Why didn't I think of this earlier!
Tick, how close to Blowtorch is your DIY version? JC published a schematic earlier.
Would you be prepared to lend it to eg Pavel or some true guru with the facilities to test it?
We could settle this "Blowtorch has high Hirata/Quan/7th harmonic dist." issue once & for all.
JC, would you lend someone your Hirata test box? I understand you might be reluctant to lend a $20,000 Blowtorch out but surely the Hirata box is OK ... especially as it doesn't seem you use it.
Hmmm! How do we make sure JC can't say Tick's box is cr*p if the test results aren't supa dupa?
JC, would you be prepared to "lay your hands" on Tick's blowtorch? ie check it out and listen to it to establish if it has all the unique goodness you designed into the original?
Or perhaps nominate a Blowtorch owner who's ears you trust to check it out on your behalf. But this wouldn't have the authority of a "laying of hands" by JC.
____________________
Surely establishing good sound (pun intended) reasons for the failure of JC2 Mk1 ... that aren't mythical "all OPAs including AD797 are evil" is constructive?ticknpop said:
I've suggested several measures to avoid such fails in future which some gurus here agree with. eg read the f**king datasheet. This might be of use to someone attempting to design or build something similar in future.
I have placed a standard clay house brick on top of my cd player in the past and the added mass altered the sound. Rotating the brick 180* further altered the sound
Dan.
Dan
I won’t touch any driver or tube today (I am still under the influence of the full moon) so I can -relatively safely- respond to this.
Pour sand on a bag, catering for the same mass and footprint as the brick you used.
Place this bag on top of this CD. Listen. Then rotate the bag 180d. Listen again.
For me, the acoustic tests is the start and the end. In between, I have to do some measurements to record subjective data in order to see if I am running after some ghost.
I will post a totally humiliating personal experience.
Some 3 years ago I started work on a three driver OB speaker.
The first passive x-over was build with what I had available.
After roughly trimming the acoustic levels of the drivers by using resistors, I spend some two hours trying to decide by listening on the relative polarity btn mid and high drivers. Back and forth several times, I was quite certain in the end that a certain polarity relation was acoustically better.
After that, I went to do some measurements. As I was setting up the jig, I approached the input of the x-over to do the connections.
There,
I saw that the + of the tweeter’s wire was disconnected from the x-over output. All the listening and decision making based on my careful noting of sonic changes was done with the tweeter disconnected. Oh well FLEETWOOD MAC - Oh Well (1969 UK TV Performance) ~ HIGH QUALITY HQ ~ - YouTube
George
PS. Nothing is safe. Too late! The smell informed me that while typing, I burned the food in the kitchen.
kgrlee, looking at the schematics, i believe there is NOTHING to be blamed about quality of the blowtorch (if devices are correctly matched, PSU good enough with no ground loop issues, and charge not in excess).
Schematic is healthy, no feed back, so no induced TIM, and if their distortions measure well, they, for sure will sound good. Nothing mysterious, exceptional or revolutionary as well.
We can disagree about the way John is always pretending to be the best of the universe, or the outrageous price of some of his products, or smile about the 'legend' around, or the john 'audiophile' and sometimes arrogant attitude, but this does not affect its engineering's qualities, on my point of view.
You can debate about some of its position, about mysterious cables, handcrafted by virgins witch are the 'only ones' etc. where audiophile marketing take the place of the correct scientific approach, but did he deserve this hate turning in circles ?
Yes, we are allowed to say that other ways can lead to good sounding products (may-be better ?) , like the use of good and wise chosen OPAs, and in a more general way, good use of feedback loops, but that does not imply that the John's choices are bad.
Give-you a favor, please, bring your inputs in a positive way, you begin to deserve-yourself with this litany, more than John with some of his broad, sweeping statements.
A pity, for me, as i take-you too for a valuable engineer.
Schematic is healthy, no feed back, so no induced TIM, and if their distortions measure well, they, for sure will sound good. Nothing mysterious, exceptional or revolutionary as well.
