Just picked up these DIY Wilmslow 3-Ways of flea bay... sound awful, help please! - Page 3 - diyAudio
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Multi-Way Conventional loudspeakers with crossovers

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Old 27th January 2014, 10:07 PM   #21
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Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
I was thinking to re-work the enclosure size (Inner dim.) to something like a 700mm by 500mm by 360mm (For 'my' 125L sim ), trying to make baffle step more manageable.
That 3" dome has an Fs of 350Hz. ....I wish most were that low!, rule of thumb of course don't cross it less the 2(Fs)....I was thinking 800 would seem OK. I can't find any response curves from Vifa.
16.87 inches center to center for the mid spacing...that's OK too, esp. with a .7M by .5M baffle front.
Vifa rates that dome down to 700 Hz. on the bottom???That's doable.

I was going to mention the polarity flip on the Mid, that should have been a no-brainer but....



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Old 28th January 2014, 01:09 PM   #22
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Ok, so crossover schematic is attached, I've also started modelling the xo with impedance curves and approximate driver responses, images of 'as is' attached...

I need to take a break from these for a while, whilst I try to work out how to get the best out of them
Attached Images
File Type: jpg xo.jpg (88.2 KB, 189 views)
File Type: jpg FR model_correctPhase.jpg (135.9 KB, 190 views)
File Type: jpg FR model_wrong phase.jpg (138.5 KB, 184 views)

Last edited by nannoo; 28th January 2014 at 01:30 PM.
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Old 28th January 2014, 01:57 PM   #23
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Some pdf's ; might be usefull.
When I take a look at your x-over it almost seems that you have a 4 ohm midrange ; please check !
These still are very satisfiing speakers.
The woofer did very well in a ported design of 65L. (dcR L woofer 0,35 ohm)

good luck ; Leon
Attached Files
File Type: pdf D75MX-31-08.pdf (140.1 KB, 14 views)
File Type: pdf P25WO-00-08.pdf (130.7 KB, 24 views)
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Old 28th January 2014, 02:06 PM   #24
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Is the inductor in the tweeter path connected this way on both speakers ? Or just on one ? If wired different then that could be the reason for the difference in sound. I would also say that it needs to be in parallel to the tweeter in order to make it a 2nd order highpass. Maybe it even was wired that way originally and someone added the L-PAD later on and made a wiring error.

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Charles
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Old 28th January 2014, 02:12 PM   #25
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Looks like it was always wired that way, but yeah I think i need to try switching the inductor into parallel rather than just bypassing and re-check all the polarities.

If the passive crossover designer is accurate, then the more I refine the data input (impedance curves, inductor resistances) the more it appears that this crossover should be fine.

Of course I still need to measure the caps, not at all convinced by these 'supersound' things yet... though they are big
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Old 28th January 2014, 03:00 PM   #26
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by nannoo View Post
... the more it appears that this crossover should be fine.
usually I would also place the midrange series inductor differently
but I don't know if it makes much difference

you could also try a small experiment ... removing one of 30uf cap on woofer
Attached Images
File Type: jpg xo.jpg (132.3 KB, 156 views)
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Old 28th January 2014, 03:24 PM   #27
Dissi is offline Dissi  Switzerland
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Quote:
Originally Posted by nannoo View Post
The drivers:
Tweeter: 27TG
Vifa D75MX
Vifa M25WP
The drivers certainly are fine for a decent 3-way speaker, but in order to avoid further confusions you need to clarify:

Vifa D27TG-05-06, 15-06, 35-06 or 45-06 ?
Vifa D75MX-31-08 or 41-08 ?
Vifa M25WP-00-08, 04-08, 09-08 or 12-08 ?

Some are similar, some are not.

The midrange dome is not sealed at the back side and definitely needs a own chamber.
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Old 28th January 2014, 04:54 PM   #28
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Guys, thanks to all of you who have contributed, it's been a great help with trying to get things sorted and setting my thoughts in the right directions.

I'm starting to get to the conclusion that these were well-designed as a kit by someone who really knew what they were doing, then assembled by an absolute moron.

I tried to attach a model of the xo, but it was too large to put on the forum, PM me if you want me to e-mail it to you.

Leonidas - Why did you think these were 4ohm domes? I've gone by the original spec sheet to approximate the impedance curve. (I hope)

The sound quality of the mid is still bothering me, the dome sounds great but getting it to integrate with the rest of the speaker is a nightmare (i.e. sounds great on it's own but less good when connected with the woofer/tweeter). I should point out that it still isn't sealed, and it only has one screw holding it to the baffle, as the person who build these was incapable of drilling more than one hole with any accuracy (!)

I'm starting to think that once I've chambered the mid, braced the cabinet (the whole thing vibrates way too much) then filled the cabinet, I may well have solved all my mid-frequency woes, and likely have taken a massive step toward a 'high fidelity' speaker.

I've fixxed the XO to what I think we'd all agree it should be, and the difference in sound quality was night and day - these already have clear benefits over any of my other speakers, mostly they sound a lot more full and open. the only questions left are how much to pad the mid/tweeter and if I need to worry about impedance leveling.

I'll try to get back to you all with more specific driver models.
Attached Images
File Type: jpg xo2.jpg (51.8 KB, 142 views)
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Old 28th January 2014, 05:19 PM   #29
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Because of the values in the x-over.
Just checked a simular VIFA design; L & C on the woofer are mostly larger then C&L on the midrange .
Your values point to 8 ohm woof and a 4 ohm mid.
I designed a lot of x-over for Vifa speakers and it just seemed a bit strange.
Can you measure the dc Resistance of the midrange ; just to be sure.
If I'm correct you will have a bad job integrating the woof and the mid.

Leon
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Old 28th January 2014, 05:22 PM   #30
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Or is it possible that the L for mid and the L for woof are switched ?
Something is not right (for my intuition) !
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