Gedlee on distortion

[philthien]

Re: Gedlee on distortion

I'm not even sure how to ask this question...

How superior are high $$$ drivers to lower-cost offerings, when it comes to distortion that we can really hear, that is offensive?

And...

When it comes to distortions that we find audibly unpleasant, are we talking about smaller woofers (for example) being drive to extremes? Or are these distortions equally obvious on larger woofers operating well below xmax?

I'm not sure I even know what I want to know. Ugh.

[winslow]

Re: Gedlee on distortion

The nonlinear distortion would be lowest in the larger woofers operating below xmax.

[Deward Hastings]

Re: Gedlee on distortion

product that is at best, mediocre

While I do agree that the SEOS horns improve on the Geddes designs (and don’t need the foam plug), there’s nothing wrong with the drivers Geddes uses (I haven’t examined his crossovers, but doubt that they are “mediocre”). I’m well impressed with the similar diysoundgroup speakers (for which Geddes paved the way years ago) and the surprisingly good Behringer ‑ B215XL for that matter. If what you’re looking for is HT and “rock” speakers there’s nothing “mediocre” about any of them.

Which has, of course, nothing to do either way with the correctness of his observations about the audibility of loudspeaker distortion . . .

[Jeff B.]

Re: Gedlee on distortion

The nonlinear distortion would be lowest in the larger woofers operating below xmax.

The most annoying nonlinear distortion is mostly caused by voice coil inductance and changes in inductance as the coil moves in the gap. This would apply to any driver that has not dealt with the inductance issue in the motor. It is probably the most noticeable in the upper midrange where we are the most sensitive to it. A large woofer operating below Xmax may still exhibit this distortion. This is why drivers with shorting rings and sleeves have so much lower distortion, because they significantly reduce the inductance in the coil. You are right though, as a driver reaches Xmax distortion will begin to rise quickly.

[dcibel]

Re: Gedlee on distortion

While I do agree that the SEOS horns improve on the Geddes designs (and don’t need the foam plug), there’s nothing wrong with the drivers Geddes uses (I haven’t examined his crossovers, but doubt that they are “mediocre”). I’m well impressed with the similar diysoundgroup speakers (for which Geddes paved the way years ago) and the surprisingly good Behringer ‑ B215XL for that matter. If what you’re looking for is HT and “rock” speakers there’s nothing “mediocre” about any of them.

Which has, of course, nothing to do either way with the correctness of his observations about the audibility of loudspeaker distortion . . .

I can't speak for the sound of Geddes speakers, but he did help the DIY community to better understand horns and waveguides which shouldn't be dismissed. I've learned a lot from his posts though they can be a bit blunt.

Speaking of SEOS, my SEOS speaker is one of the best I've heard. Immense clarity and dynamic capability from the DE250.

[dcibel]

Re: Gedlee on distortion

The most annoying nonlinear distortion is mostly caused by voice coil inductance and changes in inductance as the coil moves in the gap. This would apply to any driver that has not dealt with the inductance issue in the motor. It is probably the most noticeable in the upper midrange where we are the most sensitive to it. A large woofer operating below Xmax may still exhibit this distortion. This is why drivers with shorting rings and sleeves have so much lower distortion, because they significantly reduce the inductance in the coil. You are right though, as a driver reaches Xmax distortion will begin to rise quickly.

All the better reason to chose an underhung midrange driver. ;)

[Pete Schumacher]

Re: Gedlee on distortion

While I do agree that the SEOS horns improve on the Geddes designs (and don’t need the foam plug), there’s nothing wrong with the drivers Geddes uses (I haven’t examined his crossovers, but doubt that they are “mediocre”). I’m well impressed with the similar diysoundgroup speakers (for which Geddes paved the way years ago) and the surprisingly good Behringer ‑ B215XL for that matter. If what you’re looking for is HT and “rock” speakers there’s nothing “mediocre” about any of them.

Which has, of course, nothing to do either way with the correctness of his observations about the audibility of loudspeaker distortion . . .

