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21st November 2005
Old 21st November 2005
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Class T Amps

OK, I've been poking around some audiophile forums, and aside from learning that they're a bunch of wackos with too much money, I've discovered the world of Class T Amps or Digital Amps.

I'm not a tech so I will not try to explain but rather post a link to a PDF whitepaper that very clearly spells out the differences between class AB, D, and T, and why it represents a potential paradigm shift in amplification technology.

http://www.tripath.com/downloads/an1.pdf

Basically, Class T Amps can provide audiophile performance with low manufacturing cost, very light weight, and very llittle heat.

So, my question is, why haven't we heard about this marvel technology in the pro audio world?

Why aren't there powered monitors running on Class T Amps?

Why aren't there bass and PA rigs using this technology?

How long will it take for us to see some pro products using Class T?

I see car audio and home audio with Class T but no pro audio?

http://www.tnt-audio.com/ampli/t-amp_e.html

It seems like a win-win for the consumer and the manufacturers, so where are all the pro audio products?
#2
21st November 2005
Old 21st November 2005
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Hi

I'd never heard of Class T (sounds like a spoof because I haven't heard of anything past H) and I'm not impressed with the specs.

Audiophile, my ass...

They quote distortion in the region of 0.08%... for a single amp? Lordy, back in the 70's the Neve thd for an entire console had to be below 0.075%.

I recall the trusty Mackie has distortion with multiple zeros (0.0007%).... but is a Mackie audiophile or sound like a vintage Neve?

http://www.mackie.com/products/sr32-4vlzpro/

How "good" do you suppose these digital amps sound?



Amp classes.... http://en.wikipedia.org/wiki/Electronic_amplifier

PS My 40 year old home hi-fi amp is tube based ultra linear circuitry and manages around 0.08% at most reasonable listening levels. It sounds really good!
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21st November 2005
Old 21st November 2005
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Geoff,

I think you are in for quite a surprise when you hear one of these.

We're talking about a paradigm shift in amplifier technology, so I can understand you skepticism. You should have heard how hard I laughed when my audiophile friend called me and told me he had a $30 amp that could outperform units costing 100 times its price.

Then I heard it.

http://www.sixmoons.com/audioreviews...mpact/t_3.html



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21st November 2005
Old 21st November 2005
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Quote:
Originally Posted by cdog
Geoff,

I think you are in for quite a surprise when you hear one of these.

http://www.sixmoons.com/audioreviews...mpact/t_3.html



Hi

May be... but I'll stick with my 40 year old EL84'd tube amp!

You can pick them up off EBay for around $100... or higher depending on the version.

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21st November 2005
Old 21st November 2005
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You're preaching to the converted... I have a Fisher 400 running on NOS 7868s with all original Telefunken 12AX7s....

I'm just wondering how much I should invest in the company.... the stock is trading for pennies currently.


(OK thats enough smokey smiley faces for one thread!)
#6
21st November 2005
Old 21st November 2005
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Quote:
Originally Posted by cdog
Why aren't there powered monitors running on Class T Amps?

Why aren't there bass and PA rigs using this technology?

How long will it take for us to see some pro products using Class T?

I see car audio and home audio with Class T but no pro audio?

http://www.tnt-audio.com/ampli/t-amp_e.html

It seems like a win-win for the consumer and the manufacturers, so where are all the pro audio products?
There are many powered monitors running on Class D tho. For example: ADAM P33A, Focal SM8, PMC DB1S-A & TB2S-A. I feel that these amps outperform many normal amps used in active speakers.
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22nd November 2005
Old 22nd November 2005
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Quote:
Originally Posted by DrDeltaM
There are many powered monitors running on Class D tho. For example: ADAM P33A, Focal SM8, PMC DB1S-A & TB2S-A. I feel that these amps outperform many normal amps used in active speakers.
Class D is VERY different than Class T.

Class D is used mostly for subwoofer power where fidelity is not at a premium.

Class T is for full range sound.

There are no powered monitors using it...... yet.

If you want to get into this cool technology now, you have to buy something like one of these and use it with some speakers with sensitivity above 90db/w/m.

The amps are not high wattage but INCREDIBLY EFFICIENT, so speaker efficiency is a concern for the smaller T amps.

