# KEF Kar S-250 10" subs



## Fellippe (Sep 15, 2006)

Some of you recall this recent thread on efficient 8/10/12/15" subs:

http://www.diymobileaudio.com/forum/showthread.php?t=29891&highlight=s-250

Today I put in the BNIB 10" subs in exchange of the 2 JL 10W6v2 already in there.

Here's the spec for the 10" S-250:

10": 91 db 1w/1m, 4 ohm, 200W, fs = 25 hz, qts = .25 , vas = 4.0 cubic feet

Both subs came with a printout of the tested T/S parameters (in amusing dot matrix printer type paper, circa 1999, lol). 

The first thing you notice between the two subs VISUALLY is how much larger the JL is. The voice coil and all is much larger....sitting the two side by side on a table, the JL is about 3-4" taller. 

So naturally these shop guys are laughing, thinking the KEF is a POS and the JL is god's gift to subs. They go on about it for awhile, etc...gets kinda annoying. They forget the part that I pretty much have bought all of their flagship products (Morel Elate, Alpine PDX, JL slash, JL W6) and have built up this huge reputation as being extremely picky.....and now I'm going to pick up a "POS" woofer?? 

So the summary is this:

The KEF sub outperformed the W6v2 in every SQ category while delivering similar SPL levels. I'm still under the break in period, so naturally I'm not pushing the limits for low frequency extension or SPL...but I have listened at fairly high listening volumes nonetheless. 

Here's how the KEF improves on the overall SQ experience:

1. No overhang - the W6 clearly demonstrates overhang in comparison to this sub. The W6v2 is a bit "thick" in the lower frequency range, whereas the S-250 just plays the music. Definitely a tighter woofer.

2. Midbass is punchier - the more pronounced the midbass kick in the 80-100 hz range, the more you will see the benefit. Also, the midbass sounds fuller especially with songs that emphasize a warm bass sound...

3. Bass up front is somewhat more prevalent...the bass sounds more in the cabin than it did before. 

4. Bass instruments are more accurate/natural sounding. 

It will be a few more weeks before final break in is set. I'll have definitive SPL and low bass comparisons by then. 

The W6 may appear to sound "deeper" but it's really just the overhang and thickness of the sub. For some people they prefer that 'rumble' and now I can clearly see the appeal of the W7, the ultimate rumbler of subs. However, the rumble is not SQ or true deep bass.

Sometime in the spring/summer I'll dial in the tuning more when I let my friend play with the system. I've considered stuffing the box with some polyfill...

This subwoofer is more subtle in its presentation. For those who have listened for awhile now with various subs and are discerning SQ enthusiasts, I cannot speak more highly about it!

The KEF 10" sub joins the Phoenix Gold MS275 and MS1000 as legends from yesteryear that are top notch products that can be had in new condition for less than a lot of ish that is out there now.


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## Oliver (Jun 25, 2007)

Very nice ! very informative ! Thank You for the review  

I think the JL subs were aimed at a different sector as opposed to the Kef's,[DIYMA],subs


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## havok20222 (Sep 5, 2007)

I love my Kef home speakers. They really put a lot of quality into all of their products from top to bottom.


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## quality_sound (Dec 25, 2005)

I always did like those subs. It was a sad day in the shop when they stopped distributing the car line in the states.


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## WLDock (Sep 27, 2005)

Fellippe said:


> Here's how the KEF improves on the overall SQ experience:
> 1. No overhang - the W6 clearly demonstrates overhang in comparison to this sub. The W6v2 is a bit "thick" in the lower frequency range, whereas the S-250 just plays the music. Definitely a tighter woofer.


While, I would think those KEF's are nice sounding drivers and I am sure the low Qts. design (QTS .25) is producing a more rolled off low end vs. the W6 (Qts .469) and naturally many perceived this as cleaner sounding bass. I am sure many minimalist audiophile types would love the sound of the KEF. Some still like the sound of the IDQ over the W6. Also, there are some that still swear by the Uni-Q drivers...so KEF was doing somethings right back then.

On the other hand, the W6 does have good low-end output and based on my listening test...I find it hard to call the W6 "thick" sounding. Many bass heads don't like them because they don't sound thick enough. The BL curve on this thing is VERY linear. I think that is the best curve I have seen since I ever knew what a BL curve was.... Well, I think I know what it all means? Still need to try one in my own car, Want to play around with a 13W6.

