Zaph|Audio

6.5" to 7" Driver Comparison

About the Test

All response curves are with the drivers on an infinite baffle. Don't forget that in the real world, baffle step and diffraction will affect the curves. These curves are all far field, taken with a 10ms gating window. Older response curves have show low end inaccuracy from gating while the newer have merged in near field bass response. For a realistic representation of bass response below 200 hz in the gated measurements, use the T/S parameters to model a curve.

Cumulative Spectrum Decay (CSD) charts are 1/12 octave smoothed. Time slices are taken up to 3ms with the start marker right at the beginning of the impulse. All levels are equalized to 30dB to accurately show comparative energy storage regardless of individual driver efficiency.

Harmonic distortion charts are taken semi-far field with the mic directly on axis. The far field method shows a more realistic top end distortion but does allow some room effect to show up also. The same conditions apply to all drivers. Amp output level was adjusted for each driver so that the fundamental was 92dB at 1/2 meter. The level was set between the range of 300-1000Hz. Harmonics F2 thru F5 are tracked. F2=Green, F3=Blue, F4=Purple and F5=gray. In general, the higher the order of harmonic distortion, the more offensive the sound. The range is 20Hz to 10kHz and the level is +30 to -110 dB. The only tradeoff with doing non-linear tests far field are room effects. However, this is a much better tradeoff than nearfield, which is inaccurate in the higher frequencies due to mic location close to only one part of the cone. For normal DIY'ers like me, anything less than a full anechoic chamber is going to introduce some inaccuracies in the results.

• Special measurement issues: In this grouping, older harmonic distortion sweeps have dips in the response of the fundamental on the HD charts. This is an artifact of the way my SE was originally setup to measure harmonics, and does not affect the harmonics themselves. It's a function of the mic distance and related phase shift - the recorded signal internally summed with the original signal before plotting to the chart. Only the fundamental is affected, and the harmonics are accurate. For an accurate fundamental here, just take a look at the response curves. Rest assured however that all testing levels in this grouping were set the same for new and old, and the harmonic distortion can be reliably compared.

And finally, note - Do Not compare these harmonic distortion plots to others anywhere else, including on this site. The test method was different for this particular set and the level was a bit lower. Make comparisons within this test group only. If you want to compare results with the 5.5" grouping, the 6.5" group will need approximately 4dB added to level and harmonics.

All T/S parameters are actual measured, not from factory data. All Vas numbers are done delta compliance since that method is more accurate than delta mass. Also note that the SPL number on the T/S parameters is an efficiency number based on one watt. Additionally, this number is calculated rather than actual. The SPL shown on the response graphs is a sensitivity number based on 2.83 volts and is actual rather than calculated. If you want to "believe" one, the SPL shown on the response graphs would be best to use. Also note that the Le number on the T/S parameters is not a good comparison point between software packages because of different calculation methods. The Le is often interpeted by software particularly poorly when the motor is complex with substantial faraday sheilding. For accurate impedance vs frequency, look no further than the driver's impedance curve rather than an arbitrary Le number. Flatter is better.

All parts of this test are done with Soundeasy 12.0. This is a modeling package with a lot of extra testing applications included. It is not a full acoustic measurement system such as CLIO or Praxis however, so take these results with a grain of salt. What is important however is that all of these drivers were tested in the same way. Once again, I'll remind you that my test results should not be compared with tests done elsewhere by other people, but comparisons within this group of drivers are perfectly valid. That's why tests like this are best done in groups.

There are a few types of tests that are important, but not shown here in the interests of brevity. Keep this in mind and know that these results need careful interpretation.

