Geatan,
You are right my friend, I have worked for one of the measurement companies some years ago (Hewlett Packard) and most test equipment is developed out of necessity, not because these guys were bored.
If there was someone who could specify a repeatable subjective test I am sure there would be a company that could design such test equipment and we would have a quality number associated with it and this test would then be classified objective.
Imagine having a pocket tester that has a Sound Nice scale ranging from 0 - 100, it would put the audio magazines out of business and remove hocus pocks and buzz words out of audiophiles vocabulary and make it an exacting science. Audio designers then have a number 100 to chase to be recognised.
How does your hi-fi system sound? 77 on the Sound Nice scale. Did you know that the new AKSA amp measure 82 on the Sound Nice scale?
Marketing audio equipment would become easy and objective. No more weird specifications that the layman does not comprehend; like distortion, power output, impedance, only a single two digit number: Marantz launches new power house with Sound Nice rating 93. There would be no mistake it sounds only seven notches below reality.
Damn, I am starting to sound like Carlos.
Kind regards
Nico
You are right my friend, I have worked for one of the measurement companies some years ago (Hewlett Packard) and most test equipment is developed out of necessity, not because these guys were bored.
If there was someone who could specify a repeatable subjective test I am sure there would be a company that could design such test equipment and we would have a quality number associated with it and this test would then be classified objective.
Imagine having a pocket tester that has a Sound Nice scale ranging from 0 - 100, it would put the audio magazines out of business and remove hocus pocks and buzz words out of audiophiles vocabulary and make it an exacting science. Audio designers then have a number 100 to chase to be recognised.
How does your hi-fi system sound? 77 on the Sound Nice scale. Did you know that the new AKSA amp measure 82 on the Sound Nice scale?
Marketing audio equipment would become easy and objective. No more weird specifications that the layman does not comprehend; like distortion, power output, impedance, only a single two digit number: Marantz launches new power house with Sound Nice rating 93. There would be no mistake it sounds only seven notches below reality.
Damn, I am starting to sound like Carlos.
Kind regards
Nico
Hi Hugh,
I have kept my involvement to a minimum here for a couple of reasons: One, if I want a headphone amp I'll build one myself from the ground up - that's where my enjoyment of this hobby comes from: doing.
Second are some of the things I read in this and other threads pertaining to how things sound. Folks are entitled to their beliefs and opinions and that's why I tend to stay out of discussions about these qualities, likewise I avoid discussions on politics and religion.
Otherwise, keep up the good work!
Regarding Nico's rant, I love a grand soliloquy where the orator just lets loose, exposing all thoughts, good or bad. Refreshing!
On Objectivity:
Essential, just as Nico says, but the start rather than the end of the matter. An SET low power amp will deliver entrancing sound with 2% THD, and a 'competently designed' push pull amp of 0.002% distortion may sound ordinary. How is this, and why the emphasis on THD when clearly correlations are poor at best? Or is it the measurement process? In my view, THD should be unravelled to reveal all the harmonics (now possible even with LTSpice), and they should monotonically decrease after the H2 spike. I see little attempt in the marketplace aside from Gedlee to undertake such studies. Both MJ21193 and Ostripper have, to their great credit, peeled back the onion and revealed rather a lot.
Stability, clip behaviour, FR and slew rate are the big ones, however, and critical, since a grossly misbehaving amp will be a sonic nightmare and a costly exercise, particularly on speakers. Careful analysis under a variety of signal and load conditions is essential. But the ear is very subtle, and can pick things up a THD meter will miss, such as component choices, particularly capacitors. (This is an empirical observation, and if you have not actually tried these things you would not know). I'm not sure why this is, but the experts aren't sure either and there is continuing debate.
Therefore discussion about the sound and how the circuit presents sonically are nonsensical, and you haven't seen me discuss these aspects. They belong with the marketing department, and are often worded ambiguously so that they can serve as appropriate bait for the greatest number of fish. One of my arguments for choosing a non-inverting Baxandall tone control is the almost immeasurable phase shift (or 'distortion') when set flat. It's generally agreed technically that very low phase distortion is desirable, we aim for no more than 2 degrees at the limit of audibility. I accept that Aspen probably does have a 'house sound', but you don't catch me trying to describe it, fruitless. However, there is no denying that people latch on to these ideas and like the sound of the Krell, or the Pass, or the Electrocompaniet, etc. But there is also a good deal of auto-suggestion, borne of the marketing hype.