JL Audio 12W6v2-D4 

















Anyway, W6's have great potential but there are many variables that will have and effect on the final output. I think many cars have serious bass boost that bloat the sound of even a modest sealed sub. Maybe a low Q works better for many? WinISD shows the difference....The KEF drops off a bit before the W6: http://img.photobucket.com/albums/v711/WLDock/Car Audio/10W6vsS-250.jpg



Fellippe said:


> The W6 may appear to sound "deeper" but it's really just the overhang and thickness of the sub. For some people they prefer that 'rumble' and now I can clearly see the appeal of the W7, the ultimate rumbler of subs. However, the rumble is not SQ or true deep bass.


Again, I don't consider the W6 a "rumbler" ....The TC Sounds TC9 has more of a rumble to me. None the less, response graph show that the W6 to be pretty linear at 40Hz and 80Hz in car measurements. 

_"SPL in-car measurement at 2.83 volts, 1 meter Peak reading non-weighted
40Hz: 100.0dB
80Hz: 100.3dB
Max SPL: 129.7dB"_

I am not a JL fanboy nor am I defending it just because..... but based on the potential of the sub and what I heard when I listened to it, it seem you got different results with the sub in your car. I can think of a lot worst and thick sounding subs than a W6....and the design combined with the measurements indicate that this sub should be clean even as it approches max. So, I would think a sub with the design of the KEF would sound less bloated and get fairly loud with the high sensitivity. But, I guess I wonder if the W6 is sounding as best as it could in your car? Is there something that can be done to alter the response? I would think so....
Well, I guess it is always nice to find a sub that suites your taste and "works" in "your" car. enuff said!

Thanks for the review!


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## Fellippe (Sep 15, 2006)

WLDock said:


> While, I would think those KEF's are nice sounding drivers and I am sure the low Qts. design (QTS .25) is producing a more rolled off low end vs. the W6 (Qts .469) and naturally many perceived this as cleaner sounding bass. I am sure many minimalist audiophile types would love the sound of the KEF. Some still like the sound of the IDQ over the W6. Also, there are some that still swear by the Uni-Q drivers...so KEF was doing somethings right back then.
> 
> On the other hand, the W6 does have good low-end output and based on my listening test...I find it hard to call the W6 "thick" sounding. Many bass heads don't like them because they don't sound thick enough. The BL curve on this thing is VERY linear. I think that is the best curve I have seen since I ever knew what a BL curve was.... Well, I think I know what it all means? Still need to try one in my own car, Want to play around with a 13W6.
> 
> ...


You're welcome...glad some people found it informative. 

I don't think the W6 is a bad sub by any means. It's just not at the upper echelon audiophile level.


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## 3.5max6spd (Jun 29, 2005)

Fellippe said:


> You're welcome...glad some people found it informative.
> 
> I don't think the W6 is a bad sub by any means. It's just not at the upper echelon audiophile level.


Nice Review Felippe. Cant wait to hear them.
I thought the w6 sounded nice in your car but for some reason tended to lay it on too thick at times, while no where as bad as other drivers I've had the pain of listening to, it def had its point of peakiness where it took away from it extending smoothly other information as you expect a driver to do at a specific amplitude. Could've been the enclosure, or level matching or tuning...but i'm glad you are getting a smoother response in car now with your new setup.

I'm not against high xmax drivers, but i do feel theres a point of diminishing returns for their use in the car.Theres only so much air you need tossed around in such a compact environment in a level matched SQ system, specially running multiple drivers.


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## WLDock (Sep 27, 2005)

3.5max6spd said:


> I'm not against high xmax drivers, but I do feel theres a point of diminishing returns for their use in the car.Theres only so much air you need tossed around in such a compact environment in a level matched SQ system, specially running multiple drivers.


Great points! For moderate to loud SQ listening there is only so much bass one needs and tunning is the key. Tunning makes it possible to blend two 15" subs powered with 2000 watts and crossed over low, with two 8" drivers in the front and not overpower the rest of the system. 

And it seems the subs from JL Audio create some of the most wildly varied opinions about the quality of the sound. W7's and W6's have been measured and are proven products in terms of linearity, frequency response, low distortion, output, etc. However, some see these as bass heavy monsters and others see them as modern technology SQ marverls? As with anything car audio related results will vary and tunning will ALWAYS needed but different drivers in different vehicals in different enclosures will Always sound different. There is one upper echelon audiophile level car that we all knew of that had a W6 in the rear... 

