Hi all,
I recently purchased the Wilmslow Audio Prestige's that Loz1 had listed here. I have read the KatieandDad thread twice yet have a couple of specific questions.
The speakers I bought have the original ('troublesome') design shown below:
The previous owner has upgraded all the crossover components (to Monacor/Caddock resistors, Mundorf Mcap Supremes (for the tweeter) and Jantzen air cores) and mounted them externally. I want to rebuild the crossovers inside the speaker cabinets, without the huge 100uF capacitor! He has done a nice job building the external crossovers though:
The specific parts I have are:
Volt Rv3143 Bass (8 ohm)
ATC SM75-150 Mid (16 ohm)
Scanspeak D2905-99000 Tweeter (6 ohm)
The KatieandDad thread mentions that this generic crossover (designed by Steve, system7) may suit:
(Originally posted here: http://www.diyaudio.com/forums/multi-way/210627-wilmslow-audio-prestige-platinum-72.html#post4326410)
Is this crossover correct for my parts listed above? I think it may require some modification as my drivers have different impedance.
Which brand/level of resistors, caps and inductors should I go for - does it really make that much difference?
I recently purchased the Wilmslow Audio Prestige's that Loz1 had listed here. I have read the KatieandDad thread twice yet have a couple of specific questions.
The speakers I bought have the original ('troublesome') design shown below:
The previous owner has upgraded all the crossover components (to Monacor/Caddock resistors, Mundorf Mcap Supremes (for the tweeter) and Jantzen air cores) and mounted them externally. I want to rebuild the crossovers inside the speaker cabinets, without the huge 100uF capacitor! He has done a nice job building the external crossovers though:
The specific parts I have are:
Volt Rv3143 Bass (8 ohm)
ATC SM75-150 Mid (16 ohm)
Scanspeak D2905-99000 Tweeter (6 ohm)
The KatieandDad thread mentions that this generic crossover (designed by Steve, system7) may suit:
(Originally posted here: http://www.diyaudio.com/forums/multi-way/210627-wilmslow-audio-prestige-platinum-72.html#post4326410)
Is this crossover correct for my parts listed above? I think it may require some modification as my drivers have different impedance.
Which brand/level of resistors, caps and inductors should I go for - does it really make that much difference?
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My advice would be to measure what you have got before spending any money on making changes. It isn't clear why you don't want to simply stick the current crossover inside the speakers? If the crossover requires a 100 uF capacitor what do you propose replacing it with?
My issue with the 100uF capacitor is what I read in the KatieandDad thread by system7:
"I had a very rough look at your speaker, and that midrange crossover certainly doesn't inspire confidence. I don't know why that 100uF is there at all, and it's certainly not a classic topology."
"I had a very rough look at your speaker, and that midrange crossover certainly doesn't inspire confidence. I don't know why that 100uF is there at all, and it's certainly not a classic topology."
Make your own simulation with the factory plots of
the drivers in the kit and then you will be much wiser.
the drivers in the kit and then you will be much wiser.
Any will do. Boxsim, Xsim, Bagby's powerful spreadsheets
are particularly handy because you can create files or modify
existing ones any way you want it. SPL Tools also.
are particularly handy because you can create files or modify
existing ones any way you want it. SPL Tools also.
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What is it about this post that strikes you as ringing true? If system7 doesn't know why the 100uF is included does it therefore follow that whoever designed the crossover didn't know? Perhaps they included it on a whim because they had one spare.
The reason katieanddad made a mess of his project was that he would not gather information and make decisions based on that. Had he measured his speakers when he first heard they were wrong he would have known he had a faulty crossover which he could then have proceeded to sort out. Instead he flitted from one thing to another based on I know not what until he got fed up and gave up. Might you be proposing to do something similar?
Nope, not a chance. I could make the crossovers in an hour or two. I just want to get some expert crossover advice first is all. Do you know why the 100uF cap is included?
100 uF cap probably forms a 3rd order HP with C2 and L3R3 to make
a better phase matching with woofer which is offset in Z axis from the
mid dome.
I haven't looked but if I wanted to find out I would input the circuit along with the published manufacturer's curves into one of the programs suggested above and then interactively fiddle about to learn what is what.
Hi,
There is no chance S7's generic x/o is more suitable.
If you don't know what is wrong with it, don't attempt
to fix it by making assumptions of some sort of errors.
rgds, sreten.
There is no chance S7's generic x/o is more suitable.
If you don't know what is wrong with it, don't attempt
to fix it by making assumptions of some sort of errors.
rgds, sreten.
I would guess and back up the previous statement:the 100uF is there to match the phase with the bass AND hit target slope. without it the mid will be pushed a little harder lower down but be out of phase with the bass driver causing a loss of low mid/high bass - a lot of the 'warmth' or 'fullness' of the sound, it would effect the 150-400Hz region most I'd expect. crossing over mid domes is a real trick, I have a very similar speaker I'm working on at the moment, that topology isn't surprising at all, I've trialed about 20 variations with my current set up and am rapidly coming to the conclusion 4th order on the mid tweeter is essential to sound good, I'm still playing with the mid/bass, currently though it's very similar to what you have there.
Given the quality of the parts, unless there's something wrong with the sound I'd urge you to keep it as is.
Given the quality of the parts, unless there's something wrong with the sound I'd urge you to keep it as is.
