Thoughs on Future Box Idea for 4 HDC3 18s

[Jeffdachef 5,000+ posts]

Welp, i'm getting rid of my 3rd row seats and buying some motors for cheap and reconing them. With these subs I usually i'd give these subs 6.5+ cubic feet each but a lot of people very loud people have been telling me to go with 5.25(lot of power) to 5.5(1k input before rise) cubes if I want to get loud and musical.

I'll also be in the proper sub up port rear orientation now that the 3rd row seats will be gone so I already gain a good bit from that. Decided against doing a wall to make it easier on life.

So i'm planning a very flexible box with 5 10" sonotubes 10 inches long each. 3 of these are removable/blockable. This is so I can play with the tuning for specific purposes or find the sweet spot. I can even invert the subs to gain cubic feet back if I want that peak.

Here are the possible tunes. Let me know what you guys think. Power will be banda 7k at 2 ohms(parallel/series) for now and getting another one in the future or a korean 8k-10k amp to run at 0.5 ohms(series/parallel) later on. Goal is to have a decent bandwidth for daily and demos with the ability to switch over for metering easily.

Subs Normal Mount

5 sonotubes = 22.09 Cubic feet tuned to 42.64 hz with 17.77 port per cube (Burps and Comps)

4 sonotubes = 22.50 Cubic feet tuned to 39.09 hz with 14.25 port per cube (Burps & Choke out demos)

3 sonotubes = 22.90 Cubic feet tuned to 34.98 hz with 10.28 port per cube (Daily)

2 sonotubes = 23.30 Cubic feet tuned to 29.88 hz with 6.74 port per cube (When I want them whale song low lows)

Inverted Mount Subs

5 sonotubes = 23.00 Cubic feet tuned to 41.78 hz with 17.06 port per cube

4 sonotubes = 23.42 Cubic feet tuned to 38.32 hz with 13.41 port per cube

3 sonotubes = 23.82 Cubic feet tuned to 34.29 hz with 9.89 port per cube

2 sonotubes = 24.22 Cubic feet tuned to 29.31 hz with 6.48 port per cube

Click to read more...

 

[Jeffdachef 5,000+ posts]

@mlstrass @hispls

 

[hispls 5,000+ posts]

18's will BARELY move on that power even in a fairly large box. As you said the loud guys are using small box to control the cone. Also would they be louder still if they had more box volume? AFAIK SQ subs are still basically an older DD95 platform knockoff so I'd personally use DD box ratio and sizes.

I've done multiple round ports to block some off for tuning. From personal experience I'd say one huge port is going to give you more output.... at the expense of easy flexibility in tuning. Consider that anything within a port width of the inside or outside of the box will slightly change how that port behaves so making them all work as though the length is exact may be difficult or unreliable.

I love the idea in theory, in practice, results may be hit or miss.

The sucky part is that a box fit for 4 18's even on the "small side" after you double up a couple sides is going to be a fair investment in wood, glue, screws, etc. so you probably don't want to have to do it over too many times.

Good luck, can't wait to see a build log.

 

[Jeffdachef 5,000+ posts]

18's will BARELY move on that power even in a fairly large box. As you said the loud guys are using small box to control the cone. Also would they be louder still if they had more box volume? AFAIK SQ subs are still basically an older DD95 platform knockoff so I'd personally use DD box ratio and sizes.
I've done multiple round ports to block some off for tuning. From personal experience I'd say one huge port is going to give you more output.... at the expense of easy flexibility in tuning. Consider that anything within a port width of the inside or outside of the box will slightly change how that port behaves so making them all work as though the length is exact may be difficult or unreliable.

I love the idea in theory, in practice, results may be hit or miss.

The sucky part is that a box fit for 4 18's even on the "small side" after you double up a couple sides is going to be a fair investment in wood, glue, screws, etc. so you probably don't want to have to do it over too many times.

Good luck, can't wait to see a build log.

I can do 28 cubes net if need be and have an 18 to 24 inch octoport. I'll be using 1 inch thickness and lots of dowels for bracing and maybe fiberglassing the inside if i'm okay with the sound and output.

You seriously think a banda 7k at 1 ohm for each pair of hdc3 18s is not enough? I was bottoming out my old hdc3s with my current box with the gains set for 5k rms on the banda with 12.5 cubes for a pair of 18s with 16.5 sq inches of port area per cubic feet. Might be due to the high port area.

The guys said that with a too big of a box or port they lose the cone control with more power added, they actually lost dbs due to the subs getting kind of sloppy.

DD recommended box specs are even smaller than soundqubeds.

http://www.ddaudio.com/support/dd-box

 

[hispls 5,000+ posts]

I can do 28 cubes net if need be and have an 18 to 24 inch octoport. I'll be using 1 inch thickness and lots of dowels for bracing and maybe fiberglassing the inside if i'm okay with the sound and output.