I would not mid hearing that KEF....I am sure I have an idea what they sounds like. Having heard the old school Infinity Beta series, PPI PRO, Coustic DR, Soundstream Exact, IDQ, IDW, etc back in the day. That was the sound I was after....especially when the local shop was trying to sell me some Rockford Punch subs.


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## 98 SNAKE EATER (Mar 19, 2008)

Newb here with a few KEF questions :blush: 

Are the KAR S-250's the same as the old KAR 250B's  

I just picked up another pair of 250B's for my daily beater  




























I got my first pair over 15 years ago and have been a KEF nutswinger eversince 


Back in the day, I actually had them in a custom bandpass enclosure :blush: (my basshead phase)

http://www.youtube.com/watch?v=HLjLHNKPkJI

I know, I know...... wtf was I thinking?  

They actually sounded great in there and the output was insane for just a pair of 10's  

I later tossed the box and put them to far better use in my home theater system  


Anyhoo, they'll be going in the back of my Land Cruiser...











Thing is, I can't decide what type of enclosure to go with  (sealed, ported, downfire, isobaric, etc., etc.)

My old KEF brochures say they're _FREE AIR_, but I have yet to see them used in that manner  

I've long outgrown my basshead days and SQ is now top priority  

What do you suggest?





Rick


*98 Aztek T/A WS7*
*70 Ram Air IV T/A*
*97 FZJ80 Locked*
*00 Lifted G16E*
*GhettoChopper*


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## DS-21 (Apr 16, 2005)

98 SNAKE EATER said:


> Newb here with a few KEF questions :blush:
> 
> Are the KAR S-250's the same as the old KAR 250B's


No. Yours are English-made KEFs. The Coustic-made S250's have more in common with the old Infinity Beta line or Coustic Design Reference line than with your echt KEFs.

Both are good subs, though.


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## 98 SNAKE EATER (Mar 19, 2008)

DS-21 said:


> No. Yours are English-made KEFs. The Coustic-made S250's have more in common with the old Infinity Beta line or Coustic Design Reference line than with your echt KEFs.
> 
> Both are good subs, though.




Have any pix of the S250's?


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## vmaxnc (Mar 22, 2008)

I saw these subs but never got to hear them.


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## DS-21 (Apr 16, 2005)

98 SNAKE EATER said:


> Have any pix of the S250's?


No, but they look like an Infinity Beta or Coustic DR (shiny mica-filled poly cone, etc.) inside a basket similarly styled to the echt KEF sub basket.


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## 98 SNAKE EATER (Mar 19, 2008)

DS-21 said:


> No, but they look like an Infinity Beta or Coustic DR (shiny mica-filled poly cone, etc.) inside a basket similarly styled to the echt KEF sub basket.



Yeah, found these on FleaBay earlier :blush:


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## 98 SNAKE EATER (Mar 19, 2008)

Sorry to rehash such an old thread, but just a heads up for anyone looking to buy an English made KEF 250b, there's a guy on fleabay selling a pair right now 

Kef Kar 250B 10" subwoofer new, never used. - eBay (item 270305265944 end time Feb-16-09 20:40:16 PST)

Kef Kar 250B 10" subwoofer used but in near new cond - eBay (item 270305538828 end time Feb-17-09 12:15:43 PST)


Items # 270305265944 and 270305538828


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## Chuck (Jan 15, 2009)

DS-21 said:


> No. Yours are English-made KEFs. The Coustic-made S250's have more in common with the old Infinity Beta line or Coustic Design Reference line than with your echt KEFs.
> 
> Both are good subs, though.


Once again I fulfill my office as official resurrector of old threads to destroy a myth. Every once in a while this story of Coustic making components for KEF pops up, and I have to smack it down. Never, ever, at any point in history, did Coustic make KEF drivers. Coustic was KEF's US distributor. 

This is direct from Ron Locke of KEF:

"Coustic USA were our automotive loudspeaker distributor for the US. They at no point ever manufactured our loudspeakers, they purely sold them
alongside their amplifiers and head units. "

Hope this helps spread the truth.

Carry on.


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## 98 SNAKE EATER (Mar 19, 2008)

Ah, a blast from the past :blush:


Here's what I ended up doing with my Cruiser:


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## DS-21 (Apr 16, 2005)

Chuck said:


> This is direct from Ron Locke of KEF:
> 
> "Coustic USA were our automotive loudspeaker distributor for the US. They at no point ever manufactured our loudspeakers, they purely sold them
> alongside their amplifiers and head units. "
> ...


