capacitors) if i could only find a guide to building line level passive crossovers. i saw some RCA units somewhere, but they're $25 a piece. multiply that times 2 highpass and 2 lowpass units, and that's $100 for what amounts to a few small inductors and capicitors not to mention the needed RCA jacks when a soldered circuit would be better. |
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Bronze Member Username: LovegasolineNYC Post Number: 62 Registered: Jul-05 | Are the speakers in this class configuration as spectacular in sound for their price as the amps? That's what I was driving at with my question... |
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Silver Member Username: CheapskatePost Number: 372 Registered: Mar-04 | i doubt it. i think the amps are simply being used more for their efficiency. what would be a killer combo (if they were full range and didn't cross over at 250Hz) would be monsoon's planar speakers for PCs. they use only 11wpc amps with another 22w for the 5" sub. i'm toying with the idea of mating the monsoons with the class-t. i already love the sound of planars... match it with a killer portable amp and WOW. the problem remains how to design a sub (subs) that crossover at 250Hz and amplify (biamplify) the whole thing. for the price of those portable dock systems, you could get a class-t and a much better pair of two way speakers. there are some decent 2 ways out there for $100 with real woofers and real tweeters. the only problem would be carrying 2 speaker boxes, an amp and a source. the nice thing about the class-t is that it'll accept ANY 1/8" input be it radio, CD player, tape player or ipod wheres the altecs are designed for specific players i think. if you really want a "killer portable", cambridge sound works makes a suitcase system where the case serves as the woofer enclusure (8" i think) and the amp, satellites and source are carried inside. it sells for $500 i think. for less than that, you could build your own box i'm sure, or even build a way to carry two regular speakers. my yamaha boombox came with spring loaded "mushroom" shaped tabs (that broke right away... yamaha remedied with permanent steel tabs) that you insert into the side of the amp section. i'm sure that in a few years... virtually every amplified portable will be class-d though. |
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Silver Member Username: Frank_abelaBerkshire UK Post Number: 912 Registered: Sep-04 | The thing is, as usual, the amps are completely dependant on the quality of their power supply. It is this which will effectively determine the performance envelope of the amplifier. A puny power supply will make a puny amp even if the basic circuit should develop 100wpc. Chapter Audio is a high end manufacturer who are developing class D amplifiers with highly specified power supplies. Their integrated amp uses a standard linear power supply, whereas their pre/power components use switched mode power supplies. And now, Naim Audio have come into the frame. They have just announced an HTIB box which has a switched mode power supply and 5 class T power amps in it. Since you've got a DVD/tuner/processor/5xamps all in one box it was essential to run it as cool as possible (class T amps run very cool since they're so efficient) and to use as little space as possible - hence the SMPS. They still maintain that the class T amps don't sound as good as their linear amps, but given the heat and space constraints they had to go this route. Still, for a purist brand like Naim to come out with this product, there's much to say for the technology. Regards, Frank. |
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Silver Member Username: CheapskatePost Number: 395 Registered: Mar-04 | naim isn't the only high end manufacturer doing class-d. at every price range right up to $20,000 halcros, class-d amps are getting great reviews. the panasonic owner in another forum i've chatted with describes the sound as between tube and solid state. the biggest drawback with class-d amps, especially the cheaper ones is that they don't like o be ridden hard, probably because of cheaper power supllies, but at lower volumes, they're more detailed than similarly priced A/B amps. read the reviews for nuforce, acoustic reality or flyiing mole amps. naim has always been a quality brand, and always way out of my budget. class-d technology is still in it's infancy. the current crop is only second generation. there are still discoveries to be made like nuforce's using audio itself to modulate the power supply. when it first came out, solid state was pretty crappy sounding. class-d is already doing well. halcro's numerous "best amp in the world" awards have to count for something. |
