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Discussion Starter #1
Note:
I put these drivers up together because they are different versions of the same driver and from a comparison standpoint I thought it might be nice to have the FR at 0deg plotted together.

Thanks to the folks who donated them.

For test setup, procedures, and information on how the data was obtained see sticky here:
http://www.diymobileaudio.com/forum/product-reviews-erin-harrdison-bikinpunk/103414-driver-testing-methods-setup-frequency-response-harmonic-distortion-only.html
Do not ask setup questions in this thread. This thread is only for driver discussion.

To understand how to read the data, try here:
http://www.diymobileaudio.com/forum/product-reviews-erin-harrdison-bikinpunk/103817-how-read-frequency-response-harmonic-distortion-plots.html



Drivers Tested:
Hybrid Audio L4
Hybrid Audio L4SE

L4:


L4SE:

Impedance and T/S Parameters:

L4:


L4SE:



Frequency Response of both drivers at 0 degrees, 3dB scale:


Frequency Response at 0, 30, and 60 degrees, 5dB scale:

L4:


L4SE:

Harmonic Distortion at 95dB:

L4:


L4SE:
 

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Discussion Starter #2
Wanted to note that this is my last test data that will be posted here. Gotta take down the baffle to sell the house which may take a while so testing is suspended indefinitely. To be honest it doesn't seem like anyone really pays attention anyway so I don't feel that bad about it. Gave it a good go to get the science back here and give us something to chew on rather than subjective opinions only, but it just isn't sticking to the wall so I'm out.

I had fun learning. Hopefully I can pick back up sometime in the future with my own site.

Thanks to those who did contribute to the discussion and helping me out with funding some of this stuff. I hope you guys found usefulness in the data.

- Erin
 

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Your work is appreciated, but I think a lot of the guys like to hear opinions on how the speakers sound as well to go along with the graphs, albeit subjective.
 

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Discussion Starter #4
I understand. However, my goal has been to educate people on what they're hearing.

I'm doing a listening test on these drivers now. I'll post up some quick thoughts (but nothing too detailed).
 

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It would be nice if you could compare 2 of the same driver to see how far off 2 identical driver would be.
 

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Wanted to note that this is my last test data that will be posted here. Gotta take down the baffle to sell the house which may take a while so testing is suspended indefinitely. To be honest it doesn't seem like anyone really pays attention anyway so I don't feel that bad about it. Gave it a good go to get the science back here and give us something to chew on rather than subjective opinions only, but it just isn't sticking to the wall so I'm out.

I had fun learning. Hopefully I can pick back up sometime in the future with my own site.

Thanks to those who did contribute to the discussion and helping me out with funding some of this stuff. I hope you guys found usefulness in the data.

- Erin
Thanks for the effort and work required to do this. I look forward to seeing your subjective review.
 

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Discussion Starter #7
It would be nice if you could compare 2 of the same driver to see how far off 2 identical driver would be.
I did this initially with about 4 different sets of drivers. The results were close enough for me to make up my mind and decide there's no need in doing it further.

T/S parameters were sometimes different but I honestly could care less about that since the enclosure has a much more dramatic effect than two driver's fs being different by 2hz.

I'm sure some would disagree, but that's my viewpoint.
 

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Erin, I don't understand any of the numbers or graphs (yet, I'm trying to learn), but even an uneducated yokel like me can appreciate the time and effort you put into it. It's much appreciated and hopefully I'll be able to discern everything soon!
 

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Discussion Starter #9 (Edited)
Since this is my last test, I'll break my own "no subjective opion" rule. Besides, I'm comparing the two drivers so there's less issue personally with doing that.

Here's a brief subjective review between these two drivers... it ain't much but I didn't plan on giving anything anyway. However, since the two measure so similarly I had to listen myself and will share some impressions.

20 minute listening session, swapping drivers on the baffle with no crossover or EQ. Playing straight off iTunes which is wirelessly streaming music from my mac downstairs. No level matching so take it with a grain of salt...