High Power:

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA%3AIT&rd=1

Low Power Cheapo:

http://www.pcmall.com/pcmall/shop/de..._id=pwbfroogle

Low Power Audiophile

http://www.redwineaudio.com/

#8
22nd November 2005
Old 22nd November 2005
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http://www.powerphysics.com

These are digital amps, a variation of class-d, I believe, but they hold a patent on an approach that makes them much lower distortion. They sound incredible.
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22nd November 2005
Old 22nd November 2005
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#10
22nd November 2005
Old 22nd November 2005
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Never heard of it either, dont believe you will see this in any true high end mic pre. A little confused on how they combine 2 different class amps, A and A/B into one...
The distortion is a good decimal worst than a GOOD class A amp...
#11
22nd November 2005
Old 22nd November 2005
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Quote:
Originally Posted by cdog
Class D is VERY different than Class T.

Class D is used mostly for subwoofer power where fidelity is not at a premium.

Class T is for full range sound.

There are no powered monitors using it...... yet.
Yes, I wasn't trying to say D and T is same, sorry for the confusion. There just is no reason to diss Class D, as very good class D amps can be build, for full range sound. And that's proven by the manufacturers i mentionned.
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22nd November 2005
Old 22nd November 2005
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The Flying Mole amplifiers seem to be gaining a good reputation. It might also be worth taking a look at Bruno Putzey's amplifier modules which are starting to find their way into some well respected manufacturer's products.

I don't know whether either of these would be labelled as class T but they are certainly switching amplifiers.

Cheers

James.
#13
22nd November 2005
Old 22nd November 2005
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The Flying Mole amps are Class D afaik and are being used by PMC in their DB1S-A and TB2S-A.
#14
22nd November 2005
Old 22nd November 2005
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I read a couple of reviews on the Bel Canto power amp and would like to hear it. I believe it is Class T. According to the article I read, class T is some sort of variation of class D developed by a guy who wanted to rename it (maybe his last name started with T? I forget).
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24th November 2005
Old 24th November 2005
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this seems like alot of marketing crap for just another low end consumer product
if you want power efficenticy and quality stick with proven class D designs like Crown's class-I and Lab Gruppen's class TD
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24th November 2005
Old 24th November 2005
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aussie,

I would respectfully ask that you give one of these Tritone based products a listen before scoffing them off as "marketing crap."

I am an extreme skeptic when it comes to things like this, so I appreciate your skepticism.

As to a product being "low end" or "consumer grade," I think thats all "marketing crap." Whats "high end" and whats "low end" is quite subjective and not always correlated with price.

That being said, they're not just being sold in tiny 6 watt versions at Wallmart.

They're also being used in expensive "high end" desings like those of Bel Canto:

http://www.belcantodesign.com/prod_eOneREF1000.html#

The Sonic Impact T amp is only $30, you've got nothing to lose but your foot in your mouth.

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24th November 2005
Old 24th November 2005
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calling it class T is marketing crap, as Geoff said there is nothing past class H. Crown Class-I is marketing crap as well as its just a bettet designed class D amp.
i know low end/ high end/ consumer/professional is all very subjective. in the end the only thing between consumer or profesional amp is if it has balaned inputs and the power

i cant find an amp labled class T that has any power. the best carver only has 600W @ 4ohm stereo. and efficiency of class T, this thing needs 9.09A to get 600W a class B amp can do it using less power than that

i dont think im going to find one of those amps around here just yet. it may well sound good and have good place in the consumer market
#18
24th November 2005
Old 24th November 2005
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Hey after looking at the data sheet it seemed it would be a cool cheap way to drive a pair of Sennheiser 650s differentialy because that is how the output is driven on this chip. So if it sucks so what.. I'll have spent about 1/2 if not less of what I might spend at the bar tonight! I'll report back later. As an added note in my new issue of Multi media manufacturer they have a mono 400 watt amp that costs $3.80 a piece mind you..if you buy 100, OEM thing you know. Hmmm Litttle Labs power amp ....NAhhhh *~)
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#19
24th November 2005
Old 24th November 2005
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Quote:
Originally Posted by cdog
aussie,

I would respectfully ask that you give one of these Tritone based products a listen before scoffing them off as "marketing crap."
That's Tripath actually - they're a fairly well known manufacturer of audio amplifier chips and chances are that you will find them in many devices - it won't necessarily be obvious because driver chips aren't considered a major selling point. I'm not sure if you noticed but the document you quoted is 7 years old. The fact remains that they are still just a variant on Class D.

