Wharfedale Shelton XP2, A minor classic IMO

God bless my soul, how I love my local charity shop and the random speaker bargains they serve up. :)

They had a flippin' random 1980's bargain that even I would take on for £30 this week. For those of you who don't know, Wharfedale had a superb cabinet building shop up in Idle, Yorkshire. Even if the speakers are broke, they are sufficiently solid to be used as stools to sit on round your home. :D

Enter the Wharfedale Shelton XP2. I had a vague idea that this was a 20L closed box 8" bass plus 3/4" mylar tweeter design. A design about the size of a very big box of Kellogg's Corn Flakes. Which probably meets the WAF criterion.

TBH, they aren't bad for £30. It all works. Good bass response. The expected lively mylar tweeter response in the KEF T27 mold. I am very pleased with them. I was expecting a big roll of stuffing inside the closed box. And it turned up. The crossover completely surprised me. 8 elements!

So far I have counted 2x 1mH coils, two 16uF Elcap NPE caps, and a smaller tweeter coil around 0.3mH and perhaps about 3uF cap. Big surprise is a couple of tiny elements around 33R resistance and 0.47uH. I think this must be a BW3 design with some consideration to RF impedance. Ah well, we shall investigate further this Golden Age of British speaker design.

It sounds excellent for sure. Diana Krall, Kate Bush and Chris Rea all sounding better than on most Android tablets. :cool:
 

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Hmm, I am very fond of the shoes Mrs.Krall is wearing. The speaker is not bad either.
She has very nice shoes. Along with the "Three T's" that every Broadway showgirl understands. Teeth, Tushie and something else I shouldn't mention. :D

I think people take loudspeakers far too seriously. They are what we Brits call "Small Beer" compared to the problems of the Universe. I mean, here's a fairly random thing from my deep mathematical background. According to Douglas Adams, the answer to Life, the Universe and EVERYTHING was 42. NONSENSE. It's actually 163! :cool:

I just refer you to this, if you doubt me: Complex multiplication - Wikipedia

163 is the greatest number in the Universe, IMO. As it goes, 5 is a good one too, whether in the icosahedron or the largely-equivalent dodecahedron: A New Path to Equal-Angle Lines | Quanta Magazine.

I won't try and justify these ideas. I just follow my intuition most of the time. :D

BTW, I'll get back on the Wharfedale crossover here, when I have more time.
 

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I'll have to work on improving my collection of Diana Krall cd's. I am absolutely in agreement with you that overly serious bothering with loudspeakers may easily become a counterproductive thing that's turning a nice hobby into a frantic worrying over everytning. I am far more happier making something out of trashed stuff than throwing money at top notch non plus ultra highest quality components. On the numbers theory, I think I have found a reason why number 13 is considered to be an unhappy number for the world, and in fact is the greatest number of universe that holds the explanation of what perfection is. For example water is known to exist in 3 different states and it is still one and the same compound, H2O. Enough of the OT ramblings.
 
I'm not sure you have proved anything about the number 13 as being terribly bad. I certainly have no personal beef with 13. It's quite a dull number, IMO. :D

AFAIK, the pentagram number 5 was associated with Old Nick. You know, the bad guy. 5 is actually a magic number. It transforms into the Golden Ratio Phi (1.616) which we use in our loudspeaker boxes with little effort.

What not many people know about Phi, is that it is actually the most easiest and perfect number to simplify into Continued Fractions. Everything goes to ONE. :cool:

Continued fractions are not the most intuitive thing to work with. We all agree that a hundred years after Einstein with his Special Relativity, General Relativity and the Quantum Theory, we really have no idea what he was talking about. :eek:

I happen to think that continued fraction expert Ramanujan will take far more time to get a grip on. This is the man who discovered elliptic curves about 60 years before anyone else. Elliptic curves lead to the proof of Fermat's last theorem which baffled mathematicians for 300 years, albeit a dullish priblem compared to the Riemann Hypothesis, or my personal favourite "Euler's Zeta Function". And all by observing that the Taxicab number 1729 was a whole heap of fun when trying to find two cubes that summed to another one. It always missed by 1.

To get back on-topic with loudspeakers, these are devices that convey musical information. It seems to be that the basic quantum unit of the Universe is the smallest unit of information, related to Planck's Constant. Noisy-channel coding theorem - Wikipedia

All our GOOD speakers do really is convey more information with less noise or distortion. :cool:

Because I always like to include an image in a post, I just throw in the Mexican Hat potential, vital to symmetry breaking in Physics. But it has no relevance here, AFAIK. :eek:
 

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boswald, much as I have enjoyed many of your contributions here, I have serious doubts whether the Real Universe actually employs Zero at all. :D

It looks good on paper, but what we know from the Einstein Quantum Theory is that ground-state energy is never Zero. You can squeeze a physical system as close to Zero as you like by cooling or such. But it always has a ground-state Energy above Zero.

You can't get rid of the last BIT. Which is the minimal unit of information. :cool:

Anyway, much more interesting are Elliptic Curves.

David Hilbert is said to have remarked that the theory of complex multiplication of elliptic curves was not only the most beautiful part of mathematics but of all science.

