Thanks MiiB, (and Kindhornman for getting things started). Aluminum Oxide is EXTREMELY hard, especially when with serious thickness. That is what we use for TO-220 insulators, today. It should be an 'almost' ideal material, EXCEPT that it has a fairly high Q. I understand the use of aluminum with the aluminum oxide. Wonderful! I see progress here.
I don't design loudspeakers today, but I once did, some of the best that could be made at the time. However, I am not a good loudspeaker designer, and will stick to analog electronics, thank you. '-)
It is important to recognize the limits of direct radiator speakers, as you well know. You cannot easily eliminate Doppler distortion, for example with a direct radiator speaker system. It is always a tradeoff. Horns, will limit it, but they add horn throat distortion in its place. There is no free lunch!
I don't design loudspeakers today, but I once did, some of the best that could be made at the time. However, I am not a good loudspeaker designer, and will stick to analog electronics, thank you. '-)
It is important to recognize the limits of direct radiator speakers, as you well know. You cannot easily eliminate Doppler distortion, for example with a direct radiator speaker system. It is always a tradeoff. Horns, will limit it, but they add horn throat distortion in its place. There is no free lunch!
I heard prototype speakers with these cones in an earthquake prone loudspeaker lab, and they work. Nice material to play with destructively, beats bubble wrap. You can make it crack but the alu keeps it together, providing a unique tactile sensation. Might be as good as a well done paper cone
Noise? How is noise an issue with higher efficiency and larger size?
And by larger size, I wasn't intending that to be the size of an individual driver.
Are you saying that if you use four drivers in parallel/series that you will have the same cone breakup and will be just as dynamically flawed as a single driver driven to have the same acoustical output?
se
For higher efficiency you need a narrow air-gap, This creates higher pressures and more turbulence (noise) than a larger but less efficient gap, thus you end up in a trade off noise VS efficiency pick your poison
We do make other speakers than small stand-mount two-way monitors. Four drivers are good for bass, and also with some kind of power-sharing for mid-bass, for mid-range the area is too big and you get focus issues. Optimum would be an ever larger membrane area as you go lower in frequency. We do something like that in one of our speakers.
We do make other speakers than small stand-mount two-way monitors. Four drivers are good for bass, and also with some kind of power-sharing for mid-bass, for mid-range the area is too big and you get focus issues. Optimum would be an ever larger membrane area as you go lower in frequency. We do something like that in one of our speakers.
Your writing is always helping me.
The new generation of miniDSP range seem to be designed for such work in mind.
If I had to start now-or be able to upgrade- I would choose these for sure.
Re REW automatic room equalization: I have spent some days some months ago doing such a thing, with REW5 exporting directly to MiniDSP but I was not satisfied with the results (most probably due to my mistakes setting the target level as that was my first encounter with room eq).
I prefer manual setting some filters btn 20Hz- 120Hz but I may try again the auto mode.
I wish miniDSP 2x4 could work FIR filters but I think it can not, as it handles only 2nd order linear recursive filter (Biquad) with 5 coefficients each.
Thank you Richard, I will look at these all.
Scott
You didn’t put words in my mouth. This is exactly what I wrote I would like to achieve. But now I understand a bit better that -practically speaking-it is quite difficult and not only due to environmental noise.
Here is an informative post (starting after “Getting a bit technical”) referring to de-convolution and the issue of noise that you warned me of.:
foo_convolve - Impulse response convolver - Hydrogenaudio Forums
Of interest:
http://www.audiovero.de/en/
You mean our time
Pavel
Re1 , pl. read my response to Tom.
I haven’t touched the RePhase sw though. It seems to do many good things (linear phase filters mmm!)
I guess I have to work through the PC with everything I use as a source for to enjoy it’s merits.
Now I use Foobar as a player only when I listen to music files stored in the laptop.
Re2: Thank you for the link, it had skipped my attention.
