Looks like there was never a second PDF for the 4ohm. Madisound sent the 8ohm sheet; they should be the same according to MS.
(same as you found Sy7)
4K! That's up there yes? Well above the xo range?
(same as you found Sy7)
4K! That's up there yes? Well above the xo range?
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It's interesting that 4 ohm speakers don't seem to have the AAL3 resonance problem at around 4-7.5kHz which 8 ohm midbass speakers have, depending on what they are made of. It does look like a notch isn't necessary with the 4 ohm units (W170S) I looked at.
Vibration analysis
That all looks very nice to me, and I don't see much more tweaking there, though the 1.5R bass resistor is possibly on the large side for a 4 ohm unit. I'll probably start with 1 ohm with hindsight. The 3R/10R attenuator is right on the Vifa XT25 given its unique properties. It does look like the time-aligned modelling tends towards first-order treble, but that would be making what Lynn Olson calls a "Little Girl With A Guitar" speaker that sounds terrible with complex music. 😎
Enjoyed this thread. It's firmed up some ideas for me. Thanks. 🙂
Vibration analysis
That all looks very nice to me, and I don't see much more tweaking there, though the 1.5R bass resistor is possibly on the large side for a 4 ohm unit. I'll probably start with 1 ohm with hindsight. The 3R/10R attenuator is right on the Vifa XT25 given its unique properties. It does look like the time-aligned modelling tends towards first-order treble, but that would be making what Lynn Olson calls a "Little Girl With A Guitar" speaker that sounds terrible with complex music. 😎
Enjoyed this thread. It's firmed up some ideas for me. Thanks. 🙂
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Nephew came over for the day yesterday, he's getting into speakers etc. We hooked up several pairs and these were hands down the best; maybe my set best ever!
[the Vifa tweeter is very nice - you may want to pick up a pair before the price goes up]
Nephew's a computer guru and set up the wireless TV in seconds; we moved the RCAs cables around and watched a "streaming movie " Bourn Identity
Holy Cow...I didn't see this coming but the speakers sounded like they are angry little possessed monsters, bass like a sub woofer, shaking widows, crazy sound everywhere!!
D**m shame they don't make these little drivers anymore - I know the DIYers would love these (they were only $25 each).
Thoughts on bass: I don't know, I'd be worried messing with that.
btw -, dust cap was removed and cone has silicon layer.
Still fooling around with cap for tweeter - need the bigger size(s) to bring out the detail. I'm thinking the 6uf is to large and using a 4.7uf with a piggy back 1.0uf.
(I may add a toggle switch to the 1uf).
Also need to order some new caps in the 5 - 5.5 range.
[the Vifa tweeter is very nice - you may want to pick up a pair before the price goes up]
Nephew's a computer guru and set up the wireless TV in seconds; we moved the RCAs cables around and watched a "streaming movie " Bourn Identity
Holy Cow...I didn't see this coming but the speakers sounded like they are angry little possessed monsters, bass like a sub woofer, shaking widows, crazy sound everywhere!!
D**m shame they don't make these little drivers anymore - I know the DIYers would love these (they were only $25 each).
Thoughts on bass: I don't know, I'd be worried messing with that.
btw -, dust cap was removed and cone has silicon layer.
Still fooling around with cap for tweeter - need the bigger size(s) to bring out the detail. I'm thinking the 6uf is to large and using a 4.7uf with a piggy back 1.0uf.
(I may add a toggle switch to the 1uf).
Also need to order some new caps in the 5 - 5.5 range.
I used a 2.2 bass resistor in the last set - I do think I like that one better.
I'm going to order some parts today anyway - I'll get an assortment of the smaller ones.
Ended up using a 12uf cap (vs. 15uf) I don't remember why that happened..
Bolted together a third pair - the darker wood set, and going to use a Morel MDT-30 for tweeter.
Edit...Morel is 8ohm 89db - Vifa 4ohm 91db :-/
I'm going to order some parts today anyway - I'll get an assortment of the smaller ones.
Ended up using a 12uf cap (vs. 15uf) I don't remember why that happened..
Bolted together a third pair - the darker wood set, and going to use a Morel MDT-30 for tweeter.
Edit...Morel is 8ohm 89db - Vifa 4ohm 91db :-/
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Yikes...my HT room sounds like a dud now.
The wife and I have been listening to the pair of 2-ways for a few nights and now the 5.1 room sounds like there is no high end. I didn't see that coming....
The room with the 2 speakers has a china cabinet with a round glass door, getting a good echo for a rear channel effect (movies).
Correction to last post, the morel is the same 91db, but 8ohm; so the xo is never going to work as is.
I'll use the old 6bd xo for the tweeter; morel MTD 30 tweeter works well with a simple 3.3 cap and Lpad.
The wife and I have been listening to the pair of 2-ways for a few nights and now the 5.1 room sounds like there is no high end. I didn't see that coming....
The room with the 2 speakers has a china cabinet with a round glass door, getting a good echo for a rear channel effect (movies).
Correction to last post, the morel is the same 91db, but 8ohm; so the xo is never going to work as is.
