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Old 23rd June 2010, 07:32 PM   #1
Boscoe is offline Boscoe  United Kingdom
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Default Crossover fequency worry. Help please.

I'm going to buy these speakers (unless you can suggest better in the UK for the same price ) HERE and HERE well I already have bought the bass to mid speaker. That speaker has a recommended crossover frequency of 3.5KHz and the tweeter 5KHz I have already made the enclosures too so I can't add a mid to it. My worry is that it won;t sound good at this frequency if I put a crossover frequency too high or too low for the speakers. So do you think it'll be okay and could you suggest me a crossover frequency or recommend me a different tweeter from, prefferably, the same site.

Thanks a lot.

Boscoe
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Old 23rd June 2010, 09:34 PM   #2
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Hi,

that combination does not look like playing music together.
But things can be surprising.

If you do not want to change to a tweeter able to cross at
say 2-2.3 Khz i would do the following:

Build an appropriate box for the woofer, ensure that the damping
behind the driver (sheep wool e.g.) is able to suppress coloration
in the midrange to presence region.

Try to make a minimalistic filter , which utilizes the natural rolloff
of the driver: That could be compensation of voice coil inductance only,
or additionally using a very small INDUCTOR in series.

It could also be nothing.

Try to get the sound of the woofer as "correct" as you can without
the tweeter, make some measurements if possible, listen to speech
and music without the tweeter.

The combination has to be optimized for a certain listening distance,
because the directivity of the woofer is narrowing with frequency.

Do your listening tests at that prefered distance (should not be
too far away)

Play with listening angle, result may be better slightly off axis.

This will be a speaker which has to be positioned due
to a sweet spot according distance and angle.

Then add the tweeter and experiment with filters from 2. order.
Look what happens, if you use textbook values and try making
the parallel coil "too big" or the series capacitor "too small".

Decide whether the tweeter has to be padded down using an L-Pad.

Recessing the tweeter to the plane of the dustcap of the woofer
may be good, keep the tweeters plane movable while tuning the
filter (Put it ontop of the cabinet, near the woofer).
Play with the distance offset and the polarity
(should be in antiphase normally).

If you can't do measurements listen to white noise from a tuner and
signals like applause while tuning the tweeters position and filter.

Keep the crossover frequency out of the presence region,
rather move it as high as the woofer allows.

No risc no fun ...
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Last edited by LineArray; 23rd June 2010 at 09:56 PM. Reason: deleted "capacitor" added "inductor"
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Old 23rd June 2010, 10:03 PM   #3
Did it Himself
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It's a ribbon tweeter with resonance at 4500Hz, there is no way it can be used below 5000Hz. The 8 inch driver you have chosen will not really stretch up that well to 5000Hz, you may get away with THIS tweeter.
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Old 23rd June 2010, 10:14 PM   #4
Boscoe is offline Boscoe  United Kingdom
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Nice one thanks for your time.

I will just have to change the tweeter i think, it just seems the easiest option.

What do we think of the quality of theese drivers?
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Old 24th June 2010, 05:11 PM   #5
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They are reasonable, perfectly fine for a first design. In fact better than what I used in my early designs!
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Old 24th June 2010, 08:49 PM   #6
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Here's a thought - a wide-band mid-high driver. Perhaps a 2-3" driver, with decent efficiency. Cross it over where you like, but you'll need a small enclosure to stop it being pushed around by the woofer.

Just to throw another idea out there...
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Old 24th June 2010, 10:24 PM   #7
Boscoe is offline Boscoe  United Kingdom
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Quote:
Here's a thought - a wide-band mid-high driver. Perhaps a 2-3" driver, with decent efficiency. Cross it over where you like, but you'll need a small enclosure to stop it being pushed around by the woofer.

Just to throw another idea out there...
Yeh thanks I did think of this but I had already made the enclosures and I don't want to add to them as their are already too big for what I wanted in the first place.
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Old 24th June 2010, 11:14 PM   #8
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How about the Stage Line DT-300 103860. It has an fs of 750Hz, 93db and 50watts RMS.
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Old 25th June 2010, 01:02 AM   #9
tinitus is offline tinitus  Europe
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This 2" TB fullrange tweeter is quite good, and cheap
its actually more like 1.5"
resolves exstremly well at moderate spl
acoustic instruments like violin, piano etc. are just spot on
almost as good as it gets
and you can cross it low
I have a very special but simple xo for it, if you are interested
all you need to do is adjust woofer xo to match it
probably just a series inductor with a zobel
crossing relatively low makes it easier to do the BSC thing
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