# BC 8NDl51-8 8"



## npdang (Jul 29, 2005)

A big thanks to Blair for donating the drivers.

First impression upon looking at these drivers is that they are meant for serious business. No fancy chrome or finishes, just a clean minimalist design. Surprisingly, although not designed for car audio it incorporates many nice features such as venting of the spider through the holes in the plate holding the motor beneath the spider, rather than the usual method of large open windows in the basket which may attract dirt and moisture. And rather than a pole vent, there's a series of 6 holes drilled about the rear of the motor. As a nice touch, there's also a mesh screen covering all the openings in the driver. The paper cone is also treated on both sides for stiffness. And thanks to the neo motor, the driver sits just about as tall as your typical 7" driver in a much more compact form. The basket is a solid cast aluminum. All in all, very well built.


























xmag: 6mm 
xsus: > 8mm

Excellent Klippel results; among the best I've seen. Everything is well centered with an astonishingly low inductance variance and flat, extended plateau in the bl curve. Distortion performance is superb (not shown). Measuring the second driver in the pair showed similar results. Mechanical noise is low, although there is some lead slap. Although I don't have any measurements, I would suspect thermal performance is quite good given that this driver is marketed for pro audio, and the manufacturer's IEC power ratings.

Subjectively, I found the midrange performance to be good for an 8" paper cone driver... perhaps on par with the Seas CA18RNX. It's definitely warm sounding, and just taking a guess I'd say it's a result of poor energy storage performance in such a large, soft cone driver. FR gets a bit rough above 1khz as well, another indicator. Efficiency is quite good though, and definitely a strong point.

Overall, a well built driver with very low distortion. I'd suggest using it between 80-1khz ideally. Performance drops rather quickly beyond those limits. P-P throw is pretty limited around ~16mm, so you won't be able to get much low end output from this driver, but for midbass applications it should hit quite nicely in a car given the high efficiency.


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## MarkZ (Dec 5, 2005)

The FR looks a little odd on this thing. Am I right to assume that you're going to need some pretty heavy EQing if you want to use this thing down to 80Hz?


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## Whiterabbit (May 26, 2006)

looks to me like (on axis) a single wideband EQ cut strategically placed would relatively flatten the driver out to 2k easily. The rolloff seems pretty nice and predictable on the bottom end, making it ideal to match up to a subwoofer using a high crossover point.

I've noticed in many installs that a higher cutoff can ease subbass integration anyways.

I wonder if any EQ will be needed on the bottom end at all for this driver (unrelated to install conditions)


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## 300Z (Mar 20, 2005)

Are you guys forgeting about the cabin gain effects?


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## oldschoolsq (Nov 29, 2006)

Great write up  I am wondering how a JBL 2118H/J would compare to this driver


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## 300Z (Mar 20, 2005)

I would expect the B&C to be a bit better considering the JBL is over 20 years older then the B&C... lol


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## oldschoolsq (Nov 29, 2006)

300Z said:


> I would expect the B&C to be a bit better considering the JBL is over 20 years older then the B&C... lol



Older can be better


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## 300Z (Mar 20, 2005)

LOL... True.


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## bassfromspace (Jun 28, 2016)

NP,

If you have a pair of ribbons, try pairing them up with the 8's in car and see how you like it.


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## npdang (Jul 29, 2005)

Some EQ is definitely needed to get down to 80hz (you can see the driver drops -5db at that point), although this may vary with each car/install. Here's a comparison with some other drivers you may have heard... might help to determine whether or not eq is necessary for your personal tastes.


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## npdang (Jul 29, 2005)

bassfromspace said:


> NP,
> 
> If you have a pair of ribbons, try pairing them up with the 8's in car and see how you like it.


This driver doesn't fit in my car. Personally, I don't think it'd mate well to a ribbon which should ideally be filtered above 2khz at the very least.


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## fhl (Sep 20, 2006)

npdang said:


> This driver doesn't fit in my car. Personally, I don't think it'd mate well to a ribbon which should ideally be filtered above 2khz at the very least.


Any ideas on a tweeter that could work?

