Eton 7-375 "new low distortion motor"

[Jed]

Since it has been well documented that the eton range of drivers have excellent cones but average motors, I was intrigued when I read about the "new" 7-375 driver with aluminum dust cap and low distortion motor. Does anyone have any experience with this driver and how does the actual distortion measure up? Any sources for real measurments?

[JonMarsh]

It better be "killer" for 179 Euros! :B

Published specs on their web site look pretty good, though not "killer", as K3 is in 0.5% range by 2 kHz, and is in 0.4% range around 500 Hz. Still, an improvement compared with the 7-370. Linear Xmax of 4 mm doesn't make me swoon, though.

Overall, the spec sheets are more detailed than before, which is good.

[TacoD]

Avalon uses it in one of their budget models. Relative low distortion, but limitted low x-max. This driver is not new at all, HobbyHifi tested this driver some years ago.

[JonMarsh]

Thanks, Taco!

~Jon

[TacoD]

IIRC from the distortion tests in the german magazin Hobby Hifi (2002) the Eton performed not as good as the Seas Excel W18E (in the same test). Unfortunately I do not have the magazine at hand.

[FrancoB]

Jon does! :P

[JonMarsh]

I'll have to look that up in the stack! :B

But right now, I'm working on a tech paper for the day job... :roll:

[Jed]

I'll have to look that up in the stack! :B

But right now, I'm working on a tech paper for the day job... :roll:

Don't worry about it Jon. I was a bit obsessive and downloaded a bunch of Klang and Ton magazines last night. I happened to come across a test from 2005 of the 7-375. Not state of the art, but one thing I noticed was when distortion appeared in the driver test it disappeared or was greatly decreased with a crossover network in place. A good example of this is the Eton 5-880, and 8-800 in the Minuetta speaker. 3rd order distortion at 1K-3K is reduced to .3% from 1% when implemented in the system. I bet the same would be true for the 7-375 with a crossover point around 1.8K or 2k.

[TacoD]

Every driver has lower distortion when filtered correctly in the passband.

[Jed]

Every driver has lower distortion when filtered correctly in the passband.

Why the obsession with distortion across the entire FR? (pardon my ignorance on this subject- still learning).

[TacoD]

No it is not an obsession. I just want to comment that when the drivers are used in a limited FR range, especially away from cone modes and too low frequencies, the drivers show better performance compared to 'unfiltered' response. That's why high passing an 18 cm midbas in an 3way concept does a better job in the midrange when compared too a 2-way concept with the same driver.

[Jim Holtz]

Not state of the art, but one thing I noticed was when distortion appeared in the driver test it disappeared or was greatly decreased with a crossover network in place. A good example of this is the Eton 5-880, and 8-800 in the Minuetta speaker. 3rd order distortion at 1K-3K is reduced to .3% from 1% when implemented in the system.

Isn't this exactly what John K. has been saying for some time? I won't try to quote his exact comments but basically, he questioned the value of using distortion tests like SL has promoted stating that a crossover network changes everything so it was only a piece of the puzzle.

Perhaps Jon can comment on this. The tests certainly seem to validate his position.

Jim

[jkrutke]

Isn't this exactly what John K. has been saying for some time? I won't try to quote his exact comments but basically, he questioned the value of using distortion tests like SL has promoted stating that a crossover network changes everything so it was only a piece of the puzzle.

John Kreskovsky might have said that, but I just wanted to make sure everyone knows that I'm not "John K". Mainly because I partially disagree with that statement.

I think it's best to look at distortion both full range and after the filter. Looking at it full range helps you decide on a crossover point and topology, and looking at it with the filter in place confirms that it does work as intended.

In the attachments below, looking at the "before" plot told me that yes, the XT25 can work fine crossed over LR4 at 2kHz. The "after" filter plot confirmed it, but also told me I better use a conjugate notch filter. Once more with the notch (not shown) got rid of the shelved 2nd order distortion.

