I think I get your question now:
The more demodulation (ie shorting rings) the lower and more stable Le(t,i) and the lower motor distortion we get.
Higher BL means that less current is needed for the same spl which also may reduce the current dependent Le distortion.
But these two mechanisms kind of lift all the boats in the harbour.
the force to sound transfer having peaks from high Q break up adds on top and the high impedance notch trick still works.
Our blog post uses a driver with very low motor distortion to begin with and the distortion is down quite close to the noise floor. but yet the notch filters effect can still be measured.
I hope I covered your question. otherwise ping me again please😀
The more demodulation (ie shorting rings) the lower and more stable Le(t,i) and the lower motor distortion we get.
Higher BL means that less current is needed for the same spl which also may reduce the current dependent Le distortion.
But these two mechanisms kind of lift all the boats in the harbour.
the force to sound transfer having peaks from high Q break up adds on top and the high impedance notch trick still works.
Our blog post uses a driver with very low motor distortion to begin with and the distortion is down quite close to the noise floor. but yet the notch filters effect can still be measured.
I hope I covered your question. otherwise ping me again please😀
What I am asking if the notch trick would work less (or not at all) when a driver doesn't have such a low Le and high BL?
Or could it also be a matter of how distortion elements works in the entire motor system, similar like Eddy currents in like the voice coil former.
Because instead of using a series notch, the distortion would totally disappear in CC amplifier as well.
Which remind me of this research paper;
https://acoustics.ippt.pan.pl/index.php/aa/article/download/1780/pdf_255
(Comparative Measurements on Loudspeaker Distortion: Current vs. Voltage Control)
In certain cases all harmonics, incl cone resonances, disappear, while in others this effect is a lot less significant.
Which therefor automatically means and suggests that the effect of the notch trick would not always be equally effective.
Depending on the type of speaker we are using.
I'm using simle normal DBA https://www.diyaudio.com/community/threads/my-double-bass-array-with-low-q-subs.392998/; none of the EQs was hurt
Thx for link
Does that include using peak eq on the rears to tailor the response?
Isn't "simple normal" having all speakers in phase at the listening point where as you use your rears to cancel the impulse as it comes from the front?
Nope.
Rears are delayed (delay=room lenght) and slightly attenuated, thats all in my case now. See DBA treads
I am aware, but that wasn't really what I was asking?
What I am trying to find, if this solution would be effective in general. For all kinds of woofers, or if there are certain situations where the distortion of breakup peak can't be corrected?
Most important is why and how to determine that beforehand.
Because again, I think I have seen otherwise in the past with certain drivers.
Again it looks extremely promising, but thus far I haven't seen any comprehensive research, testing and fundamental explanation on this.
Doesn't mean it's not true, but to be able to give a general answer more is needed.
The data that has been shown so far looks very exciting, but is just to small to make any general objective conclusions just yet.
please don’t confuse distortion generated by the break up peak and distortion amplifiers by the break up peak. The otter is affected by the electrical drive whereas the former is not.
I can’t help with your belief or need for further evidence but if you have conflicting data points it is of course very interesting.
I can’t help with your belief or need for further evidence but if you have conflicting data points it is of course very interesting.
Belief? We are not talking about believing here? lol
It's not that I am against the whole idea, in fact the contrary.
I think it's a very solid idea.
Again, it looks super promising, but just a single blog post about one specific driver and a FB post can't be seen as evidence either.
I would just like to keep it objective and scientific.
If one makes claims, he also has the obligation to try to disprove that claim.
That doesn't mean the idea is untrue, but it most definitely can't be seen as proper evidence just YET.
The dataset is way to small, limited and (unintentionally) biased for that. (potentially)
I am confusing your system with this one ->https://www.diyaudio.com/community/threads/double-bass-array.401001/Rears are delayed (delay=room length) and slightly attenuated, thats all in my case now. See DBA treads
Attachments
I am confused. If someone does an alternative approach to response peak reduction and observes a reduction in distortion and explains in detail what he did, including the difference relative to the usual approach, why is that not evidence?
A simple mathemaitical driver model explains the mechanism we discuss. The effect is simply predicted from a model based on first principles. We realised this and then made the experiment to verify it. This is science and not like medicine where you test drugs using RCT's. We dont do RCTs to see if Ohms Law works.