Commentary and review: 5 Star Rating System, drivers sorted by cost. Cost - Driver cost per one unit in USD. Prices and availability updated 12/14/2008. Usability - This is a function of both linear and non-linear distortion combined. The standard of reference is use in a "normal" stand-alone 2-way speaker with a "normal" tweeter. Some examples: Subtract points for a response curve that requires extra crossover components to fix or peaks in harmonic distortion that push the tweeter crossover point below a normal frequency. Add points for drivers that have particularly wide usable bandwidth or easily controlled response curves. Build Quality - This is a combination of fit and finish, along with well engineered features. Some features may help performance in ways not covered here by the normal set of tests. Some examples: Subtract points for glue gushing out at the edge of the surrounds, an off center dustcap or a rough frame casting. Add points for venting behind the spider, clean tinsel lead connection, or an estimate of low air restriction through a frame design. Consistency - Difference between units. This is primarily a comparison of a response curve and impedance plot, and assumes that I have two units to test. If I have more experience with a driver, this rating will have a greater level of accuracy. If I only had one to test, this category will have a "Not Rated." Value - This is a comparison of cost to everything else combined. Prices are USD as listed at the time of testing. Remember that aside from cost, the ratings below my subjective opinion. I am one person, namely John Krutke of Zaph|Audio. The ratings are provided for those who wish to know the opinion of this web site's author. I encourage people to use the objective test data, consider their own needs and form their own opinions. I also reserve the right to change these ratings, as I think about things over time and gain more consistency data. Audio Technology 18H520613SD Cost: $525 Usability: Build Quality: Consistency: Value: Comments: This driver from Skaaning is a custom ordered unit with an underhung voice coil and an "SD" motor with a copper sleeve in the gap. Very solid construction with a well ventilated motor. Very sensitive. Very flat impedance curve. The response curve has a rise in the top end but is controllable. Merely average harmonic distortion considering the motor design. Poor price/performance ratio compared to the competition. Tested December 2006. Scan-Speak 18WU8741T00 Cost: $324 Usability: Build Quality: Consistency: Value: Comments: This is the new 18cm flagship Illuminator from Scan-Speak. It is a large excursion underhung neodymium motor design with low distortion and excellent build quality. There is a small hiccup in the response curve at 1200 Hz and a mild breakup between 3 and 4kHz. The frame design is particularly free flowing and begs to be installed in a dipole. Overall it's an excellent performer but unfortunately not quite up to the class leading (and cheaper) Revelator 18W8531G. Tested December 2008. Seas Lotus RW165/1 Cost: $275 Usability: Build Quality: Consistency: Value: Comments: (discontinued) This is a car audio specific version of the magnesium Seas Excel. Similar magnesium controlled cone breakup. Well built cast metal frame, sized for 6.5" openings. Very stiff suspension and very high Qts would only be acceptable in a car door. Like the standard Excel, it's best crossed over very low to avoid the 3rd order peak in harmonic distortion. Very expensive for this level of performance. Tested December 2006. Scan-Speak 18W8531G Cost: $225 Usability: Build Quality: Consistency: Value: Comments: Exceptionally well engineered driver in all areas. Uses Scan Speak's proprietary slit cone construction to control breakup nodes. Strong and well ventilated frame. Very low harmonic distortion and smooth, extended frequency response. Lots of copper in the motor is reflected in the impedance curve and overall performance. Not a whole lot to complain about here except for the high price. Needs a slightly larger enclosure than one could hope for. Expensive, but much higher on the value scale than any other +$200 woofer. Tested June 2006. Seas Excel W18EX001 Cost: $200 Usability: Build Quality: Consistency: Value: Comments: This is Seas definitive high end driver with the familiar magnesium cone and copper phase plug. Typically excellent Seas Build quality. Excellent performance in the midbass and lower midrange. Upper end usability is somewhat limited by the breakup induced 3rd order harmonic distortion at 1700hz. Most people claim to hear this if the system is crossed over too high. Overall it's a reasonable value and can sound great depending on