On Subjectivity:
I avoid public comments like 'it sounds more open', 'that cable offers more resolution', 'the top end is crystalline' or 'the imaging is more focussed on the woodwinds'. It is completely subjective, and unhelpful. Besides, people's tastes vary at least as much as food, so classification is doomed from the outset. Better not to muddy the waters. The sound may indeed be different, but you can be sure it will defy accurate description even in the hands of a wordsmith.
I am an English literature buff. I don't believe people fully realise the power of the written word, particularly when published in a forum, delivered without nuance or physical gesture. As a general rule, the naked word has the effortless power to cause conflict. It must be tempered to avoid misunderstanding. As a general rule, technical people, and I count myself in this category, tend to write blunt, factual prose, without much regard for the warm and fuzzies, as they are variously called. Furthermore, technocrats tend to argue the point with each other, seldom agreeing and often launching colorful insults. The tendency to take offence both when it was and was not intended is a problem with forums, and I am determined that this does not happen in this thread. The 'grand soliloquy' should be avoided where possible. It is rare in a public forum that saying what you really think is either desirable or helpful. Ask any politician......
Nico, if you have further such 'soliloquys' you wish to share, please email me privately.
Cheers,
Hugh
Essential, just as Nico says, but the start rather than the end of the matter. An SET low power amp will deliver entrancing sound with 2% THD, and a 'competently designed' push pull amp of 0.002% distortion may sound ordinary. How is this, and why the emphasis on THD when clearly correlations are poor at best? Or is it the measurement process? In my view, THD should be unravelled to reveal all the harmonics (now possible even with LTSpice), and they should monotonically decrease after the H2 spike. I see little attempt in the marketplace aside from Gedlee to undertake such studies. Both MJ21193 and Ostripper have, to their great credit, peeled back the onion and revealed rather a lot.
Stability, clip behaviour, FR and slew rate are the big ones, however, and critical, since a grossly misbehaving amp will be a sonic nightmare and a costly exercise, particularly on speakers. Careful analysis under a variety of signal and load conditions is essential. But the ear is very subtle, and can pick things up a THD meter will miss, such as component choices, particularly capacitors. (This is an empirical observation, and if you have not actually tried these things you would not know). I'm not sure why this is, but the experts aren't sure either and there is continuing debate.
Therefore discussion about the sound and how the circuit presents sonically are nonsensical, and you haven't seen me discuss these aspects. They belong with the marketing department, and are often worded ambiguously so that they can serve as appropriate bait for the greatest number of fish. One of my arguments for choosing a non-inverting Baxandall tone control is the almost immeasurable phase shift (or 'distortion') when set flat. It's generally agreed technically that very low phase distortion is desirable, we aim for no more than 2 degrees at the limit of audibility. I accept that Aspen probably does have a 'house sound', but you don't catch me trying to describe it, fruitless. However, there is no denying that people latch on to these ideas and like the sound of the Krell, or the Pass, or the Electrocompaniet, etc. But there is also a good deal of auto-suggestion, borne of the marketing hype.
On Subjectivity:
I avoid public comments like 'it sounds more open', 'that cable offers more resolution', 'the top end is crystalline' or 'the imaging is more focussed on the woodwinds'. It is completely subjective, and unhelpful. Besides, people's tastes vary at least as much as food, so classification is doomed from the outset. Better not to muddy the waters. The sound may indeed be different, but you can be sure it will defy accurate description even in the hands of a wordsmith.
I am an English literature buff. I don't believe people fully realise the power of the written word, particularly when published in a forum, delivered without nuance or physical gesture. As a general rule, the naked word has the effortless power to cause conflict. It must be tempered to avoid misunderstanding. As a general rule, technical people, and I count myself in this category, tend to write blunt, factual prose, without much regard for the warm and fuzzies, as they are variously called. Furthermore, technocrats tend to argue the point with each other, seldom agreeing and often launching colorful insults. The tendency to take offence both when it was and was not intended is a problem with forums, and I am determined that this does not happen in this thread. The 'grand soliloquy' should be avoided where possible. It is rare in a public forum that saying what you really think is either desirable or helpful. Ask any politician......
Nico, if you have further such 'soliloquys' you wish to share, please email me privately.
Cheers,
Hugh
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KT,
Anyone who believes that product development is exciting is kidding themselves. If it were so, many more people in this forum would develop products. It is hard work, and the devil is in the detail. The only thing that gets you through is a smoldering passion for the craft, and in truth, particularly viewed from the outside, that's REAL boring.
