Sharing 3 different reviews is gonna be a royal pain for me to copy/paste here because I do a LOT of testing from standard FR to multiple distortion tests (HD, IMD, multitone) and a whole lot of writeup with formatting. It would take a long time to paste it all here. So, if you are interested in these drivers' performance, check the following links to my reviews.
ScanSpeak Illuminator 18WU4741T-00 7 Inch Midwoofer Review
SB Acoustics SB17CAC35-4 6 Inch Ceramic Midwoofer Review
Purifi Audio PTT4.0W04-01A 4 Inch Midwoofer Review
You can watch the YT versions if you wish. Or just look at the data provided. I provide both versions because I know some people appreciate someone "walking through" the results. And, as always, the opinions on implementation may differ but my takeaways are based on the data and (when possible) personal use experience.
At any rate, I hope this helps some of you guys with choosing the right drivers for your project down the road.
ScanSpeak Illuminator 18WU4741T-00 7 Inch Midwoofer Review
SB Acoustics SB17CAC35-4 6 Inch Ceramic Midwoofer Review
Purifi Audio PTT4.0W04-01A 4 Inch Midwoofer Review
You can watch the YT versions if you wish. Or just look at the data provided. I provide both versions because I know some people appreciate someone "walking through" the results. And, as always, the opinions on implementation may differ but my takeaways are based on the data and (when possible) personal use experience.
At any rate, I hope this helps some of you guys with choosing the right drivers for your project down the road.
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wow, what a massive amount of measurments, to bad i do not understand half of them
that scan-speak midwoofer looks like trully long stroke design, i did not know they where
your impedance plots looks a bit distorted, the shape of the peak resonances looks affected by some rattling or some nearby surface
that scan-speak midwoofer looks like trully long stroke design, i did not know they where
your impedance plots looks a bit distorted, the shape of the peak resonances looks affected by some rattling or some nearby surface
Yea, the impedance plots should be re-done because they were taken with the drive units in the fixture rather than in the test baffle (as they are tested for FR/distortion). The test fixture holds the drivers in place at the motor for the excursion testing and naturally blocks a bit of the backside.
The resonances around the 1-2kHz range in the Purifi 4" drivers are quite alarming, especially for the price they want for them.... In my experience, next to overall tonal balance over the audible range, large spikes and dips in the 500 to 2000Hz range is the most immediately noticeable "something is wrong" cue.
That was the same thing I thought; seems pointless to have the big ol' surround... but they do tout it as a "midwoofer". They do offer a 5-inch version of this speaker, however, I think it would make more sense to make the 5-inch version of this speaker with a thinner surround to improve efficiency. Like the Revel PerformaBe series (which, unlike the previous Performa line, no longer use SB drivers). You can find my review on the Revel F226Be here if you are interested, though, no drive unit testing.
Revel PerformaBe F226Be Floorstanding Speaker Review
And, yes, the less than spec'd linear excursion per my measurement methods is typical of SB woofers. They surely are using physical measurements for their spec rather than the IEC standard 62458 like I do (using Klippel measurements). Here are some I tested for my old site and have yet to port to my new site:
SB Acoustics 17NRXC35-4 | Medley's Musings
SB Acoustics SB23NACS45-8 8″ Woofer | Medley's Musings
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Great info, thank you for sharing.
A note / question about the results: your plots labelled
"Horizontal Frequency Response Normalized Against 0 Degree Axis" look oddly good below 1kHz, compared to others I've seen.
The equivalent normalized plots at hificompass.com of similar drivers are not as perfect as this, e.g. this smaller illuminator driver isn't nearly as flat in their plots:
ScanSpeak 12MU/4731T00 | HiFiCompass
...and their plots for the Purifi driver have more deviation around 300Hz.
Purifi Audio PTT4.0W04-01A midwoofer | HiFiCompass
Their test baffle is stated as 1650x850 mm, yours is wider (1256mmx1508mm) - is that the likely reason for the difference?
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From what I can tell, the Peerless by Tymphany NE180W-08 6-1/2" looks like a good substitute for the Illuminator, if budget is a consideration.
$675 a pair versus $165 a pair.
Reviewed here:
Vifa NE180W-04 | HiFiCompass
The TS properties of the Tymphany driver look similar, the on-axis response look similar (it appears to fit into a 3dB window up to 3kHz), and the distortion stuff looks similarly good.
In my country, I'm also biased cos of my shopping experience - I can get the Tymphany range promptly, with free postage (Digikey) or with cheap postage (Parts Express), whereas when I have shipped European* drivers to Australia, it was massively costly.
*some Focal mids, bought years ago, when they still sold to the public
A note / question about the results: your plots labelled
"Horizontal Frequency Response Normalized Against 0 Degree Axis" look oddly good below 1kHz, compared to others I've seen.
