I’m trying to replace a 2 way crossover in a ported enclosure.
The vifa H26TG-05-06 tweeter has a recommendation for crossover of:
Strongly recommended at least 2nd order (12db/oct).
Nom. Power 100w 4000Hz L 0.22mH C 8Uf.
None of the crossover designers for 2way come up with these spec’s.
Tweeter Vifa H26TG-05-06
6ohm
100w
95db
Coil resistance 4.6ohm
Woofer
Scanspeak P21WO-20-08
8ohm
80w
91db
Coil resistance 5.7
How do I match the woofer to their recommendation?
The vifa H26TG-05-06 tweeter has a recommendation for crossover of:
Strongly recommended at least 2nd order (12db/oct).
Nom. Power 100w 4000Hz L 0.22mH C 8Uf.
None of the crossover designers for 2way come up with these spec’s.
Tweeter Vifa H26TG-05-06
6ohm
100w
95db
Coil resistance 4.6ohm
Woofer
Scanspeak P21WO-20-08
8ohm
80w
91db
Coil resistance 5.7
How do I match the woofer to their recommendation?
I strongly suggest you read this thread, unless you have the appropriate measurement gear, or wish to simulate the on-baffle driver responses & design the crossover with these.
http://www.diyaudio.com/forums/mult...designing-crossovers-without-measurement.html
http://www.diyaudio.com/forums/mult...designing-crossovers-without-measurement.html
Yup, this is going to be tune it by ear I think!
Since it's an Le of 0.9mH on the polycone woofer, a 2.5mH coil and 4.7uF for some rolloff might be a start on the woofer. Depends what you have lying around. Don't forget you can add up two small coils to make a big one.
The 95dB tweeter has a waveguide so is going to be peaky around 5kHz. Hard to say how it works without modelling, but you'll need an attenuator for sure.
I think you might end up with something a bit like the SEAS Idunn: Idunn
Since it's an Le of 0.9mH on the polycone woofer, a 2.5mH coil and 4.7uF for some rolloff might be a start on the woofer. Depends what you have lying around. Don't forget you can add up two small coils to make a big one.
The 95dB tweeter has a waveguide so is going to be peaky around 5kHz. Hard to say how it works without modelling, but you'll need an attenuator for sure.
I think you might end up with something a bit like the SEAS Idunn: Idunn
These are a couple of 3kHz KEF crossovers for 8" bass and 1" tweeter.
Impedance should be reasonable with 6 ohm DC drivers.
The 104 was a plastic bass and the second 0.6mH is probably optional, the Celeste III was a paper bass. You will need an attenuator or some sort of resistance in the treble circuit and you need to take care you don't take impedance too low for your amplifier. I can't help you with the tonal properties of your unusual waveguide tweeter, and polarity might be unpredictable.
But a start, I think. A 10uF shunt on the bass here will take crossover down to nearer 2kHz, but the tweeter filter will need to change too. I'd start at 3kHz to be on the safe side.
Impedance should be reasonable with 6 ohm DC drivers.
The 104 was a plastic bass and the second 0.6mH is probably optional, the Celeste III was a paper bass. You will need an attenuator or some sort of resistance in the treble circuit and you need to take care you don't take impedance too low for your amplifier. I can't help you with the tonal properties of your unusual waveguide tweeter, and polarity might be unpredictable.
But a start, I think. A 10uF shunt on the bass here will take crossover down to nearer 2kHz, but the tweeter filter will need to change too. I'd start at 3kHz to be on the safe side.
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But Vifa have done the measurements! And give enough data to make a reasonable stab at a reflex cabinet.
The 8" Vifa polycone looks quite well behaved. It'll probably sound OK on just a 1.5mH BSC coil and rolloff naturally around 3.5kHz. The waveguide tweeter might give you a hard time though. But who knows? Lynn Olson spends 6 months fine tuning a speaker. Mostly by ear, once he's in the right ballpark.
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Andrew, it is an excellent primer for the unaware, and gives someone a much better start than they would get if they just put together some text book crossovers.
