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"Ah yes, audio DIY. Even in this day and age it is still possible for an individual in his garage to create something that is absolutely the equal of commercial gear, for less money. But at the same time that isn’t all that much of a claim because
(a) The price of commercial gear can be obscenely high.
(b) Commercial gear may not be all that good!
At one time I thought I was interested in building amplifiers, and later I thought I was interested in making my own DACs, but I now realise how pointless those activities were. I was seduced by the thought of experimenting, creating, and by the idea that I could make the signal path simpler or purer, and that I might possibly be able to hear the difference though, even as an engineer, I wouldn’t be able to tell you why; I had bought into the whole “hi-fi is mysterious” thing. I was not considering that the basic topology of a standard hi-fi system (source, single amp, passive speakers) might be fundamentally compromised. My ‘rationalism’ at the time was at the level of scoffing at those who would spend the price of a car on an amplifier, but I certainly didn’t question the basic topology of a standard hi-fi system. In fact I am certain that I would have imagined active speaker systems in the same way that you, perhaps, imagine them now: surely they’re going to be hard, clinical, disjointed – because they don’t have the soft, organic purification stage of the passive crossover, that ‘smooths out’ the horrible quantised digital audio – and by using several amplifiers the system just won’t ‘pull together’. Or something like that.
Building speakers – in contrast to DACs and amplifiers – is very appealing because it involves messing about with woodwork and playing with acoustics. But second hand speakers from eBay are very cheap. It occurred to me that one way to learn about speaker design would be to modify some existing speakers, and that the most versatile method would be to drive them actively using DSP. Then I could experiment, and hear for myself the huge audible differences to be expected from different crossover slopes and frequencies that the experts assure us we should hear. So I duly modified a pair of cheap two way floorstanders and wrote some simple DSP software to do basic FFT-based complementary filtering, using a multichannel sound card to drive the amps. I wasn’t expecting anything spectacular, but even at this stage the sound was remarkable; the bunged up, congested sound of the standard speakers (that I hadn’t noticed so much until then) was gone and the music just poured out! The in-room EQ wasn’t perfect but there was no sign of hardness in the sound, nor of disjointedness – just the opposite. I very quickly realised that hi-fi can be a lot easier and better than people allow it to be.
Thus, it was clear to me that it was going to be worth doing something more ambitious. Three-way with unusually large sealed woofers (why not? – I had a budget of tens of pounds upwards), full DSP crossovers with driver correction (including phase) and time alignment (i.e. adjustable delay for each driver).
With hardly a hiccup, this has worked out much better than I might have imagined. Dangerously so. It has given me a certainty that much of the received wisdom in hi-fi is bunkum and that, in fact, the now-discredited idea* of pursuing basic linearity including the time domain, was correct all along. Even among so-called objectivists there’s an almost-universal notion that only the frequency domain matters; the world’s foremost authority on speaker design has recently delivered a lecture that reinforces this view. If this conventional view is wrong then I think it explains everything about the supposed mysteriousness of audio and the lack of correlation between orthodox measurements and perceived audio quality (some publications may perform more complete measurements than others, yet disregard or only mention in passing the time domain-related stuff). My DIY system suggests to me that if you get the frequency and time domains correct (including the bass i.e. no ports) then you have it all. Automatically. It also tells me that such a solution is ‘robust’, not balancing on a knife edge where the slightest modification to, say, a crossover frequency completely changes the sound. Indeed if this were so, it would render invalid the whole concept of the multi-way speaker – I cannot vouch for the implementations of conventional passive systems, however.
In my system the mid driver and tweeter are mounted in suitably solid 1980s Acoustic Research bookshelf enclosures, and the large woofers are in very large sealed ex-Goodmans enclosures. Using PC-based crossover filtering and driver correction based on near field measurements, the resulting sound is gloriously ‘non-digital’ (in the sense that the expression is used here). We are talking about aspects of reproduced sound that you cannot know are defective until you hear a system that is ‘correct’, and then everything falls into place. Not only is the sound the opposite of ‘harsh’ or ‘clinical’, but having gone the three way route with large sealed woofers it is full-on ‘high end’, effortless sound that goes as deep and dynamic as necessary, and keeps the instruments and/or voices separated and imaged precisely (if that’s what the recording contains)."
