I have just refoamed my CX100's and noticed that the top and bottom drivers are slightly different. They have part numbers 1 apart and one of them (cant remember if its top or bottom now) has a hole in the back of the magnet.  I always thought they were the same top and bottom and was wondering what the difference between them was.

By the way, refoaming CX's it quite a pleasant and satisfying task, if a little messy with the old foam!

One of them has a hole in the back!!

The one with the hole is the bass driver the other the midrange.
It is one of the easier ones to refoam but fun non the less

joeyboygolf:

One of them has a hole in the back!!

  Boom Boom!

Kevin:

The one with the hole is the bass driver the other the midrange.
It is one of the easier ones to refoam but fun non the less

CX100's don't cross the woofers over at two different frequencies.  It's a basic 2-way crossover.  B&O used woofers from different sources throughout the long life of the CX100 range (even though the specifications on them would have remained identical), so I wouldn't be surprised if you just happened to have one pair that was made during a time when they were transitioning between two woofer suppliers.  It's more typical to see CX100's in which both woofers are identical.

camshaft:

Kevin:

The one with the hole is the bass driver the other the midrange.
It is one of the easier ones to refoam but fun non the less

CX100's don't cross the woofers over at two different frequencies.  It's a basic 2-way crossover.  B&O used woofers from different sources throughout the long life of the CX100 range (even though the specifications on them would have remained identical), so I wouldn't be surprised if you just happened to have one pair that was made during a time when they were transitioning between two woofer suppliers.  It's more typical to see CX100's in which both woofers are identical.

I disagree here. All the CX100's I've seen have one driver with a hole in the back and you can still order exact replacements. The spares database has two different part numbers for the drivers!

Hmm, interesting Graham.  I could have sworn the two woofers on the pair I'm working on now are the same.  I'll check later today.  I don't really see much of an advantage in having two slightly different woofers in a 2-way crossover though.

All the ones I have seen are as Graham describes. However I understand that replacing one with a hole in with one without seems to make no difference at all!

Heh, I just went downstairs and checked, you guys were right.  The "hole" I remembered being in both was just a "dimple" in one of them.  Sorry about that.  I hate when people like myself go around talking about things as if they know without having actually checked
 

The crossover is actually a partial 3 way.... call is 2.5 way if you like!

One woofer just covers the bass, the other covers bass and midrange.

 

Cheers,

Ben.

Glad to see this caused some confusion

Cheers for clearing it up for me.

They are indeed different:

8480174 Upper Woofer (closed magnet) - also used in CX50
8480173 Lower Woofer (ventilated magnet)

Martin

Dillen:

They are indeed different:

8480174 Upper Woofer (closed magnet) - also used in CX50
8480173 Lower Woofer (ventilated magnet)

Martin

Just so I don't feel left out - yes they are different. BTW the part number has changed for the replacement bass driver, unfortunately I can't remember where I wrote it down.

 

Chris.

Come on guys I already said I was wrong, stop rubbing it in 

Hi,

I new to this forum (recently joined)

I have recently aquired a pair of cx100s, and just finished refoaming them. The woofers in my units are absolutely identicle (no holes on either), but examination of the crossover suggests that they are indeed crossed over at different frequencies- the negative leads of the upper and lower woofers are connected to the same terminal on the crossover, but the positive leads attach to different places on the crossover. This suggests to me that one woofer handles low bass, while the other deals with upper range bass and midrange. I read somewhere recently that putting more speaker insulation into the cabinets improves and tightens the bass. Has anyone tried this and can confirm? I've also read that the crossover frequencies can drift with age, due to the capacitor drying out. New, higher quality capacitors can apparently make a noticible sound difference. Any comments?

Thanks,

James

Hey James!

I have stuffed my cx100's with acousta-stuf and also changed the caps for polypropylene ones.  The difference is minimal but noticeable.  If you heard the speakers alone you may not hear the difference.  But if you play them side by side with un-modified cx100's, the bass does sound tighter.  I'd describe the speaker as sounding a tad less hollow.  I never bothered to try each mod separately though, so I don't really know which difference I'm hearing.  As for the caps, you just need to replace it with a polypropylene cap.  Going with a very expensive polypropylene cap won't give you any audible difference over a cheaper polypropylene cap.  The only problem is that some of the really cheap polypropylene caps are cheap Chinese knock offs that are actually just electrolytics.  Seeing that you're -5 GMT I'm guessing you're in the US with me.  In that case, you can order the speaker stuffing and caps from partsexpress and try it yourself for about $15.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=027-424

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=260-317

 

(testing)

Thanks for the advice-

I'm having difficulty reading the label on the capacitors... I can see "din 41236 bipolar." There's more, but I can't read it. Would you happen to know the other info I need to order new caps?

Thanks!

James

The link I posted is the exact cap you'd need.  It's a 6.8uF

After posting I compared them again.  I have to tell you, the difference is very small.  Unless audio is a hobby for you as it is for me, it may not be worth your time.
 