Frode


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## Tommythecat (Apr 6, 2006)

A horn, otherwise use as midbass.


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## SSSnake (Mar 8, 2007)

I've been running these in my car for about 1 yr now and I have been very pleased. With equalization these speakers perform very well down to 80Hz. I also have a pair of the 6MD38s that I am using as mids. If used with the 8" they are a very competent combination.


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## oldschoolsq (Nov 29, 2006)

SSSnake said:


> I've been running these in my car for about 1 yr now and I have been very pleased. With equalization these speakers perform very well down to 80Hz. I also have a pair of the 6MD38s that I am using as mids. If used with the 8" they are a very competent combination.


Are you using them with horns ? This is the exact setup I have been thinking about using , any negatives


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## SSSnake (Mar 8, 2007)

I am using them with:

Alpine DVA9860
Alpine H701
MB Quart QTD-25
B&C 6MD38 6.5" Mid
B&C 8NDL51 8" Midbass
IDMAX 12 D2V3 (3)
MTX 81000D (3)
MTX 8302 (2)
MTX 6304 (2)

I tried to go with horns but I never could get the high end (above 10K) to sound like I wanted it (I loved the in your face tone of the upper midrange tones but counldn't get them to go low enough to use as a mid or high enough to use as a tweet). If you are running horns that will get down to 1Khz or lower then you would only need the 8"s.

The only negatives is that to get the 80hz output where I needed it I had to tone down the higher freqs. If you are using horns I would try to see if you can get these in a ported enclosure (.35 cubes tuned around 75hz models very nice). I have been debating about trying to port mine. The driver's side would be easy but the passenger side would be VERY tough. Also, I am worried that the tight response could get a little more sloppy.


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## ca90ss (Jul 2, 2005)

If you're looking for a horn driver with good upper end response the BMS 4540nd has response up to 30khz although I wouldn't cross it lower than 1.6k.


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## SSSnake (Mar 8, 2007)

My problem is that I LOVE horn MIDS. If you find one that gets down in the 500Hz range it doesn't get to 20Khz. If you find one that gets to 20Khz it doesn't get to 500Hz. I know that some of the ID team members claim 500 Hz to 20Khz but I was not able to achieve this.


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## ca90ss (Jul 2, 2005)

Have you considered one of the larger coaxial horn drivers?
http://www.bmspro.info/index.php?show=item&usbid=10279&id=5059986
http://www.bmspro.info/index.php?show=item&usbid=10281&id=54369
http://www.bmspro.info/index.php?show=item&usbid=10281&id=54370
300hz-22khz


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## thadman (Mar 1, 2006)

I find it EXTREMELY hard to believe you could fit a true 300hz in a horn...even a 600hz horn sounds wildly impractical. The horn becomes so massive at that point that proper CTC spacing with the midbass is impossible. A 1.6khz horn body seems like it may work, but remember once the wavelengths overcome the horn they begin to refract all over the place and it loses its efficiency.

Ideally, you'd want a shallow wide horn as opposed to a deep oddly shaped horn otherwise you are going to mutilate your transient response and experience the horns refracting wrath at the edge of the mouth. This of course is impossible in a car, so I'd advise against using them completely.


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## DS-21 (Apr 16, 2005)

thadman said:


> I find it EXTREMELY hard to believe you could fit a true 300hz in a horn...even a 600hz horn sounds wildly impractical.


One could always rebuild the dash to incorporate the windshield into the flare, or do something like John van Ommen's really cool work with Unity horns in car. (Impractical from an aesthetic and theft-prevention standpoint, perhaps, but probably the only really interesting thing going on in car-fi right now.) 

Otherwise, you're right.


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## dBassHz (Nov 2, 2005)

Patrick Bateman is working on a unity waveguide that uses 2 2" Tang Band wideband drivers in 4th order bandpass enclosures coupled with a Alpine XT19 tweeter. He was previously using a BMS 4540nd and 3 Aurasound whispers but it was too large. He fabricated an eliptical waveguide that incorporates the dash, windsheild, and side windows as part of the flare. I'm still waiting on his results...

