So far it appears that the sophistication comes in when you need to make sure digital works, but I still haven't seen mention of software, or a combination of software, that can extrapolate automatically from a concept schematic of purely analogue electronics, to determine what parasitics come on board when a circuit board is designed, automatically or whatever.
Does such exist, or not?
Frank
I suppose that more than one license is needed for different workstations, to get output ready for ERP input. Otherwise what's the point in software that is not integrated into manufacturing process?
Gentlemen, I thank those of you who have leapt to my defense.
But please consider the obvious motive for my questions. I want to know.
I'm genuinely interested in how Blowtorch performs on the Hirata & Raul tests. Some gurus have been at pains to tell us that they are paramount. I'm sure many on this list would like to know too. But JC is perfectly entitled to say, "NO. I'm not subjecting my designs to idiotic tests that have no relevance to good sound." In which case I have no option but to shut up.
I made a statement about LF response of cardioids; a subject I've studied in detail in my previous life. When someone pooh poohs it (somewhat aggresively I thought I feel I'm entitled to defend it. But I didn't defend it.
Because I've been out of circuit for more than a decade, I'm eager to see if the SOTA has moved forward. It's quite possible that someone on this forum, working in his spare time, has obtained better results than Dip. Ing. Wuttke and Rob Schulein. So I asked for more evidence.
Wave tried something that both Mr. Marsh and I have some small experience but seemed to have had rather different results. So I was trying to find out why. His answer was slightly obfuscating as he seemed to imply that Digital EQ would obviate the need for this simple technique.
As it was probably a misunderstanding due to my lack of facility with English, I was simply asking for clarification.
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I'm now going to make a claim and invite all of you to judge its veracity.
I ONLY post when I feel I can make a useful contribution OR if I'm trying to increase my own small store of knowledge.
I assure all of you I do not intend "neah! neah!" arguments or indulge in Wave's "dick competitions".
But when I do post, the temptation to mischievous re-wording is irresistable. Mea culpa, mea culpa, mea maxima culpa.
I hope I do this with tact & good humour but I'm reminded Socrates came to a nasty end with a similar approach.
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So Wave, the answer to your question is, "I'm not making ANY point. I'm just hoping for some answers."
Kgrlee, I think you are only making 'trouble'. For example, do you have any idea how the Hirata test works, or what might set it off to read something significant? Have you seen examples or done the test, yourself? If not, please read up, first, before demanding satisfaction.
Your PIM argument is more 'reasonable', but again there is no clear mechanism to create PIM. The input capacitance is LOW, and the input is cascoded. Where oh where can we get PIM from this circuit?
Your PIM argument is more 'reasonable', but again there is no clear mechanism to create PIM. The input capacitance is LOW, and the input is cascoded. Where oh where can we get PIM from this circuit?
Oh please, gentleman, would-you like to take a seat ? Have a drink ... and a cigar ?
Someone just told me a joke about original sin ..."Adam was near a tree... "
JC, Is that your official, "NO. I'm not subjecting my designs to idiotic tests that have no relevance to good sound." answer?
As I said, this is a perfectly valid answer. But it does beg the question why is there a problem doing the test on Blowtorch. No demands JC. Just asking the question.
I think you said you had a Hirata box. I'm sure many people here would be interested.
Is there sufficient info in the AES preprint to do Raul's test?
You are welcome. But I still can't understand why defense would be needed in discussion. If you did not understand what I mean, you always could ask to clarify. Without twisting my words and calling names.
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... dis Min. Phase sh*t
There are actually 3 regimes to consider, when correcting speakers in rooms. At HF, if the speakers are away from walls, the direct sound can be distinguished from reflections and the methods in Greenfield, Lee etc below are effective.
At LF where wavelengths are near the size of the room, the room is a 'point' and very simple filters can be used. This is REW etc.
The huge difficult middle region is where you can't separate the direct sound from reflections. I think the jury is still out on this one. The sound is almost certainly non-minimum phase unless you live in an anechoic. But excess phase correction is probably not required and may be bad.
I favour Benjamin & Gannon which is used by Meridian. The Effect of Room Acoustics on Subwoofer Performance and Level Setting. The paper covers a lot more than just subwoofers.
The important thing to watch is correcting for one spot & making things MUCH worse elsewhere. I'm not sure the naive strategies to deal with this are appropriate.
The full Engineering Memo on Peter's work on the Audibility of Speaker Distortions actually simulate & discuss how Delayed Resonance can be Min. Phase or not which determines whether they are easily corrected or not
If fact, certain High Q resonances are best left untouched. The pseudo prophet Floyd corroborates some of this.
I'm not so sure about "altering the timbre of acoustical instruments .. " though. For that, I put forward Is Linear Phase Worthwhile? and also a Dynamic Duo paper On the Audibility of Midrange Phase Distortion in Audio Systems
IMHO, these still represent the state of the art particularly as it applies to speakers.
