5KHz passive crossover

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Hi there,
To have a fighting chance of making a crossover you will need to know what the impedence of the drivers is at least. Do you have ALL of the driver specifications or model numbers and brand? If you have these, post them here, or go to google and find an online calculator, Simple as that!:)

Regards, Mick.
Ex-Moderator R.I.P.
Joined 2005
you need to use the ACTUAL impedance at the crossover frequency, not nominal, or Re....

Yeah, ok, but even that isnt enough really

We need more info on your woofer, especially response curve, but impedance would be good too
But at least some info on size and type
Also a picture may help

Hey, maybe just mount a small cap in series with tweeter +, and maybe a series resistor
That way at least you will experience whether your woofer is capeable of 5khz
I have once made a small speaker that worked fine that way
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As these guys are trying to point out, your trying to walk on water without getting wet!

Basicly, without manufacturers specifications, your flying blind, ie, its next to impossible to build a cabinet that will give any meaningful bass performance, and the XO I suggested post#4 would probably be the best you could hope for, (rough at best), bass aside.

Bottom line; A long way shy of 'ear candy'.

Sorry I can't be of more help, Mick.:)
First thank you all for your replies and I'm for my delayed reply...

The speakers in question are a pair of Technics SB-HD501. (http://is.gumtree.com/ad_image/live/big/239779020.jpg)

the thing is... The original amplifier had an active xover @ 5KHz...
Since I'm working with another amp, i would like to add them a passive xover...

I don't know any more specs than what it said on the back of the speakers:
Impedance: high 6ohm, low 6 ohm
power: tweeter 30W(music), 15W(din)
woofer 60w(music), 30W(din).


Rui Jorge.
First thing is to check inside the box to see if there are any crossover components in there already as even though these are bi-amped, they may not have an active crossover. The SB-HD301 is not bi-amped and still crosses over at 5kHz which makes me think not.

Usually on this type of equipment they tend to run the woofer so it rolls off naturally and the tweeter then fills in with the use of a simple cap in series. The 6 ohm is the overall speaker's nominal impedance and not necessarily the tweeter.

Listen to the woofer by itself and get a feel for the driver to see how much top end is missing. Then add a 3.3uF cap in series to the tweeter and listen again. If the top end sounds OK then the tweeter may be around 8 ohm and if a bit light on then it's lower such as around 6 ohm. Have two 1uF caps handy and add 1 in parallel at a time to increase to 4.3uF and then 5.3uF. If it's all too hot, then try 2uF by running the two 1uF caps in parallel. It shouldn't need any higher than 5.3uF as the tweeter would not have a low Fs. If the tweeter is a bit bright add a resistor in series before the cap and start with about 1R (5W ceramic). 2.2uF and 3.3uF caps are very common in this type of speaker.

It's easier to blend this with a 1st order on the tweeter as you don't get phase issues you can get with higher orders when playing with unknowns. 1st order can give a peak or dip at the crossover frequency but playing with caps will sort that out as the crossover for the tweeter is moved up or down. With 1st order you will not get the deep nulls or polarity problems of say 2nd order if it's all wrong. All you're trying to do is fill in the info above the woofer. It's not going to be perfect but should be quite acceptable and tweaked to personal taste. Also try the tweeter in reverse polarity as well as another check.... it may be better and reversed polarity is used on a lot of 1st order tweeters.

Good luck with it and let us know how you get along.
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