Just picked up these DIY Wilmslow 3-Ways of flea bay... sound awful, help please!

[Moondog55]

Fair enough
I always thought this dome came with an integral rear cup; but a small plastic cup shouldn't break the bank

 

[tinitus]

Could you tell me more on this?

I always prefer the gentle approach and preferably with a minimum of effort ... and it always ends with some kind of 12db variation

I use this xo is for my bass guitar speaker

 

[Sonce]

Could you tell me more on this?

Impedance falls down very low with too big capacitor.

 

[laplace]

The sound quality of the mid is still bothering me, the dome sounds great but getting it to integrate with the rest of the speaker is a nightmare (i.e. sounds great on it's own but less good when connected with the woofer/tweeter). I should point out that it still isn't sealed, and it only has one screw holding it to the baffle, as the person who build these was incapable of drilling more than one hole with any accuracy (!)

You really must chamber the mid before doing anything else. Otherwise it's acting as a passive radiator for the woofer, which will drive the mid's coil outside of its Xmax and make it sound incredibly bad, if not damage it. And of course you lose any acoustic support to the mid that the chamber might provide.

 

[Sonce]

The sound quality of the mid is still bothering me,
I should point out that it still isn't sealed

Oh, I did not see this - it MUST be sealed!
laplace is absolutely right about that.

 

[tinitus]

the Vifa mid dome does not have a back cup, but I do not think its open back either ... is it ?

or maybe there is the magnet venting hole ?

in which case the cup should just fit the magnet
many pics show a piece of felt placed on back of the magnet

 

[nannoo]

it's vented

 

[Richard Ellis]

Really looks sealed by this.....
Really couldn't hurt by enclosing it with 2-3 Liters worth. If it does have a pole-piece vent hole beneath that felt !@#$ , no wonder! All that pressure setting the dome in motion!

______________________________________________________Rick...........

 

[tinitus]

... setting the dome in motion!

can't remember reading the mid dome is moving ... but is it ?

 

[sreten]

Hi,

The mid dome needs to have a rear sealed chamber.

This will bring up its low end response but also Fb and Qb.
The x/o cannot be designed properly without the rear chamber.

You may or may not get away with not compensating
the mids Fb impedance peak, modelling will reveal all.

rgds, sreten.

http://audio.claub.net/Simple Loudspeaker Design ver2.pdf
FRD Consortium tools guide
Designing Crossovers with Software Only
Jay's DIY Loudspeaker Projects

 

[nannoo]

I should probably mention, an additional project of mine at the moment is a 4-channel power amp, which would be pretty ideal to driver these speakers... is there such a thing as a 'cheap' high fidelity digital crossover? The plan would be to run the tweeter and mid from one amp and bass from another, I'm also thinking this on the basis it will definately improve overall sound quality, any of you who disagree please let me know and advise!

thanks

 

[nannoo]

... Ok, so I can only find the sealed seas chamber in the US, and the cost of delivery (about $40) means they're not gonna happen, I'm currently thinking to use a 2 litre soda bottle as a former to build my own chamber unit, just wondered if anyone had any suggestion of how best to do it? (i.e. what material to use, if I should keep the plastic bottle or just use it as a mold etc) or even if there's a simpler way to make a 1.7 litre chamber...

 

[Lojzek]

I would make a chamber of mdf or anything that can be easily glued.

 

[nannoo]

I thought about that, but the easy availability of a 1.7 litre mold (well, 2 litre, but would be cut down and molded inside so would come up very close to 1.7) may be something to capitalise on, maybe with a resin and mesh?

 

[Lojzek]

I have not followed the thread carefully. Why does it have to be 1,7 litre ?

 

[Sonce]

I'm currently thinking to use a 2 litre soda bottle as a former to build my own chamber unit, just wondered if anyone had any suggestion of how best to do it? (i.e. what material to use, if I should keep the plastic bottle or just use it as a mold etc) or even if there's a simpler way to make a 1.7 litre chamber...

Plastic bottle is too thin, it will flex by woofer action and pump air inside the dome midrange. Use thick plastic flower pot instead (do not forget to seal the bottom hole!).

 

[wintermute]

Could you tell me more on this?

As mentioned by others, impedance dips need to be checked. Get into the habit of checking the impedance of the final network in your simulation not just the frequency response/phase. It may save you a lot of time and money!

Tony.

 

[mctavish]

For a quick and easy back chamber one can also use the large diameter PVC pipe and endcaps from your local Home Despot and trim for correct volume. Works great!!

 

[laplace]

I'm not sure where you are out what their shipping cost is, but I've previously bought very cheap chambers from madisound.

Failing that, I think the PVC drain pipe option is very good; you can use an end cap as a kind of reverse flange too.

 

[nannoo]

I'm in the UK, so shipping was prohibitive