Hello !
i have noticed that in drivers datasheets almost never distortion figures are reported. 🙄
Is this a useless information ? 🙁
This is for me even shocking ... because i am convinced the low distortion must be always the final goal in a speaker.
Maybe we will see a day when in the datasheets there will be no more figures but only the listening impressions of some audio guru ? 😛
Thanks a lot and kind regards,
gino 😀
i have noticed that in drivers datasheets almost never distortion figures are reported. 🙄
Is this a useless information ? 🙁
This is for me even shocking ... because i am convinced the low distortion must be always the final goal in a speaker.
Maybe we will see a day when in the datasheets there will be no more figures but only the listening impressions of some audio guru ? 😛
Thanks a lot and kind regards,
gino 😀
Because they are advertising! Most people would not know how to interpret the charts. Same with measurements of stored energy. We must do these things ourselves. They are only revel ant if done exactly the same way.
Thanks a lot for the very valuable and "sad" reply, because i do not have the needed set-up to perform these distortion tests.
Maybe i am romantic but i think that distortion measurements can be extremely telling.
For instance, I was amazed to see on a scope the IMD of a mid woofer with two signals test, one of 50 Hz and another one of 300Hz ... some very high peaks in between were evident.
In a very highly praised loudspeaker someone was criticized for mentioning a little weak deep bass.
A distortion measurement showed that actually there was no deep bass at all !!!
Thanks a lot. Kind regards,
gino
Maybe i am romantic but i think that distortion measurements can be extremely telling.
For instance, I was amazed to see on a scope the IMD of a mid woofer with two signals test, one of 50 Hz and another one of 300Hz ... some very high peaks in between were evident.
In a very highly praised loudspeaker someone was criticized for mentioning a little weak deep bass.
A distortion measurement showed that actually there was no deep bass at all !!!
Thanks a lot. Kind regards,
gino
The driver distortion might not be a useful figure, as the actual behaviour would depend on the enclosure. Would you want BJT datasheets to give the distortion produced by a bare BJT in a test fixture? That would put some people right off SS amplifiers.
Hello you are right ! The enclosure matters.
But also other parameters like Qts or freq response are affected by the enclosure and still they are stated.
Moreover if a driver has already a high distortion could an enclosure cure that ? i do not think so.
Thanks and regards,
bg
But also other parameters like Qts or freq response are affected by the enclosure and still they are stated.
Moreover if a driver has already a high distortion could an enclosure cure that ? i do not think so.
Thanks and regards,
bg
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Parameters like resonance Q need to be known in order to design the enclosure.
Driver distortion can be caused by many things, some of which will be modified by the enclosure. The most obvious one is the 'spring' resistance to movement - partly the driver suspension, partly the air in the enclosure. A driver intended for an infinite baffle would rely quite heavily on the air as the major restoring force, so any distortion figure for the driver on its own would be almost meaningless.
Having said that, I am not a speaker expert; I just know enough to know how little I know!
Driver distortion can be caused by many things, some of which will be modified by the enclosure. The most obvious one is the 'spring' resistance to movement - partly the driver suspension, partly the air in the enclosure. A driver intended for an infinite baffle would rely quite heavily on the air as the major restoring force, so any distortion figure for the driver on its own would be almost meaningless.
Having said that, I am not a speaker expert; I just know enough to know how little I know!
Beyma and BMS are notable exeptions, they publish distortion vs frequency diagrams for all their drivers. Low frequency distortion do depend on the type of the box.
Not the equipment? Well, yo only need the same equipment we need to build a speaker. If you are not building a speaker, it is a moot point anyway. Mic, preamp, HOLM, ARTA, TrueRTA, SoundEasy etc.
Eton and Usher also provide distortion measurements and SEAS used to on their Excel line. I more get the impression that SEAS did this because they wanted to show off how low the distortion actually was.
Yes the enclosure can affect the distortion performance of a driver. This is especially true around the tuning of the enclosure. Also if the driver has a very thin cone, or a basket that compromises air flow, often measures have to be taken to ensure that reflections don't mar the results and that enough breathing room is provided around the drivers rear so as to not affect things in a negative way.
That said most manufactures produce their measurements with their drivers flush mounted on a very large open baffle. This is a perfect environment for performing a distortion measurement as it's pretty much the best way to show off what a driver can, or cannot, do.