Hi Jim, aka underzone. 🙂
A very clear initial post that described your speaker extremely well. TBH, you might describe the sound issues that might be fixed here. IIRC, it was a dip in response around 4kHz due to excessive rolloff from the mid, and some clumsy phase alignment. http://www.diyaudio.com/forums/multi-way/210627-wilmslow-audio-prestige-platinum-72.html#post4326410
Bass plus dome mid plus dome tweeter is one of those slightly ugly combinations that really doesn't play nicely together IMO. But evidently can be made to work.
Spendor do something like this too:
What I called a generic solution was something that you might adjust by ear by changing a few resistors.
It pretty much follows the Juancho filter on the mid. The bass is best left unchanged from whatever Wilmslow went for with your particular driver IMO.
What we are calling the "troublesome " circuit is certainly inelegant and has too many components. FWIW a 15R mid with 10R resistor across it behaves much like a 8R mid, so not an issue. But the polarity is wrong, the mid gets too much rolloff IMO, and a second order tweeter is indicated.
A 20uF mid HP filter followed by a 100uF cap just ends up close to 16uF! Simple as that. Those damping resistors in the mid shunt might as well be replaced by a single bigger input resistor. The tweeter filter is hardly critical. 4.7uF/0.2mH looks much the same as 3.3uF/0.3mH in practise.
Overall, I think getting the polarity right at ++- and changing that 0.9mH coil to 0.47mH is the fix. The rest is optional. Speakers aren't hard. 😎
A very clear initial post that described your speaker extremely well. TBH, you might describe the sound issues that might be fixed here. IIRC, it was a dip in response around 4kHz due to excessive rolloff from the mid, and some clumsy phase alignment. http://www.diyaudio.com/forums/multi-way/210627-wilmslow-audio-prestige-platinum-72.html#post4326410
Bass plus dome mid plus dome tweeter is one of those slightly ugly combinations that really doesn't play nicely together IMO. But evidently can be made to work.
SP38/13
Spendor do something like this too:
An externally hosted image should be here but it was not working when we last tested it.
What I called a generic solution was something that you might adjust by ear by changing a few resistors.
It pretty much follows the Juancho filter on the mid. The bass is best left unchanged from whatever Wilmslow went for with your particular driver IMO.
What we are calling the "troublesome " circuit is certainly inelegant and has too many components. FWIW a 15R mid with 10R resistor across it behaves much like a 8R mid, so not an issue. But the polarity is wrong, the mid gets too much rolloff IMO, and a second order tweeter is indicated.
A 20uF mid HP filter followed by a 100uF cap just ends up close to 16uF! Simple as that. Those damping resistors in the mid shunt might as well be replaced by a single bigger input resistor. The tweeter filter is hardly critical. 4.7uF/0.2mH looks much the same as 3.3uF/0.3mH in practise.
Overall, I think getting the polarity right at ++- and changing that 0.9mH coil to 0.47mH is the fix. The rest is optional. Speakers aren't hard. 😎
So, you are saying if we remove the 100uF cap and replace the 20 uF with
a 16 uF cap, then we should see the same response.
Grey is 20 uF and 100 uF, black 16uF.
Attachments
Not in this case though as there are shunting elements connected at the junction between them.
With x-sim I can find a sample woofer and a sample tweeter from the 2-way inbuilt example. I can't find a mid-range driver though and the Find A Part# seems bust. Any ideas?
Copy/paste a driver from the schematic to act as a midrange
or learn to use SPL Tools to create frd's and zma's from the
factory measurements.
or learn to use SPL Tools to create frd's and zma's from the
factory measurements.
Jim, aka underzone, I'm only looking in here because you asked me to look in. 🙂
I certainly don't enjoy the usual ugly skirmishes with the Peanut gallery. 🙄
Three way speakers of this ilk have a certain predictability once you know the ropes:Casablanca III
To understand how crossovers work, I'd encourage you to import some basic mid dome designs into the projekte folder of Boxsim. Then within 10 minutes you can modify some values and components and see what it does.
TBH, I think the "troublesome" Wilmslow Prestige circuit has some schoolboy errors, which were commendably mostly corrected in the Juancho filter except for polarity:
Simple and doable? C4 of 100uF, C6 of 8uF can certainly be shorted out. Change polarity to ++-. Unwind L2 0.9mH coil by taking 30% of its turns to get it down to around 0.47mH, because inductance is the square of the number of turns.
I think it'll sound better. But don't let me stop you building an anechoic chamber, buying microphones and all that other stuff. But the perfect is often the enemy of the good as they say, because it never arrives. 😎
I certainly don't enjoy the usual ugly skirmishes with the Peanut gallery. 🙄
Three way speakers of this ilk have a certain predictability once you know the ropes:Casablanca III
To understand how crossovers work, I'd encourage you to import some basic mid dome designs into the projekte folder of Boxsim. Then within 10 minutes you can modify some values and components and see what it does.
TBH, I think the "troublesome" Wilmslow Prestige circuit has some schoolboy errors, which were commendably mostly corrected in the Juancho filter except for polarity:
Simple and doable? C4 of 100uF, C6 of 8uF can certainly be shorted out. Change polarity to ++-. Unwind L2 0.9mH coil by taking 30% of its turns to get it down to around 0.47mH, because inductance is the square of the number of turns.
I think it'll sound better. But don't let me stop you building an anechoic chamber, buying microphones and all that other stuff. But the perfect is often the enemy of the good as they say, because it never arrives. 😎
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