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Class D Switching Power Amplifiers and Power D/A conversion

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Old 21st March 2011, 06:26 PM   #21
paulb is offline paulb  Canada
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Quote:
Originally Posted by Craig405 View Post
Sampleaccurate, That was an impressive bombardment of hot air, good grief.
I thought it was a very rational account and it leads me to want to look at the Hypex or other Class-D modules. Do you have some specific issues you want to point out in his reasoning? Otherwise I (and I think most other readers) will just disregard your post.
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Old 21st March 2011, 06:54 PM   #22
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Originally Posted by sampleaccurate View Post
That's not correct.
It IS correct. Now please stop shouting.

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Originally Posted by sampleaccurate View Post
I compare a completed amp USING Hypex modules to an F5 purchased pre-built which according to the websites I'm looking at is $3k.
That's just an awful comparison. You're still comparing diy to a finished unit. Let's look at the completed hypex unit, the MidimonO Amplifier. It's $1200, less than 1/2 the price, but still isn't cheap.

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Originally Posted by sampleaccurate View Post
Yes, it can be built a lot cheaper, but, the F5 also weighs a ton compared to the Hypex, and it puts out a measly 25 watts per channel (assuming we're talking about the same F5).
If by, weighs a ton, you mean less than 30 lbs, you're right on. If by measly 25 watts, in pure class A, yeah. 50 watts in AB. More than enough for my 100dB speakers.

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Originally Posted by sampleaccurate View Post
If the class D amp "wasn't even close" to the F5 then you are listening to the wrong class D amps IMHO. There should be at the MOST a subtle difference. If there's a big difference and the sound is "not even close" something is seriously wrong with one of the amps.
Actually the distortion during complex passages was entirely noticeable. Driving ESL 63s, a fairly demanding loudspeaker.

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Originally Posted by sampleaccurate View Post
You can build a 180 watt/channel Hypex amp for $350 including the chassis. How much less expensive is a DIY F5? Less than $350 for all the parts new including the chassis (purchased not salvaged)???

Easily. Parmetal chassis, antek transformer, components from digikey, and heatsinks from barredboss.


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Originally Posted by sampleaccurate View Post
Add to that the labor involved in constructing the F5 (a Hypex module based amp can be put together in one or two evenings) and the F5 becomes a much more expensive proposition in terms of money and TIME, unless you want to shell out $3k for a pre-built unit.


Not really. I think the F5 was a rather straightforward build. Our Audio group did a massive "F5 build" project, and people who had never soldered before didn't have a single problem. Weekend project.

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Originally Posted by sampleaccurate View Post
The F5 also has less than 1/7 the power of the Hypex least expensive module (almost an order of magnitude) or about 9dB less volume at full power.
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Originally Posted by sampleaccurate View Post
The two amps aren't even in the same ballpark in terms of power output. If you want to do a fair comparison find a class A amp that puts out 180 watts RMS and compare THAT to the Hypex UcD180.
180 Watts with 15% switching distortion. Youch.

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Originally Posted by sampleaccurate View Post
Did you conduct your tests double blind or did you know what you were listening to when you conducted your tests? Which "expensive" class D amps did you use for direct double blind A/B comparisons?
Really? Double-blind?

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Originally Posted by sampleaccurate View Post
Did you try the Hypex modules?
I did not. I'd be interested in hearing some though. Anybody in the TC?

Quote:
Originally Posted by sampleaccurate View Post
To my ears the latest versions of the Hypex modules sound better than any amp I've ever owned, and I've owned class A and A/B amps that cost a couple of thousand dollars that don't put out as much power and don't sound as good as the Hypex which is MUCH less expensive and EXTREMELY easy to build.
Sweet. Enjoyment is what's important.

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Originally Posted by sampleaccurate View Post
You're question presupposes that there are a lot of people doing personal double blind listening tests of various class D modules with various class A or A/B amps. I wish I had the time and money to do just that, but I had to rely on various reviews and specifications, as well as the papers written by Bruno Putzeys and those of other manufacturers to make my purchase decision.
Wait, you're not doing double-blind listening?

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Originally Posted by sampleaccurate View Post
I have read most of the class D manufacturer websites and none of the technical descriptions of the amps they make come close to the level of detail given by Putzeys and the reasons the Hypex modules are designed the way they are. Based on what I have read the Hypex modules are the best. To my ears they sound awesome. If you give those a try and you still believe the F5 sounds better then you can conclude that for YOUR purposes that class D is inferior to class A and the technology has yet to yield sonic performance equal to or better than class A amps like the F5.
That's a fair statement, but like both the OP and myself have stated, I don't want to buy and build every amp under the sun.

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Originally Posted by sampleaccurate View Post
Time is money, and that's something you fail to take into account when you compare a DIY F5 to a DIY Hypex class D. The construction time for an F5 is much longer and more labor intensive than a DIY class D using modules and prebuilt SMPS. You also fail to take into account that the Hypex is in a totally different league in terms of power output. In short the comparisons are not valid.
Yes, they are. See above.

