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The "T-Amp" is a small amplifier costing less than $30 that is said to deliver "hi-end sound".

I assume you are talking about the $29 amp described at http://www.si-technologies.com/frontEnd/cm_productDetail.jsp?productID=18 ?

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Maybe the price MUST be proportional to sound quality? Are such low cost amps very unlikely to be ever advertised on a magazine ?

I don't see why not, although it should be noted that the amp above can be sold so cheaply because it doesn't have a power supply, requiring the user to supply batteries or a wall wart. Even with the high conversion efficiency of a switching amplifier, the quality of this power supply will still affect ultimate sound quality.

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Keep in mind that such chips are used, among others, by Carver and Audio Research .... of course in pricey components.

We have also reviewed amplifiers from Bel Canto that use TriPath modules.

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Really, we (or at least I) really need the opinion of Stereophile's "golden ears". Are we all becoming mad?

I'll think about getting hold of one of these giant-killer amps for possible review.

John Atkinson
Editor, Stereophile

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I'll think about getting hold of one of these giant-killer amps for possible review.

Okay, I gave my credit-card a workout and ordered one. It's fair to note that with the 2A/12V wall-wart and shipping, the amp actually costs almost $60, though yes, this is still very cheap.

John Atkinson
Editor, Stereophile

Now this is a really cool topic!

I'd LOVE to see a review and JA's MEASUREMENTS on something like this.

This is a great idea for generating interest, discussion, and shared experience!

Even if it isn't worthy of space in the print issues, it would be a very cool cyber-feature to see an investigation of these babies!

Awesome topic, Anonymous!

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Okay, I gave my credit-card a workout and ordered one. It's fair to note that with the 2A/12V wall-wart and shipping, the amp actually costs almost $60, though yes, this is still very cheap.

You the man, JA. (And by "the man," I mean: You rock.)

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I'll think about getting hold of one of these giant-killer amps for possible review.

Okay, I gave my credit-card a workout and ordered one. It's fair to note that with the 2A/12V wall-wart and shipping, the amp actually costs almost $60, though yes, this is still very cheap.

John Atkinson
Editor, Stereophile

This new track inspired by a forum post is the sort of thing that gives real value to this forum!

John - If I'm not mistaken, it appears that the P-1A portion of Dusty Vawter's Monolithic Power Supply for the Perpetual Technologies gear will work with your new purchase:

http://ciaudio.com/p3b.html

I use modded versions of this supply in my main rig and headphone rig (with aftermarket Revelation DC power cables in the big rig.)

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Stephen wrote:

You the man, JA. (And by "the man," I mean: You rock.)

Sorry to take your quote out of context, but your right, JA ROCKS. Records 2 Die For has him getting his groove on with Creams music video DVD's in DTS/Dolby digital. Rock On JA!

RG

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Okay, I gave my credit-card a workout and ordered one. It's fair to note that with the 2A/12V wall-wart and shipping, the amp actually costs almost $60, though yes, this is still very cheap.

John Atkinson
Editor, Stereophile

Thank you John for being so open minded. As you say, with the power supply and shipping the amp really does cost $60 and based on the what is written in the various links posted in some of the previous messages, the original $30 T-amp seems to have a serious lack of bass. Perhaps it would be better if you also included the newer $140 Super-T amp in this experiment cum review?

However, if the T-amp and/or Super T-amp does turn out to be even somewhat worthwhile, I can think of many, many uses for just such a handy device. Upgrading office and computer audio systems. On boats and in remote locations like work shops and sheds. With a decent pair of speakers and a portable cd player with fm one could put an audio system almost anywhere. And if the sound quality turns out to be the "giant killer" that it's claimed.....well

In any event, this is really great to see happening, even if the T-amps turn out to be a sonic dead end, Stereophile is moving so far ahead of the other audio publications in its ability and willingness to interact with its readship that it's down right scary.

How does one become a lifetime subscriber?

and they were pertty much a joke. Maybe the newer ones are better. The one I used choked at about 70db on a good pair of speakers. I was totally unimpressed.

Again, maybe this is heading somewhere, but it might take time.

P

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You guys are behind the times. The new version is out and it doesn't have the bass problem of the original, which has undersized coupling caps at the input.