First off, there's no way I would personally use either driver by itself further off axis than 15*. They didn't sound bad, but they certainly need a tweeter to me to help cover on the top end what is lost though both drivers play well up to 8khz up to 30 degrees off axis as evidenced by the graphs above. Some people will differ in opinion on needing a tweeter to supplement off axis response (ie: wideband driver fans) but that's my honest opinion.
The difference in lower frequency content (vocals, mainly) were immediately noticeable between the two with the nod going to the SE. Which, if you look above, is contradictory since the L4 has lower distortion by a small margin. So, maybe I prefer a bit of distortion? Good to know. :)

The L4's didn't sound bad, per se, but they seemed to lack what I can only term as "life" compared to the L4SE. What I mean is that on the upper end, the L4SE was more geared toward what I like or am used to hearing which is a more vibrant top end. Right... who wouldn't want a vibrant response?... (see why I'm not a fan of subjectivity?). Okay, let me see if I can clarify:
Toms had a nice attack down low but the harmonics up top seemed to render more dynamically. Sax was like it would be if I heard my buddy let loose at work (and I have heard this), whereas the L4 didn't seem to have the body on the top end... maybe attack or detail could fit here but I digress....
Does that mean the L4 original is bad? Nope. It could simply mean I hadn't been accustomed to its sound and I might even prefer that driver in longer listening tests. ;)

Both drivers had really nice low end response. Remember, again, I was using these on the test baffle with no crossover. At moderate volumes the LFE was quite nice. Not overdone while still being 'there'. I give these drivers props in this regard. Though, it truly did seem the L4SE had a bit more bottom to it since I was able to listen a bit louder without hearing the artifacts of distortion, at least to my untrained ears.

So, is the difference enough to warrant the price upgrade?
Can't tell you. Same as the L6 vs L6SE. It's up to you and your install.
Would I do it? I honestly do think so, yes.. I felt the audible differences were enough to lean toward the SE. But, I'm also a nut who loves going through gear. Additionally, the user, install and tune will really effect the outcome so if you're considering either of these, try to look at the data given and draw some conclusions based on the bandpass which you intend to use them. You may find the upgrade to the SE isn't worth the additional cost to you.

Bottom line: I like the L4SE.

Again, this is only my quick impressions. 20 minutes tops. Take it for what it is.

Compare these drivers to others? NOPE!
I won't lie and say my hearing memory is good enough and furthermore, I've not had another set of 4" drivers on this test baffle to even begin to compare against. Compare these against the scan 12m's in my car? HELL NO! Think of what you're asking... two totally different environments. It's too misleading to give opinions based on anything other than the same setup within as near exact same constraints as I have.
*Preaching to the choir, I hope ;)*

- Erin
 

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Thanks Erin! I echo what everyone has said thus far - your work is appreciated for sure. I hope I didn't make your 'job' too painful for trying to be sure the scientific method was followed to the letter. Great job man!
 

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Erin-

Thank you again for everything you've done. I also especially appreciate the subjective comments on this one since they measured scary close to each other. Enough so that many would probably have a hard time paying the price if they just went off what the charts showed IMHO.

I can understand the better low-end response in the SE with the greater xmax and a QTS (which equals QTC in an OB setup) closer to .707. The part that surprises me though is that the SE has a higher inductance on your TS parameters. I would expected that with a shorting ring (they included that in the SE right?) that the LE would be lower, not higher.

Also, I don't think you could have handled the subjective comments any better. No comparisons to other drivers in other environments, EQ'ed drivers, or "memories" of a drivers performance. Just a straight A/B comparison. Thanks.
 

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Discussion Starter #13
Erin-

Thank you again for everything you've done. I also especially appreciate the subjective comments on this one since they measured scary close to each other. Enough so that many would probably have a hard time paying the price if they just went off what the charts showed IMHO.

I can understand the better low-end response in the SE with the greater xmax and a QTS (which equals QTC in an OB setup) closer to .707. The part that surprises me though is that the SE has a higher inductance on your TS parameters. I would expected that with a shorting ring (they included that in the SE right?) that the LE would be lower, not higher.

Also, I don't think you could have handled the subjective comments any better. No comparisons to other drivers in other environments, EQ'ed drivers, or "memories" of a drivers performance. Just a straight A/B comparison. Thanks.
Yea, I noticed this as well and meant to say something about it.
The two drivers' impedance curves are very similar above resonance, again indicating good high frequency content.