Yes if you want to extract the best (with the least pain) from your speakers you need measurements, but I can tell you now that if I had a guide like this 30 years ago, I'd have saved a whole lot of money and had much better sound for many years
Tony.
Yes if you want to extract the best (with the least pain) from your speakers you need measurements, but I can tell you now that if I had a guide like this 30 years ago, I'd have saved a whole lot of money and had much better sound for many years
Tony.
I'm new to speaker design. I've only made one other pair that I'm very happy with, using CSS fr125 full range in mini onkens.
I got these speaker 2nd hand and cheap.
Something is missing in the sound though.
They're wired for one or two amps. Each with two L-pads, a 4U7, 6U8 Claritycap and one homemade coil made from some braided wire! Is this OK. Solidly built, 62l bottom ported and tuned to 40Hz I think he said, but can't be sure.
Maybe my amps haven't enough power. I'm using a My ref C, or Nad 3029.
They seem to be lacking mid range. I just want to get rid of the biamping stuff and get them sounding better.
I've been working through AllenB excellent tutorial and it just seems these two drivers are not well paired. Crossover recommended at 4KHz which I think brings the scanspeak upto 14ohm's Is this correct? AllenB also mentions that 4k is not a good place for woofer to cross. The resonance frequency of the tweeter is quite high at 1500Hz.
I got these speaker 2nd hand and cheap.
Something is missing in the sound though.
They're wired for one or two amps. Each with two L-pads, a 4U7, 6U8 Claritycap and one homemade coil made from some braided wire! Is this OK. Solidly built, 62l bottom ported and tuned to 40Hz I think he said, but can't be sure.
Maybe my amps haven't enough power. I'm using a My ref C, or Nad 3029.
They seem to be lacking mid range. I just want to get rid of the biamping stuff and get them sounding better.
I've been working through AllenB excellent tutorial and it just seems these two drivers are not well paired. Crossover recommended at 4KHz which I think brings the scanspeak upto 14ohm's Is this correct? AllenB also mentions that 4k is not a good place for woofer to cross. The resonance frequency of the tweeter is quite high at 1500Hz.
The tweeter attenuator (L-pad) goes AFTER the tweeter filter.
But you might be quite close to the 3kHz KEF Celeste III tweeter filter here with 4u7 and 6u8. The bass unit will need some work by the sound of things.
I'd be surprised if it sounds any good without at least a BSC coil. That's a 0.7mH bass ferrite unit bottom left, the coil top right is a much smaller value tweeter 0.2mH aircoil in that different example:
You need to draw up the existing filter to work out what comes next. It's gonna be hard without a good multimeter with the ability to measure capacitance and particularly, inductance.
But you might be quite close to the 3kHz KEF Celeste III tweeter filter here with 4u7 and 6u8. The bass unit will need some work by the sound of things.
I'd be surprised if it sounds any good without at least a BSC coil. That's a 0.7mH bass ferrite unit bottom left, the coil top right is a much smaller value tweeter 0.2mH aircoil in that different example:
An externally hosted image should be here but it was not working when we last tested it.
You need to draw up the existing filter to work out what comes next. It's gonna be hard without a good multimeter with the ability to measure capacitance and particularly, inductance.
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No, the 0.33mH bafflestep coil on the woofer is completely wrong. It should be much bigger.
You can model most electrical characteristics with some software like this:
Downloads
You can import completed similar designs directly into the Projekte folder: Boxsim Projektdatenbank Systeme
The trick is to find a Visaton driver that resembles what you have. I get criticised for this, but it works for me. Especially with impedance for various resitors in a filter. Drivers / Accessories
I do consider a good multimeter useful. Not cheap though. Mine was £70. Here I use the inductance scale on a 1mH coil to see what a nearby metal plate (or circuit board) does to it.
You can model most electrical characteristics with some software like this:
Downloads
You can import completed similar designs directly into the Projekte folder: Boxsim Projektdatenbank Systeme
The trick is to find a Visaton driver that resembles what you have. I get criticised for this, but it works for me. Especially with impedance for various resitors in a filter. Drivers / Accessories
I do consider a good multimeter useful. Not cheap though. Mine was £70. Here I use the inductance scale on a 1mH coil to see what a nearby metal plate (or circuit board) does to it.