All that said, people don't need to do distortion plots, it just helps to minimize the tweaking as a designer struggles to figure out why a system doesn't sound good.

John

[jkrutke]

All that said, people don't need to do distortion plots, it just helps to minimize the tweaking as a designer struggles to figure out why a system doesn't sound good.

Ps. Those XT25 plots above come after about 2 years worth of listening to designers say the XT25 needs to cross over at 3kHz or higher. A pet peave of mine is designers pushing out poor designs and then blaming the failure on the drivers.

One more thing, sort of on-topic. I just tested the Eton 5-880 and it was really nothing special. Not bad, but there's certainly better drivers out there. Good motor design does not seem to be an Eton specialty.

[tktran]

"The XT25 can work fine crossed over LR4 at 2kHz."

Hi John,

Just to clarify, when you say this, do you mean the targetted acoustic response, or (electrical) order of the filter?

If it's acoustic, then shouldn't we be describing the filter instead? After all, it's the one responsible for the attenuation and reducing the non-linear distortion.

regards,
Thanh.

[Jim Holtz]

John Kreskovsky might have said that, but I just wanted to make sure everyone knows that I'm not "John K". Mainly because I partially disagree with that statement.

I think it's best to look at distortion both full range and after the filter. Looking at it full range helps you decide on a crossover point and topology, and looking at it with the filter in place confirms that it does work as intended.

In the attachments below, looking at the "before" plot told me that yes, the XT25 can work fine crossed over LR4 at 2kHz. The "after" filter plot confirmed it, but also told me I better use a conjugate notch filter. Once more with the notch (not shown) got rid of the shelved 2nd order distortion.

All that said, people don't need to do distortion plots, it just helps to minimize the tweaking as a designer struggles to figure out why a system doesn't sound good.

John

Hi John,

Thanks for responding. Also, thanks for the great driver testing. I've already spent a good deal of time going through your results. Good stuff!

Back on topic. Your results seem to validate John K.'s position. It strikes me that even though distortion is reduced once the crossover is in place, if you start with a very low distortion driver, the resulting distortion with the crossover in place will be even lower, which of course is better.

Could you clarify something for me? Most of the drivers have distortion levels in the -50 range or lower. What does that convert to in percentage of distortion or is that not a valid way of stating it?

Thanks!

Jim

[Jed]

Most of the drivers have distortion levels in the -50 range or lower. What does that convert to in percentage of distortion or is that not a valid way of stating it?

Thanks!

Jim

-10 = 30%
-20= 20%
-30= 3%
-40= 1%
-50= 0.3%
-60= 0.1%


Also, your assertion that starting with a low distortion driver across it's FR will result in even lower distortion with crossover sounds good to me, but take for example a ribbon tweeter (hehe), and without a crossover the distortion without crossover makes the driver look well- VERY bad because of resonance peaks and such- but crossed over steep enough and high enough and you get low distortion in a frequency area that was previously thought to be useable. Not stating this as a uinversal fact- just more of an analogy.

Jed

[Jed]

One more thing, sort of on-topic. I just tested the Eton 5-880 and it was really nothing special. Not bad, but there's certainly better drivers out there. Good motor design does not seem to be an Eton specialty.

Etons sound good to me when played at lower levels. The 7-375 is one of the few etons where it looks like they have implemented a new motor and vented basket similar to what SEAS does with their drivers. $158 though.

[Jim Holtz]

Oh no!!!

-10 = 30%
-20= 20%
-30= 3%
-40= 1%
-50= 0.3%
-60= 0.1%


Also, your assertion that starting with a low distortion driver across it's FR will result in even lower distortion with crossover sounds good to me, but take for example a ribbon tweeter (hehe), and without a crossover the distortion without crossover makes the driver look well- VERY bad because of resonance peaks and such- but crossed over steep enough and high enough and you get low distortion in a frequency area that was previously thought to be useable. Not stating this as a uinversal fact- just more of an analogy.

