Saturday, 28 November 2015

A More Ambitious Upgrade - Part 10

Hooray! I recorded a couple of instances of the NAD system playing, in a pretty bad position: single mic, about 3 metres behind the right hand speaker, no attempts to optimise the recording quality at all, just to see how the sound came across ... a bit of The Faces and some old Blues from an el cheapo CD. Not bad methinks, gives a pretty good idea of what it sounds like ... so, as a pure, first experiment uploaded The Faces take on YouTube ...

Now, believe it or not, this is my very first attempt to put anything on YouTube, and I didn't get the settings right - only relatively low quality settings come up on playing ... so, plenty to do to get a far better experience for a viewer. But, I feel the essence of the replay largely working right comes through even in this first miserable go - check it out ...   .
Have uploaded a new version, with multiple resolutions, and a couple of things fixed,  The Art of Audio Conjuring - Take 4 ...

Starts part way through "Too Bad" of the CD, and then the complete "That's All You Need" with me announcing at beginning of the latter - head about 1 metre away from mic.

And a bit later ... uploaded the Blues combo, The Art of Audio Conjuring - Take 3, ... this starts during "Crying", Jimmy Witherspoon, followed by "Everybody Rock", Jimmy McCracklin - this is in HD, which may or may not help the replay quality ...

Wednesday, 25 November 2015

A More Ambitious Upgrade - Part 9

All quiet on the western front  ... okay, a decent delay without much being done here - life gets in the way at times, and my fiddling on the NADs has taken a back step while other things were handled ...

What is very clear is that filtering of mains interference is crucial in this system - my simple experiments minimising these particular factors has lifted the standard to very close to "conjuring" quality; the latest touch is allowing very nice, tonally sweet recovery of ambience and depth in very old, shellac derived recordings. The potential of this combo of audio gear has shown itself to be such that engineering some proper, long term usable filtering circuitry on the mains side will be worthwhile ... so, I'm currently investigating some of my older tweaking projects, and any good info on the net, gathering all that's necessary in ideas for making a cost effective solution happen.

The system is now good enough to do some recordings, with the new mic, to demonstrate progress made - I'll post these on YouTube for easy perusal - and also upload full quality versions on say, Dropbox.

One thing "new", for my own understanding of the relationship of the factors in making a combination have sufficient quality, from the experiments so far - a system which has had a good amount of intelligent thought put into the topology of the key circuitry, like the NAD units, will present recordings far better on cold start up than 'cheap' components - immediately after pressing Play on a morning switch on, we have a very likeable sound that projects quite a 'big' sense of the musical event; there is very little obvious unpleasantness, or lack of 'musicality', in well made recordings. Very low cost units, like TVs and PC monitors definitely aren't capable of this, they need extended warm up to reach an adequate stability of all the parts.

A reference recording I use for evaluating competence is Franck/Faure, The Medici String Quartet - Nimbus NI 5114 - Ambisonic recording, the piano sounds like it's half a mile away, very low levels of the primary sounds of the string instruments with relatively high levels of reverberation information. This is a nightmare for a conventional digital playback system, will typically be very dreary and flat in the listening, "boring" sound of the worst order. Only a fully sorted out system will resolve the fine detail, and reveal the musical structures correctly - and this is clearly showing the weaknesses of the NAD combo at this point: the acoustic of the recording is complex but subtle, and that fine detail is too entangled with the remaining low level distortion - the playback of this recording is not "working" yet.

Friday, 20 November 2015

Why does conventionally set up audio normally fail to 'conjure'?

There are many factors at work, but the fundamental reason is that insufficient experimenting and research has gone into understanding how people can pick up on subtle clues in what they're hearing, usually unconscious, which allows them to easily separate 'real' sounds from an attempted mimicking of such via a high fidelity system. Most playback manifests clearly audible "flaws", which then makes it trivially easy for the mind to "spot the fake", and once this happens the mind will automatically keep referencing these "defects", reinforcing one's awareness that the illusion has failed. An analogy would be watching a stage magician after being made aware somehow of how he does it - the tricks will be quite obvious, and part of one will be somewhat surprised that others in the audience don't also see how the manipulation occurs - your attention has been drawn, irreversibly, to the "chinks in the armour" of the stage act, and while you may be impressed by the magician's skill you no longer marvel at the "trick" itself.

It is unfortunate that during the history of audio reproduction that more in depth examination of the crucial factors didn't happen - many of the pioneers had an intuitive understanding of what was necessary, but this didn't evolve into an industry wide set of highly effective standards and rules which everyone could usefully reference; Paul Klipsch is a good example of such a person.

So, the illusion usually fails ... again, why? The answer, because the distortion, meaning elements of the audible sound which don't match the recording content, is too obvious, and intrusive. Most of the industry with a technical focus has become infatuated with easily obtainable raw numbers on behaviours of the individual components of a system: the source mechanism, the amplifier, the speakers exist in completely different spaces, are seen as separate units on a test bench; the overall performance of a complete system in its final environment is seen as something that is too hard to measure - that aspect which is in fact the most important of all is never sensibly dealt with. Unfortunately, the types of distortion which will always cause the illusion to collapse or fail to manifest easily arise in an end system, many times as a result of interaction between the components and the environment in which it finds itself. The fact that the "measurers" are remarkably blind to this is a bind that the audio industry is currently trapped in, and there are no signs as yet of any meaningful progress ...