Check out his thread: http://www.audiogroupforum.com/csforum//showthread.php?t=62789


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## SSSnake (Mar 8, 2007)

If the horn bodies are mounted correctly to the bottom of the dash you can have freq responses that extend down to 500 Hz. Also, horn depth should not be considered a large issue, delay within the horn is miniscule (to the point many assume 0 delay).

The BMS products look interesting but there is VERY little detail to substantiate their claims. Do you have any personal experience and can you provide and measurements (I'm not doubting you but measurements help me tremendously)?


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## ca90ss (Jul 2, 2005)

SSSnake said:


> The BMS products look interesting but there is VERY little detail to substantiate their claims. Do you have any personal experience and can you provide and measurements (I'm not doubting you but measurements help me tremendously)?


I don't have any measurements but from my experience with the 4540nd's and 4552nd's they are very nice drivers. I also believe Chad has used them in some of his pro sound work and he had good things to say about them. Maybe he can shed some light on the subject.


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## Patrick Bateman (Sep 11, 2006)

DS-21 said:


> One could always rebuild the dash to incorporate the windshield into the flare, or do something like John van Ommen's really cool work with Unity horns in car. (Impractical from an aesthetic and theft-prevention standpoint, perhaps, but probably the only really interesting thing going on in car-fi right now.)
> 
> Otherwise, you're right.


Eek, how did you know my real name?

I try to keep that on the down-low, since I'm semi-well known in my "real" profession. (audio is just a hobby for me, software pays da bills!)


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## Patrick Bateman (Sep 11, 2006)

dBassHz said:


> Patrick Bateman is working on a unity waveguide that uses 2 2" Tang Band wideband drivers in 4th order bandpass enclosures coupled with a Alpine XT19 tweeter. He was previously using a BMS 4540nd and 3 Aurasound whispers but it was too large. He fabricated an eliptical waveguide that incorporates the dash, windsheild, and side windows as part of the flare. I'm still waiting on his results...
> 
> Check out his thread: http://www.audiogroupforum.com/csforum//showthread.php?t=62789


The new unity is documented over on diyaudio, since audiogroupforum seems to be kinda dead these days.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=117537&perpage=25&pagenumber=1

The inventor of the real Unity chimed in (Tom Danley.)
Earl Geddes, world renowned expert on waveguides has posted in the thread.
Mark Seaton, former coworker of Danley's is there too.
Jean Michael Le'Cleach, a well known horn expert from France has give his two cents also.


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## mitchyz250f (May 14, 2005)

I tried plotting these on WinISD beta for a ported box, they were flat to 100hz, but the 'vent mach' showed 'Qes/PE' instead of having a number, what does that mean?


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## trebor (Jun 30, 2008)

Could anyone that has this driver be kind enough to tell me the diameter and height of the neo portion of this driver? It's not mentioned anywhere in B&C's literature and it could mean the difference of whether or not it will fit in my door due to the position of the cross brace in there.


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## Oliver (Jun 25, 2007)

trebor said:


> Could anyone that has this driver be kind enough to tell me the diameter and height of the neo portion of this driver? It's not mentioned anywhere in B&C's literature and it could mean the difference of whether or not it will fit in my door due to the position of the cross brace in there.


Overall Diameter 225 mm (8.8 in)
Bolt Circle Diameter 210 mm (8.3 in)
Baffle Cutout Diameter 187 mm (7.4 in)
Depth 90 mm (3.5 in)
Flange and Gasket Thickness 11 mm (0.4 in)
Net Weight 1.8 kg (4 lb)
Shipping Weight 2.2 kg (4.8 lb)
Shipping Box 300x160x180 mm
(11.8x6.3x7.1 in)

50 mm (2 in) copper voice coil
70 – 3000 Hz response
94 dB sensitivity
Neodymium magnet allows a very light yet powerful motor assembly
Shorting copper cap for extended HF response
400 W continuous program power capacity
Ventilated voice coil gap for reduced power compression


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## trebor (Jun 30, 2008)

A valliant attemp Mr H, thank you but how about that diamater and height?  
It's not the overall depth and diameter I'm looking for, just the neo portion at the back, I haven't been able to find that info anywhere unfortunately. Can't figure why car manufacturers would want to put any obstruction where clearly a large speaker should go.


