You appear to be the only test for DDR on this forum.
You got this crappy undefined term from this guy?
Downward Dynamic Range - a fuller description. - Allen Wright - Vinyl Asylum
Who only references his book "ToobPreamp CookbooK"
Allen Wilson puts up a bunch of words:
In the context of his experience in a quiet recording studio described in the provided link, DDR just boils down to just Dynamic Range in the context of threshold of human hearing. Both of these are well studied with straight forward metrics.
So every time a thread is bombed with DDR comment it is like saying, "Hey guys what about the blah blah blah thingy's dynamic range?"
Yes objective comparisons may also be made of speaker drivers.
In following diyAudio I have found that most of the people here with vested interest in speaker building have no new knowledge that they are willing to share in a constructive manner.
People have been using all sorts of different crappy terms for this thing for a long-long time. Allen was the 1st one to give it an all encompassing name that would give us a clue on how to start looking at how to measure it... asking people to Think Different. A cohesive term close;y related to a gem told me when i 1st started out... the difference between good hifi and great hifi is what is happening 30, 40, 50dB down.
Allen was an exceptional engineer, worked with HP for quite awhile, likely had the beginnings of some tests underway and may well be showing us technical data now but for his untimely death at a young age.
Maybe. It certainly has to do with Dynamic Range, it is after all in the name. Can you point us at some?
dave
DDR
Let's look at this deeper. Downward Dynamic Range. We know what Dynamic Range is. Adding the prefix Downward has us remembering to/looking at the ability to reproduce the quiet end, even in the precense of "explosions" or other loud stuff. Nothing crappy about that.
dave
Let's look at this deeper. Downward Dynamic Range. We know what Dynamic Range is. Adding the prefix Downward has us remembering to/looking at the ability to reproduce the quiet end, even in the precense of "explosions" or other loud stuff. Nothing crappy about that.
dave
DDR is a thing. Dynamic range is straight forward.
Context of human hearing is also rather straight forward, for example:
http://www.diyaudio.com/forums/atta...ls-blowtorch-preamplifier-part-ii-coding2.pdf
See figures 10 (p23), 12 (p24), 3 (p25), and 4 (p25). These show an awful lot about what humans can and can not hear and under what conditions. All the plots are based on analyzing lots of real data.
Allen's term doesn't lead to any clues, only obfuscation by those that bandy this term about.
Real systems have real measurements for dynamic range, harmonic distortion, intermodulation distortion. Results with such tests in conjunction with threshold of hearing for harmonic distortion and various intermodulation distortions fills in the rest.
Context of human hearing is also rather straight forward, for example:
http://www.diyaudio.com/forums/atta...ls-blowtorch-preamplifier-part-ii-coding2.pdf
See figures 10 (p23), 12 (p24), 3 (p25), and 4 (p25). These show an awful lot about what humans can and can not hear and under what conditions. All the plots are based on analyzing lots of real data.
Allen's term doesn't lead to any clues, only obfuscation by those that bandy this term about.
Real systems have real measurements for dynamic range, harmonic distortion, intermodulation distortion. Results with such tests in conjunction with threshold of hearing for harmonic distortion and various intermodulation distortions fills in the rest.
After reviewing the thread I would request that the arguments about subjective vs objective impressions be dropped. There is no end to this type of debate. The thread is about objective measurements of the various drivers, and the interpretation of said measurements. People will have their own opinions of what is important and what isn't, that is unlikely to change.
What I think would be welcome is a bigger sample set. There is a lot of acrimony (perhaps that is too harsh a word) over the measurements of a single driver which may or may not be faulty. Unless the subjective impressions are of the exact same drivers as measured in these tests, then I think that any debate is pointless.
I encourage Dave to post (at a minimum) his impedance data for the driver under dispute, and would suggest that he also post FR data, even if he thinks it is irrelevant, just in the interest of getting a second data point.
I'd like to see a test with a few of these small fullrange drivers all equalised to the same target. Blind listening tests with a group of listeners.
I'd leave out the ringing type speakers as one should be able to identify those.
After equalising them to the same target, let's see how they distinguish themselves. Can we really pick out our favourites after the first identifier is removed from the test (being the frequency response deviations).
You'd probably need to do it with Fir filters to counter the phase rotation of the EQ needed, bringing in new variables (possible pre-ringing), so it won't ever be an acceptable test for all.
A test like this would remove one aspect of difference to see if that difference is cause for preference.
I agree that the current discussion leads us nowhere.
I'd leave out the ringing type speakers as one should be able to identify those.
After equalising them to the same target, let's see how they distinguish themselves. Can we really pick out our favourites after the first identifier is removed from the test (being the frequency response deviations).
You'd probably need to do it with Fir filters to counter the phase rotation of the EQ needed, bringing in new variables (possible pre-ringing), so it won't ever be an acceptable test for all.
A test like this would remove one aspect of difference to see if that difference is cause for preference.
I agree that the current discussion leads us nowhere.
"maybe" - take or make a good recording of speech with a good mix of consonants and vowels (could even be "whispered") - or if music preferred, perhaps some simple acoustic guitar - make sure the recording room and playback room are as free of noise as possible. Play back this recording at very low levels to the speaker recording it again. Upload the results to the internet to be examined with headphones by whomever interested to hear articulation. It might be unpleasant listening.