But fortunately this does not stop the individual being able to bypass these limitation of thinking, and now and again one can read how this has been done by someone who has chanced upon a lucky combination of factors that reduce the key distortion sufficiently.

Thursday, 12 November 2015

A More Ambitious Upgrade - Part 8

Another nice little step forward ... I was noting that a very low key ambient music CD, designed for meditation background filler, which has very long, richly harmonic notes had a decided rattly tone coming in - this sounded like speaker misbehaviour. I had sorted out the obvious weaknesses of the internals of these cheap speakers some time ago, was there something more to be done ...? Turned out that an elastic material that I had applied some time ago to decouple the tweeter from its support had gone rock solid in the interim, it just crumbled away in slivers when a knife was applied! OK, this was a definite issue!

As a simple experiment - the type I prefer! - I applied good ol' Blu-Tack to the support areas in such a fashion that this goo was the sole method holding the treble driver in place; the screws were left off entirely. Definitely not a production line process, but good enough to give me answers - and so far a positive outcome. An improvement in clarity, dynamics ... another step closer to convincing sound ...

Update: an interesting aspect of higher quality sound is that one's brain can assimilate and process all the information coming from the playback source, and separate that from all peripheral and echo sound data with ease. I say this because the NAD system while I've been working on it is positioned 1/3rds length ways into the work room, facing the closer wall to it; when I sit at my laptop and do whatever, like updating this post, the speakers are facing completely away from me, so the sound for me is that bouncing from the walls and glass, mostly indirect input to my ears. Yet the sound totally "works", is completely authentic in character, requires no excuses for the fact that my hearing position is as bad as I could make it ...

Sunday, 8 November 2015

A More Ambitious Upgrade - Part 7

Good progress made! I bit the bullet and added an effectively almost 100% bypass of the volume potentiometer, to make clear how much was being lost here; at maximum volume setting the level is set by a pair of series metal film resistors acting as voltage divider, the mechanism of the pot is almost completely invisible to the rest of the circuit. This I made a sensible, comfortable listening level well below the capability of the amplifier - and, I still retain the ability to attenuate the volume by adjusting the potentiometer back from fully clockwise.

This immediately showed a major benefit, the irritating buildup of low level distortion was now gone - a CD of 60's Jan and Dean surf music recorded by Brian Wilson showed tremendous depth, complexity and sparkle on tracks, quite spectacular to listen to!

The listening just a short time ago demonstrated a behaviour that happens over and over again when deliberately targeted tweaking to remove weaknesses is done: even though the sound had lost the unpleasant edge caused by the potentiometer part there was now a sense of loss of information in some disks, the sound wasn't as "big" as it should have been. Some experiments and thinking of what had been tried so far gave me the Ah-haaa! answer: so far I've been using rough, simple experimental manipulation of the power supply quality outside the component boxes to clean up interference; and I had doubled up the filtering on the amplifier side - this was in fact a mistake, the filters in action weren't combining in positive ways at all times. The cleaning up of the sound to a better level by improving the volume mechanism now made this much clearer; before, the masking by the dirt added from the potentiometer hid this effect.

So ... at all times be ready to step back and reassess where the sound is at, and be willing to undo an earlier change even though it made sense at the time, and appeared to be a positive. The flaws in a system causing the end sound to not be as good as it could be are a complex interaction of factors - the best, final results will always flow from a willingness to completely change one's approach in some area, on the basis of new evidence from ongoing, careful evaluation of the sound one is hearing.

Where's the sound at now? Very spacious, full - the ambience of the recording environment is getting mighty close to taking over the listening room - not quite at "invisible" speakers, it is still possible to pinpoint their location - but, there remains tonnes of things to be looked at, many aspects I normally do consider have yet to be addressed ... I'm sure I'll get there!

But ... what about, you know, 'conjuring'? Is it there yet? No. I'm getting more detail, a bigger sound ... but that is also making it easier to pick up where the remaining failings are ... possibly quite a few more rounds to go, c'est la vie ...

Saturday, 7 November 2015

A More Ambitious Upgrade - Part 6

The volume control will have to be sorted! I've been dallying around, noting other factors that impact the quality, but I keep coming back to that part. Especially this morning, it's clearly crippling the replay of a nice, sparse orchestral, recent recording - Bev is picking the impact from the other end of the noise, the low level ambience and sparkle is compromised, there's a deadness, loss of verve to the sound which makes the listening a bit of a chore. This can be momentarily fixed by refreshing the pot's setting but that only lasts for a very short time; up close to the tweeter this short term "fixing" can easily be heard in action - before adjusting the volume there is distinct distortion from the tweeter - classic "hashy" unpleasantness, after cleaning the pot, that degradation completely disappears.

So how to do it? As mentioned before, I don't want to spend silly effort and money - will getting a significantly better variable resistance mechanism make the issue go away as an audible problem under normal listening? This is the first time I've really grappled with an analogue volume control problem, so I'll do some more research and then get hold of the best value, easily available replacement, and see what that gives me ....

On a strongly positive note, I have acquired a decent USB condenser microphone, and the first test is showing a very good result - I aim to make recordings of what comes out of the speakers, such that it clearly shows the points I'm making, and post them them so that they're easily accessed, say YouTube for quick perusal, and Dropbox for better quality versions.