I'll use the old 6bd xo for the tweeter; morel MTD 30 tweeter works well with a simple 3.3 cap and Lpad.
The morel of the story is never mix speakers with different impedances and keep the woofer and tweeter sensitivities the same.
Worse than you know - I just tossed 3 MTM boxes for these drivers - I could have double up the woofers.
Always looking for good drivers that don't cost $100 each.
Peerless/Vifa/Morel have been good so far. I had a pair of Seas Prestige that were trouble (could have been something else I guess).
SOOO many driver to chose from, hard to pick one!
Peerless/Vifa/Morel have been good so far. I had a pair of Seas Prestige that were trouble (could have been something else I guess).
SOOO many driver to chose from, hard to pick one!
In my opinion all drivers are the same, I currently use el cheapos in my Camm DynaTones and they work well, it's how you test and use them that counts.
Voigt Pipe, DIY Tapered Quarter Wave Pipe (TQWP) loudspeaker plans - The Book Worm
Voigt Pipe, DIY Tapered Quarter Wave Pipe (TQWP) loudspeaker plans - The Book Worm
Well I guess they are all the same in a global sense.
So your speakers remind me of some subwoofers - check posts 301 - 310:
http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-31.html
So your speakers remind me of some subwoofers - check posts 301 - 310:
http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-31.html
I'm sorry, but this is not a good rule of thumb. Mixing different voltage sensitivity and impedance is fine.
Later,
Wolf
Thanks Wolf,
I see that a 8ohm tweeter would need a smaller cap (1/2 the size of 4ohm)
2-Way Crossover Designer / Calculator
Is that all I need to change in the xo designed for the 4ohm tweeter?
I see that a 8ohm tweeter would need a smaller cap (1/2 the size of 4ohm)
2-Way Crossover Designer / Calculator
Is that all I need to change in the xo designed for the 4ohm tweeter?
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Well then you are discounting 50 years of research by the top people in their field and it's statements like this that make a mockery of High Fidelity.
A mockery indeed. Or not. Let's get back to ODougbo's speaker. 🙂
It does seem to me this is a very high inductance woofer. 0.8mH is a LOT for a 4 ohm unit. Usually you'd be around 0.4mH here.
It's gonna fight anything you do to roll it off with a small bafflestep coil. 🙁
That means you get a midrange peak when you add shunt capacitance unless you filter it very low. So you need some shunt resistance too.
My experience with high-inductance woofers is they filter best with a simple coil or a coil plus a Zobel, which here at 3.7R and 0.8mH is 4.7R and 35uF.
You then get left with a natural rolloff around 4kHz and a need to bring the treble in quite high at 4kHz.
Something to ponder. http://www.diyaudio.com/forums/multi-way/225310-system7-steve.html#post3277124
It does seem to me this is a very high inductance woofer. 0.8mH is a LOT for a 4 ohm unit. Usually you'd be around 0.4mH here.
It's gonna fight anything you do to roll it off with a small bafflestep coil. 🙁
That means you get a midrange peak when you add shunt capacitance unless you filter it very low. So you need some shunt resistance too.
My experience with high-inductance woofers is they filter best with a simple coil or a coil plus a Zobel, which here at 3.7R and 0.8mH is 4.7R and 35uF.
You then get left with a natural rolloff around 4kHz and a need to bring the treble in quite high at 4kHz.
Something to ponder. http://www.diyaudio.com/forums/multi-way/225310-system7-steve.html#post3277124
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Steve,
Ahhh the plot thickens...I'm sure the woofer/tweeter xo is below 2K (but will check) The XT25TG30-04 says it goes to down to 1,500.
btw, back in the day when we made a bunch of these, we used a simple 6 db slope with a .7 coil (for the woofer).
Zobel network - is diagram correct?
I have the parts, large caps & resistors.
Thank you again
Ahhh the plot thickens...I'm sure the woofer/tweeter xo is below 2K (but will check) The XT25TG30-04 says it goes to down to 1,500.
btw, back in the day when we made a bunch of these, we used a simple 6 db slope with a .7 coil (for the woofer).
Zobel network - is diagram correct?
I have the parts, large caps & resistors.
Thank you again
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Yup, the bass filter is right. Whether that sounds right is a matter for trial and error. The treble filter would need adjusting either for low slope or a high crossover frequency. It seems the polycone bass will have a natural rolloff around 4kHz.
The reason I complicated the issue is you were following my suggestion of reducing the crossover shunt resistor. Well, that might not work with a high inductance woofer at 3-4kHz, which yours is.
I think I would have to do some modelling with a suitable 4 ohm 0.8mH driver to see how it all works. My comments may not have been entirely helpful until that is done.
Usual random pictures...🙂
The reason I complicated the issue is you were following my suggestion of reducing the crossover shunt resistor. Well, that might not work with a high inductance woofer at 3-4kHz, which yours is.
I think I would have to do some modelling with a suitable 4 ohm 0.8mH driver to see how it all works. My comments may not have been entirely helpful until that is done.
Usual random pictures...🙂
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Look around, mixing these considerations is done all the time, it's not just me.
I wouldn't for tube-amps, but that's a different story.
Later,
Wolf
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