I think most manufactures neglect to provide distortion performance because if they did it would really set the men from the boys. For example SEAS produce a number of 6" drive units in their prestige range, all tend to do pretty much the same thing, but a couple of them are significantly more linear. If the designer knew how to interpret the data correctly then no one would ever buy the poorer performing drivers. Which really, is as it should be, why would you spend money on something that isn't as good?
Energy storage is just another way of displaying resonances and these show up in the frequency response anyway.
Yes the enclosure can affect the distortion performance of a driver. This is especially true around the tuning of the enclosure. Also if the driver has a very thin cone, or a basket that compromises air flow, often measures have to be taken to ensure that reflections don't mar the results and that enough breathing room is provided around the drivers rear so as to not affect things in a negative way.
That said most manufactures produce their measurements with their drivers flush mounted on a very large open baffle. This is a perfect environment for performing a distortion measurement as it's pretty much the best way to show off what a driver can, or cannot, do.
I think most manufactures neglect to provide distortion performance because if they did it would really set the men from the boys. For example SEAS produce a number of 6" drive units in their prestige range, all tend to do pretty much the same thing, but a couple of them are significantly more linear. If the designer knew how to interpret the data correctly then no one would ever buy the poorer performing drivers. Which really, is as it should be, why would you spend money on something that isn't as good?
Energy storage is just another way of displaying resonances and these show up in the frequency response anyway.
Distortion in the sense that anything that comes out that doesn't go in is important.
Distortion as it is typically measured is of questionable merit. Geddes has done scientifically valid studies that show that it needs be VERY high to even be noticed. Geddes went from very concerned about measured distortion, to saying it is no never mind.
As well the measured distortion of a loudspeaker cannot be divorced from the amplifier that is used to drive it. There has been at least one study where "highish measured" distortion SE Amp+loudspeaker produced lower measured distortion than "very low measured" distortion amp + same speaker.
Further there are no industry standards for how distortion in a speaker is measured.
The net is that worrying much about distortion specs is like trying to push something using a piece of cooked spagetti.
dave
Thank you very much indeed for your very valuable reply.
This was my point. Low distortion is so important that Seas considers this something to show off also to justify a higher price tag.
Low distortion IS the thing. I am sure of this.
I do not know the conditions of measurements anyway.
I agree even more and still ... tell me how many measurements you see around on finished loudspeakers ... almost no one ... not one 😱😕🙁
This is insane ...
This simply explains it all. I agree completely again.
And one time i wonder why a so important aspect of a speaker is so neglected.
One last case ... the mighty classic Infinity IRS ...
The EMIM crossed too low tended to distort ... a simple IMD measurement would have shown this clearly ... unbelievable 😉
Thanks again and kind regards,
gino
As a general rule, distortion is inversely proportional to efficiency. This allows one to narrow the field considerably when choosing drivers.
Hi and thanks for the kind and valuable reply
This is very interesting. Of course i agree that the we should take into consideration the amp+speakers system.
By the way I have seen Mr Geddes creations ... i think they belong to the low distortion family, maybe i am wrong.
Actually your words explain very clearly why this kind of measurement is very uncommon. Maybe they are of no practical use.
Thanks a lot again
Kind regards,
gino
Thanks a lot for this ! i did not know
So the higher the driver efficiency the lower the distortion ?
This sounds extremely important to me.
And justifies the HE choice quite easily.
Kind regards,
gino
Not general enuff for my liking. Take the Eminence alpha 15 or Silver Iris 15 as examples. I don't know how they measure, but they are high distortion & high efficiency.
dave
Hello ... i am about to give up forever.
What does Mr Geddes care about then ? listened distortion ?
I tried to get info but is his site down ?
Perception
at least superficially the speakers do not look out of this world.
I see a pad placed on the tweeter horn and that is indeed original.
I do not nothing about filters ...
And above all i have never listened to them.
I guess they are a reference product because i heard of him.
Just to provoke some discussion are they so much better than this one for instance ?
Last question ... is Mr Geddes the only one who got it right ?
in this case i will focus completely on his work without wasting time around. Straight to the truth.
Kind regards,
gino
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Given how poor even the best loudspeakers are (10-15% of potential?), there are lots of ways to juggle the compromises and get what is considered a very good loudspeaker given current technology. And a loudpeaker cannot be judged outside of the amps driving them or the room they ar ein.
dave
He does not care about "measured" distortion since he has shown scientifically it is meaningless. That does not say that distortion in the broad sense is not important.
dave
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