We can disagree about the way John is always pretending to be the best of the universe, or the outrageous price of some of his products, or smile about the 'legend' around, or the john 'audiophile' and sometimes arrogant attitude, but this does not affect its engineering's qualities, on my point of view.
You can debate about some of its position, about mysterious cables, handcrafted by virgins witch are the 'only ones' etc. where audiophile marketing take the place of the correct scientific approach, but did he deserve this hate turning in circles ?
Yes, we are allowed to say that other ways can lead to good sounding products (may-be better ?) , like the use of good and wise chosen OPAs, and in a more general way, good use of feedback loops, but that does not imply that the John's choices are bad.
Give-you a favor, please, bring your inputs in a positive way, you begin to deserve-yourself with this litany, more than John with some of his broad, sweeping statements.
A pity, for me, as i take-you too for a valuable engineer.
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Christophe, my attitude exactly. I'll take shots at the horse chips John likes to fling around, but when the rubber met the road, I recommended his power amps for my boss to buy (he likes the performance a lot, he hates the lousy XLR connectors they use).
The BT is most likely just as audibly transparent as any other good preamp despite the voodoo atmosphere that John likes to create around it.
The BT is most likely just as audibly transparent as any other good preamp despite the voodoo atmosphere that John likes to create around it.
That's very easy. The magnet is forcing the steel to move along it's hysteresis curve. As a result, the small signal permeability the low level magnetic fields of the wire sees gets lower.
Good magnetic irons really lose permeability in the 1.5 to 2 tesla range, and when they do, they begin to lose field containment and more of the magnetic field goes beyond the iron. 1.5 to 2 tesla is actually not that hard for the Neo magnets at their surfaces. You need a lot of them if you wish that kind of field present in a reasonable air gap, that's a lot of magnetic energy.
Well, that leaves me out...
jn
ps..I did find this interesting article on arc welding lorentze force measurement. They shield the linear displacement transducer from the arc electrical noise by alternating copper foil and mu metal, mentioned in para 3.. IIRC, somebody on this very thread mentioning that..
http://eagar.mit.edu/EagarPapers/Eagar031.pdf
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Not Possible...Not Invented Here....
In the observational cases I have described, I am sincerely asking for physics explanations from the theory adept fellows collected here....oh well....
Dan.
Hi John, yes I respectfully take that as good advice.
In the observational cases I have described, I am sincerely asking for physics explanations from the theory adept fellows collected here....oh well....
Dan.
Some Days....
.
.
Dan.
Typical clean sand has no permanently magnetisable iron content, however sandbags can be a good mechanical damping method.
Enough A/B comparisons and even very fine effects are reliably discernable. Measurement will of course confirm this....provided that the correct testing methodology is performed. Diffmaker can be your friend in cases where standard steady state testing is not easily revealing.
So you were hearing changes according to the polarity of only the mid driver then ?....if so, then there is nothing to be embarrassed about. Not noting the missing highs is another matter......After roughly trimming the acoustic levels of the drivers by using resistors, I spend some two hours trying to decide by listening on the relative polarity btn mid and high drivers. Back and forth several times, I was quite certain in the end that a certain polarity relation was acoustically better.
After that, I went to do some measurements. As I was setting up the jig, I approached the input of the x-over to do the connections. There,
All the listening and decision making based on my careful noting of sonic changes was done with the tweeter disconnected.
.Best you stay in bed then....put your mattress on the floor and don't move
.Dan.
Thanks, SY.
I believe we are several, here, to try to *understand* the numerous causes of audible distortions, in order to address them the correct way. Others ( 'audiophiles') are more interested in 'Tips'.
Tips can work in a situation, and be totally useless in an other. Cable's sound is a good example.
When we design some circuit, we have to know the all landscape, deeply, i mean, near instinctively. In order to ask ourself the good questions, and find the best solution at each step.
I understand how John, after so many years, can be tired of those concerns, means forget the curiosity and maths and use exclusively what he think 'works'. The aluminum case is a good example.
I can even understand why, because he need his reputation and strong positions for a living, reassuring for customers and commercial partners, he can be so abrupt and definitive.
Just one day, John, you will realize a DIYer forum is not the right place for such an attitude, reserved for audio shows or presentations of some products to the audience or mass media.