You seriously think a banda 7k at 1 ohm for each pair of hdc3 18s is not enough? I was bottoming out my old hdc3s with my current box with the gains set for 5k rms on the banda with 12.5 cubes for a pair of 18s with 16.5 sq inches of port area per cubic feet. Might be due to the high port area.

The guys said that with a too big of a box or port they lose the cone control with more power added, they actually lost dbs due to the subs getting kind of sloppy.

DD recommended box specs are even smaller than soundqubeds.

5. DD Box Design | DD Audio

If you're bottoming out on 2500W per 18" sub you are doing something terribly wrong. Either you should be tuning lower or using subsonic filter.

Note that DD box specs range from 3 cube to 5 cube for a single 15 so we can extrapolate that 5 cube is absolute bare minimum! The Shocker Sigs that I have used a LOT are comparable design philosophy to DD 95 and do like a big box. You can get away with small but unlike some other subs they really gain quite a bit as you increase box volume (test for yourself in WinISD or other modeling software). I've done more with 12's and 15's but with mine for example, a 12 sounds really good in 3 cube but keeps gaining nicely up to almost 5 cubes where a 15 is louder... the trade-off is that as you gain beyond 3 cube the response is much peakier, and there's some overlap where going too small on a 15 is pretty much as loud, but at the expense of some low extension.

Anyway, if you don't own the frames, cones, and spiders yet, consider going 15" to save cost and make sure you're not cutting corners on space hoping that some day you'll have 20K to really shoehorn all those 18's into 20-22 cube. From my testing modeling software is quite accurate (once you get a feel for where your vehicle adds a peak even more so). So see how much linearity and output you'll sacrifice going up or down with box volume.

Also worthy of mentioning, 18" parts + frames are going to be significantly more expensive than 15" parts and frames. 4 15's in 16-20 cube net allows you more room for bracing, double layers, and port depth/area.

 

[Jeffdachef 5,000+ posts]

If you're bottoming out on 2500W per 18" sub you are doing something terribly wrong. Either you should be tuning lower or using subsonic filter.
Note that DD box specs range from 3 cube to 5 cube for a single 15 so we can extrapolate that 5 cube is absolute bare minimum! The Shocker Sigs that I have used a LOT are comparable design philosophy to DD 95 and do like a big box. You can get away with small but unlike some other subs they really gain quite a bit as you increase box volume (test for yourself in WinISD or other modeling software). I've done more with 12's and 15's but with mine for example, a 12 sounds really good in 3 cube but keeps gaining nicely up to almost 5 cubes where a 15 is louder... the trade-off is that as you gain beyond 3 cube the response is much peakier, and there's some overlap where going too small on a 15 is pretty much as loud, but at the expense of some low extension.

Anyway, if you don't own the frames, cones, and spiders yet, consider going 15" to save cost and make sure you're not cutting corners on space hoping that some day you'll have 20K to really shoehorn all those 18's into 20-22 cube. From my testing modeling software is quite accurate (once you get a feel for where your vehicle adds a peak even more so). So see how much linearity and output you'll sacrifice going up or down with box volume.

Also worthy of mentioning, 18" parts + frames are going to be significantly more expensive than 15" parts and frames. 4 15's in 16-20 cube net allows you more room for bracing, double layers, and port depth/area.

I can go to 28 cubes easily or I can just go ahead and do a C-pillar wall and get 36 cubes if need be. Keep in mind i already accounted necessary thickness, port, sub and bracing displacement already. Thats just pure airspace leftover. I just dont care about low low end to be honest I rather just have it hurt in the music range i listen to and I dont want it to be overly peaky either which i kind of noticed with the larger boxes. Decaf is nice and all but actual music is where its at for me. Shooting for 30hz to 70hz/80hz+ response. Old box had 25h to 55hz On winisd the overall upper end response gets better with a smaller box and high tuning. Big box and high tuning gets really peaky and medium box tuned around 35 is relatively flat which i modeled after for my current but got very little upper end response for my listening preferences.

Currently have a sub in an infinite baffle setup and I just realize I missed how good a strong punch in the 60-100hz range sounded when A sub plays it cleanly.

I have over 46 cubes gross staying at the C pillar. Even more if I move the second row seats up 5 inches.

I could just lose one sub and do a series tuned 6th order wall as well but thats a gamble imo.