To correct a non-minimum phase system, I put forward Efficient Filter Design for Loudspeaker Equalisation Note the separate correction of Min-Phase & excess phase which is the approach I take.
Thanks for this George. It saves me (pseudo?) pontificating though I think important points could have been made clearer
There are actually 3 regimes to consider, when correcting speakers in rooms. At HF, if the speakers are away from walls, the direct sound can be distinguished from reflections and the methods in Greenfield, Lee etc below are effective.
At LF where wavelengths are near the size of the room, the room is a 'point' and very simple filters can be used. This is REW etc.
The huge difficult middle region is where you can't separate the direct sound from reflections. I think the jury is still out on this one. The sound is almost certainly non-minimum phase unless you live in an anechoic. But excess phase correction is probably not required and may be bad.
I favour Benjamin & Gannon which is used by Meridian. The Effect of Room Acoustics on Subwoofer Performance and Level Setting. The paper covers a lot more than just subwoofers.
The important thing to watch is correcting for one spot & making things MUCH worse elsewhere. I'm not sure the naive strategies to deal with this are appropriate.
The full Engineering Memo on Peter's work on the Audibility of Speaker Distortions actually simulate & discuss how Delayed Resonance can be Min. Phase or not which determines whether they are easily corrected or not
If fact, certain High Q resonances are best left untouched. The pseudo prophet Floyd corroborates some of this.
This brings back many happy memories as Peter Fryer's Phase Meter pre-dated the B&K. He knew Henning very well in da old days.
I'm not so sure about "altering the timbre of acoustical instruments .. " though. For that, I put forward Is Linear Phase Worthwhile? and also a Dynamic Duo paper On the Audibility of Midrange Phase Distortion in Audio Systems
IMHO, these still represent the state of the art particularly as it applies to speakers.
To correct a non-minimum phase system, I put forward Efficient Filter Design for Loudspeaker Equalisation Note the separate correction of Min-Phase & excess phase which is the approach I take.
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Thanks for that, Wrinkle, it's got me started on a Sherlock Holmes to track down this will o' the wisp ...
A few things are clear: the major companies have gone on a mad orgy of buying up everybody and his dog, to make sure none of the Swiss knife blades are missing. Which means there is a possibility that there is an combo that will do the job, but it's not obvious from the promo literature, and the companies are not pushing it if they have it.
It also appears that either you look at the problem "simplistically", as in anything Spice; or you dive in head first and treat the whole thing as a microwave frequency circus ... there's no halfway house that I can see, which is actually what you want!
So, at the moment I still don't know whether you can buy, at any cost, an integrated solution; the literature by the big boys gives me no confidence that it can be done, so far in what I've found ...
Frank
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Perhaps I haven't been stressing it enough, but I haven't had any convergence issues that couldn't be resolved. Like all software it has its idiosyncracies -- for me, there are times when it refuses to start a simulation, on a circuit that it has been happily digesting up to then. A restart solves that one ...
A nice touch is that you can directly communicate with the developer; if it's something chewy there's a good chance you'll get an email response from Panama Mike ...
Frank
Hi Frank,
As you can see they still have free trial software available.
Microwave Office - RF/Microwave Circuit Design Software | AWR Corporation
But for a hobbyist the trial is never long enough...
Wrinkle
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George, actually it is good to EQ in the range of mid band, but you should EQ only what does not depend on microphone position. What depends on microphone position is not audible like distortions of frequency response, it is audible like ambiance. It belongs to the room, to the sound in the room. In order to deal with this "room sound" there are 2 major ways: either directional speakers, or dipoles. The former increases ratio between pressures of reproduced and early reflected sounds, even though the ratios between direct and reflected energies integrated is still the same. But anyway reproduced reverberation sounds from the speakers, and when it is heard reflected from walls it sounds like reverberation of a big hall bouncing inside of smaller room, quite artificial. Dipoles better blend this 2 reverberations so it is harder to localize that reflections of reproduced reverberation from walls around you in the listening room. That's why dipoles sound more "natural" in the rooms with less sound absorption. That does not mean they reproduce better, that means they in such rooms fool imagination better.
Moving the microphone across the listening positions, both horizontally and vertically, you can find what to EQ, no matter on which frequency. Both uneven response of speakers on middle frequencies and results of rectangularity of the room on low frequencies. However, it is better when before application of EQ all high Q resonances were properly minimized mechanically. Why? Because as I said before, even when you EQ frequency response you can't make decays shorter and they will be audible.
And second, thanks to Tom Danley for the reminder, resonating media are non-linear, so you can't EQ what happens after EQ.
Moving the microphone across the listening positions, both horizontally and vertically, you can find what to EQ, no matter on which frequency. Both uneven response of speakers on middle frequencies and results of rectangularity of the room on low frequencies. However, it is better when before application of EQ all high Q resonances were properly minimized mechanically. Why? Because as I said before, even when you EQ frequency response you can't make decays shorter and they will be audible.
And second, thanks to Tom Danley for the reminder, resonating media are non-linear, so you can't EQ what happens after EQ.
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