I just ordered one of these for my office system. I do not know if I will do a review but, if not, I'll comment here.

Kal

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I've tried to improve the original amp with better parts, new output filters (based on "air core" instead of "ferrite core" inductors), careful board layouts .... The results are very good in my opinion, yet we're still in the 100 to 250 $ range ...

I experimented with the Tripath TA0104A and its successor, the TA0105A, over the course of a year, several years ago. If you're not familiar with these modules, they are/were the "top-of-the-line" Tripath technologies. I, too, noticed improvement with an air core output inductor (and upgraded output capacitors). I opted for a more complex output filter design to reduce the potentially excessive resistance that would be added with a single large inductor and to make it less susceptible to impedance variation (see typical variation due to impedance here http://stereophile.com/solidpoweramps/442/index5.html ). If you go this route, verify the circuit design using simulations with actual loudspeaker loads and practical cables -- the load can cause significant misbehavior above the audio band (in some cases causing additional loudspeaker/crossover power dissipation at high frequencies, at the switching frequencies [note Tripath's switching frequency varies]). Substituting the standard bipolar electrolytic input capacitor with a (very large) non-metalized polypropylene of suitable value also made a significant improvement in sound quality. Altering the feedback amount may provide some subjective improvement, though the values spec'd tend to be chosen based on reducing measured distortion. Finally, overspec'ing the power supply section (we used a 1000VA toroidal transformer and, I believe, 4x47,000uF caps) will of course be beneficial.

How does the top-of-the-line modified Tripath technology sound? The following comparisons were made using both long term listening sessions and blinded A/B comparisons under listener control (the listener was not aware which amplifier was being played when depressing a switch). These comments represent my opinions, though at least one other listener compared the amplifiers. Listener opinions were in general agreement. Where opinions substantially differed, they are noted.

Compared to the Denon AVR-4800 that uses transistor-based output devices, the Tripath sounded weightier, with more impact, and a more effortless midrange and top end. This disparity was not huge, though it was consistently noted. (The Denon was also compared to the pre-modified Tripath and in that case they were very comparable, with the exception that the Tripath tended to sound somewhat artificial in the highest octaves).

Compared to the Muse Model "One Hundred Sixty," the Tripath sounded much less impactful, especially in the bass. The Tripath made instruments and vocals sound reticent and lackluster in comparison to the Muse, which tended to portray these as more "real" and live. The Tripath was slightly less veiled in the top octaves, though, compared to the Muse.

Compared to the Bel Canto Evo 200.2 (which I believe is based on the TA0103x technology) the modified Tripath sounded much more extended in the lower octaves. This was not a marginal difference -- it was clearly evident to all listeners. On the other hand, the Bel Canto excelled in top-octave production, lending an enticing character to upper register instruments and upper harmonics. However, this same characteristic tended to sound artificial after extended listening and in terms of overall realism and balance, the modified Tripath, I believe, easily outperformed the Bel Canto.

Compared to the ICE Power 500 Module (unmodified), the Tripath sounded slightly less dynamic across the spectrum, though this deficiency was most pronounced in the bass. Aside from the dynamics, the Tripath presented a more natural sonic picture, and sounded slightly less "processed" overall. However, with these two amplifiers, there was considerable disagreement between my observations and those of the other listeners' (punctuation help?).

Compared to the Boulder 500, the modified Tripath showed all its weaknesses. The Boulder easily beat the Tripath in every subjective area. ...not much else to say here.

I also performed some bench tests comparing the Denon, Muse and Tripath. As I recall, the Tripath had the lowest overall distortion of the three amplifiers across frequency. The Muse had significantly more second harmonic distortion than the Tripath, though the Muse's higher order products dropped off rapidly. This would be consistent with the low feedback design and "musical" sound of the Muse. I believe the Denon had higher overall distortion products than the Tripath. Although I measured IMD, I can't recall those findings. If anyone is interested, I'll see if I can dig up any of the measurements from my archive.

How might this compare to the $30 version? The lower-power cousin would of course be well out of its league with the amplifiers mentioned. With $100-$300 retail receivers? Who knows?

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I'll think about getting hold of one of these giant-killer amps for possible review.