it's careful usage. LR4 or an elliptical crossover around 1600 would work great. Tested December 2006. Seas Excel W18NX Cost: $197 Usability: Build Quality: Consistency: Value: Comments: This driver is similar to the W18EX001 with a few notable differences: There is a Nextel coated paper cone, a new type of internally damped surround and a higher Xmax. There is a breakup node, but it is easily controlled and does not influence the harmonic distortion as much as the magnesium driver. While the midbass performance is not as clean as the mag cone version, the midrange is much better and easily worked into a more normal crossover point. This driver is a little pricey but generally worth it. Tested October 2005. 18Sound 6ND430-16 Cost: $130 Usability: Build Quality: Consistency: Value: Excellent performing 16 ohm pro midwoofer. Smooth response and an extremely clean midrange. Very usable T/S parameters and excursion though somewhat limited bass extension for what is meant for woofer service. Very sensitive. It would make a fine midrange also. Lightweight neo magnet assembly with cooling fins. A couple of these paired up for an MTM and used with a subwoofer would make a reference level system. High value for this level of performance. Tested August 2008. Beyma 6MI90 Cost: $120 Usability: Build Quality: Consistency: Value: This is a dedicated midrange and as such it's bass extension and performance are not part of these ratings. It's a high sensitivity pro midrange with a cast frame and phase plug with slightly below average build quality. It has a flat foam surround with nearly no Xmax, so it's low end is very limited even for a mid. The response is smooth enough with a mild 5kHz breakup, but tall order nonlinear distortion is not particularly good. If you need a high sensitivity mid, there are better options out there. Tested August 2008. Fostex FE166ES-R Cost: $120 Usability: Build Quality: Consistency: Value: Comments: (discontinued) Very sensitive wide range driver. Like the FF165, it doesn't exactly fit in with this group because it's designed to operate without a tweeter. This is a solid 95 dB driver. Response is relatively smooth in the midrange but a little ragged in the range a normal tweeter would cover. Below average harmonic distortion performance in the midrange and lower treble. Very low maximum output due to a limited Xmax. Tested October 2005. Morel MW166 Cost: $111 Usability: Build Quality: Consistency: Value: Comments: The response is smooth enough to work with, but this driver is plagued by highish tall order distortion through the midrange. It has a huge voice coil (3") but a tiny spider supporting it. I don't recommend this driver as it's non-linear distortion of all types is pretty obvious with most music. Tested October 2005. Usher 8945P Cost: $110 Usability: Build Quality: Consistency: Value: Comments: Class leading harmonic distortion numbers. Excellent build quality. Well ventilated motor with a fabric dust guard. Machined phase plug with tight gap tolerances. Well engineered motor with an undercut pole piece and copper sleeve. Not a whole lot to complain about except for a 4dB dip in the response curve at 1200 hz. Good cost/performance ratio. Tested December 2006. Usher 8945A Cost: $110 Usability: Build Quality: Consistency: Value: Comments: This woofer was considered by many to be a clone of the Scan Speak 8545. The cone and surround are similar but there are some differences internally. This has a slightly smoother response than the 8945P version, but slightly higher harmonic distortion also. The motor has shorting rings above and below the gap but not through it like the P version. Still, distortion is excellent by any standard. Very clean low end. Tested December 2006. Usher 8836A Cost: $101 Usability: Build Quality: Consistency: Value: Yellow Kevlar coned woofer. Excellent all around performance with a very smooth but rising top end and acceptable harmonic distortion, though not as clean as the 8945P. Excellent T/S parameters will allow for deep bass in a modest vented enclosure. This trunctated frame is not vented behind the spider like some of the better Usher woofers. Overall, a good driver for the price. Tested August 2008. Adire Extremis 6.8 Cost: $99 Usability: Build Quality: Consistency: Value: Comments: (discontinued) The Adire Extremis 6.8 uses Adire's XBL^2 motor design. It is essentially a dual-gap with a single short coil of a precise length that moves from one gap to the other during high excursion. At low excursion, it straddles partway into both gaps. It is a design that does indeed provide high output and a linear BL curve. This driver also has a thick copper sleeve through the motor which improves