I've just put speakers into the enclosures this morning and the sound is impressive but it's gets to a point when increasing the volume where the tweeters heavily distort. I think it's due to the roll off from the woofers as I think I can actually see the soft domes flexing but i don't know how as if looks as if the magnet on the tweeters would stop any pressure getting to the dome. They are sealed enclosures with a bit of padding I had lying around but I have ordered some more just in case. Could this be the cause?
Thanks
Boscoe
Thanks
Boscoe
What cross-over are you using with these speakers? Your description of the tweeter behavior sounds like there is no cross-over at all or crossed far too low and you are in fact running them (near) full range - if so their life will be very short.
The other possibility is that you are clipping the amplifier, but I would not expect there to be visible moment of the tweeter dome even in that case, although it would sound rather nasty. (Also quick way to kill the tweeter in question.)
The other possibility is that you are clipping the amplifier, but I would not expect there to be visible moment of the tweeter dome even in that case, although it would sound rather nasty. (Also quick way to kill the tweeter in question.)
I'm using THIS (except mines 250W and 12db/oct) crossover and I think it's fine and I know why this is happening. Basically the dome is mounted in palstic that sity directly on the magnet. This is then mounted in the plastic that holds the unit into an enclosure and so the is quite a gap for air to get around the magnet and influence the dome and with mesh on the front of the tweeter at high bass volumes i think some of it's influencing the tweeter resulting in the distortion. I took the tweeter out and it sounded a lot better out of the enclosure. I am running the crossover at 2.5KHz when the recommened for that tweeter is 2KHz.
All I need to do is fill the gap between the magnet and plastic holder and then all should be good!
All I need to do is fill the gap between the magnet and plastic holder and then all should be good!
Yes, any open-back mid or tweeter should be protected from the back-pressure of a woofer in the same cabinet. What model tweeter is this? Did it not initially appear to have an open back?
This is usually done by making a small sealed enclosure behind the driver with its own damping material inside, and the volume can be chosen to set the low-frequency acoustic rolloff of the driver, similar to an acoustic suspension woofer. Not sure how much this matters at 2.5k or how much design you're putting into this, but I'd think twice before just "filling the gap" of any air path around the back of a driver.
This is usually done by making a small sealed enclosure behind the driver with its own damping material inside, and the volume can be chosen to set the low-frequency acoustic rolloff of the driver, similar to an acoustic suspension woofer. Not sure how much this matters at 2.5k or how much design you're putting into this, but I'd think twice before just "filling the gap" of any air path around the back of a driver.
That is sealed. You don't need to seal it up in the back. How about the polarity? Try to reverse the polarity on the tweeter. It may be operating out of phase of the woofer and it is more noticeable when you turn it up. Also, when you pull out the tweeter from the box you start to hear the back side of the woofer which then would be in phase if the whole problem is phasing to begin with.
Also, was the tweeter supplied with a capacitor? Did you use it along with the crossover? If so, remove the one that came with the tweeter as you are creating an additional phase shift with adding additional components to only the tweeter part of the crossover.
Also, was the tweeter supplied with a capacitor? Did you use it along with the crossover? If so, remove the one that came with the tweeter as you are creating an additional phase shift with adding additional components to only the tweeter part of the crossover.
So your sure its 2nd order? The problem you describe sounds like the tweeter is operating @ its Fs. Check that the components on that XO of yours, match the tweeters impedence.
If not your tweeter could well be operating at resonance.
Also check, Is there air leaking around the tweeter?
Then maybe try disconecting the woofer and have a listen to the tweeter by itself, (still through the XO and easy on the volume), you may find a clue there.
Mick.
Like Pete said, it clearly says 6db in the link to supplier
Theres even a huge risk that xo point is way off, when using only a series cap...especially with a one size fits all
try to mount a small inductor in paralel, 0.2-0.4mH, between cap and tweeter, in paralel with tweeter
thin wire is fine
and yes, you may have to reverse tweeter polaity, as mentioned before
Sorry, He sounded so sure of that when I read it. Agreed, the curtains don't match the drapes.
Just tried reversing the polarity with no luck still sound the same and now I have noticed that the tweeter sounds like it's going through a tunnel (as if it sharing the enclosure) both before the polarity switch and after it also sounds as if it's distorting too. i think having a go at sealing them wouldn't do any harm seen as a lot of other tweeters are?
Trouble is, it looks just like the first, which appears to be a 1st order XO.
You are almost certainly running that tweeter down to Fs, (read, 'very bad').
Polarity can't fix that. You need to use at least a second order network at 2.5k for that tweeter.(As mentioned earlier).
Can you read the value of the components on that XO?
Mick.
You are almost certainly running that tweeter down to Fs, (read, 'very bad').
Polarity can't fix that. You need to use at least a second order network at 2.5k for that tweeter.(As mentioned earlier).
Can you read the value of the components on that XO?
Mick.
Okay I've found the problem, the crossover. I don't know wether it's broken or just cheap and nasty but I used a frequency generator and could hear a tone although quietly because I didn't want to break it down to 75Hz and i think it's full range and it just can't play it!
New crossover time is it?
I have tried to read the values before but they aren't print on them!
New crossover time is it?
I have tried to read the values before but they aren't print on them!
Should I just use regualr electrolytic and what sort of voltage ratings am I looking at?
EDIT: Is a 2nd order butterworth correct?
Okay looking at THIS website. What inductors do I need core type, wire thickness all that?
And capacitors do they need to be electrolytic ceramic or what?
Thanks
EDIT: Is a 2nd order butterworth correct?
Okay looking at THIS website. What inductors do I need core type, wire thickness all that?
And capacitors do they need to be electrolytic ceramic or what?
Thanks
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2-Way Crossover Designer / Calculator
I use this one, 'cause there is plenty of options, and plenty of other circuit calcs.
But google BSC and check this Difraction Loss / Baffle Step Compensation (BSC) Circuit Calculator for Speakers one out too, It may pay off sometime soon.
Mick.
I use this one, 'cause there is plenty of options, and plenty of other circuit calcs.
But google BSC and check this Difraction Loss / Baffle Step Compensation (BSC) Circuit Calculator for Speakers one out too, It may pay off sometime soon.
Mick.
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