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Gmad has shown that with DSP and a convolver, the ringing in the RS100-4 can be eliminated and perfect Dirac pulse can be generated. It was the *best* looking impulse response I have seen anywhere - like textbook perfect.
Even better... we can include those in the test too!
That makes testing speakers with different cone material more fair.
I suspect it will be a lot harder to tell the drivers apart once you remove something as essential as frequency response. There will still be differences and it would be interesting to find out about preferences after removing the most obvious.
A BMR included in this test would be fun too!
Well, it's fun thinking about it but it would be very hard to actually run a test like this and get it accepted by all parties involved.
That makes testing speakers with different cone material more fair.
I suspect it will be a lot harder to tell the drivers apart once you remove something as essential as frequency response. There will still be differences and it would be interesting to find out about preferences after removing the most obvious.
A BMR included in this test would be fun too!
Well, it's fun thinking about it but it would be very hard to actually run a test like this and get it accepted by all parties involved.
Yes, who will do the test, which listening room? Etc. maybe all we can do is have a good stereo mic and record sound clips for all to listen to via headphones. Wonder if an instrumented mannequin head and torso are needed? If everything is DSP to a flat response and perfect inpulse, I would say that within the driver's dynamic and frequency range, the drivers would be indistinguishable. The CSD of drivers is an intrinsic property that is not the same and maybe very well trained ears can spot that.
Impuls respons, ringing, of amplifier used is also very much influenced by speakerload. PRV unit is hurt the most by this amplifier behavior, Vifa is hurt the least.
I am using DUG amp with 10uH coils and 0.68uF filter cap - I wonder if I switch to the TPA3116D2 with 22uH coils designed for 8ohms the ringing will be less? I think ringing is due to cone breakup and less to do with electrical oscillations or ringing.
Wow, I was actually thinking along the same lines (eq to level the playing field) before even seeing the last few posts here. I was even going to offer to generate the correction filters based on X's impulse responses. Remember though that my (almost) perfect IR was based on a measurement with the mic just 3" or so from the phase plug...
Gmad, If I was in X's shoes I would take you up on that offer if for nothing else than a learning experience. A stereo setup would be the most revealing though.
For Vifa unit it will be less, for PRV it might not make much difference. I don't know if speaker is far bigger factor than amp, could be, if you look at SE filtercalculator like (Sample)RLC Low-pass Filter Design Tool - Result - check little box for impulsrespons and for Vifa R at filterfrequency here in SE would be like 12 ohm, for PRV it would be 120 ohm. I think. Difference 0.05mH and 0.62mH mainly.
This is worth pursuing but I feel like it needs its own thread of a Howto do it with free software and tools in a step by step fashion. That would be great if you can start a new thread for this Gmad. I will implement the DSP convolver with your help. Can a netbook handle this processing?
Ok, let me think about it a bit. I don't want to derail this thread. You would have to do the listening from where the mic was positioned for the measurement or else I could provide weaker (less position dependent) filters. Convolution doesn't take much cpu power and my netbook has no problem with it. Also, I think listening to just one speaker is good for judging tone quality.
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Great that a netbook is sufficient. Yes, that is why I think this topic needs a new thread. I also think a lot of people would be very interested in getting their full range speaker to reproduce a perfect impulse which means a flat as a ruler FR. I think it would sound, for lack of better word, neutral - it doesn't add anything or take anything away from the music. That is in fact how a good amplifier should be - you should not hear any contribution of the amp if it's good. Please think about it - we would all be most thankful if you can guide the rest of us in thsi process.
Guys,
I applaud your noble intentions, and maybe it is a test that will once and for all show that frequency response is king. In fact, I know having experienced it first hand, that completely different speaker systems equalized to the same response and matched for level, sound indistinguishable from each other. Also, why would you expect that a music file convolved with a perfect impulse will show any changes at all?
This is a very complex undertaking with many variables and many questions that you will have to answer about the setup. Also, there are ways to cheat. The sound is processed somewhere in the computer and by taking a snapshot and doing analysis, one can differentiate one soundclip from another. Know that you will be criticized for every decision you make, from the choice of your amplifier to the choice of the room to the choice of the music.
If you are going to do it, I would suggest not flattening the drivers, but instead mounting them in some neutral cabinet and recording sound clips in a room and posting them without an identifier. And then ask people to pick their favorite sounding. This means there will be no cheating because the files are expected to be different, you just gotta pick a favorite. Maybe do two or three songs.
I applaud your noble intentions, and maybe it is a test that will once and for all show that frequency response is king. In fact, I know having experienced it first hand, that completely different speaker systems equalized to the same response and matched for level, sound indistinguishable from each other. Also, why would you expect that a music file convolved with a perfect impulse will show any changes at all?
This is a very complex undertaking with many variables and many questions that you will have to answer about the setup. Also, there are ways to cheat. The sound is processed somewhere in the computer and by taking a snapshot and doing analysis, one can differentiate one soundclip from another. Know that you will be criticized for every decision you make, from the choice of your amplifier to the choice of the room to the choice of the music.
If you are going to do it, I would suggest not flattening the drivers, but instead mounting them in some neutral cabinet and recording sound clips in a room and posting them without an identifier. And then ask people to pick their favorite sounding. This means there will be no cheating because the files are expected to be different, you just gotta pick a favorite. Maybe do two or three songs.
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