harmonic distortion but reduces sensitivity due to the larger gap required. Excursion is more suspension limited than motor limited. Response is relatively smooth, midrange HD excellent and low end HD average. Tested October 2005. B&C 6MD38-8 Cost: $92 Usability: Build Quality: Consistency: Value: This is a dedicated midrange and as such it's bass extension and performance are not part of these ratings, though +/- 2mm extends low end usability over many other dedicated midranges. It is a very sensitive pro driver with a cast frame and cloth accordian surround. Relatively smooth response curve with a mild breakup at 5kHz. Very clean lower midrange with a usable upper midrange. A solid 96dB at 8 ohms. If you need that kind of sensitivity in an 8 ohm midrange, this is a good driver for that purpose. Tested August 2008. Seas L18 (H1224) Cost: $86 Usability: Build Quality: Consistency: Value: Comments: The Seas L18 is an aluminum cone driver from their standard line. Response is very smooth, aside from the expected metal cone breakup. Harmonic distortion is good in the midrange and low end while being average near the top of it's range. Seas put extra effort into the cone profile of this version (H1224) and as a result the breakup node is relatively high and controlled for a 7" aluminum driver, making for a good 2-way system. Tested October 2005. Tangband W6-1721 Cost: $84 Usability: Build Quality: Consistency: Value: This is a high excursion woofer with an underhung voicecoil design. The motor is truly monsterous in size, probably the heaviest I've seen in a 7" woofer. Very clean and smooth midrange, and the underhung geometry should help it remain clean at higher output levels. Harmonic distortion is not very good below 50 Hz, even factoring in it's strangely peaking low end response. If using in a full low end capacity, this woofer's mild midrange droop and distortion profile will require less baffle step correction than is normal. Overall a nice and certainly unique driver. Tested August 2008. Aurum Cantus AC180F1 Cost: $84 Usability: Build Quality: Consistency: Value: Comments: An apparently well built woofer that is marred by some performance and consistency issues. A very high Qts severely limits usability. A 2nd sample tested also revealed a high Qts, though a bit lower along with a large difference in sensitivity. These are large strikes against consistency, and who knows what you'll get if you buy a pair. The response curve performance is average with a slight hiccup at 1100Hz. The harmonic distortion profile points to a simple motor that generally performs about as well as some under $30 woofers. Tested June 2009. Seas P18RNXP Cost: $78 Usability: Build Quality: Consistency: Value: Comments: Very similar to the L18 in frame and motor design, but with a poly cone and an improved surround. This has a very smooth and extended top end with no breakup whatsoever. Harmonic distortion is excellent on the low end but a little high above 800hz. Overall, a very usable driver that should be easy to cross over to just about any tweeter. Tested April 2006. ER18RNX Cost: $78 Usability: Build Quality: Consistency: Value: This is a new reed cone woofer from Seas. Construction is very similar to the older CA18 coated paper woofers, with one exception: the motor has a single copper sleeve mounted on the T-shaped pole piece below the gap. This is reflected in it's improved harmonic distortion performance in the midbass and lower midrange. HD seems to be somewhere between Seas Excel and standard line. Since this woofer is priced clearly within the rest of the standard line, value is very high. The response curve is relatively smooth with a mild breakup at 4.5kHz, which may need to be dealt with depending on how high it's crossed over. Tested June 2007. Peerless HDS 830883 Cost: $68 Usability: Build Quality: Consistency: Value: Comments: This is a midwoofer from Peerless' Exclusive line. Performance is generally excellent throughout, with low distortion of all types, a smooth response and mild breakup. Off center phase plugs have been visible on some HDS drivers but not bad enough to rub or affect performance. This driver's near flat impedance curve is a result of the great motor design with lots of copper is the right places. Overall a great driver. Tested December 2006. Seas CA18RNX Cost: $75 Usability: Build Quality: Consistency: Value: Comments: This Seas standard line paper cone driver has one of the flattest and most extended response curves in the group. T/S parameters are optimal for medium size vented enclosures. Excellent bass performance. Slightly higher 2nd and 3rd order HD in the midrange, but low tall order harmonics. Overall a well balanced