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Silver Member Username: Frank_abelaBerkshire UK Post Number: 917 Registered: Sep-04 | The difference with Naim is that they've introduced class T in their lowest end product! I have read two reviews on Flying Mole. one was very favourable and the other was much less so. I have read very favourable reviews of the Halcro, ECS, Chapter and Veritas amps. Class D (or switching) amplifiers have been around for 30 years or so. I have heard the Halcro and thought it was about as boring as watching paint dry. OTOH I heard the Chapter integrated just last Sunday and thought it was pretty darned good. I think the class is important from the efficiency point of view but that the implementation is far more important than the technology... Regards, Frank. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5875 Registered: May-04 | Modulating the power supply with the music signal. Now that's a novel idea. But, that's what all the other classes of operation have done for 100 years. That seems to take the amplifier away from the idea of a "digital" switching power supply and bring it back to a typical amplifier. I have to agree with Frank as far as the Halcro's reviews are concerned. I do firmly belive if you put enough money into a product you can make any concept work. Halcro surely has put enough money into their products. Aston Martin gets a pretty good write up using an internal combustion engine. Does that mean Kia has a chance too? Is there anyone else out there who is very tired of hearing amplifiers described as "between" tubes and solid state? What exactly is that? Does it have the benefits of both or the problems of both? And, don't you need to know what "tube sound" and "transistor sound" are to the person making that statement? I would much prefer to be told it sounds like nothing but the music. |
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Silver Member Username: CheapskatePost Number: 397 Registered: Mar-04 | i like a dry and analytical sound myself. the very thing that most people find "exciting" namely a "warm presentation" annoys the heck out of me. you'll NEVER get me anywhere near a ported woofer. LOL just to make JV angry, i'll say that i didn't care one bit for the one tube amp i heard or for any of the "warm and forgiving" traits attributed to tubes that i've read about in virtually every review of the technology. to my ears, any amp that can't be ruthlessly revealing in the treble sounds dull, muffled and closed in. warm and i will never get along. LOL |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5894 Registered: May-04 | Well, that made me very angry. But, I soon got over it. You have every right to like what you like. Just realize you are in a very small minority when it comes to preferences in sound quality. I long ago realized what I liked was not what most of my clients preferred. |
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Silver Member Username: CheapskatePost Number: 415 Registered: Mar-04 | definately, everyone has their own priorities. i'm a believer that anyone into hi-fi needs to train their ears to find out what they like and don't like. the very FIRST time i ever heard it was on a friend's 45wpc denon reciever, B&O turntable and $120 infinity acoustic 4 1/2" suspension minimonitors. i'd already heard crappy klipschorns (to my ears) offensive bose and decent polk and boston acoustic full range speakers, but the speed and imaging of those infities made my jaw drop. it probably affected my absolute need to get the biggest bang for the buck. those tiny little $120 speakers totally embarassed multo thousand dollar horns and $800 conventional towers. you have to HEAR what you like to know what it is. when i heard more detail (especially in the upper bass) than i'd ever heard before... i knew what it was until i heard even more detail in planars which i didn't like the 1st time i heard them around '85... they had a tinfoil sound. i DO try to qualify my opinions when i share them. when i say "i despise NAD sound" i make a point of explaining why. if you state an audio opinion, you should explain the whys to whoever might not share your priorities. i'm a big fan of saying "all opinions are valid" you work in the field JV? that would explain why your knowledge is deeper than many a reviewer. you'd also have alot more hands on experience than a typical consumer as you could familiarize yourself with alot of gear. |
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Silver Member Username: AudioholicPost Number: 176 Registered: Apr-05 | Jan, remember the old JVC fake class A amps? Reminds me of not quite tubes...not quite solid state. These were real cute. They basically applied a small amount of bias current to keep the transistors on all the time and called it class A amplification. People bought them in drones, mis-lead into thinking they were buying a 120 watt class A amplifier for $159.95 I like what Edge is doing. They are using fiber optic cables to switch transistors on and off. Makes sense to me. |
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Silver Member Username: CheapskatePost Number: 425 Registered: Mar-04 | "fake class a" isn't dead. i just saw a marantz product description that claimed "class A for the first 25 watts" for an integrated amp. as i've seen here a few times, all class A/B amps are class A up o a point. |
