27 replies to this topic

[Captn_Awesome]

Ok so I have an XT-25 running passive using a solen 10µF cap with a 3.3ohm and 2.2ohm 10W wire wound resistor L-pad for the x/over.

Theres something "harsh" about this setup. I cant pin point what it is but its like when on axis it sounds like there is a piece of foil or tinsel "clicking". It seems to be only within a certain frequency band (I'd suggest its around the 3-10k region). Whats driving me bonkers is that off axis you can hardly hear it and its "seemingly" not always there.
I'm almost tempted to replace the tweeters - but I fear that it could be a cross over design fault.

Any one got any suggestions?

[Tiger]

Passive? There's your problem, dude! RUN ACTIIIIIIIIIIIIIIIIIIIVE


Got me stumped, to be honest. Have you tried it active though? Or the setup won't allow you to go active for demo purposes?

Edited by Tiger, 31 May 2010 - 12:19 PM.

[Captn_Awesome]

Dont have the ability to go active shags.

Attached is the HT audio Crossover pro printout.

I put the L-Pad in because the highs were way out in front of the mid/lows in the volume stakes and that seems to have had a possitive effect on this scratchy type sound.  X·over Pro.pdf   51.18K   20 downloads

[Captn_Awesome]

I wonder if I'm x'ing over too low? but 2500 really isn't that low for these tweeters from what I've read (and heard in the past).
Could be crossover order?
Could be dodgy caps?

[Tiger]

Try 3k.
Where have you got your XTs situated?

[Captn_Awesome]

They're in bookshelves tiger
I know its not "mobile" but I know a lot of guys on here have experiance with this tweeter and with Solen x/over gear

[blanketman]

well they are home audio speakers
LOL

[Captn_Awesome]

People you'd be supprised to know that in a former life blanket was a rocket scientist. No one knows why he was reincarnated as a dumb ass in this life ...

[Big_Valven]

2.5K seems too low to me with a first order (6db/ octave) crossover. Try a second order (12dB/octave) at 2.5K.

[Captn_Awesome]

its is a second order high pass

[Pulse-R]

a few problems with your design kirk:(in no particular order)

1. look around for the parallel/shunt filter to suppress the harmonic hump at 700Hz.
2. measure the T-S specs, not the published ones.
3. make sure you choose the impedance at the crossover frequency for your calculation.
4. use zobel correction on the tweeter, it makes a difference.
5. the L-pad goes before the crossover, not after.

[Tiger]

Dead set! I couldn't view the file! It was damaged and couldn't be repaired apparently!

[Big_Valven]

A capacitor with an L pad before it isn't second order?

[Captn_Awesome]

Theres an inductor in there too Big V Although now I'm at home I too note that the PDF file cant be viewed. Will correct that tomorrow.

L pad goes before the x-over? Thats interesting AND confusing I was always under the influence that it came after the x-over. Will swap that around first. I'm actually quite intrigued by this actually...

I measured the TS specs Simon and they came with-in a bees winky of the published specs (its been about 12 months since I did that so I couldnt tell you exactly whats there were or the minor deviations)

You got links on Zobel correction on a tweeter. Always thought this was something for mids and woofers. Didnt realise this was important for tweeters.

You really think a harmonic hump @ 700hz will be audible on a tweeter crossed over @ 2500hz @ 12db? Thats a pretty complex filter to rid something like that and Id really preffer to KISS. In all honesty the only reason I went 2nd order over first was to cross over slightly lower

[br85]

This is no ordinary tweeter, you're not the first to experience what you're describing.

Believe it or not, your problem originates much lower (probably the 700hz as simon suggested). I have played around with them a LOT, and they seem to have issues rolling off before the distortion gets incredibly annoying. A few things they benefit from:

(a) waveguide, but you need eq or active crossover (or very complex passive)
(b) high order filters (active crossover, LR24 passives are just stupid)
© higher crossover point (3k LR12 / 2.5K BW18 MINIMUM)

They seemed to like 3K BW18 in free air when I was mucking around with them, it's about the same actual acoustic rolloff as most domes have with 2nd order electrical. I wouldn't call them a "plug and play" tweeter, but they're worth it if you could be bothered putting the effort in.