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Old 30th January 2012, 08:37 PM   #1
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Default Repairing 3 way speakers (Looking for some help)

I have a pair of speakers with the 3 way system broken. I bought woofer, mid, and tweeter to repair them.



Woofer: MHB Subwoofer 200 mm 8 Ohm
  • Specs: paper cone, 100 W Max, 90dB, 45-9000Hz, 8 ohms.


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Mid: Goldwood GM-35 5.25" Midrange + 6.8µF capacitor (Filter)
  • Specs: Paper cone, 3 oz. magnet, .75" KAPTON voice coil, 40 watts/RMS, 97 dB, 600-15,000 Hz, 8 ohms.


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Tweeter: Sound Lab L062E 10cm + 2.2µF capacitor (Filter)

Specs: 40W RMS/70 W Max, 1500-20000Hz, 92dB, 8 ohm.


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I will use this capacitors if its a good way or cheap way to avoid the installation of a 3 way crossover (but i want know the best for my speakers)

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żFilter with capactiors or crossover?




Speakers without tweeter


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Spakers connection (Parallel)


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Thanks
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Old 30th January 2012, 09:38 PM   #2
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re:'its a good way or cheap way ' - it's a cheap way, but so is the quality of those speakers.
The first problem you need to deal with is the mid is 7dB louder than the woofer, you'll need to add an L-pad to match them : L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker voltage divider - sengpielaudio Sengpiel Berlin
You will probably have to add an L- pad to the tweeter as well
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 30th January 2012, 09:45 PM   #3
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Quote:
Originally Posted by PeteMcK View Post
re:'its a good way or cheap way ' - it's a cheap way, but so is the quality of those speakers.
The first problem you need to deal with is the mid is 7dB louder than the woofer, you'll need to add an L-pad to match them : L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker voltage divider - sengpielaudio Sengpiel Berlin
You will probably have to add an L- pad to the tweeter as well
With L-Pad i will get flat frequency response żtruth?
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Old 30th January 2012, 09:48 PM   #4
system7 is offline system7  United Kingdom
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I just looked those units up. The tweeter is 92dB, the midrange 90dB and the woofer 90dB. Close enough to give them a go, I reckon. Shouldn't knock a 2.2 uF capacitor on a tweeter. I ran that for years on some speakers, but a 3R 5W series/20R 10W shunt in wirewound resistors after the capacitor would do no harm to attenuate the tweeter 3dB if it's harsh...

The simple crossover will mean you can't really give them loudness though. But presumably this is how the speaker was set up originally.

Last edited by system7; 30th January 2012 at 09:52 PM. Reason: changed to 10W Wirewound...LOL
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Old 30th January 2012, 10:03 PM   #5
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for extra tweeter protection, the red wire above could be connected to the Mid + terminal instead of the woofer

re:'Close enough to give them a go' - I agree, wire them up & see how they sound, but I wouldn't waste too much time or $ on them....
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 30th January 2012, 10:04 PM   #6
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Quote:
Originally Posted by system7 View Post
I just looked those units up. The tweeter is 92dB, the midrange 90dB and the woofer 90dB. Close enough to give them a go, I reckon. Shouldn't knock a 2.2 uF capacitor on a tweeter. I ran that for years on some speakers, but a 3R 5W series/20R 10W shunt in wirewound resistors after the capacitor would do no harm to attenuate the tweeter 3dB if it's harsh...

The simple crossover will mean you can't really give them loudness though. But presumably this is how the speaker was set up originally.
What i do? Delete 2.2 uF capacitor at tweeter? What about capacitor at mid speaker?

3R 5W series/20R 10W i dont understand too much this part. You are saying that i must put 3 ohm 5W resistor series and one 20 ohm 10W resistor paralel?

Thanks
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Old 30th January 2012, 10:05 PM   #7
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Quote:
Originally Posted by PeteMcK View Post
for extra tweeter protection, the red wire above could be connected to the Mid + terminal instead of the woofer
It's ok, tweeter positive to midrange positive. Thanks.
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Old 30th January 2012, 11:02 PM   #8
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no, you can't omit the 2.2uf Cap, the wiring is mid + to 2.2uf, 2.2uf to 3 ohm resistor,
3 ohm resistor to tweeter + and 20 ohm resistor, the other end of the 20 ohm resistor goes to tweeter -.
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 30th January 2012, 11:24 PM   #9
system7 is offline system7  United Kingdom
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Quote:
Originally Posted by system7 View Post
Shouldn't knock a 2.2 uF capacitor on a tweeter.
Sorry, my friend. I was using an obscure English idiom/colloquialism there. Lost in translation.

I meant to say a simple 2.2 uF capacitor works OK on a tweeter. Good luck with this.
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Old 31st January 2012, 12:01 PM   #10
mdocod is offline mdocod  United States
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If I were throwing darts I would choose a 10uF and 0.25mH in series with the mids, 0.8mH in series with the woofer, and and 2.2uF 6 ohm on the tweeter (that way you can re-use the current cap without a change) The 6Ohm resistor will knock down the output and lower the x-over point of the small value cap (roughly -2dB and 5000hz x-over, make sure the resistor is wired in between the tweeter and the cap). As others have suggested connect the tweeter circuit to the down-stream side of the mid-range high pass cap. (place the inductor for the mid range between the cap and the driver, and tap into this circuit for the tweeter between the cap and the inductor)

A BSC circuit made up of about ~1-1.5mH and a 2-4 Ohms (wire those in parallel, then that in series with the entire speaker circuit) would also probably make the unit more enjoyable to listen to.

As it stands currently, I think you're crossing to and away from the mid range too high, and leaving any nasty peaks that the 8" might have completely un-controlled. The mid you are using has a fast steep natural roll off above ~7K, the tweeter needs to be allowed to come down a bit more to meet it IMO.

If you can find a response and impedance chart for all your drivers I can come up with some values that would be far less "dart throwing" and actually simulated. I think your woofer might be the same as this: http://www.parts-express.com/pe/show...number=292-408

Last edited by mdocod; 31st January 2012 at 12:24 PM.
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