Okay, I gave my credit-card a workout and ordered one. It's fair to note that with the 2A/12V wall-wart and shipping, the amp actually costs almost $60, though yes, this is still very cheap.

John Atkinson

Editor, Stereophile

Thank you for keeping true to the audiophile spirit!

Knowing that Stereophile is more interested in the sound than the name, while valuing its readers ears and opinions, helps make me a Stereophile devote, kudos.

Before going to grad school, I put down a sizable chunk of change on my Krell Kav 300iL. With my Wharfedale diamond 9.6's easy 90db sensitivity, a very boomey 11x9 room my sound has been unruly. Today just for fun I plugged in the little T-amp with a 12v 4amp battery and was floored. A few weeks of good listening will help me determine if I cut the Krell loose, along with a chunk of student loan debt.

I will be interested in hearing JA's assessments, even if it is only a few words in the forums, about this new "toy".

Windzilla (aka Ben aka John Lawrence)

what speakers were you using, Pjay?

wonder who Naim has been listening to...

Geese, long time ago. I am pretty sure we used my 89db Vifa XT/morelMTD30 units. I remember the amp petering out early and we moved it to some small MTMs of some sort, maybe a SEAS metal coned unit (sorry, it was two years ago and not the highlight of the day). The MTM did not fair much better.

The second listening was in Reston. I think that time we used a Peerless MT. Same thing, not very impressive.

Again, this was a new amp at the time.

P

new amp as in not broken in, or as in new technology (couldn't have been different from the ones 6moons and TNT audio tested though, there's not been a new T-amp until very recently)

even though the specs say 15W per channel, thats into 4Ω - into 8Ω the output is closer to 6W and i think it needs to be treated like a low power tube amp as far as speaker selection goes.

I haven't heard those particular speakers you mentioned - but generally smaller speakers are less sensitive than bigger ones, so moving to a smaller MTM wouldn't have helped matters, maybe.

Anyway, clearly (and elsewhere as well) there are times when the little T-amp hasn't worked for some people and thats quite OK too - at least you gave it a fair listen and found out.

I've sat through a listening session when they tried the T-amp with a pair of Sonus Faber Concertos (87db, 5Ω) - which are somewhat hard to drive and predictably didn't impress anyone. (took a 200Wpc power amp to make it sing)

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Well, if we talk about improvements over the original T-Amp .... you can take a look at this:

http://www.audiodigit.com/index.php?section=37

or this

http://www.audiodigit.com/index.php?section=35

Now that's what I'm talkin 'bout!

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How does one become a lifetime subscriber?

Being a fan of Jazzfan and fan of jazz (say that three times real fast - I laugh Sam's evil laugh) I have to agree and repeat the question - I'm a lifer!

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wonder who Naim has been listening to...

I knew I had seen this recently! Cool...

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Well, time has passed by, are there any results of the tests from the people who decided to give out a little money and buy a T-Amp? Do you have any impression, John?

Unfortunately, I have yet to do any serious listening. :-(

John Atkinson
Editor, Stereophile

I just got my Super T amp in today...

Got 2 sets of speakers that should be great to test with... and I can test it on my friend's setups.

Soliloquy 5.0s 88db 45hz - 18khz
Soliloquy 6.5i 92db 22hz - 22khz

Should be able to test the bass response on the big towers

I'm currently powering with a Nakamichi AV9 and Creek 5350SE respectively... Source options are waveterminal 192x card and denon 1920 dvd/sacd, sb x-fi...

I've done some serious modding on my X-cans v2 so this should be a fun project.

I've only listened for an hour on the 6.5's right after it came out of the box and so far it sounds a tad harsher with a lot less soundstage. May open up by itself... not sure yet.

Either way I'm pleasantly surprised. It won't be money wasted that's for sure. At the very least it's going to the office with some small high efficency bookshelf speakers.

Initial impressions on bass are good but not as good as the creek is. It feels like it's dropping off in the 30hz range but it'll take more listening to see. Little grainy highs as well but so far not fatiguing. Not a direct "sound" replacement for a small tube, just different trade-offs...