Take a look at http://www.adireaudio.com/Home/UcDAmps.htm for something interesting in this field.

Cheers

James.
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25th November 2005
Old 25th November 2005
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The Power Physics approach is pretty good. It is sorta like a delta-sigma control using a high-speed comparitor. It's still a class D amp, but the switching frequency can be higher.

I can't determine what the "Tripath" scheme is.....




-tINY

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25th November 2005
Old 25th November 2005
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OK I'm not a tech so the whole classification of amps is beyond me (among other things).

So, yes, they are class D amps, but, they're significantly different enough in performance that to call them class D would probably be confusing, as most people think class D is only for subwoofers.

So, yes, the name "Class T" is some "marketing crap."

But, the 2 products Ive heard which use it, the Sonic Impact T Amp, and the Carver ZR1600, have impressed me greatly in terms of SONICS.

I don't give a rats ass about how much power I save.

Anyway, Tripath's designs are passing through the 1st of 4 stages of an idea here.......

1) No way it could possibly work. What a joke. Are you stupid?

2) Maybe it could work. Probably not, but....

3) This idea is genius. It works great, its groundbreaking, paradigm shifting....

4) Well of course it works, everyone knows THAT. THATS the most obvious thing EVER. What are you stupid?


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26th November 2005
Old 26th November 2005
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Hi

I may be wrong but I didn't see a post saying that the device wouldn't work... I wouldn't get so frazzled over it.

I suspect it works a lot better than the pulse width modulated amplifiers that Clive Sinclair sold in the UK back in the 60's. They were about the size of a cigarette packet and claimed to push out around 10 watts RMS from what looked like a pair of OC81's that would have a hernia handling much over one watt.

The product line quickly vanished and was replaced with a more conventional Class AB amplifier.

This was around 41 years ago... I'll see if I can dig up a link.

Here you go...

http://www.nvg.ntnu.no/sinclair/audio/x-10.htm

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26th November 2005
Old 26th November 2005
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Quote:
Originally Posted by cdog
as most people think class D is only for subwoofers.
who thinks that? all the big rigs use class D power amps for EVERYTHING. there are even class D pre amps
#24
26th November 2005
Old 26th November 2005
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First thing you have to remember about that Six Moons review.

Those Cain & Cain Ben Loudspeakers are 97dB efficient.
The Avante Garde Duo's are 103dB efficient!

So you can almost run either one with the headphone output of an iPod to a decent listening level.

Those really efficient speakers are what guys buy to go with their single-watt SET amplifiers.

But the trick with that amp is that it sounds good for a thirty dollar amp if that's the one I heard.
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27th November 2005
Old 27th November 2005
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I've recently bought a Sonic Impact T-Amp.

I've got a good Marantz hifi amp to compare with and recently used the same setup with a Linn LK140.

So far, I am impressed with the T-Amp.

I don't have a switch controller to do a quick A/B, but will try to compare soon.

Also, it is bloody loud for such a small amp. I haven't pushed it above half way yet.
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27th November 2005
Old 27th November 2005
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rodabod,

Cool, I'm glad someone out there is listening.

Max, my opinions have nothing to do with the 6moons review. I was turned on to the T Amp by a non-engineer audiophile friend, and I laughed and laughed at him, and then I listened, and then I cried, and then I jumped for joy.

Then I bought one. And then a Carver ZR1600. For testing purposes! The I was going to return it and keep just the T Amp. Oh well.....

The T Amp amp sounds good REGARDLESS of price.

Thats the whole flippin' point.

You could put it in a $1000 box and people would buy it based on sonics.

And no, I was not using highly efficient speakers. For the T Amp I was using the equally price/performance busting Athena Audition BSB1s, with only 90db/w/m sensitivity, and I could certainly hear the difference between it, my vintage Sony integrated amp, and my all tube Fisher 400.