and sensitive paper driver. Tested October 2005. Hi-Vi D6.8 Cost: $74 Usability: Build Quality: Consistency: Value: Comments: This Hi-Vi poly cone driver has a 3" voice coil with an inset magnet similar to Morel and Dynaudio woofers. The difference is that the Hi-Vi has a superior motor and outperforms them in the harmonic distortion department. If I were going to use this style of inset magnet woofer, I would choose the Hi-Vi over Morel or Dynaudio. I hope you like screwing, because the Hi-Vi has 12 mounting holes which is a bit excessive. Tested December 2006. Vifa XT18WH09 Cost: $71 Usability: Build Quality: Consistency: Value: Comments: This is the wood composite cone version of Vifa's top of the line woofer. The WH has a smaller magnet than the WO version and is best used in a sealed enclosure. Performance is generally good in both linear and non-linear distortion, better in the mids/highs and a little worse in the bass/midbass. The bass distortion profile lends this driver a somewhat warmer sound. A little more expensive than the XG18 Glass fiber version but performance is a little lower. Great build quality and a unique frame design. Tested January 2006. Seas CA18RLY Cost: $68 Usability: Build Quality: Consistency: Value: Comments: Very closely related to the RNX version, but with a smaller diameter voice coil and a smaller magnet give the driver a higher Qts. This makes it suitable for sealed enclosures. It has the same smooth and extended response as the RNX version. Tested October 2005. Fostex FF165 Cost: $64 Usability: Build Quality: Consistency: Value: Comments: Very sensitive wide range driver. Like the FE166ES-R, it doesn't exactly fit in with this group because it's designed to operate without a tweeter. Unlike the FE166ES-R, harmonic distortion levels are acceptable but the frequency response is not. There is a very large dip at 1kHz that was present in both samples. Very low maximum output due to a limited Xmax. Tested October 2005. Vifa XG18 Cost: $63 Usability: Build Quality: Consistency: Value: Comments: (discontinued) This is the glass fiber version of Vifa's high end woofer. It generally performs better than the wood cone version. Response is relatively smooth except for some minor roughness in the 4kHz area. It has extremely low upper midrange harmonic distortion, among the best in the group. HD on the low end is a little higher that normal however, and Xmax is rather limited. Would make a great midrange driver, and also works well in MTM's to help lower driver excursion for a given output level. This has a unique frame design. Tested October 2005. SB Acoustics SB17NRX35 Cost: $61 Usability: Build Quality: Consistency: Value: Comments: First and foremost, the build quality of this woofer is excellent. It looks like a $200 woofer. Harmonic distortion is excellent due to the thick copper sleeve over the pole piece. Particularly clean through the midrange, though higher distortion in the bass. Response is a little ragged with an odd shaped breakup node that will need special crossover work. The highish Qts means this is best used in a sealed enclosure. Overall, a value leader in this price range. Tested April 2008. Hi-Vi F6 Cost: $46 Usability: Build Quality: Consistency: Value: Comments: Beautiful looking yellow kevlar cone and cast frame. Acceptable harmonic distortion but some raggedness in the 3-4kHz range complicates the crossover and/or pushes the crossover point lower than most other drivers in this group. Tested October 2005. Fountek FW168 Cost: $45 Usability: Build Quality: Consistency: Value: Comments: Beautiful looking aluminum cone and cast frame with phase plug from the maker of popular ribbon tweeters. Good harmonic distortion thanks to a copper sleeve on the pole piece. Workable response curve with mild shelf at 1.8kHz and a typical metal cone breakup that will need to be resolved in the crossover. Favors a 2kHz or lower LR4 crossover, but will sound acceptable crossed higher. Tested November 2008. GR Research M-165X Cost: $45 Usability: Build Quality: Consistency: Value: Comments: This is a paper cone woofer with a well ventilated plastic frame and Adire's XBL^2 dual-gap, short coil motor design. The response curve is smooth with some mild breakup starting at 3kHz. Harmonic distortion is on the high side, and it's obvious that this motor doesn't have a copper sleeve over the pole piece like the Extremis or AA 6.5 poly. Sensitivity is relatively high, and the motor will remain linear at high output. The suspension is a bit too small to fully support the excursion the motor is capable of. Tested December 2006. Dayton RS180 Cost: $41 Usability: Build Quality: Consistency: Value: Comments: This Parts