Hugh
Anyone who believes that product development is exciting is kidding themselves. If it were so, many more people in this forum would develop products. It is hard work, and the devil is in the detail. The only thing that gets you through is a smoldering passion for the craft, and in truth, particularly viewed from the outside, that's REAL boring.
Hugh
<Nico, if you have further such 'soliloquys' you wish to share, please email me privately.>
Unfortunately I am illiterate but I fortunately have access to Thesaurus: "soliloquy's" - An actors monologue (intended for an audience).
Funny after our polite private e-mails before your last post, your attitude suddenly takes a personal tone, I try to focus on the problem not the person
I simply highlighted what I considered a flaw, but if this is intended then so be it.
I am not building this project either, but joined only to offer alternative engineering solutions as part of a group design not intending to belittle anyone. For every problem there are several solutions some better suited to the aplication than others.
Hugh, I still looking forward to an explanation of how one can hear that the signal to a speaker is inverted or not. This is what could qualify as hocus pocus.
<Hugh: One of my arguments for choosing a non-inverting Baxandall tone control is the almost immeasurable phase shift (or 'distortion') when set flat.>
now why would an inverting amp be non flat, it has nothing to do with amplifier mode, it is all to do with the capacitors in the control network.
If the controls are set flat you are looking at a balanced network which is flat. Besides introducing > unity gain will case the amp to roll off due to the bandwidth product limitation since you cannot achieve unity gain in non-inverting amplifier.
Anyway I shall refrain from comment and wait to takle the PCB, I should be spending my time making profit rather than further 'soliloquys'
Cheers
Nico
Unfortunately I am illiterate but I fortunately have access to Thesaurus: "soliloquy's" - An actors monologue (intended for an audience).
Funny after our polite private e-mails before your last post, your attitude suddenly takes a personal tone, I try to focus on the problem not the person
I simply highlighted what I considered a flaw, but if this is intended then so be it.
I am not building this project either, but joined only to offer alternative engineering solutions as part of a group design not intending to belittle anyone. For every problem there are several solutions some better suited to the aplication than others.
Hugh, I still looking forward to an explanation of how one can hear that the signal to a speaker is inverted or not. This is what could qualify as hocus pocus.
<Hugh: One of my arguments for choosing a non-inverting Baxandall tone control is the almost immeasurable phase shift (or 'distortion') when set flat.>
now why would an inverting amp be non flat, it has nothing to do with amplifier mode, it is all to do with the capacitors in the control network.
If the controls are set flat you are looking at a balanced network which is flat. Besides introducing > unity gain will case the amp to roll off due to the bandwidth product limitation since you cannot achieve unity gain in non-inverting amplifier.
Anyway I shall refrain from comment and wait to takle the PCB, I should be spending my time making profit rather than further 'soliloquys'
Cheers
Nico
While 3rd harmonics are symmetrical, 2nd harmonics are not.
Our ears have their own harmonic distortion, much of which is 2nd harmonic and asymmetrical as well.
A SE distortion profile has a certain "polarity" because of the 2nd harmonic, and if you put it in series with a similar stage with an opposite polarity, the harmonics will actually cancel and create some 3rd harmonics. It is certainly the same way with the ear. Half of a monotonic profile is 2nd harmonics, and if we are to believe that the monotonic profile is empirically "pleasing" (because IIRC the ear's own distortion is monotonic), then maybe polarity really is important.
This makes sense to me logically, no hocus-pocus here unless you can point it out.
If you don't want to converse publicly on this matter I would be happy to converse privately.
- keantoken
Nico,
I cannot give you a reason why a non-inverting phase is sonically superior because I know it is not true. BUT, the phase distortion of the non-inverting stage set flat is superior to the inverting stage, and overall phase distortion is less. Granted, all filters change phase, but in this case the NI variant is superior.
You, illiterate? Get off the grass, man, you say exactly what you think, that is the purpose of words, surely?
I have never made personal comment, Nico, and will not in public. I asked you merely to email me with your strong doubts, nothing more. Not personal at all.
Cheers,
Hugh
I cannot give you a reason why a non-inverting phase is sonically superior because I know it is not true. BUT, the phase distortion of the non-inverting stage set flat is superior to the inverting stage, and overall phase distortion is less. Granted, all filters change phase, but in this case the NI variant is superior.