Attachments
Baffle Diffraction Step
calculate the BSC inductor by using the baffle step freq (=115/baffle width in metres) in a 1st order calculator.
You'll need to re-do the tweeter L pad to match the drop in woofer output at the xover freq
Get rid of the zobel
calculate the BSC inductor by using the baffle step freq (=115/baffle width in metres) in a 1st order calculator.
You'll need to re-do the tweeter L pad to match the drop in woofer output at the xover freq
Get rid of the zobel
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explain why the Thread title says "without measurement"Andrew, it is an excellent primer for the unaware, and gives someone a much better start than they would get if they just put together some text book crossovers.
Yes if you want to extract the best (with the least pain) from your speakers you need measurements, but I can tell you now that if I had a guide like this 30 years ago, I'd have saved a whole lot of money and had much better sound for many years
Tony.
I saw the title and jumped straight in. Occasionally I look back hoping that a "without measurement" method will be described.
No luck. The Thread title is lying.
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Hi Andrew, I'm not sure that I follow. If you are referring to later discussion in the thread that talks about doing measurements then that is a diversion from the original intention of the thread.
If you are talking about the fact that Allen suggests to get hold of some datasheets that have manufacturer measurements, then I think you are being pedantic
No where in the original series of posts presented by AllenB do I recall him suggesting that you need to do your own measurements! He gives an approach that using manufacturers curves (spl and impedance), and various techniques you can achieve a crossover, which whilst probably not optimal, will be hands down far superior to anything that you would come up with using "off the shelf" crossover circuits.
Tony.
If you are talking about the fact that Allen suggests to get hold of some datasheets that have manufacturer measurements, then I think you are being pedantic
No where in the original series of posts presented by AllenB do I recall him suggesting that you need to do your own measurements! He gives an approach that using manufacturers curves (spl and impedance), and various techniques you can achieve a crossover, which whilst probably not optimal, will be hands down far superior to anything that you would come up with using "off the shelf" crossover circuits.
Tony.
I've never tried to demonstrate it quite this way before, but an 8" polycone bass will need very little filtering. Most of the rolloff is built into the driver already. All the simple 1.5mH coil here does is tilt the slope down about 2dB per octave. With first order 8" bass, usually second order tweeter works best on phase.
This is a simple filter you can adjust by ear. bling has got lucky the Vifa bass is well behaved. If you want to do higher order for a cleaner sound, the KEF Celeste III schematic is a good start. That might be for another day, because it's good to start simple and get to know the drivers. 30-60 litres is usually about right for 8" bass, so that shouldn't be hard either.
This is a simple filter you can adjust by ear. bling has got lucky the Vifa bass is well behaved. If you want to do higher order for a cleaner sound, the KEF Celeste III schematic is a good start. That might be for another day, because it's good to start simple and get to know the drivers. 30-60 litres is usually about right for 8" bass, so that shouldn't be hard either.
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Count me as another one who is mystified. Please read posts 1 to 15 in the thread I linked to again, and indicate whereabouts in these posts / the mythology outlined the user has to make their own measurements. I can tell you now: nowhere. It's all derived from manufacturer data-sheets. Or is your objection simply that Allan didn't write 'without taking your own measurements?'
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Thanks for your suggestions.
I'll try out the Celeste III as I already have those capacitors In the speakers.
Speakerbug in AU has P-cored coil 2.7mH for $21. Is air coil ok for for tweeter?
The other possibility is I invest in new tweeters, preferably that fit in a 104mm cutout.
Any suggestion?
Locally Vifa D25Ag are available, although a bit pricey at $50.00each and I believe old technology.
I'll try out the Celeste III as I already have those capacitors In the speakers.
Speakerbug in AU has P-cored coil 2.7mH for $21. Is air coil ok for for tweeter?
The other possibility is I invest in new tweeters, preferably that fit in a 104mm cutout.
Any suggestion?
Locally Vifa D25Ag are available, although a bit pricey at $50.00each and I believe old technology.
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