Featured 2018 Toyota Sienna minivan with 2 DB4515R on 2 Taramps Smart 8 Bass

[Buck 5,000+ posts]

You ever think of adding flares to your tube ends on the outside? Idk if you're going for db or not but it would be interesting to see if you can increase the acoustic coupling between the port air and the cabin air and maybe cause less turbulence. Like if you put any kind of flare even maybe a 3d printed one you can smoothen out the airflow. The air particles are coming out of the tube in a shaft or column like fashion, instead of like a cone or somewhat omni-directionally, which causes turbulence, which is what coupling is; you want to have as little turbulence between connecting high pressure, small air spaces to lower pressure, larger air spaces. Think of the difference between a transmission line and a horn (flared line vs straight line).

So sort of like flares on 6 inch aeroports, but maybe something more like what is on the front of this turbo:

I've always thought about this so I just see your box and I thought about it. I've designed and thought about box designing a lot and researched a lot just so just saying, it would be interesting to know performance.

 

[Buck 5,000+ posts]

Also have you measured the distance from the center of your rear ports to the windshield area? You can double tune in a way, because your vehicle is a transmission line enclosure, you know it's a box itself. So you're going to have 1/4 wave resonance related to distances from ports to front of the vehicle, which you can tune your box to to like double tune it. It's sort of like a series 6th order or tapped horn, in a way, because your box is inside of another box, where your sub box is air-mass loading into the t-line of your cabin. So if you can figure out the distance tuning that your box position causes and more specifically your port position within the vehicle, you may be able to peek harder giggity

I had 2400w and 2 18's tuned 29 hz but with significant vehicle panel work done on the roof and was doing 149.3 at 35 hz. And that was after demoing music for hours lol on a hot summer day. So like if you're maxed out on space and pushed class limits as far as you can go then you gotta get like more math involved or testing maybe.

 

[CertifiedHoodClassic]

You ever think of adding flares to your tube ends on the outside? Idk if you're going for db or not but it would be interesting to see if you can increase the acoustic coupling between the port air and the cabin air and maybe cause less turbulence. Like if you put any kind of flare even maybe a 3d printed one you can smoothen out the airflow. The air particles are coming out of the tube in a shaft or column like fashion, instead of like a cone or somewhat omni-directionally, which causes turbulence, which is what coupling is; you want to have as little turbulence between connecting high pressure, small air spaces to lower pressure, larger air spaces. Think of the difference between a transmission line and a horn (flared line vs straight line).

View attachment 66886

So sort of like flares on 6 inch aeroports, but maybe something more like what is on the front of this turbo:

View attachment 66887

I've always thought about this so I just see your box and I thought about it. I've designed and thought about box designing a lot and researched a lot just so just saying, it would be interesting to know performance.

That's actually a great idea. I could 3d print some flares with a missing chunk (the ports are right up against the seats), and improve port airflow. Reduce port chuffing, lower tuning, improve db.

 

[CertifiedHoodClassic]

Also have you measured the distance from the center of your rear ports to the windshield area? You can double tune in a way, because your vehicle is a transmission line enclosure, you know it's a box itself. So you're going to have 1/4 wave resonance related to distances from ports to front of the vehicle, which you can tune your box to to like double tune it. It's sort of like a series 6th order or tapped horn, in a way, because your box is inside of another box, where your sub box is air-mass loading into the t-line of your cabin. So if you can figure out the distance tuning that your box position causes and more specifically your port position within the vehicle, you may be able to peek harder giggity

True, the car is part of the enclosure. I've never calculated the car itself. I've just considered the fact I have 3 rows of seats as a disadvantage (less room spent on subs and more air to move with my setup) and my clamp power as an advantage

 

[CertifiedHoodClassic]

I had 2400w and 2 18's tuned 29 hz but with significant vehicle panel work done on the roof and was doing 149.3 at 35 hz. And that was after demoing music for hours lol on a hot summer day. So like if you're maxed out on space and pushed class limits as far as you can go then you gotta get like more math involved or testing maybe.

Damn. I have 3 rows of seats but I should be able to beat that with 16kW. Maybe just go higher than 35 hz lol, like 40ish. idk. have to fin my cabin peak.

 

[Buck 5,000+ posts]

Damn. I have 3 rows of seats but I should be able to beat that with 16kW. Maybe just go higher than 35 hz lol, like 40ish. idk. have to fin my cabin peak.

A wavelength is just the speed of whatever wave (sound)divided by the frequency. So speed of sound is about 1130 fps, so divide that by whatever frequency to get full wave length. You want 1/4 wave because of the way sound works. At least that's my complete understanding, it's just like a 1/4 wave box. There's technically 1/2 wave tuning but that's also just really like double quarter wave tuning, anyways, I think vehicles and the way we do them would make 1/4 wave applicable.

So 1130 fps is sound's wave speed. Take 1130/port distance to front windshield. That distance will be maybe close to 1/4 wavelength of vehicle peak resonance, close to it. Vehicles are shaped differently than boxes and the seats and metal flexing and all that changes it. You do 1130fps/distance in feet/4 to get 1/4 wave peak hz roughly. Idk what you're tuned at but the further away the ports from the mic basically the lower the resonance will be, because it'll be peak at the mic I think. Distance from port to mic or windshield, along those lines. That's what you're aiming for is 1/4 wave peak to hit the mic at the exact right time because of frequency. It's just the nature of how standing waves work and how sound works and how boxes and all of it works:

You're trying to get that wave peak to smack that mic, where the origin point on the left side would be that air exiting the port to travel through the vehicle. But your box may be so far back the frequency may be too low. You could shoot for 3/4 wave maybe. Idk I'd have to play with it myself lol.