Deward, I'm talking about the sound, not the design or principles around them. I've heard them and they really are nothing special, a sentiment echoed by another in the thread who actually built them as well. And while I'm sure they can "rock" they will still sound mediocre doing so to very high SPL. I would much rather listen to a Jeff Bagby design than to a pair of GedLee speakers. Jeff's stuff just sounds better. It is probably because while both designs exhibit low THD, Jeff's stuff has less linear distortion. His "voicing" is superior to Geddes. It goes back to what another poster stated when he questioned not only Pallas's ears, but Geddes's as well.

[Pete Basel]

Re: Gedlee on distortion

I can't speak for the sound of Geddes speakers, but he did help the DIY community to better understand horns and waveguides which shouldn't be dismissed. I've learned a lot from his posts though they can be a bit blunt.

Speaking of SEOS, my SEOS speaker is one of the best I've heard. Immense clarity and dynamic capability from the DE250.

Which SEOS exactly, and one of the best waveguide based speakers or of all speakers? Just trying to
clearly understand your position.

[dcibel]

Re: Gedlee on distortion

Which SEOS exactly, and one of the best waveguide based speakers or of all speakers? Just trying to
clearly understand your position.

It's a SEOS 12 using B&C DE250 with a rebuilt ATC 12" woofer. Crossover is my own design around 1200Hz. And I mean one of the best speakers of all the speakers I've heard, something about the midrange is "just right" in this one.

[DDF]

Re: Gedlee on distortion

Just a personal data point, Arnie Kruger used to have a good demo of distortion using several tracks, and from this trial, I found 2nd order just as objectionable (at same percentage) as third and even 4th order. I was somewhat surprised by this but it settled in my mind at least that there is nothing euphonic about 2nd order distortion, unless perhaps its isolated to the low or mid bass range.

[Pete Basel]

Re: Gedlee on distortion

It's a SEOS 12 using B&C DE250 with a rebuilt ATC 12" woofer. Crossover is my own design around 1200Hz. And I mean one of the best speakers of all the speakers I've heard, something about the midrange is "just right" in this one.

Thanks, interesting.

[andy19191]

Re: Gedlee on distortion

It is good to see the thread has recovered to some extent.

Would that it were that simple, but it's not. Read what Geddes and Toole have written . . .

I have read Toole's book and don't recall distortion being discussed. I have read some of Geddes' posts and even responded to a few, looked at his speaker design and discussion of some of his manufacturing methods. It has not prompted me to read his writings.

"1% THD" could mean 1% 2nd or 1% 5th . . . you won't hear the former and will hate the latter.

Since you already have information about the intrusiveness of the sound from the set of distortion components why do you need a single summary value?

There are enough different ways even to measure IMD that whether any of them are "precise" or not they tell us little about what they mean to perceived "sound" (especially when applied to loudspeaker drivers).

The range of ways of measuring IMD is good not bad. It allows an engineer to focus in more detail on what he wants to know. To take a step further, quite a few in the industry have invested large sums in Klippel distortion hardware to measure distortion in even more detail. It doesn't contain a subjective nastiness summary value so have they squandered their money?

There are very good psychoacoustic reasons to apply "weighting curves" to distortion measurements (and to not get particularly exercised about things which we can't hear).

If they are very good why are there so many of them?

There is no single summary number for the effects of non-linearities whether subjective nastiness or more objective measures. The nature of non-linear as opposed to linear is that small things can have large effects (e.g. if a butterfly flaps it wings...). A single summary value that is not very strongly bounded in it's applicability will inevitably be unreliable.

Consider some of the nasty sounds from non-linearities when listening to music such as coil rubbing, drop outs, clicks on records,... which are more of a sequence of discrete events rather than continuous. Measures based on averaging like components of harmonic distortion can be applied but they are not a sensible. For example, if you halve the number of clicks the measure will halve but the intrusiveness of the clicks won't halve. By increasing the time between audible clicks you can push the averaged value below any threshold.

