The 1st born, created on Sun 10 April 2005. Soon it is setup in my living room and put through its paces. I stuffed it with polyester cotton from an old pillow. The bass was sluggish and box vibration clearly audible. The result is not very pleasing. The mid is ok but the high rather screechy. I suspect that the presence of the padding slows down the air flow thus creating a 'bigger' internal volume. I removed the padding completely and the bass becomes much tighter. The screechy high is also lessen to my surprise. I managed to source some dense foam (children play matt), cut them into pieces and braced the internal walls. Unfortunately, there wasn't enough foam to fully cover all the walls. Much improved... #1
And when compared to my 1st HIFI speaker the B&W DM603. The drivers size are the same 1" for the tweeter and 6.5" for the mid-bass. However, the B&W uses passive radiator for the 2nd bass while mine are both active. My box is significantly bigger in volume due to the +50% depth and additional 10cm height. With the drivers mounted I estimate the weigh to be above 30kg.
So how does it sound?... Quite good. As a single unit it is rather difficult to judge as characteristics such as focus and soundstage is not possible. Furthermore, stereo recordings splits the signal in unequal proportion to the left/right channels. But as it is, the high, mid and low is distinctively better than the B&W. Phew... at least it proves that the $$, sweat and blood are not foolishly spent.
Now pending its soul mate.
Having checked with HomeFix, the Elmer probond interior glue is out of stock and the date for next delivery is anyone's guess (the fact that there's no delivery for the past 2 months does not bode well). I took a gamble and bought Selley's Liquid Nail.
BIG MISTAKE!!! This is a spirit based glue which means it dries rather quickly. It is very difficult to spread especially if used on large areas. I used this for internal bracing both side panels. The seems to be some sections with ~1mm gap, arrrgh! What to do? I use my remaining probond glue to try and seal these gaps. It took me 3 days pondering over the last piece which is the crucial front baffle. I finally decided to use PVA white glue from Selleys. It spread much better, alas, the instruction warns of using too much force in clamping which might sqeeze out all the glue,.. alas I ended with a glue front baffle with some gaping section at the bottom base, FUCK!
Oh well, lessons in woodworking......... once all dried, I took it for a spin.. using the remaining hdd foam, transfer over the drivers from the 1st box.
Notice the reverse polarity wiring for the tweeter. This is due to the xo being a 2nd order for the high pass.
Stuffing Balance
To my horror, the sound of the 2nd box is no where near the 1st. If it sounds better, I would've been really excited, but it actually sounded quite horrible(relative of course). The bass is definitely out, with clear box resonance (so it wasn't the stiffeners that help?)!!
The main problem now is figuring out what is causing this major diff. Of course the dimension and fit are slight off, but surely the few mm should not have contributed to such a drastic difference. The stiffeners are quite close in placing and dimensions. The only other obvious possibility is the stuffing foams. I decided to transfer piece by piece from the 1st box and positioned it as closely as possible in the 2nd. After more tinkering, I finally got the 'same sound'#2 as the 1st box
#1 The sluggishness of the bass reduced tremendously. I think the fibrous material slows down the air inside the box thus the muffled and sloppy effect.
#2 As far as my memory can recall. Such impressions are largely subjective and likely being influence by emotional needs. In this case, could it be my desire 'to believe' that the two box sound the same or they do really sound similar? At that time it is diff to do an A/B as it entail moving the drivers across from one box to the other. Thus time blurrs.