Single DB 8" 4th Order - Noob question(s)

[override]

Long time lerker here just reaching out for a bit of directional guidance. Sealed and ported boxes are no problem for me but anything else is difficult for me to wrap my head around - Specifically with volumes and plotting response (or in other cases aeroports and getting proper port area to fit in the specific box size).

 

I do installs on the side and have recently started offering box building/planning/tuning etc. and have a guy that reached out for a 4th order and modeling this DB 8G1.4 is kicking me in the nutz.

 

Fs is 55 so already off to a bad start I assume. Model it up in WinISD (I have heard WinISD does not model bandpasses correctly) remembering off the top of my head it wants an absurd 3+ cubes for Chamber 1 and a measly .1+ cubes for chamber 2. If I adjust things to say 1 cube/.5 cube it will plot a crazy high peak that rolls off nearly instantly (about 15hz worth of bandwidth).

 

Drop the sub into Bassbox 6 Pro and it gives much better numbers but still unreasonable IMO. Chamber 1 wants .38 cubes and chamber 2 .08 cubes (this is prior to adding venting) which provides great bandwidth but realistically in a box that is likely far too small. Same applies as WinISD, If I start going up on box volume it peaks out quickly.

 

Seems to me that this driver will only allow for a one note wonder but then IDK, just do not have enough experience and knowledge yet of these style enclosures.

 

I can provide screenshots of everything and thanks in advance for any assistance.

[Joe X]

Peaky sub in the boxes I tried:

 

Input power: to rated.

 

Ported: 0.7 net @35Hz, 12 sqin  (yellow).

 

4th bandpass; 0.6, 0.6 @ 40Hz, 14 sqin (orange).

 

Cabin gain model: +12dB / octave, 50Hz.

 

Notes:

- Mechanical power handling is a bit of a mystery since I couldn't find Xmax so I am assuming 12.5mm minimum for these to work.

- 8 subs due to low cone area need to peak a little to get loud.

- these are not serious designs just first approximation to provide you some feedback.

 

[override]

4 hours ago, Joe X said:

Peaky sub in the boxes I tried:

 

Input power: to rated.

 

Ported: 0.7 net @35Hz, 12 sqin  (yellow).

 

4th bandpass; 0.6, 0.6 @ 40Hz, 14 sqin (orange).

 

Cabin gain model: +12dB / octave, 50Hz.

 

Notes:

- Mechanical power handling is a bit of a mystery since I couldn't find Xmax so I am assuming 12.5mm minimum for these to work.

- 8 subs due to low cone area need to peak a little to get loud.

- these are not serious designs just first approximation to provide you some feedback.

 

 

Right on, thank you for this bit of information, I enabled cabin gain and do have a much better looking response. Might I ask what is or how do you set input power? This is literally my second day using Bassbox, still learning it's features.

 

4th order; 0.6, 0.3 @ 45hz; Cabin Gain model, 15 sqin (port is going to be ridiculously long)

 

Shifted numbers and tuning around quite a bit and this seems to do well. I can get more bandwidth at the sacrifice of output. Talked to the guy about it and he said it's mainly going to be for show, going in a Scat - Assuming he does car shows. Doesn't seem too concerned if it sounds good or not but then that's not the way I like to be. I want every customer to walk away happy as that's a potential lead to another customer.

[Joe X]

It will use the rated power by default but you can change it directly in the plots that require it, upper right corner, click and edit.

 

Keep port length within 40" or port resonances may become a problem.

 

 

[override]

7 hours ago, Joe X said:

It will use the rated power by default but you can change it directly in the plots that require it, upper right corner, click and edit.

 

Keep port length within 40" or port resonances may become a problem.

 

 

 

I found it last night! I changed port to 12.5x.75 which needs 44" and has a 21 m/s velocity @ 39hz. I think that will work just fine, your thoughts?

[Joe X]

It's a very thin port, it is recommended to keep it 6:1, with bandpass enclosures it's also recommended to give ample port area since all output goes through it.

 

When you pick an enclosure type you need to figure out if there's a compelling argument for the added complexity, from sealed to ported with this sub you clearly see massive loss of output with sealed but there is no compelling reason to go 4th bandpass with this sub, theoretical output should be very similar to ported but you are going to have to deal with an inefficient port and non usable output above 50Hz.

[override]

12 hours ago, Joe X said:

It's a very thin port, it is recommended to keep it 6:1, with bandpass enclosures it's also recommended to give ample port area since all output goes through it.

 

When you pick an enclosure type you need to figure out if there's a compelling argument for the added complexity, from sealed to ported with this sub you clearly see massive loss of output with sealed but there is no compelling reason to go 4th bandpass with this sub, theoretical output should be very similar to ported but you are going to have to deal with an inefficient port and non usable output above 50Hz.

 

I agree with you 100% and I already discussed with the guy that 4th wasn't the way to go but that's what he wants so that's what I'm trying to give him.

 

I appreciate your input and advice on everything!

[Joe X]

Best way to learn. If you are interested in sharing your work I'll be glad to read and comment.

[override]

3 hours ago, Joe X said:

Best way to learn. If you are interested in sharing your work I'll be glad to read and comment.

 

I may just have to take you up on that, appreciate it!

 

I definitely need some more real world experience comparing the results from pen/paper to reality. Some of the boxes I've tried designing don't graph out good but then I'll see box builds that go against the rules and sound good. 🤪