You, illiterate? Get off the grass, man, you say exactly what you think, that is the purpose of words, surely?
I have never made personal comment, Nico, and will not in public. I asked you merely to email me with your strong doubts, nothing more. Not personal at all.
Cheers,
Hugh
Me too.......can't wait to plug in the iron! Thanks everyone for all your hard yakka*
(*Aussie for hard work)
Good thinking Nico! Has to have Aspen, and HAKSA Headphone Amp printed on it!
For controls, it should also have:
Bass, Treble, Level, Defeat, Series 10R/120R, Crossfeed, ON/OFF.
Front panel should carry the output jacks for the headphone, and the rear panel should carry the 24V 500mA DC power jack.
This is a graphics problem, but oddly, most of the controls will be directly mounted on the board and thus their position on the front panel has huge influence on pcb layout. Result: the front and rear panels MUST be configured before the pcb layout can begin.
Cheers,
Hugh
For controls, it should also have:
Bass, Treble, Level, Defeat, Series 10R/120R, Crossfeed, ON/OFF.
Front panel should carry the output jacks for the headphone, and the rear panel should carry the 24V 500mA DC power jack.
This is a graphics problem, but oddly, most of the controls will be directly mounted on the board and thus their position on the front panel has huge influence on pcb layout. Result: the front and rear panels MUST be configured before the pcb layout can begin.
Cheers,
Hugh
Great start, I want some artists impression and some real arguments going. Lights, bells whistles, how wide balance between controls, where is ASPEN, where is HAKSA. The guys that do the PCBs for you can screen print on aluminium face-plates as well Hugh, did you know that - it is an identical process. We can end up with conformity as well as professional looking product.
I hate DIY built into a lunch tin, because that is what it ends up being and sound like.
Nico
I hate DIY built into a lunch tin, because that is what it ends up being and sound like.
Nico
John Heisz - I want something from you. Get up out of the long grass and tell us what it will look like. I like wood as well around the outside. But think in terms of practicality so that any idiots can make it look really top-notch professional. Don't be tempted to use tools that they don't have.
Hello
Here is my face plate suggestion. I use a grey color to imitate an aluminium face plate. I made it for standard on-board switchs and pots and head-phone plug, for sure the size of the face plate need to be adjust since I do not know the size and position of the Pcb.
Since there was a balance control on the last Haksa schematic, I've include it in my face plate suggestion image.
The guy's can buy a pre-cut aluminium plate and use Letraset letters for all the writing on the face plate, so no need for special tools.
Or a group buy can be set to have it made from a case a company.
That's a first try, so any suggestion are welcome and anybody can modified that image for better results.
Bye
Gaetan
Here is my face plate suggestion. I use a grey color to imitate an aluminium face plate. I made it for standard on-board switchs and pots and head-phone plug, for sure the size of the face plate need to be adjust since I do not know the size and position of the Pcb.
Since there was a balance control on the last Haksa schematic, I've include it in my face plate suggestion image.
The guy's can buy a pre-cut aluminium plate and use Letraset letters for all the writing on the face plate, so no need for special tools.
Or a group buy can be set to have it made from a case a company.
That's a first try, so any suggestion are welcome and anybody can modified that image for better results.
Bye
Gaetan
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I would use a switched headphone jack and use it to power on or off the unit when the headphones are plugged in or unplugged. This encourages the user to put the phones away after use, instead of having them plugged in all the time. Exercises the contacts inside the connector and keeps the mechanism working and the contacts clean.
It also eliminated a front panel switch.
Crossfeed switch on the front but the lesser used 10/120 on the back panel. Volume control centre with switches and jack to the left and tone controls to the right.
It also eliminated a front panel switch.
Crossfeed switch on the front but the lesser used 10/120 on the back panel. Volume control centre with switches and jack to the left and tone controls to the right.
I would use a switched headphone jack and use it to power on or off the unit when the headphones are plugged in or unplugged. This encourages the user to put the phones away after use, instead of having them plugged in all the time. Exercises the contacts inside the connector and keeps the mechanism working and the contacts clean.
It also eliminated a front panel switch.
Crossfeed switch on the front but the lesser used 10/120 on the back panel. Volume control centre with switches and jack to the left and tone controls to the right.
Hello
Good suggestions, better to wait for mores suggestions from the guy's and Hugh before modifying the image.
For the volume control, I was finding more nice to put it on far left, I know that some Aksa amp did have it in center but they have only one button.
Thank
Bye
Gaetan
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