 

[Buck 5,000+ posts]

Here's what I mean 3/4 wave, first overtone:

So if the first one is too low like in the 20 hz or something the second one will be higher frequency resonance you could aim for, 3/4 wave.

 

[shredder1 10+ year member]

That's actually a great idea. I could 3d print some flares with a missing chunk (the ports are right up against the seats), and improve port airflow. Reduce port chuffing, lower tuning, improve db.

I've found unless you flare BOTH ends of a round port you'll always leave something on the table. Even some small flaring inside the enclosure helps when flaring the exit. Sounds awesome being able to 3D print your own flares.

 

[CertifiedHoodClassic]

Sounds awesome being able to 3D print your own flares.

It rocks.

Probably should've finished cleaning the support material off before the pic lol

 

[CertifiedHoodClassic]

I've found unless you flare BOTH ends of a round port you'll always leave something on the table. Even some small flaring inside the enclosure helps when flaring the exit.

Cool. I can make some for the inside too. They're right up against the walls, but I could do them the same way as the exterior flares. Something like this for the ones in the corners:

 

[CertifiedHoodClassic]

Got my external flares in, also I won an event today with one sub!

(I also just happened to be the only one competing in my class today )

 

[CertifiedHoodClassic]

I thought about not going because the repairs weren't done. But I ultimately just made a wood piece to seal the box up and went anyways. It obviously didn't perform great, but people were still happy to hear the demos I gave so it was worth it.

 

[CertifiedHoodClassic]

I played around with my spl labs mini meter. My cabin peak is about 38/39 hz, with the meter in the driver side kick which is where I put the meter when I compete. So the 148.4 I did at 34 hz was 4-5 hz off the peak. Not sure how much I'll gain playing at the peak. Hopefully 1.7 dB for that 150.1 lol

And I screwed up my recone. It's my first time reconing a sub. I'll probably just pay someone else to do it. I wanted to learn to recone myself since it would be a useful skill for this hobby, but those recone kits are $350 each...

I suspect I didn't clean it enough. I spent a good amount of time just cleaning the coil gap, but I think I should've just disassembled the magnet stack in hindsight. I reconed it, tested it, and then when I turned it upside down and put it in the car the coil blew as soon as I played anything. It must've still had metal in there.

 

[shredder1 10+ year member]

1 sub? I'd wager some gains even with one at the right frequency, with increased airspace and that port area you now enjoy. As much as I like a low tune and flat response sometimes I question the reality when playing music. Any tune under 30hz without a super sub like a Pride S5-18 or similar on like 5K+ ea tends to dig but without spl unless excessive cone and cabin work generally peaks 40hzish in a large cabin for spl. Walled setups are a differnt story.
Just don't do music runs till you become familiar with how it performs. A burp or 2 finding locations or seat placement for now. Focus on that frequency and numbers.

I suspect I didn't clean it enough. I spent a good amount of time just cleaning the coil gap, but I think I should've just disassembled the magnet stack in hindsight. I reconed it, tested it, and then when I turned it upside down and put it in the car the coil blew as soon as I played anything. It must've still had metal in there.

I actually called this with my bud with the SoloX-15s... I did not think the sub was salvageable. Something in the gap was my worry... impossible to clean.
You took that sub nuclear man. I haven't seen the extinguishers deployed since someone was tryin' for 180db and his amps went. That was a few years back at regionals iirc

 

[CertifiedHoodClassic]

1 sub? I'd wager some gains even with one at the right frequency, with increased airspace and that port area you now enjoy. As much as I like a low tune and flat response sometimes I question the reality when playing music. Any tune under 30hz without a super sub like a Pride S5-18 or similar on like 5K+ ea tends to dig but without spl unless excessive cone and cabin work generally peaks 40hzish in a large cabin for spl. Walled setups are a differnt story.

It was much worse on the music I like to play. I had to hold back on the gain a good bit because it didn't take much power to max the excursion. 7-7.5 cubes with one 15 is just way too big

The db4515r have 22.5 mm xmax / 45 mm xmech. Not really a big number. If they were high xmax subs, it would be a different story with one 15 in an oversized box.

It was more efficient though. Didn't take much to get bumping. I didn't mess with it a whole lot, but it's totally possible you're right and there's a way to put up better numbers with the setup like this.

Just don't do music runs till you become familiar with how it performs. A burp or 2 finding locations or seat placement for now. Focus on that frequency and numbers.

Fair. I can just spend a bit of time dialing the comp setup with my mini meter before I hit the lane again. I'll probably stay in music classes at meets though because I really like competing in those.

I actually called this with my bud with the SoloX-15s... I did not think the sub was salvageable. Something in the gap was my worry... impossible to clean.

I'm having someone else recone it this time, it's up to them to figure out how to clean it now

They offered to recone it for 80 bucks labor (I buy parts ofc). Figured at that price, it's better to just pay it over trying to do it myself again, and burn another $350 recone...