Michael Mardis at Octupus amps has just posted measurements of 4 different Tripath-based amps: the original Sonic Impact, the Sonic Impact Super T, the 41Hz.com Amp 6, and the Fenice 20A. The measurements can be found at http://www.michael.mardis.com/sonic/measure/default.html.

I have become a fan of amps based on these chips (which I believe have incredible performance for the price) and own the Sonic Impact Super T (cost $139 US). I think that Stereophile has done its readers a disservice by not looking into these amps yet.

If these "low brow"(!) amps don't catch the attention of some readers why not evaluate a more expensive amp such as one by Red Wine Audio (http://www.redwineaudio.com/index.html). The battery-powered feature of these amps may interest readers on this feature alone (my Super T is powered by a lead-acid 12V motorcycle battery!).

There are audible differences between the Super T amp I have and my other integrated amp, a PrimaLuna Prologue One. However I'm not going to be modifying the PrimaLuna for fun (ever!) but will be modifying the Super T as other more technically-inclined point the way.

After reading Art Dudley's review of the Halcro Logic MC20 class D amplifier, and reviewing the Chanel Island write up of a few months ago, there would appear to be a number of similarities between many current class D and class T amplifiers. The absolute solidity of image placement and intriguing detail retrieval are paramount virtues of the "digital" amplifiers. Timbral accuracy and immersive ambience seem to be beyond reproach in all but the lowest octaves with the class T amplifiers (and this seems very much load dependent when dealing with the more sophisticated class T designs). PRaT is well rendered by the class D and excels in the better Tripath chip amplifiers. Indeed, pace and timing are areas where the Italian class T amp succeeds quite handsomely (here the SLA battery "power supply" made a vast improvement over "AAA"'s at a cost of less than $40). In all, if these designs were subjected to a Zogby style poll, they would more than likely get an overall approval rating in the high nineties for their handling of the musical performance.

The negative comments come only when these (sometimes ridiculously inexpensive amplifiers) are compared against the best of what is left in class A and AB amplifiers. The traditional designs can still manage to outclass the newcomers in the final conviction the music is being created at the listener's pleasure. The three dimensionality of the analog, and most particularly the tube based, designs still trump the class D and T amplifiers. But at what cost? And, for how long will the traditonal amps hold this superior position? The $30 T amp is remarkable for what it does at any price. To hear this level of quiet from an amplification chain is well worth the price of admission. The better class T amplifiers push the limits of the comparison to ridiculous levels. Surely these designs, although mostly kit based, deserve an honest review in Stereophile and the subsequent debate over what is important to audiophiles. My guess is these amplifiers will engender the same vitriolic name calling and certitude which spews forth from the cable wars. Class T will be the uniter, not the divider, which pulls tubes and solid state into the same camp against a common challenger.

Mr. Vigne, that was a great post.

It is, indeed, and exciting time for amplifier designs!

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It is a shame that he has been so busy since September 2005 that he has not had time to actually listen to the T-amp.

Yes, I have been busy. I currently work a minimum 60-hour week and I still don't have time to do everything I need to do.
:-(

I do have the T-amp in my listening room, however.

Puzzled by the reference to waiting for the review since "September 2005." I purchased this amp at the end of January.

John Atkinson
Editor, Stereophile

I am not interested in a $30 amp made of plastic, but would love to see the next NAD 3020 reviewed. Or even the next Pionerr A400. I want to see the next generation of working joes get back into music. Unless we 'discover' NAD 3020's and Classic "Budget" speakers, we are going to lose most of a generation. I have 4 kids all with some kind of sound system. All buy Cds, all go to rock concerts, and buy tshirts etc etc. None are weathly and would be even more drawn into the beauty of music if they could buy a 'classic" Hifi budget system. They seemed to be around in the 70's. What ever happened to classic BUDGER starter Audio gear?

This will sound much more impolite than I intend, but ... if you aren't interested in a $30 plastic amp, you probably should have started a new thread rather than post on the one discussing $30 plastic amps.

Or, you might have read the entire thread and found there are alternatives to the $30 amp which offer improved performance and some interesting features. You say you would like to have some budget oriented products reviewed for your kids in order to get them interested in audio. Do you need reviews of these amplifiers in order to get your kids interested? How interested will they be when the power supply caps on a twenty five year old amplifier go to that big reservoir in the sky? I'm all for vintage audio and own a bunch of it, but make it vintage worth sinking repair/refurbish money into. Which would you rather refurb, a '62 Studebaker or a '65 Mustang?