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Silver Member Username: Frank_abelaBerkshire UK Post Number: 935 Registered: Sep-04 | That's what makes them class A/B. They're designed to work in class A up to a point and then revert to class B when more power is required due to the better efficiency of class B operation. A typical spec would be 20w/ch class A with 80w/ch class B. It's not fake class A, just a question of different biassing. A pure class A amp is extremely inefficient since it is running at full power all the time irrespective of input signal. Class A/B and class B are input signal dependant, allowing the amp to idle efficiently. one of the benefits of this is that the amp can be left on all the time in order to keep it running at optimum temperature. Doing this typically uses less power than one evening's TV viewing (or, incredibly, one day's TV staying on standby), but means the amp is runing at optimum temperature constantly, lowering wear rates than switching off and on. Regards, Frank. |
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Silver Member Username: DiabloFylde Coast, England Post Number: 252 Registered: Dec-04 | For anyone interested in the cheaper end of class T amps, there is now a review of the SI version and 3 others available on the TNT Audio site. I had hoped to give my own review of two different Tripath types from Autocostruire. The boards, which I ordered three weeks ago, have still not arrived yet, due to faults by Palpal, my bank and the delivery firm. Adding up all the costs, the boards, power supply components, switches, pots, terminals and some form of case, I will have laid out at least £260 just to try out this technology! Maybe I ought to have bought one of those Panny XR55 things that Edster is always selling and saved myself all the trouble. I'm still hoping to end up with something usable at the end of it, though. diablo |
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Silver Member Username: Frank_abelaBerkshire UK Post Number: 946 Registered: Sep-04 | I think the Panny is class D, not T. I was very tempted to try my hand with the test boards myself, but then I got bogged down in the power supply design. The power supply design is what really counts as usual. Hey I just found out class H is a refinement of class G which uses class AB in the output stages but is a switching amplifier scheme (as in class D). Regards, Frank. |
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Bronze Member Username: SubiedriverPost Number: 60 Registered: Apr-05 | JV I can't resist taking the bait. How does your taste differ from most of your clients? What do they like and what do you like? |
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Silver Member Username: DiabloFylde Coast, England Post Number: 253 Registered: Dec-04 | Frank, Yep, I'm sure you're right about the Panny. They use class T in some of their car audio, but not receivers, as yet. I didn't really want one anyway, as one of my aims in assembling the Tripath stuff is to regain the confidence I had when I last built amps about 25+ years ago. The Tripaths don't really require a near-perfect supply, in fact they will work very well using a 'wall-wart' if you believe the reviews. As I understand it, they have high ripple rejection and being efficient and low-power, there are no huge demands to cope with transients. I've opted for an oversized transformer, simple LM1084 regulator and ample capacitance. When ( or should that be if?  ) I get the thing working, then I may go on to a more complicated amp (including valve stages) which I am planning. Now that will require a serious PS, which will probably need twice the heatsinks of the output stage. The lower demands which class T (and class D) put on the power supply should enable the manufacturer to avoid the skimping in this area which is often found in low/mid priced equipment? Maybe this is part of the reason for the good press which the XR55/XR70 has received? Should also cut global warming by 0.001% diablo |
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Silver Member Username: DiabloFylde Coast, England Post Number: 255 Registered: Dec-04 | 6moons review of the new Sonic Impact T Amp. Pretty good review for a $139 product. Maybe they didn't improve quite enough on the power supply though. |
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Silver Member Username: Frank_abelaBerkshire UK Post Number: 952 Registered: Sep-04 | diablo Ultimately, these devices are actually very powerful devices, provided the power supply can deliver enough juice to them. A little wall wart power supply is not going to be able to handle enough current for your 100w class T amp to be able to deliver the 100w. In the case of a linear supply (transformer, regulator and capacitor), the limitation is the transformer. In a switched mode power supply I have no idea what the limitation is! Valve amps typically have a low component count and the power supply is usually just as simple as a standard linear amp. The danger is that valve amps tend to run very high voltage internally so you tend to need a big transformer, and to exercise extreme caution when building the amp. A typical 300B based amp runs voltage rails of 300V or so, and a big valve such as a 211 or 845 run voltage rails of 500V! This can bounce you off the walls if you're not careful... Regards, Frank. |
