Newbie: New enclosure for Dali 3003 speakers

[ASMNL]

Hello all,

I am a newbie here and not that educated in speakerdesign apart from readnig at forums. I have some old Dali 3003 speakers amd would like to make a better cabinet for them, the vineer is bad, sound could be beter too. NOw, the idea is:

- Make the enclosure heavier/thicker/stiffer
- Adding braces
- enclose the tweeter internally
- Renew the cables inside

However, I would like to make them taller... If I would keep the same volume, but because of thicker walls / bracing / tweeter enclosure, make them taller to get to the same volume, would that have any negative influence ?

Thanks for all your advise.

 

[dragonweed]

They look like decent speakers, worthwhile for upgrading. Making them stiffer might be a good idea with extra crossbracing, but thicker, heavier, I am not sure.
Making the enclosure from heavy thick panels does not prevent panel resonances, only shifts them downwards, also remember, the heavier a resonating element is, the longer its decay time will become.(it will ring longer). What I would do, is keep the rounded front panels, and build a taller well braced box for them, with a physically separated (closed) bottom portion.This way you can keep the original volume of the box. Also gives you the advantages of elevating the tweeters to ear level (good idea with any D'Apollito arrangement), then you can place the crossover in the separated bottom box, free from the driver induced resonances. Enclosing the tweeter in a suitable small compartment is a good idea too, as well as rewiring them with your heart's desire cables. Check the component quality on the X-over, might be some more room for improvement there. Good luck!

 

[ASMNL]

Hi Dragonweed, Thanks for your good advise.. I know one thing or two about resonances as well, work at an acoustic firm for yacht acoustics (preventing noise and vibration in a cabin for the rich and whealthy...). I can construct the walls from special heavy wooden sandwich panels, wich have a very high internal damping, So any resonance wil be dampened by the semi flex core. I thought about using the original baffle, maybe strengthen theboard if needed and make the side panels with a front roudned edge as well, to overcome tweeter secondary paths... ?
THe seperate section on the bottom, good idea ! fill with sand ?

 

[dragonweed]

You are lucky, if you have those special boards at your disposal... use them! Filling the bottom enclosure with sand sounds like a good idea, but then you must think about where to place the crossover board. Maybe in the main enclosure, but still try to think about mounting them some way decoupled from the resonating surfaces. One more thing comes to my mind, just by looking at the size of the reflex tube (oh well, I worked for a well known audiophile speaker manufacturer for more than 10 years), I would play with the length/diameter of the tube, because as far as I remember lots of companies "overtune" their reflex speakers for a little extra efficiency, bur sometimes lowering the Fb can seriously improve low bass response, and its ripple, sacrificing a little bit of efficiency. Believe me, it's worth a try.. (just roll a suitable cardboard tube, and insert it into the original tube, so you can change the effective length of the tube by pushing it in, or pulling it out a bit)

 

[ASMNL]

Thanks again for that well received and appreciated advise. The tube trick I will try for sure as I feel the bass response is a little spongy and too much up front, but may also be the lack of spikes.... I will cancel the sand, is heavy too and moving around will be an issue than. Sounds like getting the filter away from the main cabinet is a much better feature. Any tips on the bracing ? Big holes ? horizontal or vertical ?

 

[dragonweed]

Two or three properly placed horizontal braces made of 2/3" MDF or plywood should be sufficient for the size of the box, (with BIG holes, or the "picture frame" type), one above, one below the tweeter , the third one in the middle of the lower portion of the box. Try to make the placement uneven somehow (not to equal distance from each other).This way the panel resonances are divided into three different frequencies, instead of one which would be more audible. Also -since you are making a new enclosure- try to place the reflex tube on the rear panel (unless your room requires close to wall placement), because this way the
upper bass- lower mid colorations will be less audible throughout the reflex tube. And yes, if you rejected the sand filling option, then definitely put your X-over into the separated bottom portion of the box.