How about this idea? You buy one of the class T amplifier kits (read my comments on the Autocostruire amplifier on this thread here; #5924 - 03/18/06 03:51 PM) and you and your kids sit down and assemble it together. Do the whole enchilada; the power supply, the cabinet/enclosure, switches, connectors, etc. It's cheap enough each kid can have their own to outfit however they want and they can compare results. The amplifiers instruction manual includes a description of the modifications you can make to the amplifier to improve its sound quality so you can get your kids interested in the value of what makes an amplifier sound good rather than just buy some vintage stuff from the want ads. This sounds like the perfect opportunity to learn a bit more about audio, have some quality time with your kids and end up with an exceptional sounding amplifier for a few bucks and a few nights with the kids. Or buy the T amp and start the modification process to bring it up in performance. Once again, a learning experience for you and your kids. A pair of DIY speakers and you've got more than any inexpensive integrated amplifier could ever provide. Unless, of course, you consider riding around from repair shop to repair shop quality time.

I can't wait to see what the JA thinks of this little gem. I just got mine a couple of weeks ago and have been renewing my frienship with music that I haven't listened to in ages. I am powering a pair of Paradigm Monitor 7 v.3s with this "little plastic box" and have found it completely enjoyable. It blisters my Yamaha receiver and has made me change my mind about selling my Paradigms.

I have found the T Amp very fast, accurate, and revealing in the midrange.

I am now curious to hear one of the more powerful digital amps can do to enhance the bass and maybe increase the soundstage...

But for $30!!! If you haven't tried one yet, go to Target.com and get one today. You won't be disappointed.

I'm sorry, but did you say "increase the soundstage"? In my experience and that of many others who have reported the same perceptions of the class T amps, the soundstage already places instruments and performers outside the physical boundaries of the listening room. I would say you might want to tweak your speaker placement and listening position or else deal with some room needs if this is not what you are hearing from the T amps.

Bass response is still not at top notch levels for most of the class T amps. The last half octave is why you will spend the extra few thousand dollars for traditional amplifiers. The Sonic Impact, at $30, is the most rolled off of the bunch. This is an area where most of the modifiers turn their attention in the first round of tweaks to the T amp changing out input caps and output filters. The Autocostruire and the Charlize have the reputation for much more extended, tuneful and defined bass response. Owning both the SI and the Autocostruire amplifiers, I can vouch for the sonic improvements to be made by moving to the Italian unit. The power supply you choose will make substantial improvements in sound quality, bass extension and quality and the overall PRaT of the amp will take a leap forward with something other than the rechargeable "AA"'s that fit in the plastic case. The unregulated wall warts offer only a mild improvement. The real improvements come when the amps are paired with either a SLA rechargeable battery or a regulated power supply, both should supply sufficient amperage (around three to seven amps is enough). The choice of speakers makes a significant improvement in sound quality overall and most especially in the bass response. Give these amps straight eight ohm loads and no oddball phase angles. This allows plenty of headroom from the little six watt amps if the speaker is at least 89db efficiency. Input and output caps and protection networks affect the bass response of all the class T amplifiers. The Autocostruire and the Charlize both use "custom" made air core inductors and have the edge in bass response and smoothness of sound. If you've not looked into the modifiers' pages for the T amps yet, take a look at what's being offered.

There are links provided at the end of this thread:

http://forum.ecoustics.com/bbs/messages/47077/209464.html

Comments on the class T amps can be found here:

http://forum.ecoustics.com/bbs/messages/1/193312.html

http://forum.ecoustics.com/bbs/messages/1/193045.html

Thanks Jan, for your post and the links.

Very Informative.

Cheers !

I can hear JA beating his head against the wall from here.

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I can hear JA beating his head against the wall from here.

That was me.

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Could it be that Sonic Impact doesn't have the $ to advertise in Stereophile?

John Atkinson has tackled this question.

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Could it be that Sonic Impact doesn't have the $ to advertise in Stereophile?