I tested these in free-air after spotting this last night (didn't want to mount on the baffle) and the L4SE inductance still measured a bit higher.
Realistically, though, the values are already pretty low.


Thanks for the comments, John. :)
 

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Discussion Starter #14 (Edited)
The following are things I see...

Impedance and T/S:
Both drivers have similar Fs and overall magnitudes, though the SE has higher Qts. The SE and V1 both have nearly the same magnitude in impedance on the high end, indicating both would be useful for wideband projects. Both have a swing of about 3dB from Re to Remax (what I'm calling the highest frequency impedance). The V1 has higher motor force (Bl = 4.0) vs the SE (Bl = 3.6). This should translate to lower end response but I honestly didn't seem to notice this much. These values are pretty close, though, too so I don't think I'd spend a day pouring over this difference. To me, this is where the enclosure comes in to play and why I personally don't put much weight into these small differences.
Overall, these drivers look really, really identical in this set of data.

FR:
With the overlain graph given in the OP, you can see both drivers have the same output until about 1.5khz. Above this point, the SE stays about 1.5dB higher in output.
Linear response for both drivers is pretty good when you compare to other well known drivers (scan 12m, Fountek FR-88, TB W3-1364, etc).
The scan 12m measured the best out of the above, and many people like to use this as a reference so feel free. Note, however, the scale given is 5dB increments.
Now, moving on the HAT drivers, you'll notice the linearity on-axis isn't quite as flat. There's a rising top end. However, if you look at both drivers' response at 30* you'll notice a pretty flat response, on par with the Scan 12m on-axis measurement. This, to me, says the HAT drivers could be mounted off axis and perform well up to at least 6-7khz for both drivers (the L4V1 going a bit higher than the SE).

Additionally, it could very well be that the rising top end response on-axis is what lends to the off-axis flat response. Now, which one will you prefer???... on-axis or off-axis???? That's up to you. Personally, I found these at on-axis position were great and the rising response actually sounded nice. But, your opinion may differ and the results in car could change things as well.


Distortion:*
Not really much I want to comment on here because I think the subjective post above might really give an inkling moreso than the bare results themselves.
The only real difference I notice, other than levels skipping between the two, is that the SE has a more smooth transition in 3rd order distortion between 50-500hz. This is where most people say you can hear differences (3rd order distortion) and to me is a primary area because much of what you hear is pretty much based off this range.
One thing I always take away from distortion measurements is "where will these sound best crossed over". If I'm going on distortion alone (which I don't necessarily advise; listening tests should always supplement data when possible) it looks like a good starting point for high volume listening and crossover point would be about 300hz. At more moderate volumes you could probably get down to 200hz safely. Yes, I know people will cross 4" drivers down to 160hz or whatever other random number. Personally, I see a rising distortion below 300hz and know that anything much below 200hz is starting to look a bit scary. If you listen at loud volumes (LOUD... 95dB testing is strenuous) then I'd say 300hz would likely be a good place to cross to beat out distortion artifacts. If you listen to reasonable volume levels then 200hz, again, would be doable. Again, you'll have to do your own listening tests here. I can't guarantee what I see and hear is what you'll hear. Different strokes for different folks.

*as a point of reference, I cross my 12m's at 300hz in my car. I can cross them down to 200hz and they sound nice. If you look at the 12m distortion results from Zaph @ 96dB (~ 1dB higher than my results), you'll see a similar trend with the 12m as with the HATs. So, this plays in to what I just said regarding crossing the HAT drivers. I've crossed the 12m's as low as 200hz and it's been fine, but it's not an everyday thing. That could prove to more backup my claim of 200hz crossing at more moderate volumes but it really has more to do with the install. Keep in mind that in my car the 12m's are in a 1L enclosure. The enclosure affects distortion, too. What works for me may not work for you and vice versa. So, again, TEST YOURSELF and don't go solely off what I'm saying here.


Overall:
Overall the results look pretty good. I won't say they're the greatest thing ever, but the big thing to me is the FR and these drivers' usefulness off-axis as most people will be installing car audio drivers at least somewhat off-axis. The smoother response looks to be an indicator for off-axis placement without sacrificing much output up top. Though, I still would recommend using a tweeter up high (ie: 7khz+) if you're using these drivers off axis. I'm probably a bit biased because I've always felt the need for more when listening to any 3-4" driver playing wide open. Again, it's not bad, per se, but the tweeter just adds something that I feel the system needs.
 

