John Curl's Blowtorch preamplifier part III

[scottjoplin]

The reason to have a centre speaker is to give solidity to the centre image, stereo comb filtering can make it "out of focus"

 

[scottjoplin]

You know what’s really cool is a flat screen between the speakers....the phantom center affect is crazy! It takes a little jockeying to get it right though.

Yes, similarly having them out in the room creates more depth

 

[PMA]

Comb filtering is an interesting phenomenon. Our ears/head have comb filters and our brains can easily work it out.

 

[jneutron]

Are you thinking more now about shift due to speaker jitter? That may have an audible amount

No, just a way to determine ITD capability. By in the wild, I mean without headphones.
If I were determining thresholds, I would have them judge the test signal's position in reference to an actual source located at the center, a real speaker.
Jn

 

[PMA]

Jn, why don't you try?

 

[Bonsai]

A hearing threshold is usually defined at the 50% correct response level and an adaptive procedure is used, starting at higher levels of the independent variable and lowering it in dependence of the correctness of the response (up-and-down procedures), so the 50% p(c) level is likely marking the threshold where the responses are randomly given.

This figure showed the responses of the trained listeners and if they were guessing at the lower ITD´s one would expect to have some distribution of corrects responses around the 50% level.
If, as in this case, all listener´s responses were above that level, it is quite unlikely that they were just guessing.
Iow, under the assumption that the hypothesis of random guessing at 2,x us ITD is true, the occurence of the observed data is quite incompatible to the random guessing hypothesis.

So what you are saying is that tests that fell below the 50% correct threshold are basically taken as the threshold. Ok - makes sense to me - thanks

 

[scottjoplin]

Comb filtering is an interesting phenomenon. Our ears/head have comb filters and our brains can easily work it out.

With point sources, yes, but what about a phantom centre?

 

[mountainman bob]

No, just a way to determine ITD capability. By in the wild, I mean without headphones.
If I were determining thresholds, I would have them judge the test signal's position in reference to an actual source located at the center, a real speaker.
Jn

Ahhh.....sorry, some terminology still eludes me! lol

 

[scottjoplin]

Ahhh.....sorry, some terminology still eludes me! lol

Interaural time difference - Wikipedia He used "in the wild" differently earlier in the discussion IIRC, to mean.....errr....in the wild

 

[jneutron]

Jn, why don't you try?

Been there, did that. My discussion is informed by experience.
Jn

 

[mountainman bob]

Yes, similarly having them out in the room creates more depth

You wanna talk depth? ....look at this screwy positioning, it’s got the real amphitheater depth!

Just a temporary thing till I get my cabinetry done for the entertainment center.

 

[Jakob2]

Except for insulting everybody’s intelligence and basic common sense. Happens that “close minded” rely on intelligence and common sense.

Seems to be a different definition of the terms "close-minded" and "open-minded" .........

 

[PMA]

Been there, did that. My discussion is informed by experience.
Jn

Would you share your data, results? As you know, I don't care much about debates.

 

[Jakob2]

So what you are saying is that tests that fell below the 50% correct threshold are basically taken as the threshold. Ok - makes sense to me - thanks

No, that is a misunderstanding. The threshold is usually defined as the point where 50% of the responses (to the experimental task) are correct.
A series of tests is considered to be a probabilistic experiment; humans aren´t machines, variables aren´t constant over time and so on.
So a series of tests will give results distributed around the real (assumed to be fixed but unknow) value of the 50% of correct responses level. The average is a good estimator (converging to the real value) for the mean.

I´ll try to come back with some further explanations tomorrow or the day after.

 

[jneutron]

Would you share your data, results? As you know, I don't care much about debates.

Again, been there did that. The problem is, some others with a bee up their bonnett will perform the tests badly using poor test methodology without understanding so as to try and prove themselves right. Pretty much what you did.
I have no desire to spoon feed you, as you won't learn that way.
Most important here is critical thinking skills.
Edit: and that is not meant as an insult, most people when forced out of their comfort zone w/r to knowledge, tent to stumble a bit.
Jn

 

[scottjoplin]

Again, been there did that.

It seems most here aren't aware of that? So, as someone said earlier, what's really going on here?

 

[mountainman bob]

Interaural time difference - Wikipedia He used "in the wild" differently earlier in the discussion IIRC, to mean.....errr....in the wild

That’s kinda what I thought but trying not to scrutinize !

 

[scott wurcer]

I guess any software they used would have to delay via the digital samples? I wonder if they verified that what they requesting of the unit actually happened as they expected?

jn

You can do sub-sample shift via FIR. http://home.agh.edu.pl/~turcza/sr/Splitting the Unit Delay.pdf

 

[Jakob2]

Folks, it would be great if you could find a way back to a less hostile/agressive style of communication.

 

[jneutron]

It seems most here aren't aware of that? So, as someone said earlier, what's really going on here?

The entire audio chain is comprised of some very complicated stuff. Electronics which many here are excellent at, speakers...same deal, sources, testing, etc.

But there is a disconnect. A virtual soundstage requires more than just low distortion electronics. It is important to understand what compromises the virtual image.
Without understanding what is needed how does one control it?
Over the years I've tested the stability of both lateralization as well as localization on myself only. And in that process I've had to do a lot of research.

We have quite a few here that are very knowledgeable in human hearing capabilities, it is important that all discuss.
Jn