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Silver Member Username: CheapskatePost Number: 441 Registered: Mar-04 | well i just recieved my panasonic SA-XR55 over a week ago and it totally kicks butt! it does EVERYTHING better than my onkyo which i liked better than my NAD. all the time i thought that my superzeros were holding my system back, it turns out to have been amplification. i hear so much more treble detail (especially at low volumes) with the panny, it isn't even funny. every CD i listen to sounds like it was remastered at a higher bit rate now! the path that lead me to the panny was a need for lower level resolution for listening strain free late night DVD viewing. this lead me to high-rez magnepans which require amps that can handle 4 ohm loads. after i found that cheap pannys sound good and can handle the load, i bought one as a 1st step towards an MMG upgrade, but i've stopped stepping now. that $240 delivered reciever improved EVERYTHING from top to bottom. now my superzeros punch bass harder and deeper than they ever have before (withing their limits of course) and reveal loads of detail in buzzing and white noise type treble events as well as metallic percussion. highs have alot more texture now. the biggest improvement though is the midrange. now my zeros sound like they've crossed 1/2 of the gap to planar vocal bliss! vocals sound downright silk and grain free now. i've gained significant top to bottom detail along with a much more liquid and relaxed sound. even when i put my ear right next to my tweeters, i can't hear a single bit of grain! i thought all tweeters sounded harsh and spitty if you get too close. i've never know just how good my little zeros were until i fed them high-rez amplification. listening to music is a joy now. as much as i'm into instrumentals, i've been digging all of my best female vocal discs and tracks up to hear a higher level of reality. i think there's something to class-d. man do i love my ridiculously cheap panasonic. ease and detail aren't necessarily mutually exclusive afterall. it's really great to an audio cheapskate like me when you ACCIDENTLY improve your system and nip upgraditis (along with listener fatigue) in the bud. LOL what was supposed to be a stepping stone ended up killing a whole flock of birds. hmmmmmmm. maybe those mission M71s next to my PC monitor sound less stressful than i thought they do too. that doesn't count as an upgrade does it? LOL |
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Bronze Member Username: LovegasolineNYC Post Number: 72 Registered: Jul-05 | I'm still a little confused about what sort of speaker the Sonic Impact T-Amp (version 1, the 'audiophile' version 2, and the inexpensive kits/prebuilt kit offerings) can drive... impedance and effciency wise? |
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Silver Member Username: DiabloFylde Coast, England Post Number: 257 Registered: Dec-04 | LG I've not yet heard the SI T-Amps or the kits, but from reading several hundred reviews, e.g. TNT opinions, it seems that fairly efficient (90+ dB or so) speakers are needed, due to the lowish power output. The most important thing is that the speakers present a fairly constant load on the amp - having no huge impedance dips or highs. Frank, I assume that you are thinking of the 41hz kits when you are writing about 100 watt T-amps. Those tend not to get as good reviews as the low power ones, as in the 'classic' T-amps by SI. The kits I have bought (and now arrived!) are for the 20/25 watt versions, so that my torroidal transformer with dual 80VA 12volt windings is more than adequate. Might take me a while to do the assembly though. Didn't realize they had so many little parts! |
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Silver Member Username: Frank_abelaBerkshire UK Post Number: 969 Registered: Sep-04 | diablo, I was simply looking at the Tripath options since I had been interested in playing around with one of these and the 100w item caught my eye since I was particularly interested in a high power application. I agree that your 80VA power supply should be sufficient for a 25w application. Regards, Frank. |
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Silver Member Username: CheapskatePost Number: 453 Registered: Mar-04 | if you're thinking of dabbling (oops i typed "babbling" in a great freudian pun originally LOL) in class-D DIY, you really should look into this dedicated forum: http://www.diyaudio.com/forums/forumdisplay.php?forumid=49 if you really want to get technical... that's the place to do it. they REALLY love their hypex UCDs there. |
