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Old 27th September 2011, 11:38 AM   #1
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Default Has DIY Audio started downhill?

I have been lurking around here for maybe five years and see a major change in the subject matter and input of new ideas. Have we lost the gurus and unique thinkers to some other medium? I have not witnessed a major heated exchange of ideas on a given subject in over a year and a half. The bickering and name calling, though at times unnecessary, released many a good thought. It got numerous unique points of view involved. A plethora of facts, charts and graphs could, at times, be displayed and saved by the bystanders for future reference.

Where has all of this gone? Any thoughts? I have much to learn and a few miles left on these old tired legs. Technology and its progress have always been great interests of mine.

Tad
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Old 27th September 2011, 11:41 AM   #2
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Perhaps you should head on over to the blowtorch II thread

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Old 27th September 2011, 12:18 PM   #3
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Quote:
Originally Posted by tryonziess View Post
I have been lurking around here for maybe five years and see a major change in the subject matter and input of new ideas. Have we lost the gurus and unique thinkers to some other medium ? ... Where has all of this gone ? Any thoughts ?
Technology means digital, more and more precise thanks to MACC formats like 32x32+64=64, running at 168 MHz like with the newest STM32 F4 single-core microcontroller, or running in the GHz range like with any PC.
Power supplies are switched mode, operating close to the MHz range, and regulated.
Amplifiers are direct-digital, fed by a I2S digital stream.
Audio is now multichannel 5.1 or 7.1, delivered by HDMI. But wait a minute. Is there a HDMI decoder available, delivering four I2S streams to be exploited by DIY enthusiasts ?
Audio is now multiformat like 44.1 kHz, 48 kHz, 96 kHz and 192 kHz. But wait a minute, how can you guarantee a "bit exact" quality when you apply an Asynchronous Sample Rate Converter (ASRC) on every input, converting all those formats to a common 96 kHz digital audio ? Should ASRCs be banned ? Should the whole audio reproduction hardware follow the sampling frequency ? But wait a minute, what to do when cross-fading two audio files having different sampling frequencies ?
Audio is said to be 20 Hz to 20 kHz. Most of the time you need a multiway system to reproduce such bandwidth. But wait a minute, how can you guarantee a "bit exact" quality when there are so many different crossover topologies like Linkwitz-Riley, Lipshitz-Vanderkooy phase compensated, Liphitz-Vanderkooy delay compensated, and Baekgaard ? How to take into account the Bode plot of the naked transducer ? Is a perfect sound wave reconstruction (linear phase) possible without introducing relative phase shifts in the transition bands ? What is the optimum compromize ?

The DIY market may be downhill because all those questions do fly too high above the heads of most DIY people.

The best DIY things I have tasted those last five years are some extraordinary 2496 vinyle rips (24 bit ADC running at 192 kHz) encoded in a lossless digital format. The Dave Brubeck "Time Out" album, the Keith Jarrett "Koeln Concert" and so on, if you see what I mean.

The new DIY wave will only show when there will be new 5.1 and 7.1 recordings available, from new artists, same quality as those famous stereo recordings dating back from the sixtie and the seventies.

But wait a minute, as sound engineer, how can you be "minimal and accurate" in a 5.1 or 7.1 context ?

Actually, I'm not sure that "minimal and accurate" is the right paradigm. The story about the Keith Jarrett "Koln Concert" is here : http://en.wikipedia.org/wiki/The_K%C3%B6ln_Concert. Apparently, Manfred Eicher (producer) and Martin Wieland (sound engineer) needed to tweak the sound using post-production.

In DIY audio, the more you dig, the less it becomes innocent.

Last edited by steph_tsf; 27th September 2011 at 12:48 PM.
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Old 27th September 2011, 12:26 PM   #4
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I like the open baffle and no baffle discussions (loudspeakers) as well as "flooder". There's a lot of alternative thinking here on DIY audio regarding speaker design.
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Old 27th September 2011, 12:39 PM   #5
SY is offline SY  United States
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So, what's the optimum polar pattern for speakers?

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Old 27th September 2011, 12:52 PM   #6
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Oh that's particularly cutting SY, knowing what I've been up to this evening

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Old 27th September 2011, 01:01 PM   #7
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Originally Posted by SY View Post
So, what's the optimum polar pattern for speakers?

A Square, just as the room they are playing in. That should be obvoius to everyone.
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Old 27th September 2011, 01:14 PM   #8
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Quote:
Originally Posted by tryonziess
Have we lost the gurus and unique thinkers to some other medium?
Sadly, no. We still have people who proclaim their guru status, and their fanboys who do it for them. We still have unique thinkers, who appear to live in a different universe with different laws of physics (or no physics at all!).

Far too many discussions get bogged down when it appears that people don't actually understand the basics, so have no basis from which to argue a case. That doesn't stop them arguing, of course. It merely means they feel free to reject counter-arguments which they simply do not understand. Going to the other extreme, we have newbies who either expect to be spoon-fed the most basic information (do they not know what the Y stands for in DIY? Have they never heard of google?) or think that after a few weeks discussion (starting from total ignorance) they can design a 'high-end' item by bolting together a few boutique components whose function and correct value seems to have escaped them.