The simple driver model is that for voltage drive then modulation of Le results in a modulation of the current. Force is then current times Bl. That means that distoriton of the current is reflected to the driving force. Driving the system with a sine (fundamental) results in harmonics and if a notch filter increases the driver circuit impedance at a harmonic frequency then the harmonic component related to the inductance modulation is reduced. The effect we discuss is simply expected from a simple model based on first principles'. If an experiment does not comply then it is far more likely that the experiment setup was messed up rather than the theory being wrong.
I suppose even the current generated by forces on the coil caused by the breakup modes will lead to additional distortion.
@lrisbo why did you pick a passive 2nd order crossover in your experiment? Would a 1st order or 3rd order passive crossover have shown the same outcome? To me the parallel cap plays a role in this.
This assumes the theory is not wrong or flawed.
Either way, experimenting also implies checking whether the experiment is executed correctly, including of course the conclusion drawn.
Also as it is not possible to isolate a phenomenon completely from its context, have an open eye for the impact of the direct context.
Either way, experimenting also implies checking whether the experiment is executed correctly, including of course the conclusion drawn.
Also as it is not possible to isolate a phenomenon completely from its context, have an open eye for the impact of the direct context.
Used alone, a second order filter tends to present a higher source impedance to the driver than first order through the passband and typically part-way into the stopband.
I am confused why it keeps staying this vague, but anyway.
Everyone with a scientific background knows that saying that a certain hypothesis is true because of the theoretical model is solid, is not performing great science.
That is NOT because the model and the outcomes of it are being doubted.
As I mentioned before, it looks super promising and solid.
It's because plenty of other (maybe) unforeseen side effects or variables can be at play.
Or in other words, things that all of a sudden are NOT expected from the theoretical models and first principles.
(a very classic example of this, Rutherford's gold foil experiment).
This doesn't have anything to do with research in medicines or RCT's.
It's valid for ALL science.
Sometimes those effects are very unlikely that is true, but by the laws of science they have to be ruled out nevertheless.
Btw, I don't understand why you mentioned RCT's, because there isn't much randomness involved here?
Just a few different configurations.
To quote yourself even;
So apparently there are more things needed to make a general statement.
It makes one wonder where the ins- and outs are?
- So why is it not working for tweeters?
Since that is literally also just another break-up resonance reflected back.
It follows the same driver model like you mentioned before.
Except the suspension is quite different.
(well and the acoustic model and behavior, but that is not something we have to worry about for this)
- Because of the previous, does the coil former has an effect?
- Is it working for ALL woofers with a break-up resonance? (followed up by the previous again)
If you search the forum and internet, people's past (years of) experiences seem to be different.
Incl some very respected people in audio.
Maybe they could be totally wrong, but to be objectively solid this must verified (and debunked) at least.
- Is the Le of importance, since it can potentially absorb the same thing?
According to the same models, I can totally see that this notch thing mostly works when there is plenty of demodulation.
Aka, Le is practically totally bypassed. But any information about the nuances is missing at this point.
Lastly, you say that the practical results of your blog post are evident.
It looks very promising, but the results itself are hard to read since they almost disappear on the bottom of the graph.
It also doesn't show other variables, like a driver with a much higher Le for example.
It's also hard to judge because a 2nd order lowpass was used at the same time.
Granted, it's not likely that this will have an effect on the results, but one must rule this out to make the results transparent.
But most importantly, one swallow does not make a summer.
I have an hard time to see why an experiment wouldn't comply?
It's nothing more than just adding a notch filter in series (and maybe scale the results accordingly)
Which brings up also so many more questions.
If we look at the results from the Dayton woofer, we see A LOT more happening in the distortion graph.
Where is all of that coming from?
Once again, this is not about believing in anything.
It's about staying skeptical on an healthy way to make sure that certain claims are objectivity true.
At this moment I see it as very promising and solid preliminary investigation, but there are to many open ends to close the entire loop.
Unfortunately it seems that we only will stay in theoretical loops.
Which is very unfortunate, because at this moment practical results say a lot more than just words.
There is no doubt about the words, there never was to begin with.
Thank you!
I forgot to add this, but yes this is very true!
Even totally unintentionally, we are all human beings and a small mistake or oversight can be made very easily.
Even by experts that have been around for decades.
True. But this is largely stop-band territory, as far as the Purifi blog is concerned. What makes me wonder whether this all is relevant or completely academic. Hence my question.