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Additionally, it could very well be that the rising top end response on-axis is what lends to the off-axis flat response.
How could it be otherwise? Cone drivers fall off at a more-or-less constant rate, determined by their diameter. Krutke doesn't even measure off axis any longer, because in his testing he's found that the off-axis curves for single drivers (as opposed to systems, where the drive units interact over broad regions) are foregone conclusions. So rising on axis has to lead to a relative rolloff off-axis, meaning that at some design axis the response is flat. When things like upholstery are blocking the on-axis response (i.e. speakers low in the doors) a rising on-axis response makes a lot of sense.

There are phase plugs and waveguides that an alter the behavior, but I've never seen any measurements that would lead me to believe the small protrusion in these drivers and several others has any effect on the off-axis response. The effect it might have is to lower dynamic compression by drawing heat out. Certainly, anyone who's ever used a Dayton Ref or Seas Lotus/Excel driver has at one point or another accidentally touched the "phase plug" after hard use, and noted how hot it gets. (The wooden phase plugs some drivers use, by contrast, just seem an aesthetic, rather than functional, choice.)

I happen to think that rising on-axis response is a very good thing for car audio drivers, mounted in typical locations. The first I heard with this characteristic were the coincidents by KEF and AVI. But of course today one can manipulate the core frequency response so easily with inexpensive, easy-to-use, and readily available tools, that what really starts to matter in drive-units is not linear distortion (FR, etc.) but nonlinear distortion.

One thing I always take away from distortion measurements is "where will these sound best crossed over". If I'm going on distortion alone (which I don't necessarily advise; listening tests should always supplement data when possible) it looks like a good starting point for high volume listening and crossover point would be about 300hz. At more moderate volumes you could probably get down to 200hz safely.
It's entirely out of the scope of your tests, but I wonder if putting them in enclosures might change that a bit, i.e. let you get lower with lower distortion due to the low-end efficiency bump. (You seem to imply as much with your comments on the Scans.) That would make a crossover an octave (maybe a little less than an octave) lower than the above suggestion perhaps doable.
 

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Discussion Starter #16
How could it be otherwise? .
I have to leave some ambiguity in my posts otherwise I get termed as "biased".
I'm serious.

DS-21 said:
I happen to think that rising on-axis response is a very good thing for car audio drivers, mounted in typical locations.
I agree completely, which is why I made the closing paragraph.

I also noted above that I found these drivers both nice on-axis but off-axis, I wanted more top end and would likely pair them with a high-crossed tweeter. When you get them in a car, however, the results may shift either way. I like them on-axis. Enough to say that I wouldn't have an issue using them in my car on-axis, but I still might even put a tweeter on them. Again, speaking for myself here...


Thanks for the comments, Jay.
 

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Both drivers use Cu-Al inductance rings. Thus the lack of a massive difference in inductance.

Truth be told, as the designer of both the L4 and L4SE, the L4SE was the most difficult to make better than its Stage III Legatia counterpart. Not to sound conceited, but the L4's were already really, really good. So it was quite the chore to attempt to make them better. Alas, a tad bit more sensitivity, a mild play with Qts and compliance, more dispalcement, and more/smoother high-frequency extension was the main design tenets. By comparison to the L6 vs. L6SE and the L3 vs. the L3SE, where there are very definable gains by using the SE, the L4 was not as notable. Wanna see a "wonder midbass?" Look at the L6SE. At both on-axis, and even 30 degrees off-axis, I'd like to go on record that its the most versatile 7" midbass available today.

The phase plug adds a measureable impact in the total inductance profile, and as stated earlier by Jay, has a defined cooling function. Alas, it's ability to "steer" and focus higher frequencies is only notable within being very close to on-axis. The pole peice has much less of a function off-axis in this regard.
 

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Erin, on behalf of the greek DIY mobile audio community (me and a couple of friends, that is :D ) we would like to thank you for your contribution and hope to see more reviews in the near future! :)
 
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