Fortunately we still have some people who can argue a coherent case for their understanding or point of view, so the rest of us can learn from them. We still have newbies who ask sensible questions and then take the trouble to understand the answers. DIY Audio is still a good place to hang out.
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Old 27th September 2011, 01:35 PM   #9
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We have lost a few great contributors to this Forum over the years.
I miss them.
One has recently come back.
Can we bury hatchets, I wonder?
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Old 27th September 2011, 03:32 PM   #10
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In the sixties and in the seventies, the vinyle was containing more information than a normal HiFi setup could reproduce. The microphones, the mike preamps and the vinyle cutting head delivered together a 30 Hz to 17 kHz bandwidth in a 3dB corridor.

In the sixties and in the seventies, at home, if you were lucky, the magnetic cartridge, RIAA preamp, preamp, power amp and loudspeaker delivered together something like a 60 Hz to 12 kHz bandwidth in a 6dB corridor, for a ideally placed listener facing the loudspeakers, same height as the ears.

The use of cone tweeters combined with baffle edge diffractions caused a pathologic high frequency dispersion, hence the need for tone controls in the highs for restoring a decent tone balance in a semi reverberant room like your living room.

Unoptimized closed boxes or unoptimized bass-reflex boxes caused an amplitude peak in the bass near the cutoff frequency, masking the deep bass range below 50Hz. For this reason you also needed a tone control in the lows, but such tone control was not selective enough, not able to damp the amplitude peak at the cutoff frequency, say 60Hz.

Knowing this, in the sixties and in the seventies, using simple means and scarce money, you could improve your audio setup, making it more linear, extending the bandwidth, uncovering the essential information from the vinyle. All you needed was to dismantle your existing two-way speakers, reuse the existing drivers as medium and tweeter, time-align them, avoid baffle diffraction, use a trivial 1st-order passive crossover, and add one or two RLC networks in the medium for suppressing the high-frequency cone aberrations. For the bass, you needed an active subwoofer, electronically equalized, for delivering the 30 Hz to 120 Hz spectrum in a corridor of 3dB. So simple ! So cost-effective !

Very few people did this, actually. Why ?

During the sixties and the seventies, the whole DIY communauty went focusing on solid-state, more output power, less harmonic distorsion, less crossover distorsion, more slew-rate and direct-coupling (capacitorless). For this reason, during more than 20 years, vinyles continued to have more info inside, than most HiFi setups could deliver in your listening room. Things could have radically changed in 1961 when Thiele published his work in Australia about optimizing the closed-box speakers and optimizing the bass-reflex speakers, but his work remained ignored during one decade, untill published in the Journal of the Audio Engineering Society in 1971. But again, even after 1971, just like there was a conspiracy about not delivering the deep bass range, most audio reviewers went focusing on loudspeaker sensitivity, writing that anything below 90dB/Watt was pathologic. A company like Cabasse managed to get a good reputation, consistently producing speakers exhibiting a sensitivity of 92dB/Watt, but lacking bass, delivering "dry bass" as some said. Like the Yamaha NS-10 as near field monitors. Companies like IMF, B&W and KEF were initially disregarded, when they introduced wide bandwidth loudspeakers having a sensitivity of only 86dB/Watt, even if for the first time those loudspeakers were delivering the actual vinyle bandwidth to your home. Jacques Mahul (Focal, JM Labs) came shortly after and showed to people how to deliver more bass thanks to a dual coil speaker. Jacques Mahul came back showing to people how to deliver more bass using the 4th-order passband dual chamber subwoofer. Bose was there since the beginning (with their 904), with the idea of electronically equalizing the woofer, but Bose never gained the DIY communauty acceptance. Philips was also there since the beginning (with their 22RH532 Motional Feedback), putting a sensor in the woofer cone and applying electronic feedback. Linkwitz, like Bose, came with the idea of electronically equalizing the woofer (the Linkwitz Transform), but again there was no wide acceptance, no adoption from HiFi manufacturers apart KLH and Yamaha (if I remember). Bose came back in the eighties armed with their patent about the 8th-order passband triple chamber subwoofer, that nobody dares to copy, even today.

We are now in 2011. The vinyle is still there, especially in the 24-bit 96 kHz ripped form, lossless format. Now we know that all first generation CDs need to be dumped, especially the ones that were remixed for promoting the "CD sound quality" like adding heavy bass and adding multiband compression for making the sound more "juicy". Now we know that sound gets recorded using 24-bit 96 kHz, so why continuing buying CDs delivering 16-bit 44.1 kHz ? What are the alternatives ?

As a starting point, the DIY audio concept should encompass a global market offering audio tracks recorded, mixed and mastered in a genuine format like 24-bit 96 kHz, without any sample rate conversion inbetween.
As a bonus, the DIY audio concept should propose 5.1 and 7.1 recordings, as experimental path. There should be sound engineers, artists and composers, affiliated to such concept.
In a digital world, something very reassuring would be to expose the algorithms and the source code for all sorts of sound processing like equalizers, dynamics compression, enhancements, crossovers. Also expose the algorithms running in digital power amplifiers, and in switched-mode power supplies.

Last edited by steph_tsf; 27th September 2011 at 03:37 PM.
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