The equivalent normalized plots at hificompass.com of similar drivers are not as perfect as this, e.g. this smaller illuminator driver isn't nearly as flat in their plots:
ScanSpeak 12MU/4731T00 | HiFiCompass
...and their plots for the Purifi driver have more deviation around 300Hz.
Purifi Audio PTT4.0W04-01A midwoofer | HiFiCompass
Their test baffle is stated as 1650x850 mm, yours is wider (1256mmx1508mm) - is that the likely reason for the difference?
---
From what I can tell, the Peerless by Tymphany NE180W-08 6-1/2" looks like a good substitute for the Illuminator, if budget is a consideration.
$675 a pair versus $165 a pair.
Reviewed here:
Vifa NE180W-04 | HiFiCompass
The TS properties of the Tymphany driver look similar, the on-axis response look similar (it appears to fit into a 3dB window up to 3kHz), and the distortion stuff looks similarly good.
In my country, I'm also biased cos of my shopping experience - I can get the Tymphany range promptly, with free postage (Digikey) or with cheap postage (Parts Express), whereas when I have shipped European* drivers to Australia, it was massively costly.
*some Focal mids, bought years ago, when they still sold to the public
I would assume it is their baffle. I recall them mentioning some deviations from Purifi's spec at 200/400/800Hz (iirc) due to their baffle.
We know a drive unit is pistonic and non-directional until about 1/2 wavelength relative to the effective radiating diameter. Just take an average 6-inch woofer... let's say it has 6-inches of radiating diameter (it doesn't, but let's make this easy).
speed of sound *0.5 / Diameter
13500 *0.5 / 6 = 1125Hz
So, the on/off-axis measurements should be the same until about 1125Hz for a drive unit with a 6-inch radiating diameter. You can apply this to other sizes. And when you look at most specs, this is what you see.
Besides, the deviations from flat in HFC's normalization below the beaming point are relatively minor (IMHO). I just chalk that up to (reasonable) measurement/setup error. No big deal to me.
We know a drive unit is pistonic and non-directional until about 1/2 wavelength relative to the effective radiating diameter. Just take an average 6-inch woofer... let's say it has 6-inches of radiating diameter (it doesn't, but let's make this easy).
speed of sound *0.5 / Diameter
13500 *0.5 / 6 = 1125Hz
So, the on/off-axis measurements should be the same until about 1125Hz for a drive unit with a 6-inch radiating diameter. You can apply this to other sizes. And when you look at most specs, this is what you see.
Besides, the deviations from flat in HFC's normalization below the beaming point are relatively minor (IMHO). I just chalk that up to (reasonable) measurement/setup error. No big deal to me.
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I tested the Vifa/Tymphany NE180W. Measured linear excursion at 5.6mm one-way.
Vifa NE180W-4 | DiyMobileAudio.com Car Stereo Forum
As a side note... my GOODNESS, I have tested a lot of speakers I have completely forgotten about. I had to google that one because I thought I remembered testing it but wasn't sure. And, yep, I did. lol
Vifa NE180W-4 | DiyMobileAudio.com Car Stereo Forum
As a side note... my GOODNESS, I have tested a lot of speakers I have completely forgotten about. I had to google that one because I thought I remembered testing it but wasn't sure. And, yep, I did. lol
Oh, and to be clear, my measurement rig isn't perfect, either. I use a 20-something foot long by 10-foot tall wall with a 14x16-inch rectangle cut out that I use to insert baffle blanks in to. This wall is a partition wall in my garage that separates "my side" from the main side so I can have a workshop separate from the main garage. So, essentially it is an infinite baffle (to the speaker, it certainly is).
This causes an issue, though, when it comes to off-axis measurements. When the mic is placed at >45deg the mic is closer to the baffle wall than it is to the floor and thus my first reflection becomes the wall... and it's shorter in time than the floor. So I have to adjust my time window for off-axis measurements to be smaller than my on-axis. Which annoys me. But that's what I've got.
I'm hoping this will change soon... if I can get enough change to purchase this:
Near Field Scanner System (NFS)
Notably, with the baffle attachment as shown below:
This causes an issue, though, when it comes to off-axis measurements. When the mic is placed at >45deg the mic is closer to the baffle wall than it is to the floor and thus my first reflection becomes the wall... and it's shorter in time than the floor. So I have to adjust my time window for off-axis measurements to be smaller than my on-axis. Which annoys me. But that's what I've got.
I'm hoping this will change soon... if I can get enough change to purchase this:
Near Field Scanner System (NFS)
Notably, with the baffle attachment as shown below:
Attachments
Thanks. That's what I expected - and the deviations when you put it in anything other than a huge baffle or soffit mount will be many times larger, anyway.
There are many reasons for a driver to start displaying non-linear behaviour but some are far worse than others.
As has been noted the compliance variation between the in and out stroke is significantly less than the rated xmax for the SB driver. This is not the same as the driver only having that much physical xmax as measured at the coil.
