Hi,
So, I've been looking at various sub designs, which amps to use, etc., and so far, all I've managed to do is get to the point where I understand that I don't understand a thing about this.
So, first, the goals:
1) SQ is priority 1
2) High power handling will be needed, now that I'm running separate amps for my mains (500 wpc). Current plan is to use a sub controller module and EP4000 amps for their high power and fairly high damping factor. This also gets me past what will probably be a relatively low SPL design due to another requirement.
3) Mid-bass capability is not important. 2 x-over points will be used: 50 Hz while listening to music, 80
Hz during movies. I'll continue to use the 3 7" drivers in my mains for mid-bass (1st x-over point on mains is 125 Hz).
4) Lower -3db point of 8 Hz, or at least useful extension down to that point. Yes, 8 Hz. I like organ music, and a pipe organ can produce a fundamental tone of 8 Hz. Now that SACD and DVD-A are around, and now that engineers are putting 14-16 Hz effects on Blu-Ray, I want to be ready.
So, now the questions begin:
1) Basic design, ported or sealed? I understand that while you can tune a ported enclosure for any freq you want, roll-off is 12 db/octave below tuning frequency. So I'd probably have to tune to, what? Something like 4-6 Hz? Sealed is less efficient though, so I just don't know enough about the upsides and downsides of each design to make a decision. However, enclosures which exceed the available floor space of the room will be difficult to get past the wife. The wife is, however, an angel of tolerance when it comes to my little acts of folly in this area. As long as it looks good and sounds great, she accepts pretty much anything I do with minimal comment (yes, I am aware she's a keeper, and that I'm a very lucky moo to have found her).
2) Driver size. I'm trying to decide between 15 and 18. Again, SQ is the number one goal, and it seems like the bigger the driver, the higher the damping factor the amp would have to have in order to control the driver. Is there a significant difference in the damping factor requirements between 15 and 18 inch drivers? I have about 1500-1800 sq ft that I'm trying to pressurize, due to the fairly open floor plan of my house. I can place up to 4 subs in the listening area, depending on size (4 refrigerator sized enclosures probably won't work though).
3) What am I missing? I know there are things I have to be missing in this. As Donald said, what are the unknown unknowns?
That's all off the top of my head. I'm sure more will follow. It always does with me.
So, I've been looking at various sub designs, which amps to use, etc., and so far, all I've managed to do is get to the point where I understand that I don't understand a thing about this.
So, first, the goals:
1) SQ is priority 1
2) High power handling will be needed, now that I'm running separate amps for my mains (500 wpc). Current plan is to use a sub controller module and EP4000 amps for their high power and fairly high damping factor. This also gets me past what will probably be a relatively low SPL design due to another requirement.
3) Mid-bass capability is not important. 2 x-over points will be used: 50 Hz while listening to music, 80
Hz during movies. I'll continue to use the 3 7" drivers in my mains for mid-bass (1st x-over point on mains is 125 Hz).
4) Lower -3db point of 8 Hz, or at least useful extension down to that point. Yes, 8 Hz. I like organ music, and a pipe organ can produce a fundamental tone of 8 Hz. Now that SACD and DVD-A are around, and now that engineers are putting 14-16 Hz effects on Blu-Ray, I want to be ready.
So, now the questions begin:
1) Basic design, ported or sealed? I understand that while you can tune a ported enclosure for any freq you want, roll-off is 12 db/octave below tuning frequency. So I'd probably have to tune to, what? Something like 4-6 Hz? Sealed is less efficient though, so I just don't know enough about the upsides and downsides of each design to make a decision. However, enclosures which exceed the available floor space of the room will be difficult to get past the wife. The wife is, however, an angel of tolerance when it comes to my little acts of folly in this area. As long as it looks good and sounds great, she accepts pretty much anything I do with minimal comment (yes, I am aware she's a keeper, and that I'm a very lucky moo to have found her).
2) Driver size. I'm trying to decide between 15 and 18. Again, SQ is the number one goal, and it seems like the bigger the driver, the higher the damping factor the amp would have to have in order to control the driver. Is there a significant difference in the damping factor requirements between 15 and 18 inch drivers? I have about 1500-1800 sq ft that I'm trying to pressurize, due to the fairly open floor plan of my house. I can place up to 4 subs in the listening area, depending on size (4 refrigerator sized enclosures probably won't work though).
3) What am I missing? I know there are things I have to be missing in this. As Donald said, what are the unknown unknowns?
That's all off the top of my head. I'm sure more will follow. It always does with me.