Express woofer has an anodized aluminum cone and black phase plug. It gives this woofer stealth fighter looks, but it does have the performance to back it up. Respectable harmonic distortion for this price range, and a very clean sounding low end. The response curve is very smooth, but the breakup has twin peaks that may be harder to manage in the crossover depending on how high you cross over. The low price, build quality and level of performance put this driver near the top of the value chart. Tested October 2005. Mach 5 MLI-65 Cost: $36 Usability: Build Quality: Consistency: Value: Comments: This woofer has a very good build quality however price has doubled since it was tested. There is a cast metal frame and a nice coated pulp fiber cone. The harmonic distortion isn't going to win any awards, but it's usable enough and the response curve is relatively smooth. This is a higher Qts, 4 ohm driver and will probably need to be in a larger sealed box for home use. It would work well in infinite baffle situations, including car doors. Consider aperiodic damping if you need to use it in a smaller sealed box. Tested December 2006. Ascendant Audio Poly 6.5 Cost: $35 Usability: Build Quality: Consistency: Value: Comments: (discontinued) This woofer uses Ascendant's dual-coil single gap motor design which is effectively the opposite of Adire's XBL^2 but serves the same purpose of allowing more excursion. It may also linearize the BL curve, but I'm unsure of that. The response curve is very smooth and extended. The harmonic distortion performance of this woofer is very low and it's the leader in this price range, thanks to a thick copper sleeve. Slightly higher 2nd order below 200Hz, but the low tall order HD should still allow this to sound good at the bottom of it's range. Like all the higher Xmax woofers in this group, the suspension will lock up hard before the motor runs out of Xmax. Somewhat highish Qts make this more suitable for a sealed box or very large vented. Tested December 2006. Silver Flute W17RC38-045 Cost: $30 Usability: Build Quality: Consistency: Value: Comments: well built cast frame with a wool fiber cone and a reasonably smooth response with a minor breakup at 5Khz. Average harmonic distortion performance, to be expected at this price point. Bass is relatively clean, though not as extended as others in this group. High sensitivity even for a 4 ohm driver. Overall a very usable and well built driver of good value. Tested June 2009. Dayton DA175-8 Cost: $26 Usability: Build Quality: Consistency: Value: Comments: This aluminum cone woofer from PE is a good value in this group and generally a good deal at this price. The harmonic distortion is good for a driver with a simple motor like this. The response curve is relatively smooth while the breakup node is benign and controlled enough that a notch filter might not be needed if you cross over low enough. The stamped frame surely helps keep the price low but doesn't impact performance too much. Tested October 2005. MCM 55-1860 Cost: $20 Usability: Build Quality: Consistency: Value: Comments: Same cone and surround as the DA175, but a different shielded magnet, a different spider and lower Xmax. The response curve is a little more ragged at the top end and harmonic distortion is a tiny bit higher throughout it's range. Overall, there's not a whole lot of reason to buy this over the DA175 unless it goes on sale and you need to save money. It does go on sale often. The frame is a poor design, requiring tiny screws to avoid mashing the edges. Tested October 2005. Dayton DC160 Cost: $20 Usability: Build Quality: Consistency: Value: Comments: This woofer does not perform very well, with horrible tall order harmonic distortion right smack in the midrange. The response curve between 1 and 2kHz is pretty rough also. Bass response is deep for a reasonable size enclosure, but there's not a whole lot of reason to pick this driver over some of the other under $25 woofers. Tested December 2006. MCM 55-1185 Cost: $14 Usability: Build Quality: Consistency: Value: Comments: This is a basic no frills poly driver from MCM with very low pricing. Harmonic distortion is not too bad for the price. The response curve does have a breakup at 4.7kHz that will require a notch to control. The same breakup causes a peak in 3rd order HD at 1700hz, which might ask for a crossover below that point. That rules out a cheap tweeter. High Qts requires a large sealed box and probably aperiodic damping. This is the cheapest woofer in this group, but you have to look at what you can get for a few bucks more. Tested December 2006.

Page done by John "Zaph" Krutke © 2005
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