I haven't played with class D in a while, are we at PASS level yet? - diyAudio
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Class D Switching Power Amplifiers and Power D/A conversion

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Old 17th March 2011, 04:45 PM   #1
JZatopa is offline JZatopa  United States
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Default I haven't played with class D in a while, are we at PASS level yet?

Just like the title says I haven't played with any class D amps for a long time. When I was listening to them they were great for the money and small size but still had a ways to go in the sound quality department. I'm curious if some of the DIY amps and premade boards have achieved the level of, lets say an F5 Pass Labs amplifier? Personally, I think that class D will begin to start taking over the market place once it has achieved that level or better.
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Old 17th March 2011, 06:00 PM   #2
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Originally Posted by DJNUBZ View Post
Just like the title says I haven't played with any class D amps for a long time. When I was listening to them they were great for the money and small size but still had a ways to go in the sound quality department. I'm curious if some of the DIY amps and premade boards have achieved the level of, lets say an F5 Pass Labs amplifier? Personally, I think that class D will begin to start taking over the market place once it has achieved that level or better.
I'm not sure what you mean by "the level of the F5".

Class D need not meet the specifications of an F5 to take over the marketplace IMHO. Those not wishing to spend $3K on an amp can a make a class D amp that sounds just as good to most ears but with much higher power, much lower output impedance, and similar levels of distortion at the power levels of the F5 for 1/5 the price of the F5. I haven't heard an F5, but I've heard a lot of amps, and the Hypex UcD modules sound great to my ears. If you can hear a difference between those and a $3000 F5 and think the F5 sounds better and have no qualms about spending $3000 then go for the F5.

But most people would not hear a difference in double blind A/B tests and most people don't have $3k to spend on an amplifier. Nobody can hear out to 100kHz, and speaker distortion dwarfs the 0.002% spec of the F5. The Hypex is not much higher at 0.01% at nominal power levels. Once the specs get good they become meaningless. Sure, if an amp has 10% THD it will sound bad. But if it's less than 1% or so there's no reason the amp can't sound great. A THD of 0.002% simply means the amp might sound good. Same thing with most other specs. Very poor specs almost always mean poor sound, but great specs don't necessarily equate to good sound. No doubt the F5 sounds great. But how "perfect" does an amp have to be to *sound* perfect? That's an individual opinion in most cases, but SURELY there is a point where an amplifier becomes so good that it can't be surpassed in the sense that the limitations of the human auditory system are physically incapable of detecting the difference between it and an even "better" amp. The F5 may sound like the perfect amp, but so do my cheap (relatively) Hypex modules, at least to my ears.

Without a double blind A/B comparison there's no real way to know if one amp sounds better than another once they become sonically close. It's been proven that if people *think* they are listening to or tasting or looking at something that is "better" they will choose that item when asked which they prefer even when the items are IDENTICAL. Your subconscious influences your choice. The ONLY way to eliminate this effect are double blind listening tests.

There are a lot of class D amps out there now, and unless you've heard all of them and compared them side by side in the same room with the same speakers you can't draw any conclusions about the superiority of a Pass Labs amp or any other amp for that matter over something you haven't heard. It's doubtful that very many people have the money, time, or inclination to double blind test every class D amp in comparison to respected reference amplifiers, and without that experience all you will get are subjective opinions like mine.

Last edited by sampleaccurate; 17th March 2011 at 06:05 PM.
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Old 17th March 2011, 08:28 PM   #3
back is offline back  Greece
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i read a review somewhere (ithink enjoy the music)which compared hexateq(hypex)to
f5 and hexateq was very close but a little under f5.
they dent it back and hexateq changed some parts and they tried again.
the second time the hypex surpassed f5.
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Old 17th March 2011, 09:18 PM   #4
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Thumbs up Pretty close

Spend $120 - about what decent heatsinks for an F5 cost if bought new - for something like a hifimediy T1 plus the appropriate Meanwell plus shipping plus a couple decent coupling caps. Then listen for yourself.

Sounds pretty darn good, and is a lot cheaper than an F5, and doesn't sit there burning several hundred Class A watts.

Hard to compare, though, very different approaches, hard to say which is "better".