When a drivers suspension becomes non-linear second order distortion rises. How bad this is depends on how non-linear it becomes.
The typical example of this is when a driver with a narrow surround has more coil xmax than the surround can support. This has commonly been seen in XBL2 6" drivers as they can have huge xmax in the motor but rather small surrounds. The suspension runs out of travel and cone, literally, cannot move any further.
Clearly the SBs spider and suspension have ample travel, so things aren't going to be as bad as when a driver does run out of travel. This just means that the SB is going to have a higher amount of 2nd order distortion, in the bass, than it otherwise could have.
BL limited Xmax is where problems really arise. When motor/BL xmax is exceeded high order distortion products go up dramatically, with long coil short gap geometries, and this really objectionable.
So to say the SB has 2.8mm of xmax is a little bit misleading. If you took a driver that had 2.8mm of BL limited xmax and drove it out to 4mm it would sound a helluva lot worse than the SB out at 4mm because the SBs motor would still be linear.
I wouldn't have any issues using the 5.1mm, BL limited, xmax when predicting how loud the SB can cleanly go either.
As has been noted the compliance variation between the in and out stroke is significantly less than the rated xmax for the SB driver. This is not the same as the driver only having that much physical xmax as measured at the coil.
When a drivers suspension becomes non-linear second order distortion rises. How bad this is depends on how non-linear it becomes.
The typical example of this is when a driver with a narrow surround has more coil xmax than the surround can support. This has commonly been seen in XBL2 6" drivers as they can have huge xmax in the motor but rather small surrounds. The suspension runs out of travel and cone, literally, cannot move any further.
Clearly the SBs spider and suspension have ample travel, so things aren't going to be as bad as when a driver does run out of travel. This just means that the SB is going to have a higher amount of 2nd order distortion, in the bass, than it otherwise could have.
BL limited Xmax is where problems really arise. When motor/BL xmax is exceeded high order distortion products go up dramatically, with long coil short gap geometries, and this really objectionable.
So to say the SB has 2.8mm of xmax is a little bit misleading. If you took a driver that had 2.8mm of BL limited xmax and drove it out to 4mm it would sound a helluva lot worse than the SB out at 4mm because the SBs motor would still be linear.
I wouldn't have any issues using the 5.1mm, BL limited, xmax when predicting how loud the SB can cleanly go either.
@bikinipunk: Thanks for posting your quite extensive measurements on these drivers! I have done my own basic testing (FR vs angle, HD) of the NE180W-04 and the SB17CAC35-4 (I own both) and they have looked good. These are excellent drivers to use nude, by the way. It's too bad that the Peerless only seems to be available in the 8 Ohms version these days. Not sure why that is.
I am still trying to wrap my head around the different IMD measurements and presentations that I have encountered. Any general tips on reading the tea leaves?
I am still trying to wrap my head around the different IMD measurements and presentations that I have encountered. Any general tips on reading the tea leaves?
That's not as much as the illuminators you tested, but otherwise, it seems like it performs just as well for 1/4 the price. IMO this is a pretty good trade off.
Do you recall why you commented "FR is kinda weird"?
You seem to have only one FR plot (Fundamental + Harmonic Distortion Components), which looks flat, the manufacturer's plot also looks flat, and the hificompass plot looks flat (to 3kHz).
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My bias / perspective is that I have the 2" and 4" Tymphany NE drivers, and I like them, they measure well. The 4" works fine in a nearfield mini speaker.
Picture: Speaker made with Ikea cutting board + box - Imgur
I listen to the 2" often, as a mid-tweeter in a big horn - I was previously using OTT (JBL, 14kg each) compression drivers in this role, and I consider the NE65's to be an upgrade
The 2" crosses to a EV 18" midbass, with two 15" < 80Hz.
In these roles, I don't need 10mm X-max from the NE drivers.
If you’re talking about the Vifa, it was probably because it was nearly 10 years ago and I was still new to measurements. Probably wouldn’t say that today. But I’d have to go back and read it... something I don’t want to do... kind of like the feeling we get when watching ourselves on video. LOL
My google-fu gives this site, which I've never heard of before. They seem to stock exactly the same brands as digi-key (who I have bought from), so I guess they are linked.
"In Stock 1097 pcs"
NE180W-04 | Peerless by Tymphany NE180W-04 Stock available from Infinity-Component.hk | NE180W-04 with Best Price at Infinity-Component.hk
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Bit late reply, but STAY OFF THAT SITE - it is a fraudulent operation. The infamous Dutch site on steroids, really. Exclusively negative reports on the web. It seems their business model is to copy Digikey's catalogue, halve the prices, invent some availability figure, and wait for some fish to bite. There is no stock, there is no shop, there is only the website.
The have some sister operations too, maybe to confuse Google's cache or something.
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