27 replies to this topic

[muzzy66]

I'd be going 4th order on an XT25 if you want to cross that low - they really don't like low frequencies at all.

2.5khz @ 12dB is lower then I'd recommend on those tweeters, BUT not to the point where it should be causing sound abnormalities. Is it hapenning in both tweeters or only? Could it be that one of the tweeters is faulty?

[Captn_Awesome]

Well I havent built the second xover so I've just swapped the tweeters around. Which leads me to believe its either a crossover component issue, crossover design issue (leaning towards this one the more I read) or me expecting too much from the driver (which I suppose goes back to crossover design).

Im actually pretty impressed by these speakers for something that essentially I just threw together with parts in my wardrobe they sound pretty good. Not super efficient (back to cross over design - but I think I know how to change this.) but so far im impressed by the one box I have running.
This is actually my first attempt at full crossover design. I've played with (passive) crossovers before - but its only been modifying their points or upgrading components - never a complete design.
I'll try go 4th order see if that makes a possitive difference. Seriously concidering stepping up the crossover point though

[Tiger]

As I mentioned earlier.. try it at 3K and see how that goes for ya. From what I'm learning about these tweeters, they like playing that LITTLE bit higher and they'll make you hear why

[Captn_Awesome]

I've got a pair of these sitting at home http://www.scan-spea...7608-920010.pdf
wonder if I should turn these into 3 ways...

actually lets get these working as two ways first even if they dont plot well provided I can get the x-over design working then I can toy with the idea of 3 ways. One step at a time...

[Big_Valven]

Komodo, on 31 May 2010 - 11:56 PM, said:

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.

Ah OK your initial description sounded like a first-order.
Purely from the symptoms you describe it sounds like you could do with a notch out at 700Hz, I have seen networks used that way on tweeters and mids to correct resonance below the xover point.

If it was me I'd raise the xover point to 3K if your mids can do it before I'd go fourth order... but I am on the KISS bandwagon as well and think swapping one evil for another (phase issues) may not be worth it. But your mids / midbass drivers need to go to 3K fairly cleanly for it to be a good idea.

[br85]

What mids are you using, anyway? This info is definitely important...

[Captn_Awesome]

Vifa PL18WO-09-08
datasheet here : http://www.tymphany....PL18WO09-08.pdf

[Pulse-R]

the PL18's are quite ok.

here's a link to the tweeter resonance stuff:
http://www.diyaudio....s-850122-a.html

notice in there, they also talk about a zobel on the tweeter.

The theory behind the zobel on the tweeter is to maintain a linear impedance, so the amplifier's internal feedback doesn't get out of phase at higher frequencies... helps to improve stage depth, to get a good "3-D" sound stage.

[mrock]

What is the FS on them? Also having a 6 dB crossover at 2.5 k is nuts. That's why your hearing crazy noises. You have to at least go 5k at 6db. Also, you could try making a contour network to boost or cut in the high freq range.

[Pulse-R]

the crossover is 12dB

[mrock]

muzzy66, on 01 June 2010 - 12:14 AM, said:

I'd be going 4th order on an XT25 if you want to cross that low - they really don't like low frequencies at all.

2.5khz @ 12dB is lower then I'd recommend on those tweeters, BUT not to the point where it should be causing sound abnormalities. Is it hapenning in both tweeters or only? Could it be that one of the tweeters is faulty?

Your absolutely right muzzy, I just saw the datasheet, and the impedance stops rising at almost 2 k. So you do need a steep filter.

[Pulse-R]

if you fix the impedance rise with a notch filter and zobel, then you can be more free with slope and frequency, as phase is kept smoother.

Edited by Pulse-R, 03 June 2010 - 07:28 PM.

[golf_bht]

Based on my experience playing with that particular driver. 4.5K @ 24 Db seem optimum when running 3 ways. 3K for 2 ways.. I would recommend 2.2 Uf for first order 6 dB

Edited by golf_bht, 09 June 2010 - 02:51 AM.