On the Pass front, I'm waiting for Nelson to release the schematic for the J2 so I can play with the SemiSouth power JFETs.
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Old 17th March 2011, 10:08 PM   #5
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At this stage I would recommend buying a ready built/tested module.

Class D can be tricky to design and layout on a pcb for the uninititated.
I have 35 years of experience in electronics but got caught out when designing a irs2092 based amplifier. Even with a datasheet circuit to copy my first attempt didnt run. Problems with decoupling, inductors and layout were all problems.
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Old 17th March 2011, 11:28 PM   #6
JZatopa is offline JZatopa  United States
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Forget about the price aspect and THD. A good sounding amp is a good sounding amp. the best amp I have owned so far is the Decware Zen Select SET. I picked the F5 because it is a DIY amp that is relatively reasonably priced to build and has become somewhat of a standard. When class D first became popular there were a lot of terrible sounding class D amps around. I chalked this up to the fact that is was a relatively new amp design and had not been refined for as many years as tube and SS amps have been.

bdbender those power JFETs sound very interesting. I don't want to know if Class D is better then F5, I want to know if class D has reached a level of design and refinement where the difference would be a matter of personal taste. This is one of those things where describing audio in general becomes one big gray area. Would you say the T1 from hifimediy would be a good example of the best DIY class D amps offered currently?

Last edited by JZatopa; 17th March 2011 at 11:34 PM.
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Old 17th March 2011, 11:48 PM   #7
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Originally Posted by sampleaccurate View Post
I'm not sure what you mean by "the level of the F5".

Class D need not meet the specifications of an F5 to take over the marketplace IMHO. Those not wishing to spend $3K on an amp ...
This is a serious logic fail. You compare the hypex diy units to a finished amplifier. One can build an F5 for around the same money (or less) than even the cheapest hypex unit.

As to the rest of your email, I have compared some very expensive D amps to the F5 (which should I prefer then?) and PREFERRED the F5. To my ears, it wasn't even close.

Like the original poster, I'd be interested in hearing about the latest and greatest!
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Old 18th March 2011, 05:07 PM   #8
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Originally Posted by DJNUBZ View Post
Would you say the T1 from hifimediy would be a good example of the best DIY class D amps offered currently?
Well, I don't want to pose as an expert on something I am not. I was collecting parts for an F5, have the cviller boards and the matched transistors and so forth, but stalled at the heatsinks, toroids, and case. The way I was going to do it they would have been $300 or $400 easy (yes I know you can cobble something together for less).

I got distracted by the hifimediy "new TK2050 board" thread, and after reading the whole thing, ordered a T2 plus Meanwell. I got the T2 instead of the T1 because I am running 4 ohm speakers. It sounds so good to me I have never looked back, and listen to it all the time now. The only mod I made was to add some 3.3mf Auricaps as the input caps (yes I know Bruno Putzeys says that's a no-no but I have them shielded with copper tape and they not only improve the sound, they run quite a bit louder indicating lower ESR.)

From reading around since, my understanding is that a number of folks think the Tripath TC2000 controller was the best sounding class D implementation so far. If I have it right, this controller used a spread spectrum sampling method, as opposed to the more common fixed frequency sampling, which may account for its sound.

And I'm having fun with all this, which is the point of DIY, no?
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Old 18th March 2011, 07:21 PM   #9
rha61 is offline rha61  France
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Quote:
Originally Posted by DJNUBZ View Post
Just like the title says I haven't played with any class D amps for a long time. When I was listening to them they were great for the money and small size but still had a ways to go in the sound quality department. I'm curious if some of the DIY amps and premade boards have achieved the level of, lets say an F5 Pass Labs amplifier? Personally, I think that class D will begin to start taking over the market place once it has achieved that level or better.
definitely yes , some class D amps are now as accurate as the best A/B amps.
I use Hypex modules with modded output cap ( that 's what Hexateq or Genesis have done ) and i've never heard a better amp
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Old 19th March 2011, 08:01 AM   #10
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Originally Posted by rha61 View Post
I use Hypex modules with modded output cap ( that 's what Hexateq or Genesis have done ) and i've never heard a better amp
Do you have any details on this mod?
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