So, assuming that you're not just pulling stuff out of the air like in your original assertion, you're saying that 10% could. I can believe that, MP3 is pretty good, but careful listeners can hear the difference (ears only!) between MP3 and uncompressed, and even between different bitrates, assuming appropriate source material.
If you can't hear something without peeking, you can't hear it. Trust your ears, don't rely on cheating.
Hi Chris
You have given me an opportunity to set a few things straight, so I hope you will allow me.
But the short answer would have been:
Yes, yes, yes, yes, yes, yes, yes, yes, a lot. Thousands of dollars worth.
I do, and it is very expensive and the same one that Roger Sanders (ex Martin-Logan) told me he uses too, designing as he does, both amplifiers and speakers.
Joe,
What is the test set and what is the base line measurement it is capable of?
I have asked you this before but never got an answer. Why are you so cagey
about this stuff?
WRT soundcard for measurement - as I have stated elsewhere, anything with
an AKM AK5394 ADC is what you want. Very low distortion and also very low
OOB noise.
cheers
Terry
I don't have a science. Neither do you, but your implication that I might have my own personal science speaks volumes about your understanding of science. I simply use known and accepted science to consider how a circuit works. The only alternative is to not consider how a circuit works; the option apparently chosen by many in this thread and earlier threads on the same topic.Coris said:
Why can't we have a fruitful discussion about the effect of Joe's extra C and R on the virtual inductor seen at an opamp virtual 'ground'? Would this involve too much science?
I have seen very little in the way of personal attacks, but lots of technical challenges - mostly unanswered. There has been lots of personal appreciations, as though these somehow can negate technical challenges.
Well, maybe a not very right/fortunate phrase in my post. I meant with "(your) science", your amount of knowledge, but not your particular own science, as the science is that, the only accepted one. But who knows, it may be a kind of science we do not know yet...
So, you are welcome (my opinion) in this respect. I may also strongly advice you to solder that caps in place, if you may have available a such "place", before you may make an overall scientific appreciation.
So, you are welcome (my opinion) in this respect. I may also strongly advice you to solder that caps in place, if you may have available a such "place", before you may make an overall scientific appreciation.
The instrument is less than half of the picture. Coincidentally, for an invited presentation on Fourier transform measurement, I'm writing a paper which specifically deals with operator knowledge versus instrument capability (the context isn't audio, but my own professional specialty, molecular vibration). The bottom line is that a capable analyst with mediocre instruments will extract far more useful and reliable information than a mediocre analyst with superb instruments.
My bolding: So even prior to testing you seem to be ready to discard the results if they disagree with your fans.
Again, the suggestion that no test is necessary shows clearly you're not looking for the truth at all.
BTW, I see that you have not donated money to www.diyaudio.com - I see that Scott Wurcer has, billshurv too, and Coris. So have I and it wasn't the minimum amount. Strange, isn't it?
How I choose to spend my money is none of your business.
I might be able to find out IF TI are allowed to release it. But probably need to know shoot you stuff.
Cool, thanks in advance.
More detailed information would be useful to understand what is changing with Joe's mods.
Dan.
See, there we go again. Lowest common denominator stuff is applied to anything I even just mention.
Stuart, if you end up doing your tests, and that is entirely possible, nothing has been ruled out, but please, this is not the way to go about it. I have one step in mind right now, will progress from there. This manic and frantic stuff turns me off, and not only me. You must surely realise that there are many reading this thread, and has it not occurred to you whose side they may be on? I know, because my Inbox etc tells me.
In the meantime, the DIY is there for anybody to explore, back in those first six posts there is a lot of good stuff that people can do - that must be important too - do it yourself.
As I just pointed out in a PM to someone else here:
Insulin was discovered by Fred Banting in 1921, it was not until 1949, when Rachmiel Levine, MD, discovers that insulin works like a key, transporting glucose into cells. How many hundreds of thousand lives were saved by something that was not understood - so if something works, that's what matters.
If we are to discover the basis for what we hear, and make no doubt about, people are hearing this, even skeptics convinced, then I think it must be measurable - only a matter of how. Can we at least agree on that.
The real answer to this may not be fitting capacitors and resistors on the DAC pins - in fact I think there is reasonable indications that this is in the realm of digital filtering.
Even Scott said this, just yesterday my time. But that could also possibly mean that we end up with a non-flat response @ 20KHz that may need to be corrected elsewhere, on the digital or analog side, I don't know.
I think that Steve Bolser is also pointing that way. In my limited capacity I am quite willing to admit my limitations. But what I won't back down from is that we are not dealing with a phantom event. I am convinced there is something that needs to be solved - and I would rather see people pulling together than the haggard process so far - I am weary and tired. But one thing for sure, I don't for a nanosecond regret in making this public. My optimism remains even though I am puzzled by the events afterwards.
So until Steve Bolser is ready I am going to be a little more quiet - and then spring back to life.
I might still chime in here or there - but I won't rehash anymore and the character assassination that I am a quack etc won't hurt me - they are made by non-persons as far as I am concerned.
I got my ARTA compatible analyser yesterday, because that was Steve's suggestion, so that we can all check and analyse the data because it is accessible equipment - so that I am on the same page as others, no more.
So there... it won't take 28 years like it did with insulin.
Joe,
As far as I can tell from manuals / brochures etc this is, as you say, a very
powerful speaker measuring system. Having said that I don't think it has the
bandwidth or resolution to measure what you are looking for in a good DAC.
As stated before (do you read my posts? LOL
) look for a good soundcard with AK5394 ADC and run it at 192k to get some bandwidth. This
ADC is extremely linear at high frequencies and may show something you
are looking for - or not!
For the life of me I can't see what is so bad with a decent 3rd order Bessell
LPF at somewhere between 50k and 100k. This will give much more RF
attenuation than your single order sledgehammer at 20k.
T
I am inclined to think, as I just suggested to Stuart, that is where it might be at - that capacitors and resistors is not the real solution.
But it may still mean we end up with a non-flat response and what to do about it?
I doubt we need to go there. A good start would be to write down the system function for an op-amp I to V with a cap across the input. The op-amp can be a first order integrator with a unity gain frequency, the LM4562 shown is ~55MHz. The simple second order equation tells you a lot about what's going on including the nearly 200X noise gain at 20kHz. It's only simple algebra that's needed, but every op-amp will give a different answer.
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