Class D Technology
Noise needs to be heard to existNot correct, EG: take an opamp for instance, it can oscillate (if not implemented well) at VHF, too high to hear, but it will make a known opamp with smooth sound, sound hard/bright because of the oscillation that you can’t hear. And if the noise is filtered out afterwards then the opamp is compromised and can sound too bland, better off not having the oscillation to start with in the first place. Cheers George |
Question: If a tree falls in the forest, but no one was there to hear it, does it still make a sound? Answer: Yes, the theory being the tree hitting the ground moved the air and created the sound. Because someone was not there to hear this sound does not mean the sound did not exist. Question: If a class D amp is playing in a system, but no one could hear anything other than finely reproduced music, does noise still exist? Answer: Who cares, although there are theories that state the SMPS and a low switching frequency has affects on the sound in the audible band, no human has ever claimed to hear these affects or even describe what these affects would sound like. Thought this might be helpful, Tim |
no human has ever claimed to hear these affects or even describe what these affects would sound like.Plenty have with saying, hard sound, soft sound, lacking in harmonic structure, dead gaps between notes (no harmonics) like the amp has been turned off. There are many that hear these effects, myself also, but like I said before I "could" live with the Belcanto Ref600's, with their in house special filter for the switching frequency, but they were driving an expensive two way with a very benign 8ohm Raven ribbon tweeter load. Cheers George |
The concerns of the OP and of George are correct, at least from a historical point of view.... When I first started looking at class D amps, in the middle of the last decade, there were many examples of class D amps which were either sounding dark, or limited in the harmonics of the upper frequencies, or harsh, or high-fiish, or a combination of several of the above undesirable characteristics.... For Example: * Flying Mole -- All the delicacy of music reproduced with 150grit sand paper! NuForce Reference 9 SE V2 monoblocks -- Clean but quite climical, even after 1K hours break-in... And treble was clinky and limited. Red Dragon monos -- Both harsh and dark at the same time... Quite an achievement! Wyred4Sound monos -- Listened extensively at RMAF several years in a row... Harsh and fatiguing to the point of non-listenability. Rowland M501 monos Powerful, but lacking subtlety. Bel Canto Ref1000 Mik.1 -- Better than the above, but still somewhat rough in the treble... Note that the problem simply does not exist on the Mk.2 version. Rowland M302 stereo -- Sweet and delicate, but will little macrodynamics... And just slightly cold. But... The World has moved along... A dozen years have gone by, and modules and device designs have evolved enormously in the land of class D amplification, starting with the Rowland M312 stereo, and the Bel Canto Ref1000 Mk.2 monos: products that simply... Make real music. Today, amps like the Bel Canto REF600 monos and the Merrill Teranis stereo based on Hypex NCore NC500 modules, once appropriately broken in -- yes I insist it is needed -- make extremely fine music for their quasi entry level pricepoints, without pretending to achieve the ultimate subtlety of reference level amps. But if one were keen in hearing what musical refinement has been achieved by current reference-level class D amplification without audible compromises, please have a listen at least to some of the amps that have captured my heart over the last few years: * Merrill Veritas monos based on NCore NC1200. * Rowland Continuum S2 integrated -- Based on Pascal M-Pro2. * Rowland M825 Stereo -- based on NC1200. * Rowland M925 monos, based on NC1200. * Bel Canto Black -- based on customized NCore modules. And there are more marvellous class D devices, which I have not had the fortune to audition at all price points. Are all current class D amps today superb music makers? That is unlikely.... For example, last time I heard W4S -- admittedly this was 3 years ago -- the sound of my music camples: piano, string sextet, Diana Krall, orchestral, and vocal + sax was still so harsh to give me an "ear bleed".... But by now, W4S may very well have matured as well. Please note that exactly like proclaiming that all class D amplifiers are inherently flawed constitutes a logical fallacy, so would be the assertion of the opposite... Reality is, that with all topologies, some amps will meet our particular taste in music reproduction, some will miss by a country mile, and some will be somewhere in between. G.
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modules and device designs have evolved enormously in the land of class D amplificationI say more of a gradual upwards evolvement, with tweaks and band aid filtering, no real technical breakthroughs. The only one I know who is stretching out for real progression is Technics with their SE-R1, with the supply finally of newest technology to double the switching frequency, with this latest device from EPC Corporation Inc. Who invented the Mosfet Power Transistor years back. This is where the real evolvement for Class-D will come from the manufactures of the components, not the manufacturers of the amps. In a way it’s up to the audiophiles to get them to use this new technology then the price will come down for something like the $30k Technics through demand of those components and other device manufactures copying them. http://epc-co.com/epc/GaNTalk/Post/13752 http://www.technics.com/us/products/r1/se-r1.html Cheers George |
