Just picked up these DIY Wilmslow 3-Ways of flea bay... sound awful, help please! - diyAudio
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Multi-Way Conventional loudspeakers with crossovers

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Old 26th January 2014, 06:33 PM   #1
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Default Just picked up these DIY Wilmslow 3-Ways of flea bay... sound awful, help please!

As the title says, saw these on ebay and they reminded me of the old PMC 3-ways. Checked out the drivers online and thought they had potential to sound good, but now I have them I couldn't be more disappointed.

Anyway, the facts:

The drivers:
Tweeter: 27TG
Vifa D75MX
Vifa M25WP

Crossover: uses monacor inductors and wilmslow 'supersound' caps.
series denoted by (s), parallel by //, described in order form input:

tweeter: (s) 5.6uF Cap, (s) inductor, unknown value, (s) variable potentiometer.

Mid: (s) 0.81mH inductor, 25uF cap, // 4.7mH inductor, // 5.6uF cap, (s) 3.3Ohm R, // 10 Ohm R.

Bass: (s) 2.7mH inductor, // 60uF Caps (2*30 uF)

Cabinet: No stuffing, approx 30*40*90 cm, a few foam pads, no enclosures for mid or trebble.

Thoughts so far:
Why the hell is there...
an inductor on the tweeter?
a 2nd order elect. xo on the mid low pass but a 1st order on the tweeter high pass? (given the FR of the drivers would have thought this to be the other way round)

The sound:
One speaker seems to have lost the connection to the tweeter.
The other speaker sounds dull and lifeless. The bass is extraordinarily bad, I can only describe it as loose and floppy, mad worse by the face it seems to roll off quite steeply after 40Hz...

The plan:

Cabinet: Cut off the bass and install a transmission line for the bass speaker, seal the mid.

Check the drivers individually sound OK.

measure the caps to confirm values, but probably ditch all but the large bypass caps on the bass drivers, keep the coils if possible, replace resistors with better quality items of fixxed value, remover the series inductor from the tweeter

model the crossover in software and re-design...

Anyway, quite literally any and all feedback, ideas and suggestions would be more than welcome, as at the moment I like the drivers but feel the cabinet and crossover are both letting the team down!

Probably worth mentioning that despite the terrible cabinet finish, the build quality is good.
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Old 26th January 2014, 06:45 PM   #2
PJN is offline PJN  United States
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This sounds like a fun project, I'll be watching with interest. If you haven't done so already, go to the FRD consortium website, they have lots of great software to help with the new crossover design. Good luck.

PJN
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Old 26th January 2014, 06:55 PM   #3
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Quote:
Originally Posted by PJN View Post
This sounds like a fun project, I'll be watching with interest. If you haven't done so already, go to the FRD consortium website, they have lots of great software to help with the new crossover design. Good luck.

PJN
I was just struggling to get a 3-way model to work and trying to work out where to get FRD files!
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Old 26th January 2014, 07:02 PM   #4
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I'd contact Wilmslow Audio and see if they can provide the original specs for the speaker, they are normally good with their tech support.
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Old 26th January 2014, 07:18 PM   #5
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Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
Drawing out the schematic for the cross-over will help immensely.
Looking up the woofer, an out of production unit (The other two still in production) I think I was able to come up with the T/S parameters (Need confirmation).
Running the sim I got these results.
Fs 28,Qms 2.0, Qes 0.34, Qts, 0.29, Le 1.3, Re 5.8, BL 10.4, Vas 145L

EBP for a ported design.
48L, Fb 39.25 Hz., -3.04Db@44.69 Hz., 102X245mm port.

Retuned
125L, Fb 35 Hz., -3.06Db@32.53 Hz., 102X83mm port.



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Old 26th January 2014, 07:23 PM   #6
tinitus is offline tinitus  Europe
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disconnect all drivers, and check if they are working properly

maybe test them with their respective high pass filter only
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Old 26th January 2014, 07:36 PM   #7
DrBoar is offline DrBoar  Sweden
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Connect the drivers without crossover and listen to them
Bass on normal levels
Midrange on low level
Tweeter on even lower level (or protected by a large cap say 10-50 micro
Do they sound OK
Do the pairs sound the same?
The box seem to be less than 50 liter the Fs in box is then about 60 Hz with a Q of about 0.7

A very small coil could be used in series with the tweeter, but it looks like a ferrite core coil and that is plain wrong.
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Old 26th January 2014, 08:11 PM   #8
tinitus is offline tinitus  Europe
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Originally Posted by DrBoar View Post
A very small coil could be used in series with the tweeter, but it looks like a ferrite core coil and that is plain wrong.
I sure hope it is in parallel

in any case, tweeter parallel coil is small, so still no need to use ferrite, no

and maybe change that variable tweeter att
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Old 26th January 2014, 08:55 PM   #9
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it looks like a ferrit coil, it's definately in series!!!

On first inspection it seems that removing the tweeter coil is essential, I can't think of a possible reason to ever have it...
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Old 27th January 2014, 11:25 AM   #10
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Ok, that should say ferrite coil.

I've made a model of this in passive xo designer today, it's a bit crude but gets a better understanding of what's going on.

From a phase point of view the transfers all look good, but I have to say from FR it looks pretty bad... I need to measure the components to verify the values before I can proceed, and increase the accuracy of the FRD in the simulation.

I'll put up some pretty pictures in a while...
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