I just noticed your choices were near always good, even if the reasons you provided were not.
The good answer about electronic enclosures is to explain Eddie Currents effects, not 'I use aluminum cases'.
The good side of the things is that, reacting against this marketing attitude, some knowledgeable engineers, here, provide the good stuff in return. In a way us, stupid scientist oriented guys, can understand and correlate.
This thread is the one where i have found the most valuable and numerous inputs in the same place (with the use of a good noise-gate). Learned a lot of thinks here, or had a lot brought back to the surface, buried in my memory.
Thanks a lot at all, including John. Your passions are gifts.
And to John, even if i do not agree with you unconditionally, even if i tease you often, in reaction to your provocative attitude, i read your inputs with great interest and attention.
I believe we are several, here, to try to *understand* the numerous causes of audible distortions, in order to address them the correct way. Others ( 'audiophiles') are more interested in 'Tips'.
Tips can work in a situation, and be totally useless in an other. Cable's sound is a good example.
When we design some circuit, we have to know the all landscape, deeply, i mean, near instinctively. In order to ask ourself the good questions, and find the best solution at each step.
I understand how John, after so many years, can be tired of those concerns, means forget the curiosity and maths and use exclusively what he think 'works'. The aluminum case is a good example.
I can even understand why, because he need his reputation and strong positions for a living, reassuring for customers and commercial partners, he can be so abrupt and definitive.
Just one day, John, you will realize a DIYer forum is not the right place for such an attitude, reserved for audio shows or presentations of some products to the audience or mass media.
I just noticed your choices were near always good, even if the reasons you provided were not.
The good answer about electronic enclosures is to explain Eddie Currents effects, not 'I use aluminum cases'.
The good side of the things is that, reacting against this marketing attitude, some knowledgeable engineers, here, provide the good stuff in return. In a way us, stupid scientist oriented guys, can understand and correlate.
This thread is the one where i have found the most valuable and numerous inputs in the same place (with the use of a good noise-gate). Learned a lot of thinks here, or had a lot brought back to the surface, buried in my memory.
Thanks a lot at all, including John. Your passions are gifts.
And to John, even if i do not agree with you unconditionally, even if i tease you often, in reaction to your provocative attitude, i read your inputs with great interest and attention.
George,
Many years ago I had a consultant with me tuning a baseball field sound system. He was dictating the adjustments and I twiddled the knobs. Now one thing I picked up on was when he told me to make a filter deeper, he wasn't happy until I made it wider. Same thing when he said wider I gave him deeper. When we got to the tweeters nothing I did seemed to have any effect. I mentioned we should check things out. His response was that the correlation function showed good results, so we were limited by level, noise etc. After he left I checked and the tweeter amplifier racks indeed had no power. Now if you are charge $2,000 a day, apparently you don't have to be embarrassed.
For chuckles try:
http://www.analog.com/static/imported-files/tutorials/MT-042.pdf
http://www.analog.com/static/imported-files/tutorials/MT-043.pdf
Many years ago I had a consultant with me tuning a baseball field sound system. He was dictating the adjustments and I twiddled the knobs. Now one thing I picked up on was when he told me to make a filter deeper, he wasn't happy until I made it wider. Same thing when he said wider I gave him deeper. When we got to the tweeters nothing I did seemed to have any effect. I mentioned we should check things out. His response was that the correlation function showed good results, so we were limited by level, noise etc. After he left I checked and the tweeter amplifier racks indeed had no power. Now if you are charge $2,000 a day, apparently you don't have to be embarrassed.
For chuckles try:
http://www.analog.com/static/imported-files/tutorials/MT-042.pdf
http://www.analog.com/static/imported-files/tutorials/MT-043.pdf
JN, yes I did and noted your explanation, and thank you.
In the case of the cd player concerned the lid was fully three inches+ above the main pcb, and the brick concerned was on top of the top chassis cover.
Considering the physical seperations and wall of RF noise produced internally, I find the effect most curious
Dan.
This was repeatedly explained in this thread, or in the part I. So the DIYaudio search engine would help. Try to take another view - people might consider searching before they ask questions. It is time consuming and boring to reply same questions in circles and to give same answers. Problem of forums everywhere.