John Atkinson has tackled this question.

Yet another anonymous Internet [censored] pops up in our forums, Stephen. No, the delay in the T-Amp coverage has nothing to do with the company's advertising status. FYI, Sonic Impact has also just sent me their Super-T amp for review.

John Atkinson
Editor, Stereophile

Could it be ... ?

Could it be the Mothership has called JA home for a while?

Could it be the NSA has Atkinson's phone lines tapped and he can't communicate with anyone?

Could it be there is no Atkinson, there is no Stereophile and there is no T amp and you've just dreamed another dream?

Nah!

Could it be the T amp has sold out three production runs and doesn't need any more advertising at the moment? Could it be the people who make idiotic complaints about audio magazines and advertisers' money never buy anything good anyway because they're afraid to get "taken". Could it be those same people think the world is out to get them?

Could be.

Just because you are paranoid doesn't mean everyone's not out to get you.

Monty - You must have read that somewhere. No, no one is out to get me and I'm not the least bit paranoid. Some one can "get" you only when you let yourself be "got". A bit of intelligence and a good sized helping of common sense will go a long way toward ensuring a happy and contented life. In that respect, at least. No dreaming of conspiracies that don't exist or audio magazine editors with hidden agendas.

What sort of emails do you think anon sends to the editor of "Car and Driver" or "Wine Spectator"?

I'm always surprised to find that the real nut cases, who always prefer to remain anonymous, making these heavy browed comments about collusion between manufacturers and magazines or manufacturers and dealers can put down their Alprazolam bottles long enough to type. Certainly operating electronic equipment of any sort (yes, the toaster does have a camera inside) must take a double dose of medications. They must be aware of the Stereophile Security forces, on loan from Fox News and Bill O'Rielly, and that they are now being monitored on a continual basis. Their only security comes from the fact they allow themself the indulgence to say anything that sneaks in under the aluminum cone on their head while the rest of us accept a certain amount of social grace and refrain from calling them the fool they truly are.

http://www.6moons.com/audioreviews/sonicimpact2/t2.html

UL/ETL listed? http://www.si-technologies.com/frontEnd/cm_productDetail.jsp?productID=35

Yeah, I would have attributed the remark, but I have no idea where it originated. I was, of course, joshing.

I own 2 SI t-amps, have had them for 1yr. They do not need any mag to promote them for SI cannot keep up with demand Without a doubt the t-amp is the best bang for the buck, bar none, in hi-fi audio.

Monty - I kind of thought so. Sounds kind of Hunter S. Thompson-ish. Fear and Loathing, and all that kind of stuff. I don't know if there is a legitimate source.

http://search.yahoo.com/bin/search?p=just%20because%20you're%20not%20paranoid%20doesn't%20mean%20their%20not%20out%20to%20get%20you.

I'd also like to get back to the original thread. As I noted much earlier I have a Sonic Impact Super T amp and have been very impressed with the incredible 'bang for the buck'. I'm now also playing with with the Autocostruire (AudioDigit) Class T-amp 100 kit and have found it similarly amazing for the money but this kit is not $30!

Not thirty dollars? Who ever suggested you don't get what you pay for? The Autocostruire amplifier has been a much better sounding amplifier in my system than the Sonic T ever managed. True, the Itialian amplifier kit costs several times that of the complete Sonic T amplifier, and requires some work on the owner's part to achieve the best results, but the difference in sound makes the cheaper amp a give away to a friend.

So has there been any free time for the editors and writers of stereophile to give a listen? any impressions?

I just completed some simple modifications (though i did botch them initially by not properly isolating my outputs from the metal case!)

anyway it now plays deeper, and its easier to hook up. I made a sideways move in input cap quality (electrolytics from radio shack) and potentiometer. The sound is great for the price, given i had an SLA battery lying around the house (car jumpstarter) and i inhereted the tools. my total cost came to 36 bucks (Ecost had the amp on-sale for 20 bucks last year, i bought 3)

I have listend to it on a pair of kef coda 9.2's with a 91db sensitivity.

for 36 bucks it is more open, more detailed, has a better sense of space, better decay, natural sound on plucked strings, and great imageing, which trounces a sony 5 channel reciever, and a panasonic 50 disk all in wonder.

when hooked up to my diamond 9.6's it sounds nice, but, save for the imaging, dosn't hold up to the krell kav-300il which usualy runs them. unlike the krell which spanks my speakers around the room, I get the fealing that the little amp is struggleing to keep the relatively benign wharfedales in check.