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## ClinesSelect (Apr 16, 2006)

If I am understanding what you are looking for, the machined "bump" is 1" tall and just under 3" across. If that is not it, let me know as I can measure what you need.


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## trebor (Jun 30, 2008)

Thats exactly what I'm needing, thank you sir!


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## sundownz (Apr 13, 2007)

I think I will be using these in my car


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## cbrunhaver (Jun 28, 2006)

Where is the least expensive place to purchase these? US Speaker is pretty expensive as compared to Parts Express.

I may just end up with the Eminence LA8-CNMB which is also quite a good performer, based on the Klippel data that I have seen on it.

-Chris


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## mikey7182 (Jan 16, 2008)

I just picked up mine through a guy in Colorado, who sources them from a B&C distributor out of NJ. I paid $140/ea shipped, BNIB. His site is here:

Best prices B&C Speakers,Eminence,Selenium, Custom speakers

His site isn't much to look at, but super nice guy and easy to deal with. He basically orders them wholesale and the distributor drop ships them (Price on the site is $119.95, then shipping was $20, and drop ship fee was an additional $20). They have been known to go on sale for as little as $110-$120 per, but those deals don't come up very often. FWIW, I absolutely love these drivers. I've only had them in for a day or two, but already they have made a noticeable improvement over the 18Sound 6ND430 I had. Tons of output, and more snap than a handful of rubber bands!


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## ca90ss (Jul 2, 2005)

B&C 8NDL51 8" Driver


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## cbrunhaver (Jun 28, 2006)

Thanks guys. 

I wonder what it takes to source these from B&C's us office in NJ? Maybe a group buy of a decent quantity could get favorable pricing from them.

I have had good luck in this regards form the guys at Eighteensound and others and so, while the B&C looks great, it is a good deal more expensive.


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## FoxPro5 (Feb 14, 2006)

cbrunhaver said:


> Thanks guys.
> 
> I wonder what it takes to source these from B&C's us office in NJ? Maybe a group buy of a decent quantity could get favorable pricing from them.
> 
> I have had good luck in this regards form the guys at Eighteensound and others and so, while the B&C looks great, it is a good deal more expensive.


The PS version (8PS21) is cheaper and is almost the same on paper T/S params wise, except it has 2mm less xmax. The major difference between the two is the overall weight due to the use of the neo mag on the NDL version. Also, the NDL has a weather-treated cone and a different former material.

I have the PS versions in my car playing 80-250hz with a 2 dB bump at 80hz. I'd definitely agree with what npdang said about the NDL's - to me the PS's are "warm" sounding, basically "neutral" and to my ears. Best thing about them is that when you ask them to crank, they don't back down...they just keep bringing it.

Zaph's test results and comments on the top of the page: http://zaphaudio.com/tidbits/


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## m115919h (Jun 12, 2008)

I would love to try that speaker out, but I will have to wait.


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## Patrick Bateman (Sep 11, 2006)

FoxPro5 said:


> The PS version (8PS21) is cheaper and is almost the same on paper T/S params wise, except it has 2mm less xmax. The major difference between the two is the overall weight due to the use of the neo mag on the NDL version. Also, the NDL has a weather-treated cone and a different former material.
> 
> I have the PS versions in my car playing 80-250hz with a 2 dB bump at 80hz. I'd definitely agree with what npdang said about the NDL's - to me the PS's are "warm" sounding, basically "neutral" and to my ears. Best thing about them is that when you ask them to crank, they don't back down...they just keep bringing it.
> 
> Zaph's test results and comments on the top of the page: Zaph|Audio


The cheaper one IS quite compelling. You lose a little xmax (5 vs 7) and the neo model has a bit stronger motor. The neo one has a higher MMS, likely to offset the extra motor strength.

But being able to get it from Parts Express, and saving a few bucks, is nice.

I went with the neo version in my old Accord because the enclosure was so absurdly small. The 8NDL51 is designed for a fairly large vented box, and I crammed it into the smallest sealed box I could, and put it UNDER my brake pedal. It's THAT shallow.


