Wilmslow Audio Prestige Gold. Crossover help.

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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:

483135d1431655978-wilmslow-audio-prestige-platinum-wilmslow-prestige-circuit.jpg


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:

aEvoYC1.jpg


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)

483137d1431655978-wilmslow-audio-prestige-platinum-s7-generic-soft-dome-mid-circuit.png


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 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."
 
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."
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?
 
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.
 
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.

I liked the sound from this set-up very much and was planning to make all the measurements needed for publication. I never was quite satisfied from the phase-tracking between the 18W/8531 and the D3806/8200.
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.

483137d1431655978-wilmslow-audio-prestige-platinum-s7-generic-soft-dome-mid-circuit.png


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.

483136d1431655978-wilmslow-audio-prestige-platinum-wilmslow-audio-prestige-monacor-bass.jpg


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.

483135d1431655978-wilmslow-audio-prestige-platinum-wilmslow-prestige-circuit.jpg


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. :cool:
 
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. :rolleyes:

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:

483135d1431655978-wilmslow-audio-prestige-platinum-wilmslow-prestige-circuit.jpg


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. :cool:
 
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