Old thread, but not dead yet. (Just like me.)
This is actually a discussion of 3 or 4, or maybe 5 great topics:
1. Ported or sealed
2. Front port or rear
3. Directionality of low frequencies
4. Box tuning for high fidelity reproduction or musical instrument sound production
5. Why some speakers sound better than others
• So I guess it's 5 topics after all
As I might have mentioned before, I have been doing this a long time. Started building boxes about 1967, called it Wright Sound in 1980, you can do the math.
1•))) To port or not to port
A port (phase inversion port) allows some of the energy from the back of the cone to augment the front. This happens when, around the tuned frequency, by the time the rear wave gets around to coming out the port hole, it is in phase with the front wave. But as we rarely get something for nothing, it is at the expense of notes that are not around the tuned frequency. Mostly lower. A proper graph would show a bump at the tuned freq. but a steep rolloff below it, compared to a sealed enclosure. So does that mean it has more bass? Well, at that note, yes, but down to 20 cycles, no. I have built a great many boxes, most of them ported, but everything I am doing now is sealed.
2•))) Front port or rear
While making all those boxes, I did do a few with the port on back. Sorry. Wish I hadn't. The concept is crackpot. While it can sound OK in some cases, it is hit or miss, mostly miss. It really does depend on the stage, the wall, the other stuff sitting around it and maybe more.
That also brings me to:
3•))) Directionality of low frequencies
It is a fact that directionality goes down as freq. goes down, but locateability does not. (I know it's not a word, but this is my speech and I can make up words if I need to). A blind guy can tell if the bass is on the left side of the stage or the right. And unless your feet are stuck to the floor, as you move around you can tell if the extra lows from the ports are coming from here or there. Just because lows are less directional dosen't mean you can't hear where they are coming from.
4•))) Box tuning
If you are aiming for high fidelity, you will tune your box design to achieve the flattest response possible. (Best sounding boxes to me are not ported). However, all of my combo guitar amps are open back and sound great, but I would not want an open back speaker in my living room for music or movie sound. The BagEnd little box with the big hole in the back is on the same track as my open back Fender Super. If you like the sound, that's good for you. I wouldn't do it that way, but it's no good arguing with what works. But if you find it is better sometimes than others, that might be the reason why.
5.•))) Speaker sound
If you like the sound of a given speaker, you will probably like it no matter what box it is in. The box, unless it is rattling and falling apart, has only a little to do with the timbre or sound.
Most great sounding speakers for guitars and bases have light weight cones. Don't expect to get the sweet sound you want out of a 600 watt heavy cone pro woofer. The things that make it handle more power also impede its movement making it sound stuffy or harsh. Celestion greenbacks and Jensen orange label, for example, have fantastic sound and very light cones, and low power rating. (Back in time I used a Marshall 4-12 with greenbacks for bass. Sound was great but I was deathly afraid of blowing them.). If you want a concert monster bass rig, that's a different story, but if you want that Ampeg B15 tone, it's low power, light weight cones for you.
Keep on rockin'.
Perry out.