Jed

Jed,

You're just trying to stir it up with the ribbon comment. :rofl:

Actually, this is one of my quandaries. I follow the distortion tests closely. They just make sense to me. BUT, I have 16 Fountek JP2 ribbons in my Omegarrays and 1/2 dozen of the best domes according to the distortion tests in house. We are extremely fortunate to have such talented and passionate speaker designers that create great sounding DIY designs that are free to build. I honestly feel that every one of the speaker designs I've built excel in their respective class.

Now, guess what. With all of those ultra low distortion domes I have to listen to, the ribbons sound the most like a live performance. My line arrays take me closer to a live performance than any other design, di-pole, sealed box, ported box, you name it. The arrays take me to the performance. Period! :T

If the darn ribbons didn't sound good, I'd say so, but they do, in spite of what the measurements say. I'd like to understand why and get an explanation that goes beyond measurements only. There has to be something we're missing.

My $.02 worth

Jim

[cotdt]

Jim, but Zaph's ribbon measurements show that ribbons do indeed perform very well as you go up in frequency. Amongst the better tweeters (domes, ribbons, etc.), the only audible difference to my ears is the top octave (subjectively 8kHz+), and this is where ribbons perform very well in the distortion tests.

the distortion tests are better suited as diagnoses rather than absolute performance. my reasoning is that 5% nonlinear distortion is inaudible in blind tests i've done on myself (the literature value is 3%), and today we have tweeters and woofers that have 0.1% distortion in the entire passband. However, I do notice that lower odd-order distortion drivers tend to sound more resolving (more "detailed"). Apparently, lower distortion means better motor design, it's like a trend, a diagnostic.

[tktran]

If the darn ribbons didn't sound good, I'd say so, but they do, in spite of what the measurements say.

Jim,

John's distortion test won't tell us which drivers will sound "good" or "bad"

IMHO these measurements are most useful to the speaker designer, and gives another insight into better or more ideal crossover and box implementations.

There's no reason why a driver with moderate amounts of harmonic distortion can't sound superb. In fact, I was not be surprised that the favourites (eg. OW1, Millennium) are NOT amongst the ones with the lowest distortion. Bear with me...

When I look at John Krutke's harmonic distortion tests, I look at the fundamental sweep as the "flat" frequency response.
Now I look at all the other curves down below, and consider them not as harmonic distortion=bad, but as harmonics= "extra sounds"

Why? Because in a group of 10 or 20, it's very hard to find a "best" driver or "X is definitely better than Y". Because they ALL have non-linear distortions. Different levels, different harmonics, in all different places (ie. it's a ragged mountain where K2, K3, K4 and K5 go up and down and all over the place. From the "spectrum" or picture it's never really clear which is the one with the lowest non-linear distortion overall. If you take any driver A and B, are all of the 2nd, 3rd, 4th AND 5th harmonics lower throughout the entire desired passband? 95% of the time it's not clear, because all the curves fluctuate.

I still believe that the driver with the flattest in-box frequency response, and the lowest post-filtered harmonic distortions are the most faithful to the original electrical signals. Furthermore, the drivers with modest 2nd order, but the lowest odd and higher ordered (non musically related) distortions may be the most musical pleasing to listen to.
"It just sounds more musical"

So yes, it depends on what we want. Closer to the input signal? YES, that's desirable, but not the only thing, or even a necessary thing to give us the illusion of the real thing.

Which, as music nuts, is ultimately what we want.

How often does non-linear distortion manifest as
"Ow! Now I can hear that definitely distorting" Probably only during a test signal, when we know we're supposed to a hear a single 250Hz sine tone, pure, loud and clear.

With complex musical signals, the added harmonics may be masked. We might not hear them as obvious distortion, but instead as subtle added sounds.
Micro-detailing, richness, naturalness, or the Real Thing(tm) are words that come to mind. After all, don't real instruments have all kinds and levels of harmonics?
When a musical instrument creates harmonics we call it timbre, but when a driver creates harmonics we jump up and down and call it distortion...