 

[hispls 5,000+ posts]

I can go to 28 cubes easily or I can just go ahead and do a C-pillar wall and get 36 cubes if need be. Keep in mind i already accounted necessary thickness, port, sub and bracing displacement already. Thats just pure airspace leftover. I just dont care about low low end to be honest I rather just have it hurt in the music range i listen to and I dont want it to be overly peaky either which i kind of noticed with the larger boxes. Decaf is nice and all but actual music is where its at for me. Shooting for 30hz to 70hz/80hz+ response. Old box had 25h to 55hz On winisd the overall upper end response gets better with a smaller box and high tuning. Big box and high tuning gets really peaky and medium box tuned low is flat which i modeled after before but got very little upper end response.
I have over 46 cubes gross staying at the C pillar. Even more if I move the second row seats up 5 inches.

I could just lose one sub and do a series tuned 6th order wall as well but thats a gamble imo.

The first rule of Fight Club is that you'll NEVER have as much space as you initially thought you had. If you're 100% sure you've got that space and don't mind the extra cost of frames and softies I guess you're good to go. Just throwing it out there for you to consider.

Otherwise, IMO if you have room to get all 4 + port on a flat wall you're crazy not to.

Hope you have a lot of time and money if you expect to make 6th order bandpass sound good.

 

[Jeffdachef 5,000+ posts]

Yeah Suspension is one of the reasons why i dont wannt flat wall just yet. Thats why a normal box with proper loading and tuning options sounds much more appealing. I wont be placed in extreme class either

 

[mlstrass 5,000+ posts]

22-24^3 net is what I normally build for those subs. I prefer center slot port, tuned high/bigger port area, then use a reducer to drop tuning for daily.

Just did a Denali like that, 4 HDC4 18's, 4 old AQ3500's, demo monster....

 

[Jeffdachef 5,000+ posts]

Thanks for that!

Anyone Ever tried wiring parallel/series before? Not to be confused with series/parallel but actual parallel voice coils and series sub to subs. Just never done these many subs before.

 

[Massive spl]

Do a wall forsure!

 

[Massive spl]

I can go to 28 cubes easily or I can just go ahead and do a C-pillar wall and get 36 cubes if need be. Keep in mind i already accounted necessary thickness, port, sub and bracing displacement already. Thats just pure airspace leftover. I just dont care about low low end to be honest I rather just have it hurt in the music range i listen to and I dont want it to be overly peaky either which i kind of noticed with the larger boxes. Decaf is nice and all but actual music is where its at for me. Shooting for 30hz to 70hz/80hz+ response. Old box had 25h to 55hz On winisd the overall upper end response gets better with a smaller box and high tuning. Big box and high tuning gets really peaky and medium box tuned around 35 is relatively flat which i modeled after for my current but got very little upper end response for my listening preferences.
Currently have a sub in an infinite baffle setup and I just realize I missed how good a strong punch in the 60-100hz range sounded when A sub plays it cleanly.

I have over 46 cubes gross staying at the C pillar. Even more if I move the second row seats up 5 inches.

I could just lose one sub and do a series tuned 6th order wall as well but thats a gamble imo.

What vehicle do you have to get so much space at Cpillar? My Tahoe it built as big as possible and got 30cubes at Cpillar. So do you have a burban or a excursion or something?

 

[Jeffdachef 5,000+ posts]

What vehicle do you have to get so much space at Cpillar? My Tahoe it built as big as possible and got 30cubes at Cpillar. So do you have a burban or a excursion or something?

its a Sienna Minivan Technically i have my curent box technically in the D pillar section behind the 3rd row seats and a few batts.

This is a pic for reference, its not my car year but it should give you an idea

Current box is 39 Height x 38 width x 23 Depth with 200 sq inches of port area tuned to 35hz. with enough space to store some group 31 batts on the side stacked up.

C pillar behind the 2nd row seats, i have 46 height x 44 width x 47 depth max However after 40 depth the top hatch bends in which reduces the width and height down a little bit. Keep in mind I already subtracted an inch from each just for safety and fitment precautions. If I were to do a full fit its 47h x 45 x 48.

I can get even more depth if i move the 2nd row seats forward which i can squeeze out 4 more inches of depth.

I also have that whole dip in the back hwere the 3rd row seats fold up to store my amp and my battery bank.

Car can store a lot. Just the biggest setback is power capabilities, there is ZERO engine room. Dual alts will never happen. There's barely enough space to fit that single alt. i'd have to remove several parts just to get to the alt.

 

[Massive spl]

Mini van can hold some weight. They meant to hold 5-7 ppl so they can hold a heavy subwoofer enclosure just fine. Wall it and join the mid 155db club

 

[Jeffdachef 5,000+ posts]

Mini van can hold some weight. They meant to hold 5-7 ppl so they can hold a heavy subwoofer enclosure just fine. Wall it and join the mid 155db club

I kinda want to try to achieve that without wall first and do it under the window line so i dont get placed in the extreme classes. However everyone's been egging me to do a wall with them.