OK so one could try to build a measure that lumps the intrusiveness of the clicks together with the intrusiveness of the continuous non-linearities from the driver and cabinet but it isn't going to be reliable. In exactly the same way as those weightings are not a reliable measure of the intrusiveness of sound. They help a bit but not particularly consistently.

What we have got at present works well so long as the reader understands what is and is not included in the measure. Wishing for a single summary intrusiveness measurement is all well and good but you are not going to get even a semi-reliable one unless it is strongly bounded by the types of sounds it can be applied to. And dismissing what we have now because this mythical measure doesn't exist is just daft.

[JRT]

Re: Gedlee on distortion

Just a personal data point, Arnie Kruger used to have a good demo of distortion using several tracks, and from this trial, I found 2nd order just as objectionable (at same percentage) as third and even 4th order. I was somewhat surprised by this but it settled in my mind at least that there is nothing euphonic about 2nd order distortion, unless perhaps its isolated to the low or mid bass range.

An extreme example might exist in comparing harmonic overtones of soprano saxophone and clarinet, both similar in size but different in shape resulting in different harmonic overtone spectra, producing very different tonal qualities on the same musical notes. The clarinet approximates a closed end tubular instrument with mostly odd order harmonics, very low levels of even order harmonics. The saxophone approximates a truncated conical instrument with mouthpiece near the apex, and exhibits 2nd order harmonics near equivalent in level to the fundamental, and 4th order harmonics not far down from the 3rd order harmonics, etc.

http://www.phy.mtu.edu/~suits/conecyl.html

http://www.phy.mtu.edu/~suits/clarinet.html

http://www.phy.mtu.edu/~suits/sax_sounds/index.html

[fpitas]

Re: Gedlee on distortion

I'm not even sure how to ask this question...

How superior are high $$$ drivers to lower-cost offerings, when it comes to distortion that we can really hear, that is offensive?

And...

When it comes to distortions that we find audibly unpleasant, are we talking about smaller woofers (for example) being drive to extremes? Or are these distortions equally obvious on larger woofers operating well below xmax?

I'm not sure I even know what I want to know. Ugh.

This won't directly answer your question, but will give you an idea about the measurable differences:

http://www.linkwitzlab.com/mid_dist.htm

http://www.linkwitzlab.com/frontiers.htm#G

In the second link, note Linkwitz's comment, It seemed, that coming out of the loudspeaker a sound carried a comet like trail of newly created sounds with it, that formed a continuum of background sounds, which was completely absent from the live instruments and made the speaker immediately recognizable as such.

My personal observation is that low-distortion drivers allow me to hear better separation of instruments, voices etc., probably because there's less intermodulation. I've also heard the "newly created sounds" that Linkwitz describes, which to my ears are like a wall of fuzzy, ill-defined sound. That's especially true at higher SPLs. When there are many different tones present, the intermodulation products can become quite substantial.

[Deward Hastings]

Re: Gedlee on distortion

Since you already have information about the intrusiveness of the sound from the set of distortion components why do you need a single summary value?

I don't. In fact I agree with Geddes that THD is an essentially worthless number (unless it's very high or very low). At very least any composite distortion number has to be weighted for masking.

quite a few in the industry have invested large sums in Klippel distortion hardware to measure distortion in even more detail. It doesn't contain a subjective nastiness summary value so have they squandered their money?

Anyone who buys a Klippel test station thinking they are buying a distortion analyzer is . . . misguided. Klippel measures specific device properties.

There is no single summary number for the effects of non-linearities whether subjective nastiness or more objective measures.

That is correct (and what Geddes says).

The nature of non-linear as opposed to linear is that small things can have large effects (e.g. if a butterfly flaps it wings...).

That is incorrect. As non-linear distortion tends toward "small" it tends toward inaudible. We do not hear butterfly wings flapping (bird wings yes, butterfly wings no).

What we have got at present works well so long as the reader understands what is and is not included in the measure.

Most don't. It appears that you don't.