Its not banging loud but, its banging TIGHT.

The I installed the Carver ZR1600, and I listened with big ass JBL E100s.

Again, not the most accurate or high end speaker, but a decent performer.

The bass is incredible without a sub... with movies

Soundstage is HUGE, WIDE, BIG.

It outperforms my original Bryston 4B on several levels.

I don't know if it could hang with a 4BSST, but for $800 new I'm as happy as a cat in a hat in a sack full of weed.

Thats why I started this thread. Spread the word. There's a new kid in town.


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28th November 2005
Old 28th November 2005
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how about comparing that carver with a professional amp and prehaps some concert speakers
running it flat out for 6 hours at 2ohms would be a good test as well
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28th November 2005
Old 28th November 2005
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Quote:
Originally Posted by aussie_techie
how about comparing that carver with a professional amp and prehaps some concert speakers
running it flat out for 6 hours at 2ohms would be a good test as well
Well, I would consider the Bryston 4B "professional" level quality.

Whattya want, me to shoot it out with a Mackie

"Concert speakers"? I'm not involved in live sound. I'm testing these Tripath based amps to see how they perform in studio and hifi applications. Yes, I need to do more testing with more speakers and other amps.

I'm not saying the ZR1600 is the best amp ever. Only a fool would. Its just really, really good for $800. Better than anything I've tried at twice its price. When you get to SST territory and above, the competitions gets serious.

Running it flat out at 2 ohms might prove how much of a man the amp is, but it won't tell you how it sounds.

I can tell you for sure my Bryston can be run all night flat out.

But the Carver ZR1600, in my limited testing, sounds bigger and clearer.

Thats what matters to me here. Sonics.

I think I'm going to hook up my Soldano SP77 Preamp and a pair of 4x12 guitar cabs tonight, just for shits and giggles.

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29th November 2005
Old 29th November 2005
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just suggesting to test it for real world use in the field. after all one of your origional questions was why arnt these amps used in PA rigs

Quote:
Originally Posted by cdog
Well, I would consider the Bryston 4B "professional" level quality.

Whattya want, me to shoot it out with a Mackie
lol wackie, dont get me started on them but im not questioning your bryson. prehaps a crown, or a QSC, but to test something in its price range (infact lower) a Quest would be good. they are the best cheep amp ive come accross but i cant expect you to have one sitting around

Quote:
Originally Posted by cdog
"Concert speakers"? I'm not involved in live sound. I'm testing these Tripath based amps to see how they perform in studio and hifi applications. Yes, I need to do more testing with more speakers and other amps.
yep, a LOUD system being pushed to its limits to see if it can handel it. except they dont have the power but still something smaller could be done and a bi-amped system would be good and interesting to see how it performs with the different frequency bands

Quote:
Originally Posted by cdog
Running it flat out at 2 ohms might prove how much of a man the amp is, but it won't tell you how it sounds.
real world testing, if it cant stand up then it doesnt matter how it sounds. ill take 4 18" subs per side @ 2ohms all night, seriously most amps couldnt handle it
#30
30th November 2005
Old 30th November 2005
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Class T Amps

Hello !
Here the answer for me:

- At this time the ClassT amps are OK for TV, CarRadio, Corporate Audio, BassTHX etc.. but NOT yet for real Hi-Fi, because the distorsion (THD, IMD etc) increase at LOW levels... these low levels (ex. at like -40dB= 1/100 of full voltage amplitude) are never indicated on the data sheets. They often stop before (ex. THD= 0.1% at 0.5Watt, that is only 1/8= -18dB voltage only witch drive the 4Watts indicated on your White Paper).
- It's far better than "LowQuality" Class-D amps but not as good as Class-A or AB amplifiers which can have THD far less than of 0.1% at -60dB= 1/1000 of max voltage level !!... and it's the "smooth random white noise" witch predominate at these levels.
- In addition the reliability is not perfect (like switching AC/DC or DC/DC power supply "ON/OFF" concept witch stresses the output transistors).

But the manufacturers make some R&D progress, because of the numerous advantages you said, but for me it never rivals the high-ends "analog" amps !

Pierre.
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