I'd like to reply to some comments in this thread, particularly to the ones about SETs and NOS DACs. These are not in the same category as electret cream, they are real life engineering tradeoffs. I'll give some examples of both.
I'll start with the SET. I have built MANY amplifiers over the years, both solid state and tube, covering many different architectures. They all have different tradeoffs, doing one aspect better than others. Different people will prefer different implementations, they really like the optimization of one and are willing to live with it's deficiencies. The SET is an interesting case, from a sound perspective it does some things extrordinarily well that some people absolutely love, and does other things poorly, some people are willing to live with the deficiencies to to get what it does well. Other people are not. Part of the issue here is that what it does poorly is very easy to measure, and what it does well is very difficult to measure (not impossible, just difficult). It took a long time for the engineers to figure out how to measure what it was doing well. Now that what an SET does well is mostly known some designers have been able to come up with solid state circuits that sound similar, but they still have a some of the same deficiencies. In my case my current main amp is an SEP, Single Ended Pentode, it has a similar good characteristics to an SET, but it also has vastly lower distortion, less than 0.1% over the whole power range (up to 25 watts) and frequency range. This has been possible by eventually understanding what it is about SETs that make them sound good, and then figuring out how to keep that while improving other aspects. This turns out not to be easy, improving one aspecct very often makes the other worse. It's good old fashioned engineering tradeoffs. Unfortunately it's not cheap, there are about $3000 worth of parts in this thing and it weighs 150 pounds, but boy does it sound good when driving the speakers it was designed to drive. With $3000 worth of parts it would be very expensive if it were commercially produced, and that would NOT be exhorbitant profits, it just plain costs a lot of money to get that level of performance. At least for now. Over time designers might figure out how to do it for a lot less money, but that hasn't happened yet. On the DAC side, many years ago I (and others) noticed an interesting fact, that when you bypassed the internal digital filter in most DAC chips things sounded better in some ways, and also worse in others. Without the filter the sound was more musical, more alive, more realistic, BUT it also sounded "dirtier". Some people are willing to live with the "dirtier" in order to get the "more alive" sound. The dirtier of course comes from the aliases, but nobody yet knows what the digital filters are doing that squashes the "alivenes". Again it's a case of nobody knows how to measure "the goodness" but it is very easy to measure the "badness". I have spent the last 7 years trying to find out what it is that the digital filters are doing that causes the problem. My currrent understanding is that it is NOT the fact that it is a digitalfilter in general that is the problem, but the implementation that is used in ALL DAC chips that have a builtin filter. In order to get extremely good numbers in the spec sheets for certain parameters the designers have taken to using complex filters in the chips. Getting these spec sheet numbers with the traditional mathemetical function you read about in DSP textbooks takes a lot of processing power which would significantly increase the price of the chips. So they have come up with DSP "tricks" to get those numbers, but now the filter function is much more complex, and this "complexity" seems somehow responsible for the sonic degradation. At this point I have no idea WHY this is, just that it is. I have now built several DACs using external digital filters and DAC chips that either don't have digital filters or it can be turned off. When I use the basic simple function and give it enough processing power (either in software on a computer or in an FPGA) the results are amazing, you get the "aliveness" of the NOS DAC, but all the dirt is gone, the result is stunning. Again the NOS DAC is a tradeoff, people willing to live with the negative aspect to get the positive aspect. As we start to understand what is going on it starts to get possible to do away with the tradeoff and get both aspects done well. Neither the SET nor the NOS DAC are an attempt to bilk the public for monitary gain, they are legitimate engineering tradeoffs that some people are willing to take. Hopefully as we understand what is actually going on we will be able to do away with the tradeoffs, but that is not fully there yet. John S. ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=99360 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