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Bronze Member Username: PtarmiganPost Number: 23 Registered: Nov-05 | I actually used the Class T Sonic Impact amp. It sounded reminiscent of those 45 rpm record players parents would give to their 12 year old children back in the Pleistocene era. This is not necessarily a reflection on the Tripath chip, I suppose. But Sonic Impact makes quick buck trash, like a pyramid shaped speaker made out of black cardboard using flat speaker technology. The wire was absurdly thin. I tried hooking up the Sonic Impact amp with the Sonic Impact speakers, which are incredibly inefficient, and actually got some sound out of them. I then hooked up the Sonic Impact amp to some reasonably good AudioSource speakers. The sound I heard was grotesque. Not only was it feeble and of narrow frequency range, but there was a rapid pulsing that made it sound like flutter from a cheap cassette recorder. This was on batteries. So I hooked it up to a 1.5 amp Panasonic 12 volt adapter. No improvement. I ran it for several hours, but no change. When I shared these observations, a Sonic Impact fan said I needed to run it for several days to break it in and hook it up the a 3 amp regulated power supply. This would cost about $45. He said running it off batteries was no good. So why is Sonic selling the amp this way? I'm sorry, but you can't get a 15 watt amp out of a set of AA batteries. I cannot find Class T listed anywhere on the web. Class D is a digital amplifier. I am suspicious of them, afraid they may have a similar pulsing quality. But obviously if the digital modulation is in the megahertz, like SACDs, this should not be a problem. Class H is some sort of way to get around the inefficiencies of Class A biasing, which requires a huge transformer. It was showing up in Panasonic/Technics stuff a while back. From what little I could infer from the hype, I believe it uses a variable bias current, perhaps on a single transistor, that adjusts to the demands of the music - perhaps a more sophisticated version of Technics' Class A+ computer drive amps. But it was virtually impossible to find a clear explanation on the company's website, when I looked years ago. I had a Class H power amp by Phase Linear. It sounded very coarse, worse than a bad Class B amp. But it is possible that Panasonic has refined the design. Class H also shows up on subwoofer amps because it can produce very efficient power. But back to Sonic Impact. People are spending hundreds of dollars upgrading this $30 piece of plastic. If the Tripath chip is so good, they should be leasing the technology to more respectable companies, as should NXT and their flat panel design. And they are. My impression is Sonic Impact has a paid claque hyping the product, and if you speak ill of it, they blow smoke like a volcano. But sooner or later there will be amps on a chip that sound good. I remember a Yale professor who showed me an early integrated circuit around 1970, and predicted that a 40 watt amp could be put on such a tiny chip. I was skeptical, as you would still need a large power supply and some substantial power transistors. But perhaps with some high speed digital technology that dream will be realized. |
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Gold Member Username: Frank_abelaBerkshire UK Post Number: 1015 Registered: Sep-04 | J Pi, Class Z and T are all variants of the Class D switching amp principle, nothing to do with class A or B. These are all amps-on-a-chip varying in power delivery between 20 and 180 watts/channel, and each being 2-channel. They can be bridged of course, lending much more power. Class H is a variant of class G which itself is a variant on AB. However, class H modulates the popwer supply depdnant on the signal so it could be construed as a variant of class D too. There is quite a bit of information on the web talking about them. http://en.wikipedia.org/wiki/Electronic_amplifier http://www.audioholics.com/ces/CESamps/ZetexClassZAmpsTechnology.php Regards, Frank. |
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Silver Member Username: CheapskatePost Number: 507 Registered: Mar-04 | perhaps your unit was broken when you bought it. i'd be inclined to believe that the sonic impacts are as good as the claims based on my experience with my panny. eventually, i'll buy a sonic impact (or possibly even several) for PC and bike systems. i wonder why you heard pulsing. my reciever sounds super smooth. my understanding is that the power supply pulses are timed at several times the maximum audible frequency of 20KHz. (not counting asthmatic children etc.) |
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Unregistered guest | I've got 2 sonic impact amps. I had em hooked up to 87db sony bookshelf speakers and a subwoofer. The sound was great. However they ARE only as good as the power supply and the signal quality. Friday something happened to the amp powering the subwoofer. I heard some rattling in the casing after it stopped working. I opened it up and theres the unsoldered thumbnail sized chip just floating around. Not what I'd consider good quality assurance. Looks like its down to soldering 101 for me now.... |
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