He is wrong. Perhaps Coustic was the distributor for KEF Audio UK's KEF KAR brand for time. But in the mid-late 1990s KEF licensed out their KEF KAR brand to Coustic, who not only released a Rich Coe designed set of KEF KAR branded speakers and subwoofers (some containing some KEF technology) but also a series of KEF KAR branded amplifiers and crossovers. There may have even been a headunit.


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## Chuck (Jan 15, 2009)

Again, I'm going to have to say no to that. That info was from an email exchange that took place in mid-2000, and at the time he was the head of customer support at KEF (Tovil) in the UK. I was asking him about the UniQ drivers and that impossible to kill rumor that Coustic may have been involved in their production. He was very adamant that Coustic was not part of production. They may have packaged and marketed the drivers you're talking about, but they never did any manufacturing.


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## Chuck (Jan 15, 2009)

98 SNAKE EATER said:


> Ah, a blast from the past :blush:
> 
> 
> Here's what I ended up doing with my Cruiser:


Uh excuse me - whats that big empty area between the subs? Shouldn't there be a couple more woofers there? :laugh:


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## 98 SNAKE EATER (Mar 19, 2008)

Chuck said:


> Uh excuse me - whats that big empty area between the subs? Shouldn't there be a couple more woofers there? :laugh:



That's my trunkspace :blush:


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## DS-21 (Apr 16, 2005)

Chuck said:


> Again, I'm going to have to say no to that.


You are, of course, free to be wrong. 



Chuck said:


> That info was from an email exchange that took place in mid-2000, and at the time he was the head of customer support at KEF (Tovil) in the UK. I was asking him about the UniQ drivers and that impossible to kill rumor that Coustic may have been involved in their production. He was very adamant that Coustic was not part of production. They may have packaged and marketed the drivers you're talking about, but they never did any manufacturing.


Well, I have an e-mail from the KAR 160Q's designer - who went on to design the TAD Model One and other speakers for TAD - ca. 1998 that the general mentality at KEF was that car audio was an ugly stepchild, so perhaps their customer support was simply ignorant.

That may technically be true, in that I don't know whether Coustic had any intrinsic manufacturing capabilities. However, it is clear that they _designed_ a line that ended up being sold as "KEF KAR." The buildhouse that actually _manufacturered_ them, I don't know and frankly don't care that much. Perhaps KEF Audio UK did in fact manufacture the Coustic-licensed Uni-Q's, even though they shared no parts with prior or future KEF product. (As an aside, isn't it interesting that the gentleman specifically mentions Uni-Q drivers, and not subs, separates, crossovers, etc.)

Do you think KEF magically for the period of a year or two - CoustKEF being a market failure - decided to adopt things like IMG cones and a bunch of other design features that were right out of Rich Coe's designs for Infinity and then Coustic's Design Reference lne? Design features that never appeared in any KEF home speakers. 

Of course, the pre-Coustic KEF KAR Uni-Q's (black cone) are different. They share tweeters with the then-contemporary KEF Reference line, for instance.


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## K.I.T.T. (Jul 22, 2009)

Greetings from England 

I'm probably going to get told off for reviving this thread AGAIN, especially in my first ever post 

I thought it'd be better asking here than starting a new thread. Would anyone be able to tell me the optimum sealed enclosure size this sub needs from an SQ point of view? I've tried looking on the net with no success and KEF's website isn't much use either 

Any help would be greatly appreciated!

Regards,
Ash


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## 98 SNAKE EATER (Mar 19, 2008)

K.I.T.T. said:


> Greetings from England
> 
> I'm probably going to get told off for reviving this thread AGAIN, especially in my first ever post
> 
> ...



When I contacted KEF UK, they old me 1cf.



> *Dear Sir,
> These drive units would sound best if they are each in a sealed enclosure. A cubic foot would be the best size enclosure. This will give the subs plenty of punch and allow them to hit low frequencies. Due to in car cabin gain they should have a 12 dB boost, giving a smooth roll off.
> 
> Best Regards
> ...




I also contacted KEF North America and they said 1.7cf



> *Hello Rick
> The recommended volume for the 250 closed box is 2,900 cubic inches.
> 
> Have a good day
> ...





I went with KEF UK and used 1cf. sealed cubes


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## cregan6318 (Jun 22, 2009)

havok20222 said:


> I love my Kef home speakers. They really put a lot of quality into all of their products from top to bottom.


Ditto I may have to look into these


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