Yes sir, sir. Ordered ! (Time to question my current-feedback dedication).
I still miss my 2 ideal OPAs.
Both fet inputs with >20KHz open loop bandwidth, with differential inputs, witch can be configured CFA or VFA, one low noise (<1nv with >50 V/µs slew rate ), one high level (<10nV, >500v/µs, IO>=100ma). Both unity gain stable.
I'm sure it could be done. there is always something i dislike, reading at the data sheets of available devices.
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Something related with mechanical vibrations damping generated by the CD rotation ? Number of corrected errors can change the sound quality a lot.
Well, maybe it is a good time to 'clear the air' a little bit.
First, I apologize if I come off as arrogant or overcritical. It is just the way that I communicate, and I have never learned 'diplomacy'. That does not mean that I am always right, or anything, but old habits are hard to change.
Please, just remember, some people who have smoothly modulated inputs, may in fact, be deceiving you for some reason or cause, and they can do it easier than I can, because they seem so sincere.
As far as I am concerned, I try to be as truthful and accurate as possible about audio history, and my ideas of how to make better audio designs. I have ALWAYS been truthful, but that does not mean that I am ALWAYS right. Sometimes, I can be found to be wrong, and while I can be embarrassed, just like anyone else at being in error, it doesn't mean that I was not well-intentioned in the first place. I would not waste my time to make up a 'story' about something. Let's leave that to the marketing departments of the various companies that I work with.
Much of what is said about my products on this thread recently is all 'smoke'. It has no basis in reality. Especially the input from that guy in OZ. It is laughable, to me, but many here might not be able to realize that it is a complete 'fantasy' on his part, so if you are in any doubt, do a little personal checking for yourself on the internet.
In any case, I DO believe that there is more to audio design than just static measurements. I have offered some alternatives like the Hirata test, and PIM, but they have limited usefulness, and don't tell us everything that our ears seem to perceive.
If you don't believe in what your ears tell you, then I can do little to help.
I am close to 71 years old, my associates are dying around me, two passed away just this last month. I just passed though a personal cancer scare, myself. I feel that I have limited time to give free advice, and I certainly don't have the energy to do extensive measurements, even with the lab equipment at my disposal, without some practical reason behind it. If I was 35 years old, well maybe then, but not now, so please don't ask me for the effort when you could probably do it, yourself.
First, I apologize if I come off as arrogant or overcritical. It is just the way that I communicate, and I have never learned 'diplomacy'. That does not mean that I am always right, or anything, but old habits are hard to change.
Please, just remember, some people who have smoothly modulated inputs, may in fact, be deceiving you for some reason or cause, and they can do it easier than I can, because they seem so sincere.
As far as I am concerned, I try to be as truthful and accurate as possible about audio history, and my ideas of how to make better audio designs. I have ALWAYS been truthful, but that does not mean that I am ALWAYS right. Sometimes, I can be found to be wrong, and while I can be embarrassed, just like anyone else at being in error, it doesn't mean that I was not well-intentioned in the first place. I would not waste my time to make up a 'story' about something. Let's leave that to the marketing departments of the various companies that I work with.
Much of what is said about my products on this thread recently is all 'smoke'. It has no basis in reality. Especially the input from that guy in OZ. It is laughable, to me, but many here might not be able to realize that it is a complete 'fantasy' on his part, so if you are in any doubt, do a little personal checking for yourself on the internet.
In any case, I DO believe that there is more to audio design than just static measurements. I have offered some alternatives like the Hirata test, and PIM, but they have limited usefulness, and don't tell us everything that our ears seem to perceive.
If you don't believe in what your ears tell you, then I can do little to help.
I am close to 71 years old, my associates are dying around me, two passed away just this last month. I just passed though a personal cancer scare, myself. I feel that I have limited time to give free advice, and I certainly don't have the energy to do extensive measurements, even with the lab equipment at my disposal, without some practical reason behind it. If I was 35 years old, well maybe then, but not now, so please don't ask me for the effort when you could probably do it, yourself.
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