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## mitchyz250f (May 14, 2005)

Has anyone done a listening comparision of this driver and the JBL 2118?


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## SSSnake (Mar 8, 2007)

Yes. IMO (completely subjective) the 2118 is better. Not a lot, but it just seems to have more of that high efficiency POP. I don't know how to describe it any other way.


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## thehatedguy (May 4, 2007)

I know what you mean by "pop." Haven't had time to reply to your PM- whole family has had stomach virus this week.


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## SSSnake (Mar 8, 2007)

> whole family has had stomach virus this week


Sorry to hear about the family.

I wish I knew what spec gave you that pop. Efficiency is an indicator but you can rarely believe quoted efficiency. Somtimes the more I learn the less I understand.


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## thehatedguy (May 4, 2007)

JBL always specs their drivers in the pass band in which they are being used...usually like 100-500 hz. Which, I think gives a more realistic expectation of performance.


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## mikey7182 (Jan 16, 2008)

Mitch- I too prefer the 2118 to the B&C. The JBLs are, to put it like SSSnake, much more "poppy."  There is a sound to them that I don't think can be replicated. The Faital W8N8-150 is the closest thing I've heard, with the 2118 having a slight edge. The B&C are too laid back for me.


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## thehatedguy (May 4, 2007)

What about the 18Sound?


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## mikey7182 (Jan 16, 2008)

thehatedguy said:


> What about the 18Sound?


The 8MB400? ClinesSelect has a pair he tried out. Performance wise, he put them between the 2118 and the B&C IIRC. I have not tried them personally. The JBLs are my favorite in a 2 way with horns. The Faitals seem to have a little more low end than the 2118 though, so I am going to see how they perform as a dedicated midbass with some 6" Faital midranges I just picked up from azngotskills.


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## thehatedguy (May 4, 2007)

Amazing the 2118 used is about the same price as the others new. But JBL was always high priced.


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## mikey7182 (Jan 16, 2008)

thehatedguy said:


> Amazing the 2118 used is about the same price as the others new. But JBL was always high priced.


I've seen 2118 pairs go on eBay for $130 shipped. I think they sell for more here because of their value as car audio mids. But they definitely hold their value either way. I'd really like to find a pair of 800GTi now that I'll be running a dedicated midrange. I just put up a WTB in the Classifieds but they are pretty damn hard to come by, especially in good shape.


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## mitchyz250f (May 14, 2005)

I thought the Andy W. said in some post in DIYMA that the 800GTi was better for midbass than the 2218's. However, I just did a quick search and couldn't find it, so maybe I'm wrong.

2218's sell on ebay anywhere from 115 or so to 240 and maybe a little higher. The last set of H's I saw sold for $227. But I would rather buy from someone on this forum than on ebay. You have more leverage on the forum if you feel ripped off.

JBL 2118H 8" eight inch 8? Pair - eBay (item 160398861698 end time Feb-02-10 20:52:52 PST)


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## mikey7182 (Jan 16, 2008)

mitchyz250f said:


> I thought the Andy W. said in some post in DIYMA that the 800GTi was better for midbass than the 2218's. However, I just did a quick search and couldn't find it, so maybe I'm wrong.
> 
> 2218's sell on ebay anywhere from 115 or so to 240 and maybe a little higher. The last set of H's I saw sold for $227. But I would rather buy from someone on this forum than on ebay. You have more leverage on the forum if you feel ripped off.
> 
> JBL 2118H 8" eight inch 8? Pair - eBay (item 160398861698 end time Feb-02-10 20:52:52 PST)


The 800GTi were made as subwoofers IIRC, and have a lower Fs. They won't play as high as the 2118 so would be no good in a 2 way setup, but from 80-300hz in a 3-way, I bet they would be monsters.


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## cvjoint (Mar 10, 2006)

Can anybody explain to me why Xsus is >8mm?
To me it looks like the 75% point for cms is much earlier. In the tutorials it's something like 70% to 82% of rest BL and 75% of rest CMS. It seems like we're actually interested in 25% of rest CMS.


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