I posted some picks in the diy gallery
http://forum.stereophile.com/photopost/showgallery.php/cat/all/stype/1/si/T-amp

Cheers

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So has there been any free time for the editors and writers of stereophile to give a listen? any impressions?

Check out http://forum.stereophile.com/photopost/showphoto.php/photo/814

Wes Phillips' report on the deluxe ($159) version is scheduled to appear in our October issue, which ships to the printer next week.

John Atkinson
Editor, Stereophile

excellent!

I look forward to that review, good or bad.

don't know how I missed the pic in the galleries.

cheers

Well OK, it's me again, I'm the one who posted the original question about reviewing cheap amps.

First of all thank you very much, I just received my October 06 issue and read with pleasure the review of the Super T by Wes Phillips. A big thank to Stereophile's staff that demonstrated to be really open minded about the subject of new technologies, in spite of the price.

Now the firts step is done. But, hey, Stereophile guys, are you ready for the next?

It's easy, from the review, to understand that the Class T technology, as implemented by Sonic Impact, is not expressing the full potential. Changing the power supplies or using some other tweak just changes and improves the sound.

That's what I was trying to suggest with my posts after the first question. The technology is promising, we must exploit its full potential.

After the initial interest in the T-Amp, I actually embarked in designing and reselling "improved" T-Amps with a small company (see www.audiodigit.com if you are interested). We worked hard on some ideas and come out with a line of amplifiers that, for some more money (not much), really take the sound to another level, and offer both higher powers (100w x chanenel, not all speakers are high efficiency ...) amd multiple channels (4 or 8 channels, what about home theatre applications?)

It's clear that the original Sonic Impact products were designed to be cheap, not to be hi-end. Internal components can be improved, circuit layout must be different, the power supply must be a good one.

The most important aspect that we changed in our designs is the output circuit, that in the original amps (and most clones) are based on "cored" inductors. This filter circuit, actually a 10 uH inductor in series with a capacitor, is actually a low pass filter that is needed to remove the "carrier" switching frequency that is typical of switching amplifiers.

We imagined that using "air core" inductors could change a lot the sound. They are not likely to saturate at high current levels, nor have an "hysteresis" curve that actually changes the shape of signal. We were right, and ALL our amps and modules use our "air core" inductors, in plain copper or Litz variants. Our customers confirm that they deliver a "grain-less" and open sound that is impossible for the original amp.

So, what's the conclusion? We really think that designing Class T amps with hi-end sound in mind can really deliver the ultimate performance and satisfation for the price, and that our amplifier modules are the incarnation of this concept.

We'd really like Stereophile's staff to go on the "cheap amp" line by reviewing one of our amplifiers, maybe the 100W stereo or multichannel amplifier. We have also "hybrid" (Tube + class T) integrated amps, the best of both worlds.

We'd be pleased to send to Stereophile one or more review samples. If that sound interesting for you and your readers ... just contact us at support@audiodigit.com.

Thank you againg. Daniele.

Quote:

Changing the power supplies or using some other tweak just changes and improves the sound.

What the Hell?

Isn't your company really all about "changing and improving the sound?"

Helpful hint: This whole hobby, all of it, is actually about exactly that...changing and improving the sound.

If your gear doesn't change or improve the sound, then what does it do?

Why buy something that doesn't change or improve the sound?

This months TAS is devoted to class D amplification. They seem to agree that the potential for great sound is there, but hasn't matured yet. The analogy between early CD technology and the current level of performance is used.

Interesting reading that will pretty much catch everyone up to speed on where this technology is and where it might be going.

Of particular interest to me, is the general consensus that class D amps seem to be particularly sensitive to cabling and they all exhibit some degree of problem in the treble region. Perhaps the efforts to address these two issues will ultimately have the secondary effect of gaining a little more insight into the effects of cable geometry and its use in transfering audio signals.