As a reward, here are some patents for you to ponder
Digital feedback to improve the sound reproduction of an electro-dynamic loudspeaker
Motional feedback system
Mixed-mode (current-voltage) audio amplifier
AMPLIFIER AND METHOD FOR CORRECTING A FREQUENCY RESPONSE
This is my living room at it’s quietest (during daylight time, plots are some 20dBs up) . Each of the three plots is a two measurements averaged. Each measurement last for 5.9s
George
Attachments
MiB: I'm just pointing out that your argument is really about cost - you could just make a big gap and hit the same B target, electroacoustic efficiency with larger air path clearances
of course high cobalt pole pieces, the increase in magnet assembly volume is very expensive
George, others interested in DSP may like: http://www.fulcrum-acoustic.com/ass...dspeaker-transient-response-with-dsp-2005.pdf even more detailed about what you should and maybe shouldn't try to correct with DSP - at the driver level
of course high cobalt pole pieces, the increase in magnet assembly volume is very expensive
George, others interested in DSP may like: http://www.fulcrum-acoustic.com/ass...dspeaker-transient-response-with-dsp-2005.pdf even more detailed about what you should and maybe shouldn't try to correct with DSP - at the driver level
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A number of factors are at play:
* It is still very difficult to assemble a system from arbitrary components, no matter how well they spec, that just "sounds good".
* Why they don't "sound good" is because the nature of the audible distortion is enough to disturb one's ability "to go with the music".
* Chasing technical excellence in ways that are easy to measure has become the game; if an audible artifact occurs which is difficult to measure the easy, conventional approach is to assert that the problem exists in the listener's head, rather than in the equipment.
* Audio reproduction is complex, and the better a system is capable of performing, the more the "devil's in the details" aspects will be part of the audible problems. So long as people refuse to put more effort is resolving those issues, and instead concentrate on ever more sky high technical benchmarks the audible deficiencies won't go away - it's a case of inventing heavier and thicker carpets to sweep the dirt under ...
* Probably the most significant factor is that very few people have heard an audio system work at a very high standard - or if they have done so, they don't realise what's going on. IOW, most listeners don't understand what they're looking for, so what hope have they of finding the "right stuff" ... ?
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Can't say I've had any noise issues with the higher efficiency drivers I've used. Are you saying this noise is audible while listening to music or is this just some sort of ideological preference?
Also, I'm talking about four drivers which will excurse less. So we're not talking about the same excursion in a smaller gap.
Yes, I know.
I wasn't suggesting using the same drivers for midrange as are used for the bass.
Yes. I wasnt suggesting using just four parallel/series drivers for the entire loudspeaker.
se
To me the obvious solution was to simply always make 2 recordings, using 2 DACs, of a particular signal. The input to the main DAC would be way too hot, so it was guaranteed to clip, badly, quite a number of times during the event; the other, "overload" DAC would have plenty of safety margin, by converting a heavily attentuated version of the signal, and hence capture those clipping events perfectly - the main DAC would beautifully resolve all the low level detail. After the fact, the two captures would be stitched together with software - voila, all the dynamic range one could want ...
Steve, you won't know you have noise until it's gone. Noise contribution is also from material colorations, soft driver membranes and domes have it in abundance. Hard Domes primarily due to mass and mass-spring loaded resonances paired with a poor ability to track the material, Soft domes due to material break-up. SPL is not just SPL.
I see you use headphones, those a most often lower in noise and dynamic issues due to low mass and very low excursion and no crossover, they are better fit to digital, as they are not so compromised.
I see you use headphones, those a most often lower in noise and dynamic issues due to low mass and very low excursion and no crossover, they are better fit to digital, as they are not so compromised.
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This is called "moving the goal posts."
So I guess you agree that using four drivers would address the "noise" that you defined before moving the goal posts, yes? Because I don't see any argument from you on that point.
No, I am a loudspeaker person. Have been since I built my first pair nearly 40 years ago when I was 16. I only use headphones when I can't use loudspeakers.
se
Noise is not something present only in the base, more drivers less excursion less doubler issues for the same SPL, still the lower noise driver would be better in the same configuration. It's always about making the system, drivers need to match, what noise floor is needed to match our tweeter, may not be needed to fit a dome.
