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....
_____________________________________________________Rick.........
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....
_____________________________________________________Rick.........
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
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
Attachments
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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.
Regards
Charles
Regards
Charles
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
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
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
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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.
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.
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.
Attachments
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
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
Do you mean the series resistance for the tweeter should always be located so that the capacitor is between the tweeter and the resistor?
the 10 ohm resistor was part of an L-Pad for the mid, not the tweeter, as originally the L-Pad was created for the tweeter with the potentiometer.
I removed the 10-ohm resistor as it measured 3 ohms on my multimeter...
the 10 ohm resistor was part of an L-Pad for the mid, not the tweeter, as originally the L-Pad was created for the tweeter with the potentiometer.
I removed the 10-ohm resistor as it measured 3 ohms on my multimeter...
Yeah, I don't know if that makes a difference either but it certainly makes a lot of sense, i get the feeling I'll be de-soldering and re-building the crossover and will re-arrange as you suggest, was easy to switch the tweeter inductor to where it should have been.
Tried to bypass the bass caps but can't do it until I de-solder the thing, but based on the passive XO calculator model I don't think I'd want to
.. as said in post 28, the more I model these crossovers and improve the accuracy of the model, the more it appears that the original designer knew what they were doing. The adjusted values from those recommended probably reflect what was needed to achieve a reasonable phase/frequency response between the mid and woofer.
it is using a mid dome that will need higher xo point than most other cone mids
so the woofer will also be crossed high, ofcourse
besides, the smaller value inductor looks much bigger
which tells that it might be wound with thicker wire, for woofer use
in my experince you should be cautious with very big parallel caps on the woofer
a calculator is not much good
but you may use it as a 'pointer', or guide
remember to use different impedance values
accordingly to the actual driver impedance at xo point
and you will have to fiddle quite a bit more than that, on the real speaker
just don't rely on it to be real at all
a lot of things changes on the real speaker
btw, I use resistors in series with all parallel components
(I simply can't make a crossover without them)
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