Your puzzle about line arrays... I go to live musical events regularly. I'm sure you'll agree that 10 violins sound better than 1, or 3 of the same guitars sounds better than 1, With all the different musicians, they all have slightly different tonality, slightly out of time (milliseconds), and slightly different pitch, and slightly different harmonics.. well you get the idea.

Lots of variations. But to our ears it just sounds more dynamic- not just louder on averge, but full scale feel, richer, more expansive.

Line arrays are impressive things. Doesn't sound like 2 speakers in stereo.
More like a WALL full of music.

Now if only the cabinetry was easier...

[dlr]

You nailed it.

I think it's best to look at distortion both full range and after the filter. Looking at it full range helps you decide on a crossover point and topology, and looking at it with the filter in place confirms that it does work as intended.

It's an extension of things we all spend so much time on, trying to get things like the breakup down to a benign level. I think that looking closely at the raw distortion in the primary passband is possibly the most useful, with the possible exception of a woofer and it's low end extension requirements.

All that said, people don't need to do distortion plots, it just helps to minimize the tweaking as a designer struggles to figure out why a system doesn't sound good.

John

When someone speaks of how a particular driver "sounds", I always have some skepticism. Too often it's not the driver, but the system design, either bad combination of drivers or sub-optimal crossover for the drivers in use. I have had enough cases of my own in that category.

[Jim Holtz]

Jim,

There's no reason why a driver with moderate amounts of harmonic distortion can't sound superb. In fact, I was not be surprised that the favourites (eg. OW1, Millennium) are NOT amongst the ones with the lowest distortion. Bear with me...


I still believe that the driver with the flattest in-box frequency response, and the lowest post-filtered harmonic distortions are the most faithful to the original electrical signals. Furthermore, the drivers with modest 2nd order, but the lowest odd and higher ordered (non musically related) distortions may be the most musical pleasing to listen to.
"It just sounds more musical"


With complex musical signals, the added harmonics may be masked. We might not hear them as obvious distortion, but instead as subtle added sounds.
Micro-detailing, richness, naturalness, or the Real Thing(tm) are words that come to mind. After all, don't real instruments have all kinds and levels of harmonics?
When a musical instrument creates harmonics we call it timbre, but when a driver creates harmonics we jump up and down and call it distortion...

Your puzzle about line arrays... I go to live musical events regularly. I'm sure you'll agree that 10 violins sound better than 1, or 3 of the same guitars sounds better than 1, With all the different musicians, they all have slightly different tonality, slightly out of time (milliseconds), and slightly different pitch, and slightly different harmonics.. well you get the idea.

Lots of variations. But to our ears it just sounds more dynamic- not just louder on averge, but full scale feel, richer, more expansive.

Line arrays are impressive things. Doesn't sound like 2 speakers in stereo.
More like a WALL full of music.

Now if only the cabinetry was easier...

Tktran,

Thank you for the thoughtful reply. I agree with the majority of what you say and I think you may have hit upon why I'm hearing something that doesn't correspond with the measurements. The timber etc. of a musical instrument define the character of the sound. Perhaps the character of some tweeters more closely mirror that sound. I don't know but it does sound plausible.

Regardless, I'll continue to start with the lowest distortion drivers that fit fit my budget and project goals but I'll not give up on ribbons just because the measurements don't agree with what I hear. My next project will use Fountek NeoC D 3.0 ribbons and (2) RS225's in a WWMT design I think. The mid is yet to be determined.

BTW, a comment on line arrays. The line arrays that Rick designs which are based on Jim Griffins work, are not of the "wall of sound" variety. Power tapering brings imaging into proper perspective with exceptional depth if it's in the recording. Very, very realistic with life sized images that aren't over blown.

Yep, cabinets are a bear to build. If I can do it, anyone can. :W

Jim

[cotdt]

why not just build a wall array?