Thanks again Austin,

I'll give it a try nonetheless- It is becoming again somewhat of a hobby for me, as it was back when I was a teenager.

Here's my setup: I'm considering a pair of used 2yr.old B&O 8000s, to use as my main speakers in my living room (I have the cx100s in my study). The 8000s may replace the "Large Deluxe Advent" speakers I've had since 1978 (recently refoamed, for the second time, and considering repacing the caps in their crossovers too). I'll then use the preamp section in my classic NAD 3020 integrated amp for the 8000s; and an Adcom amp will drive the Advents. These Advents still sound great- fabulous tight and deep bass (better then the 8000s in that category, but I'm sure their soundstage, imaging and clarity is poor compared to the 8000s). I'll use the Advents as rear speakers (though not a true 5 theater setup- I don't want to sacrifice sound quality for surround sound), and the cx100s will be driven by the small amp that's in the NAD 3020. I've also got a mint late 80s beogram 9500 turntable with a Soundsmith mmc1 pickup.

Thanks again for advice- I'll order the acoustic packing stuff and the caps, for both the cx100s and my old Advents.

James

Hey James, that sounds like a nice setup, but I personally wouldn't recommend the 8000's for the money, even though they look great.  At moderate/causual listening volumes, I actually don't think they sound a whole ton better than the CX100's with a good amp (*guards membership with fearful eyes*), even though they cost over 5 times as much.  You're in the US right?  If you look at ebay, there are a couple Penta 2's up for auction now.  They'll cost you less than half the price of the bl8000's, and in my opinion would sound significantly better.  Remember that in the mid to late 90's, both the 8000's and the Pentas were being sold at the same time, with the Pentas costing much more, being the top of the line speaker.  Ironically, the Pentas are now worth less than half the price of used 8000's, simply because the 8000 is still being sold.  Therefore it's considered a current product.

http://cgi.ebay.com/Bang-Olufsen-B-O-6623-Beolab-Penta-2-Speakers-NICE_W0QQitemZ120242782242QQihZ002QQ

http://cgi.ebay.com/NICE-PAIR-of-BANG-OLUFSEN-5-foot-TOWER-SPEAKERS-NR_W0QQitemZ280215597447QQihZ018QQ

Austin,

My only complaint with the pentas is there sheer size. I was recently in a B&O store in Toronto (where I'm from, but living in the U.S. at present), and had a good long listen to the 8000s- I thought they sounded fabulous (and from a regular CD on a Beocenter 1 -the eliptical one). I would imagine they'ed sound even better with my NAD preamp and high quality vinyl on my Beogram 9500. I compared the 8000s to Beolab 3s, and thought the 8000s have a richer, fuller sound, if not as wide a soundstage (though I was not able to switch back and forth from one to the other- had to take the CD to another setup... I wish they would allow speakers to be compared apples to apples from the same set up with a switching board). Anyway, while I'm impressed by the sound of the cx100s for their size, I can't imagine that they could compare to 8000s, which have larger, presumably higher quality drivers, more cabinet volume, and dedicated, carefully matched and poweriful internal amps (agree?). I've been looking on ebay for 8000s, generally running for about 2gs in the last few months. Also, I think pentas look a little dated compared to the 8000s (I'm an architect, and therefore an aesthete!). There's a pair of 8000s on ebay market now that are 2 yrs old, and have the driver or amplification upgrade from about 6 yrs ago that alledgedly improves low bass response.

James

Another question for you...

I took the back off the cx100s, and the cap that's there says 6.8uf 63 v- does it make a difference if the replacement cap is 6.8uf 250 v?

I had a second look at the woofer magnets... and I was wrong! The bottom woofer dies indeed have a vent hole, the top woofer does not!

James

James,

You can use a higher voltage version, but it is also likely to be physically larger as well

For the cap, the voltage doesn't matter.  The 250v one is fine.  That's what I used.

As for the CX100's vs the 8000's, I was careful to say at moderate listening levels (I often listen to music casually while studying or something like that, and don't turn the volume up much).  I'm sure once you turn the volume up, then the 8000's advantage over the CX100's will become very apparent.  As for the drivers, they are actually the same size in both speakers.  Both have two 4" woofers and one tweeter.  As you said though, the 8000's benefit from more volume and better amps.  Increasing the volume of the enclosure can give you a lower bass extension for the same size woofer, which is what the 8000's have done.  I agree that the 8000's look great though, and I can't fault you for loving the style. I've occasionally seen good looking 8000's go for as low as $1800.  Given how bad our economy is right now, this is definitely the time to buy big ticket items like this, but still exercise some patience.  Everytime I see an item on ebay that makes me say to myself "wow, I'll probably never see that again on ebay, or at least not for a price like that," I typically end up seeing it again within 3 months.  With something as expensive as these speakers though, you may want to wait until you find a pair close enough that you can drive to see them in person before making the final transaction.

By the way, I'm by no means an 8000 expert, so take my opinions of them lightly.  The woofer size I know is correct though. 

Good luck!