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Originally Posted by sampleaccurate View Post
What s**ks about these forums is that it will never be possible to accurately test the perceptions and conclusions of the people who post here. If ONLY we could get together, put the speakers behind an acoustically transparent curtain, and compare the amps blind, we could reach some firm conclusions, at least a lot firmer than anecdotal "evidence" that one amp sounds better than another from non-scientific and uncontrolled comparisons.
That does not sound like fun. I'd rather hang out, listen to gear, chat with my friends, and listen to more gear. The idea of "critical listening" is absolutely antithetical to enjoyment. To say nothing can be gained from these settings is just wrong. Unfortunately, I found that my F5 was not the best sounding amplifier that day...
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Old 21st March 2011, 07:10 PM   #23
a.wayne is offline a.wayne  United States
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^^^ +10...
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Old 21st March 2011, 07:26 PM   #24
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Quote:
Originally Posted by d to the g View Post
180 Watts with 15% switching distortion.
Why Sir, for $50 more per side you'll get 200W at <0.1% total distortion.

(ok, i'm biased)
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Old 21st March 2011, 07:28 PM   #25
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Class A is going to be king for a long time yet..
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Old 21st March 2011, 07:45 PM   #26
OllBoll is offline OllBoll  Sweden
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I've also wondered about this, how they would compare if efficiency is ignored.

Currently I'm wondering about an amp for my subwoofer, the sub is high efficiency and rated at a maximum of 45W RMS while actual load would probably be in the range of 1-5 W at most so the efficiency of Class D wouldn't be a requirement in my case. ( The box is 430 litres :P )

The sub would cover from 20 hz and crossed with 48db at ~ 40 hz so it would be a sub, and only a sub.

Would Class A have advantages over Class D in this case, or the other way around? ( only sonic performance judged, efficiency is ignored. )

If Class D in this case would be superior or equal it would be nice with the superior efficiency but I wouldn't trade it for lower sonic performance since I don't need so many watts anyway.

P.S. In case anyone wonders about the sub, yeah... the box is 430 litres
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Old 21st March 2011, 08:17 PM   #27
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@paulb

I found the tone quite superior and developed a niggle that I was reading from someone who didn't know a whole lot on the topic (i'm not being rude, but its quite likely the truth) and had a massive opinion nontheless.

If you found that gigantic post intelligent and useful then great, but i simply don't know if 'other readers' did or not...

Cheers
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Old 21st March 2011, 09:42 PM   #28
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Originally Posted by zerokelvin99 View Post
Class A is going to be king for a long time yet..
I dont give class A a second thought.

My own design class AB and class D sound just as good.

Careful design ensures high quality.

Class A is inefficent generates a lot of unnecasary heat.,
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Old 21st March 2011, 09:43 PM   #29
back is offline back  Greece
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i have compared hypex ucd2k (with 1kw psu) to icepower 1000asp and hypex

kicked the *** of icepower.

i have try and trupath.

better that icepower but still way back from hypex.

the only modules that maybe have a chance against hypex (haven`t tried them) are

newclassd with discrete input.
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Old 21st March 2011, 10:27 PM   #30
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Default Class D potential vs A/AB/B potential

Hi there guys,
I´m also very interested in the varying experiences concerning top of the class D designs and how they compare against other more `classic´ amp topologies.

I have little interest in which subjectively is considered the best. Instead any descriptive explanations on how the different designs are experienced could be very helpful from any who has some experience with different class D and/or other `classes´ of amp designs.

Currently i have an Acoustic Reality ear two which features a pair of ICEPOWER modules spec´ed at 500W/4ohm, supplied by a linear PS with a 400VA toroid and two times two 10000uF 100V caps with a small 2.2 uF cap right before the modules. I also have a two box NCC200 based amp with two 700VA toroids in one box and 4x22000uF Kendeils and the modules in the other box. The NCC200´s have decoupled VAS stage with P/O caps and I have bypassed the output coil with a 0.22R ala naim style. (to me the coil sounded very rough and roll´ed off and had no real treble comming though)

The two amps are quite different, the AR(ICEPOWER) being very clear and seems to feature very little distorion where the NCC200(modded) seems more extended though more distorted and heavy in its presentation. I actually like both, but would really like to get the best from both as one (AR) rythmically seems to sit abit on the music, though very clear, and the other (NCC200) presents with a likable directness though smeared and wolly by comparison.

As i have read alot about the UCD´s i´m quite curious about it and whether it could be made to combine the strengths of the two. Also i like the potential in driving its modulator directly from my NAC82 preamp, if its possible...
Are there other amp designs i should consider, or is the UCD one of if not the very best current designs?

Any comments would be very appreciated

cheers,
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