Need help on enclosure question and xover design

[ibanezcollector]

Ok as some may have seen I made my entry to DIY with my towers.

Now after extensive listening I am not totally happy with the design. It had excellent low end but the midrange seemed to be thin..

I have the following drivers available to use

(4) Dayton 7" Aluminum Mid/Midbass
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-335

(2) Dayton 1 1/8" Silk Dome Tweeters DC28F-8
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=275-070

My last entry was a 2.6 cu ft enclosure tuned to 29hz


I want to make something in a floor standing speaker like the Thor by Seas. I was wondering if the above speakers would work ok in that design?

http://www.seas.no/thor.htm

Also I want to make my own crossover this time around but really need some help with making it. I would love if someone could assist me in a design. In the old enclosure I used the prefab Dayton 2way crossed at 2K.

If someone is bored and really wants to sit down with me and discuss a plan of action I would be in debt forever. I know these are not the best speakers in the world but they were in the budget at the current time and still currently.

I can afford wood cant afford new drivers

Thanks
Brett

aim ibanezcollector2

 

[RJ]

Someone on this board just did a heck of a job researching the Thor box. If I find it, I'll repost.
I have several dozen Dayton 7" Aluminum drivers that I experimented with this past year. I found them 'Not' liking to be crossed over 1750 hz. The only tweeters I paired them up with were the Seas H1212 and the Dayton Planars. Both were crossed over at 1750 8th order acoustic (Cauer Elliptic) ala Jon Marsh and handled high volumes very well.
The Dayton Silkie might be the problem in your design since all of my designs never had thin midbass or midrange. I know the silkie doesn't like to be crossed low and that's why I've never purchased one.
You might have better luck going Cauer Elliptic with your drivers and from what I've read about the Thor design it's going to be a BIG box.
I've modelled the Dayton 7's in a TL box and it comes out pretty big.

 

[thalis]

Tweeter’s sensitivity is a little marginal for the 2 woofers; else they seem to be nice silk drivers, especially for the price. With these Woofers you would easily extend down to 30Hz and even less with a cabin of ca 50 litters. I wouldn’t go to almost 75 litters as you suggested, I would find it extreme, and for many reasons you would end up with a somewhat imbalanced sound, weak at the top and dinosaur at the lows. Furthermore you would have big boxes and you would have to do considerable efforts to neutralize them.
With 50 litters you would have a port (with flush ends) of 10cm internal diameter and 35cm depth to have a -3dB of about 29 Hz. I don’t know how low you would like your speaker to go. Someone would perhaps prefer a 40 litter enclosure with some more absorbent material inside, with some 9cm diameter port with the same length, which gives a more graduate roll off in the bass, and still has a ca 32 Hz -3dB freq. point.
You can’t have greater port diameters, since length will get dangerously big. Bellow 40 litters impulse response would become questionable (bad transient response).
Regarding the cross, these drivers don’t leave much choice: It will have to be at about 1,9-2 KHz, exploiting the apparent magnitude decreasing of the woofers there. This has to be done after the construction of your boxes and the measurements that you should then perform, since boxes will somewhat alter woofers behavior there, which has to be counted in the crossover. Your crossover part values will be nearby the theoretical values for a 12,5 ohm low freq load and a 7,5 ohm high freq load since you will not have to correct for the driver’s slopes beyond their crossover point (they are good as they are).
The cross would perhaps flirt with 3rd orders, perhaps 2nd in the woofer section with some impedance compensation to be sure that it will work right and that it will adequately recess the critical 7-8 KHz where the break in its metal cone is.
In the end, you will perhaps have some problems when you get really loud since the tweeter will feel a bit stressed, but proceeding to greater slopes will not make things significantly better and will worsen the sound, apart from further decreasing the tweeter’s efficiency (another capacitor in series will cut some 0,7 dB, at about).
You can go here and download this program. It is easy to learn and since you have (from the site that you posted) both SPL and Impedance sample text files, you could enter them to this program (rename the file type ‘.txt’ to ‘.frd’ and erase everything irrelevant to magnitude-phase values) and begin experimenting. Afterwards, and having you first demo design posted here, it is sure that you will have assistance from this forum, either from other members either/and from me.
You can end up with a decent speaker, of some 88dB/2.83V, a little bass-heavy, with not very quick bass (but ‘alive’ and deep), somewhat thin mids and smooth upper frequencies, as I presume, and if we should speak regardless of price factor. Great if we consider the price
If you prefer to have less low output and better transients, you could also end up with the 2 woofers in a sealed enclosure, of ca 25 litters. This would still give you almost 55Hz -3dB and a smooth rollover after that, would give good bass, less, quicker, tighter.
Compound vented enclosures (would be great) can’t be accomplished with this driver – the low Fb together with the low volume needed, end up to extreme lengths of the port for a reasonable surface.

Regards,
Thalis

 

[RJ]

Here's the link to the Thor design. Excellent reading, in fact I'm re-reading it now.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=70862&highlight=

Here's my TL Sub design for 8 & 10" woofers;