What ohm woofer? Puzzle!

boo3000 · 24th November 2010, 01:02 PM

Hi, i have a pair of speakers that i bought missing woofers for a repair job, this turned out to be more difficult than i thought as the company which made the speakers won't tell me exactly which woofers were used in these speakers! To work it out i need to find out what resistance the original woofers were, the speakers have a nominal impedence of 8 ohms, the tweeters have nom/mini impedence of 8/6.3 ohms, judging by this schematic can anyone tell me what impedence my replacement drivers should be?

http://www.krksys.com/documents/9000b_schematic.pdf

Any help greatly appreciated!
Thanks
Justin

macboy · 24th November 2010, 01:54 PM

If the speaker is nominally 8 ohms, then the woofer is nominally 8 ohms too.

head_unit · 24th November 2010, 02:51 PM

I hate to be the first to tell you this, but it's not that simple. The woofer, tweeter, and crossover are all interdependent, and the crossover is designed for those EXACT tweeters and woofers. If you wanted the speakers to sound the same, you would really need the exact same woofer. Sticking some other woofers in there might work OK or might sound awful.

Can't you order the exact replacement woofers?

You might get more responses if a moderator changed the thread title. I'm not sure to what, but "What woofers to put in KRK 9000b cabinets?" or such.
- Are the speakers indeed KRK 9000b?

boo3000 · 25th November 2010, 10:05 AM

Hi, yes it is a krk 9000b that i need a replacement woofer for, the problem is that the original woofer was made by cabasse, and krk no longer deal with them. Krk are telling me that the original woofer was a 21m18lb4 but when i check this with cabasse there were a few variations of this woofer made, some 4, some 8 and some 16 ohm. So if i can just figure out the resistance of the original woofer i can get some replacements on the second hand market. Is it possible to calculate the resistance from this schematic?

sreten · 25th November 2010, 12:34 PM

Hi,

0.7mH on the bass mid unit is consistent with an 8ohm unit with no BSC.
With a 4 ohm unit the speaker would have to be nominally 4ohms.
The 16 ohm units I'd say were only used in pairs.

rgds, sreten.

24th November 2010, 01:02 PM	#1
boo3000 diyAudio Member Join Date: Nov 2010	What ohm woofer? Puzzle! Hi, i have a pair of speakers that i bought missing woofers for a repair job, this turned out to be more difficult than i thought as the company which made the speakers won't tell me exactly which woofers were used in these speakers! To work it out i need to find out what resistance the original woofers were, the speakers have a nominal impedence of 8 ohms, the tweeters have nom/mini impedence of 8/6.3 ohms, judging by this schematic can anyone tell me what impedence my replacement drivers should be? http://www.krksys.com/documents/9000b_schematic.pdf Any help greatly appreciated! Thanks Justin

25th November 2010, 12:34 PM	#5
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, 0.7mH on the bass mid unit is consistent with an 8ohm unit with no BSC. With a 4 ohm unit the speaker would have to be nominally 4ohms. The 16 ohm units I'd say were only used in pairs. rgds, sreten. __________________ There is nothing so practical as a really good theory - Ludwig Boltzmann When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

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24th November 2010, 01:54 PM	#2
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	If the speaker is nominally 8 ohms, then the woofer is nominally 8 ohms too.

24th November 2010, 02:51 PM	#3
head_unit diyAudio Member Join Date: Feb 2004 Location: Los Angeles	I hate to be the first to tell you this, but it's not that simple. The woofer, tweeter, and crossover are all interdependent, and the crossover is designed for those EXACT tweeters and woofers. If you wanted the speakers to sound the same, you would really need the exact same woofer. Sticking some other woofers in there might work OK or might sound awful. Can't you order the exact replacement woofers? You might get more responses if a moderator changed the thread title. I'm not sure to what, but "What woofers to put in KRK 9000b cabinets?" or such. - Are the speakers indeed KRK 9000b?

25th November 2010, 10:05 AM	#4
boo3000 diyAudio Member Join Date: Nov 2010	Hi, yes it is a krk 9000b that i need a replacement woofer for, the problem is that the original woofer was made by cabasse, and krk no longer deal with them. Krk are telling me that the original woofer was a 21m18lb4 but when i check this with cabasse there were a few variations of this woofer made, some 4, some 8 and some 16 ohm. So if i can just figure out the resistance of the original woofer i can get some replacements on the second hand market. Is it possible to calculate the resistance from this schematic?

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