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#7781 |
diyAudio Chief Moderator
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Try an SSA or TSAA amp at a point, its Andrej's in our SS forum.
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#7782 |
diyAudio Member
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I find it unremarkable that amps and speakers you have designed yourself sound better than everything else.
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#7783 | |
diyAudio Member
Join Date: Jul 2004
Location: Northern Colorado
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Quote:
What I actually said is that I design my equipment for my own tastes. Not the tastes of an employer, my neighbor, a forum, or a magazine reviewer. If it sounds good to me, I consider it good. I have no way of knowing what other people hear; for that matter, I've only met a few audiophiles whose sonic and musical tastes are similar to my own. I would imagine nearly everyone here on DIYaudio does pretty much the same thing, since we don't have to answer to a manager or a marketing department. That is one of the great luxuries of DIY; not to save money, but build what is not on the market. What's the point of copying commercial designs, which are almost always compromised to reach a price point, or aimed at a certain narrow demographic? The majority of high-end products, in the USA at least, are designed for the tastes of a small circle of reviewers who write for the Big Two magazines. These magazines, even today, have the power to make or break a manufacturer. This is not a fairy tale; I've met the people whose businesses were destroyed by a bored reviewer, or an editorial rewrite. (The tell-tale signs of a clumsy editorial rewrite is when the review suddenly changes tone in the last three paragraphs, or when the final conclusion in the review contradicts the middle part of the review. That's a quick-n-dirty rewrite by an editor in a hurry.) The DIY community is free of these commercial pressures, or the need to satisfy a reviewer. We can design products as weird as we like. They don't need to be manufacturable, or aimed at the tastes of the Big Two magazines. It is only ethical to warn people who are curious about building the Ariel, Amity, or Karna that they do not sound like the majority of equipment at a high-end show; if they expect to replicate what they hear at hifi shows, they will be disappointed. Last edited by Lynn Olson; 16th August 2012 at 08:23 AM. |
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#7784 | |
diyAudio Member
Join Date: Dec 2008
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#7785 |
diyAudio Member
Join Date: Jul 2004
Location: Northern Colorado
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Modern single-plate 2A3's have substantially lower upper-harmonic distortion than the historic bi-plate 2A3's, and really behave more like a souped-up 45.
When you ignore the 2nd-harmonic distortion (which is nearly inaudible), there are quite substantial differences between tubes. Gary Pimm and I look at the 5th-and-higher harmonics; you'll see differences of 10~20 dB in these high-order harmonics, depending on type and vendor. Changing the quiescent current by 50% will only shift the upper harmonics by 3 dB or so, but swapping tubes can result in a 20 dB difference. Within vendors, distortion is tightly grouped, so the differences are clearly the result of proprietary manufacturing processes. This is the area where the best DHT's pull ahead of the indirectly-heated driver tubes, and not by a small margin. For example, as good as the 5687/7119/ECC99 family is, the 45 DHT has 5th-and-higher-order harmonics that are 20 dB lower. Gary and I looked at the -130 dB noise floor of the instrumentation, and we could not see any evidence of 5th or higher at all. These things are clean - and to me at least, they sound the way they measure. The modern Chinese meshplate 2A3's are very good as well, and will cheerfully operate at substantially higher currents than a classical 45. Be careful about microphonics. DHTs are pretty sensitive to vibration thanks to very large grid structures, which are not as rigid as conventional pentodes or indirect-heated triodes. PP operation does not cancel vibration all that well, thanks to the large spacing required by the physically large envelopes (and an additional inch or so for adequate ventilation). In more technical terms, there's a phase difference between the vibration experienced by each grid, and that results in loss of PP cancellation. I am not familiar with the spectral signature of MOSFET followers, particularly what happens with 5th-and-higher order harmonics. If the upper-harmonic levels are moderate to high, there's no point in chasing after DHT's and their microphonic requirements, as well as hassles with good-sounding DC heating. The whole point of DHTs is their very low upper-harmonic content; if that is masked by the upper-harmonic distortion of the MOSFET followers, a triode-connected EL84, 6L6, or EL34 might be a better choice as a driver. Build it and see for yourself. Last edited by Lynn Olson; 16th August 2012 at 09:08 AM. |
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#7786 | |
diyAudio Member
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In case it matters.... |
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#7787 | |
diyAudio Member
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I also look at harmonics 5 and higher. I would not have built the amp if the spectral signature were not favorable. As I recall, distortion was low and concentrated at 3rd harmonic (transformer-dominated distortion). Noise is in the range of -150db. Yeah. |
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#7788 | |
diyAudio Member
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The range available is quite wide and deals with internal gradient structures in tone and transients and overall timing issues more than it does with low distortion or tonal purity, those being a given. I am sure there are plenty of other manufacturers that denizens here will be eager to list, I will also point out that I know these few to be at the top of that heap. How high you rate one of them over another will be determined by those characteristics Lynn points to. I would suggest that the output transformer will have an even greater impact upon the amplifiers eventual sonic character and how you respond to it than any other component. A world renowned designer of tube amplifiers I know says that the output transformer is 90% of what is wrong with a given amp and 70% of what is right. Of course, he designs guitar amps, but nearly all of the professional musicians we love to listen to own his amps, along with a huge number of just normal folks who haven't got the god light shinning on them. Bud
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"You and I and every other thing are a dependent arising, empty of any inherent reality" Tsong Ko Pa |
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#7789 | |
diyAudio Member
Join Date: Jul 2004
Location: Northern Colorado
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#7790 | |
diyAudio Member
Join Date: Dec 2008
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Suffice to say that it was a very pointed lesson in the limitations of feedback, small signal linear models and even the Spice models we had then (30 years ago). The non-linear capacitances around turn off made a mess of any attempt at stability. |
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