• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Old class A vs New class D.

savatage1973 said:
I can fully attest to this--I own 4 Krell KMA 160 monoblocks. With a mere 160w @ 8 ohms power rating, each one weighs just under 100 lbs and draws 8A of current at idle, and if you let them idle for an hour, you are ready to cook eggs for breakfast. The main power supply caps are the size of beer/soda cans and the transformer is like a brick. The advantages; however, are that they each double-down to 1280w of output into a 1 ohm load (as per the factory manual), and can be tweaked to operate below 1 ohm--basically arc weld with them.
Click to expand...
Funny you should mention the soda cans. The friend who bought the samsung system i referred to was over and I pulled the top off my audire model 2 to show him the caps. I held a sprite can next to them and proceeded to give him a mini lesson about capacitance and current :)
I've been wanting krells for a while but I'm still on a lux kick
 
noobydoo said:
Hello all. So I just watched a review of a Lepai class D amp. This little thing supposedly puts out 160 watts into 4 ohms with low distortion, all at the price of a night out on town for 2. Should I be tossing out my Luxman 5m21 , which is only rated at 100wpc into 8 ohms to make room for a pair of these? Discuss :)
Click to expand...

Clearly you should toss that technologically inferior Luxman in a box and send it to me for disposal. I'll be sure to take good care of it.
 
I've only a little experience with cheap Class D boards.
Both I own are based on TPA 3118, and definitely sound better than they have any right to.
There's a lot of variation in the builds themselves....some sound better than others.

A whole other step up are the Texas Instruments Evaluation modules using the TPA 32xx family of chips.

I haven't heard anyone complain about lack of power from EVM TPA 3255 http://www.ti.com/tool/TPA3255EVM#1
Nor have I experienced any with my new favorite EVM TPA 3251 http://www.ti.com/tool/TPA3251D2EVM
I'm also quite pleased with EVM TPA 3250 http://www.ti.com/tool/TPA3250D2EVM
 
Last edited:
I like watching videos by johnaudiotech on YouTube. He tests a bunch of these chip amps and gives nice overviews.

The amp in my main system is conventional but I've got a bunch of different chips and/or amps, some class D and some not. For the price they cost it's fun to experiment with them.
 
Theres an old story about you can't get something for nothing. Class D in a lot of ways is a something for nothing. The first Carvers I ever heard were really offensive to me. But used with less than stellar speakers provided sound. I have auditioned Crown D amps while shopping with friends kids and they do the job. Thats what they are built for to do; a job. NADS top of the line versions are quite acceptable. But they are not going to make me give up my old conventional Mcintosh power amps. The build quality isn't there. My Amps are 10 years old now and I plan to be enjoying them 20 years from now. My 2505 I purchased in 1971 or 2 and I plan on keeping it for a while.
 
Last edited:
kirk57 said:
I wish they would just rate these things like they used to, stating (reasonable, say under 1%) THD into 8 and 4 ohm loads and 20-20k bandwidth. You have to be really careful these days trying to figure out what they are leaving out when stating specs.

Seems we went backwards in that respect.

That said, I do use and enjoy my Lepai 2020+ daily in the kitchen.
Click to expand...

Most of those chip amps are rated at 10% THD / 4 ohm / at 1KHz only. So the already enormous 10% distortion is going to be even larger at lower/higher frequencies.

If those amps were rated completely honestly, one that claims "160 watts" would probably only rate around 10-20 watts at most.
 
I've a number of big, expensive Class A and A/B amps and a number of small, inexpensive Class D (and T variants) and they're all fun for what they are. I try not to be unreasonable in my expectations in either case. But as a number of us have observed, Class D etc have made spectacular leaps in SQ and other aspects as well, in just the last several years. Many are now legitimate contenders imho. Whether or not they will unseat the big dogs remains to be seen.

There are certainly tasks for which only the big dogs will suffice--for now. And there are other aspects of their appeal.

Most of those chip amps are rated at 10% THD / 4 ohm / at 1KHz only.
Click to expand...

I have seen only one chip thus rated, and it turned out to be a typo in the spec translated from the Chinese. 10% was supposed to be 1.0%. But there could be others, I'm sure. ETA: I've learned a lot from this thread: http://audiokarma.org/forums/index.php?threads/tpa-3116-vs-the-tripaths.574806/ and similar threads on other forums. Even the old 6 Moons review of the obsolete Trends Audio TA-10 was informative. I was just reading it last night: http://www.6moons.com/audioreviews/trends/ta10.html -- That's more than ten years old now and the tech has transformed since then.
 