* You may be sceptical, but the conventional view in audiophile circles is that the idea really has been discredited.
https://therationalaudiophile.wordpress.com/the-project/
(a) The price of commercial gear can be obscenely high.
(b) Commercial gear may not be all that good!
At one time I thought I was interested in building amplifiers, and later I thought I was interested in making my own DACs, but I now realise how pointless those activities were. I was seduced by the thought of experimenting, creating, and by the idea that I could make the signal path simpler or purer, and that I might possibly be able to hear the difference though, even as an engineer, I wouldn’t be able to tell you why; I had bought into the whole “hi-fi is mysterious” thing. I was not considering that the basic topology of a standard hi-fi system (source, single amp, passive speakers) might be fundamentally compromised. My ‘rationalism’ at the time was at the level of scoffing at those who would spend the price of a car on an amplifier, but I certainly didn’t question the basic topology of a standard hi-fi system. In fact I am certain that I would have imagined active speaker systems in the same way that you, perhaps, imagine them now: surely they’re going to be hard, clinical, disjointed – because they don’t have the soft, organic purification stage of the passive crossover, that ‘smooths out’ the horrible quantised digital audio – and by using several amplifiers the system just won’t ‘pull together’. Or something like that.
Building speakers – in contrast to DACs and amplifiers – is very appealing because it involves messing about with woodwork and playing with acoustics. But second hand speakers from eBay are very cheap. It occurred to me that one way to learn about speaker design would be to modify some existing speakers, and that the most versatile method would be to drive them actively using DSP. Then I could experiment, and hear for myself the huge audible differences to be expected from different crossover slopes and frequencies that the experts assure us we should hear. So I duly modified a pair of cheap two way floorstanders and wrote some simple DSP software to do basic FFT-based complementary filtering, using a multichannel sound card to drive the amps. I wasn’t expecting anything spectacular, but even at this stage the sound was remarkable; the bunged up, congested sound of the standard speakers (that I hadn’t noticed so much until then) was gone and the music just poured out! The in-room EQ wasn’t perfect but there was no sign of hardness in the sound, nor of disjointedness – just the opposite. I very quickly realised that hi-fi can be a lot easier and better than people allow it to be.
Thus, it was clear to me that it was going to be worth doing something more ambitious. Three-way with unusually large sealed woofers (why not? – I had a budget of tens of pounds upwards), full DSP crossovers with driver correction (including phase) and time alignment (i.e. adjustable delay for each driver).
With hardly a hiccup, this has worked out much better than I might have imagined. Dangerously so. It has given me a certainty that much of the received wisdom in hi-fi is bunkum and that, in fact, the now-discredited idea* of pursuing basic linearity including the time domain, was correct all along. Even among so-called objectivists there’s an almost-universal notion that only the frequency domain matters; the world’s foremost authority on speaker design has recently delivered a lecture that reinforces this view. If this conventional view is wrong then I think it explains everything about the supposed mysteriousness of audio and the lack of correlation between orthodox measurements and perceived audio quality (some publications may perform more complete measurements than others, yet disregard or only mention in passing the time domain-related stuff). My DIY system suggests to me that if you get the frequency and time domains correct (including the bass i.e. no ports) then you have it all. Automatically. It also tells me that such a solution is ‘robust’, not balancing on a knife edge where the slightest modification to, say, a crossover frequency completely changes the sound. Indeed if this were so, it would render invalid the whole concept of the multi-way speaker – I cannot vouch for the implementations of conventional passive systems, however.
In my system the mid driver and tweeter are mounted in suitably solid 1980s Acoustic Research bookshelf enclosures, and the large woofers are in very large sealed ex-Goodmans enclosures. Using PC-based crossover filtering and driver correction based on near field measurements, the resulting sound is gloriously ‘non-digital’ (in the sense that the expression is used here). We are talking about aspects of reproduced sound that you cannot know are defective until you hear a system that is ‘correct’, and then everything falls into place. Not only is the sound the opposite of ‘harsh’ or ‘clinical’, but having gone the three way route with large sealed woofers it is full-on ‘high end’, effortless sound that goes as deep and dynamic as necessary, and keeps the instruments and/or voices separated and imaged precisely (if that’s what the recording contains)."
* You may be sceptical, but the conventional view in audiophile circles is that the idea really has been discredited.
https://therationalaudiophile.wordpress.com/the-project/
S,1” etc. – this is useful because the numeric designation may change between boot-ups.