When did I limit anything I said to the bass range? Nowhere that I can see.
So of all the things you worry about, thermal compression isn't even on your radar?
se
Thermal truncation is also an issue, but less for us, as our membranes are really good at removing heat.
Earlier you stated that all drivers should not play midrange. Hence my comment on the bass
Now this is not a speaker thread, and I think my time on that subject is pretty much exhausted.
Earlier you stated that all drivers should not play midrange. Hence my comment on the bass
Now this is not a speaker thread, and I think my time on that subject is pretty much exhausted.
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In all my years of fooling in audio I don't think I have ever heard this dreaded driver thermal compression - vast gobs of amplifier compression, the poor "mega-amps" sagging into a heap when asked to deliver big SPLs - back in the 80's and 90's they seemed to be uniformly hopeless ...
MIIB,
This is thread is now in the lounge so whatever subject related to audio reproduction is open game here
Now there has been much disagreement on whether our hearing is sensitive to phase shift across the FR band of human hearing. Some argue that absolute flat phase response is important and others such as E. Geddes will argue it is only important at the crossover frequency.
On that note from an earlier post my question is are we really capable of hearing the doppler shift of a small format speaker with large excursion or is that outside of our discrimination threshold? We are not talking about a train whistle moving past us but a very small shift in effective center on a loudspeaker. This goes back to early efforts at time alignment in loudspeakers and still is present in every multi-driver speaker application. You just can never time align a multi-driver component speaker except for one exact spot in space, So why are we really worried about the slight doppler shift from a moving cone?
MIIB,
In a vented gap loudspeaker I would question the difference in gap width, that seems like an easily ameliorate situation with suitable motor design. I have looked at that situation while pondering the use of ferro-fluids. You have to consider the air pressures effect on the fluid in a closed gap as the movement of the former and voicecoil will want to push that material out of the gap during movement if you have a pressure rise on one side of the fluid. No I don't use ferro-fluid as I do not think it is stable over the life of the speaker and I don't think a consumer should have to have the fluid changed after a set number of hours, we aren't changing the oil in our cars here.
I find that the adhesive bonds and the materials that most surrounds are made of would be more important than the small volume of air that could be excited in the gap. As Steve E has pointed out in a large diameter speaker that is almost nothing at normal listening levels. Not to say it doesn't exist but I would say that there are much larger noise contributors than the air gap. A spider is going to make magnitudes more noise than could ever be produced in the gap.
This is thread is now in the lounge so whatever subject related to audio reproduction is open game here
Now there has been much disagreement on whether our hearing is sensitive to phase shift across the FR band of human hearing. Some argue that absolute flat phase response is important and others such as E. Geddes will argue it is only important at the crossover frequency.
On that note from an earlier post my question is are we really capable of hearing the doppler shift of a small format speaker with large excursion or is that outside of our discrimination threshold? We are not talking about a train whistle moving past us but a very small shift in effective center on a loudspeaker. This goes back to early efforts at time alignment in loudspeakers and still is present in every multi-driver speaker application. You just can never time align a multi-driver component speaker except for one exact spot in space, So why are we really worried about the slight doppler shift from a moving cone?
MIIB,
In a vented gap loudspeaker I would question the difference in gap width, that seems like an easily ameliorate situation with suitable motor design. I have looked at that situation while pondering the use of ferro-fluids. You have to consider the air pressures effect on the fluid in a closed gap as the movement of the former and voicecoil will want to push that material out of the gap during movement if you have a pressure rise on one side of the fluid. No I don't use ferro-fluid as I do not think it is stable over the life of the speaker and I don't think a consumer should have to have the fluid changed after a set number of hours, we aren't changing the oil in our cars here.
I find that the adhesive bonds and the materials that most surrounds are made of would be more important than the small volume of air that could be excited in the gap. As Steve E has pointed out in a large diameter speaker that is almost nothing at normal listening levels. Not to say it doesn't exist but I would say that there are much larger noise contributors than the air gap. A spider is going to make magnitudes more noise than could ever be produced in the gap.
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