Complex multiplication - Wikipedia

That's some claim, but David Hilbert was no mug. :D

Further investigations of the Wharfedale Shelton XP2 this morning. I am picking out 2x 1mH coils, 2x 16uf NPE caps. Maybe a 0.3mH tweeter coil and 6uF tweeter cap. Plus a couple of minor low-power resistors. Unfortunately, Wharfedale have glued the crossover to the cabinet, so I can't trace the connections without wrecking it. IMO, the two small resistors do almost nothing.

I got my measuring tape out. We seem to have room for a 98mm H1283-06 22TAF/G replacement metal tweeter here with a minor enlargement to the 80mm tweeter cutout. I am inclined to keep the Wharfedale 8" paper bass. For one thing the bass has my preferred almost transparent cloth dust-cap. If you didn't know, the only real reason to fit a dustcap is to stop iron particles falling into the magnetic gap.

This speaker is a fine upgrade candidate. Joachim Gerhard quite likes the SEAS 22TAF/G metal tweeter. Maybe some better capacitors too.
 

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OK. Here's the front view again. Paper cone, rubber roll surround and fairly transparent light undoped cloth dustcap. 5.6 ohms DCR.

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Woofer 185mm baffle cutout, chassis 205mm square.
Mylar tweeter 80mm baffle cutout, chassis 110x 90mm.

The labels on the back of the drivers are just stock control gibberish AFAIK. The 4 rubber grommets are flush with the frame. And the two shots you want.
 

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Ringy dingy stamped frame. Some of us consider the basket the stealth offender in standard bass-mid drivers like this. I was hoping for a slab of alloy but hey! You filter wizards can correct any flaw, right?
OK it's a cool speaker. I would be delighted with it, as I started out with AR-4x...
 
Ringy-ding probably describes pressed-Steel chassis. TBH, I don't mind them.

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IMO, the biggest filter mistake you can apply to pressed-Steel chassis is a notch filter. You might get away with a notch with solid-Alloy chassis. Like Celestion or SEAS have a good reputation for.

Why? Because you might be stopping the cone dead, But the pressed-Steel chassis rings! The Energy will always find a way out. :eek:

It sounds HORRIBLE. My own personal preference with pressed-Steel chassis is a 4th order filter.

It must make far more sense to just ask a speaker chassis to not to even go near it's weaknesses.

You gotta laugh. There's hugely more to a good loudspeaker than mere Frequency Response. And that is assuming the whole thing can convince you that you are actually in the huge Albert Hall in London UK, or on the train between Bergen and Oslo in Norway. :D
 
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Hi there speaker fans! Here's the promised update on my delvings into the remarkable Wharfedale Shelton XP2's crossover. :)

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It wasn't what I expected at all. But it was helpful that Wharfedale used that circuit board in loads of designs. Even three-ways. So I could find the back view and trace it. A flippin' 1.5kHz trap there. Haven't seen one of those since the glory days of KEF 8" bextrene units! :eek:

FWIW, here's Troels Gravesen's thoughts on this sort of high-efficiency thing: High Efficiency Speakers

The images speak for themselves. 12dB/octave electrically. Quite remarkable to get such steep 24dB/octave acoustically on the woofer just before the 3KHz breakup area. About 18dB/octave acoustically on the tweeter. Only thing I could criticise is the rather bumpy impedance. But a good sounding speaker.
 

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In comparison, here's a Wharfedale Dovedale 3 bass driver with a die-cast aluminium alloy chassis.

The well known benefits compared to pressed steel are greater rigidity, less resonance, accurate dimensions and open construction.

And it looks fab!
 

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The Shelton sat between the Denton and the Linton in both cost and size but wasn't quite as ubiquitous.

I owned a pair of the larger Lintons back in the day but, although resplendent in their genuine teak veneered cabinets, they ultimately lacked detail and clarity so were sold on.

Perhaps I was overly optimistic in thinking that the Lintons would be a substitute for my Wharfedale RS/12/DD full range, die-cast alloy chassis drivers in 3 cubic foot bass reflex cabinets!

And, for you cone oglers out there, here's a front view of the Dovedale 3 woofer!

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As you are no doubt aware, the Dovedale 3 woofers were engineered in the days before T/S parameters.

However, I can give you the following information:

The dc resistance is 6 ohm.
Flux density is 135,000 maxwell.
Free air resonance is 25Hz
Crossover frequency 600 - 1,500Hz.

More usefully perhaps - the response will be 3dB down at 45Hz in a 45 litre sealed cabinet.

Hope this is helpful.

P.S. There's a pair for sale on a well known internet auction sight right now - 2 days to go!
 
system7: My apologies for the diversion.

I am really interested in hearing more about the Shelton crossover design. How important is the 1.5kHz notch filter in relation to this particular woofer?

Wonder how the system would sound with a lower order crossover arrangement?
 
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Do you have the measured TS parameters of the Dovedale 3 woofer ?
I see you posted measured T/S parameters for the Dovedale 3 woofers back in 2014 (attributed to 'cone head', 2013).

Presumably you are hoping for verification of those figures from another source.

I too would be interested in a definitive set of parameters.

Obviously the the information I have given won't be of much use to you but may be of interest to others.