Last edited:
I totally fail to see the advantage to the end user of either the Levinson or the ARC in the whole price/performance/weight/serviceability/reliability matrix.
At their price point (and size/weight acceptability), what is to be gained (for the end user) over tried and proven A or AB amps with rock solid, durable linear power supplies?
Maybe I'm just a Luddite.
 
JoeESP9 said:
It's interesting that ARC seems to have abandoned Class D.
Click to expand...
Now that ARC is part of the WOM (World of McIntosh) group, I suspect the corporate direction is for each company to focus on their core competencies. I found some comments by McIntosh president Charlie Randall interesting in his take on the two brands:

"Many people ask me if Audio Research is a competitor, since they’re also part of the McIntosh Group. I tell them not really, and here’s why: the Audio Research customer is a true audiophile, as opposed to a music maniac. The audiophile cares as much about the product as they do about the music they are listening to, and they’re compulsive about both. They want to know how the design of the product was done, what electrical components are in the signal path, etc. If you ask an Audio Research customer what they have, they’re probably going to tell you they have an ARC preamp, a Pass Labs amplifier, a Wazoo DAC, an XYZ CD transport, whereas the McIntosh customer just has McIntosh -- they gravitate to the stack."

Indeed. While NE5532 op amps work great in my $100 M Audio sound card and $400 Oppo 103, I wouldn't spend many thousands on components using them.

As for switching designs, I've heard a number and find the best results from designer Bruno Putzeys with his "Hypex Ncore" amplifiers. Some are sold OEM to a wide range of manufacturers (I use an NC502mp based amp in the garage) as well as his own Mola Mola brand. They haven't made me replace my tube amps, but they do have a very seductive midrange if not still facing challenges at the top of the spectrum.
 
Last edited:
tarior said:
I totally fail to see the advantage to the end user of either the Levinson or the ARC in the whole price/performance/weight/serviceability/reliability matrix.
At their price point (and size/weight acceptability), what is to be gained (for the end user) over tried and proven A or AB amps with rock solid, durable linear power supplies?
Click to expand...
Yours is a good question. I have not been a fan of switchers until late and use a Hypex based unit in the garage system albeit it ran only $800.

Others would argue that the latest Ncore stuff by companies like Bel Canto is pretty darn good.
 
You and I both agree that they really aren't great on the top end. From a mfr. standpoint, they make sense. Good power (though usually not what it's claimed to be, but sells amps), light weight (saves $$$), and off the shelf chips (saves $$).
With all of smack talk I hear about CDs sounding bad due to their PCM schemes, it kinda boggles the mind to hear people talk up PWM amplifiers for high end audio use. They make great sense for use as amplifiers in self powered subwoofers, however.
 
Some of the cheap Chinese amps are interesting. And so cheap that you can buy them just to have a play. I bought a 'Sanwu' 25W stereo amp with CSR Bluetooth 4.0 receiver, delivered, for £6.82. It's the size of a packet of cigarettes. Powered by an old laptop power supply, it drives all the speakers I've thrown at it (none of which are particularly 'audiophile'; the nearest being some TDLs). The class-D chip has never got more than body heat, even with no heatsink.

I can't vouch for their audiophile capabilities, but if you're looking for a 'convenience music' system, driven by a bluetooth source, they're worth looking at, IMHO.
 
AB seems a good efficiency compromise between A and D, to me. Plus, AB designs have been refined over decades by many. Class D keeps improving, though. The cheap, high-distortion models failed to impress me. Yeah, an eight-watt Lepai can sound kinda okay, but my cheap eight-watt tube amp sounds better.
 
I am under the impression that 'class D' is not the same as 'chip', and that one does not imply the other. Is this correct?

It is my opinion that one can now buy equal or better sound than the famous NAD 3020, for $30. Not saying the power or features are matched, btw.

I believe that powered speakers will become much more popular, eventually.
 
sqlsavior said:
I am under the impression that 'class D' is not the same as 'chip', and that one does not imply the other. Is this correct?
Click to expand...
That is correct. Class D refers to how the amplifier circuit works. That and its high efficiency -- most of the power supply energy turns into speaker output, not damaging heat -- means the components can be easily turned into an integrated circuit aka a "chip", but discrete component versions are available too.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom