How to SEAL...?

[Din61]

Subwoofers with a Q of 0.45 or less are designed to operate in a vented enclosure. When they are driven with a solid state amp in a properly tuned cabinet, they have an excellent transient response.
But don't drive them with a tube amp, or one of those McIntosh amps that use a transformer at the output stage, then there is a possibility of getting a poor transient response.

LOL! Dude, no TUBES in our country, I doubt none of our people have touched one ever, it's like daydreaming, the reason is most of our people have no interest in audio quality, audio sellers know the reality, they cheat us selling cheap PMPO systems at ultra low prices, and we think we get a 1000W 5.1 (with amp/receiver) for just $150, that's why I chose to diy setup instead, we get genuine stuff only at a pro audio shop (a solid-state amp for example), as the sound coming out of a big stage can't be forged with cheap equipments.

 

[Din61]

You don't need designers in your country, you can model your own with appropriate software, or just borrow designs posted up in this and other audio fora/groups. There are "car" subs that can work in a home sub, I've done so (Infinity 1262Ws in my case) and there are others. I used larger multiple sealed diy subs in my main setup in a larger volume space than yours but the driver I used isn't available even here any longer (SI HT18D2s). I built sealed because they were easier to move around and was a beginning woodworker too.....thought initially about ported but thought I'd start out simpler.

Yep, there are ways, should try.

I can easily go for a genuine car audio woofer (Infinity is available), but many replicas there, have to be careful.

I got some questions btw...

How many SEALED boxes have you made to shake your larger-than-my-room volume?

How much could you go down (hz) at a desirable spl (db) in that setup?

What if I found a car audio woofer respond down to 20hz and mount that in a SEALED box?

What do you think of 4th order with one SEALED chamber for better cone movement and the other PORTED for better spl?

 

[lovinthehd]

Yep, there are ways, should try.

I can easily go for a genuine car audio woofer (Infinity is available), but many replicas there, have to be careful.

I got some questions btw...

How many SEALED boxes have you made to shake your larger-than-my-room volume?

How much could you go down (hz) at a desirable spl (db) in that setup?

What if I found a car audio woofer respond down to 20hz and mount that in a SEALED box?

What do you think of 4th order with one SEALED chamber for better cone movement and the other PORTED for better spl?

I have 3x18 and a 2x15 dual opposed box in that room....been procrastinating on replacing the 2x15 with my last two 18"s in a dual opposed box. 20hz isn't a problem. Have no idea about the 4th order thing let alone combining it with other designs (unless perhaps you can find someone who has done a successful design and build for such with a driver you can obtain)..... As was mentioned, you'll pretty much have to rely on sufficient amplification and eq with sealed designs for lower bass.

 

[highfigh]

The Qts has to be limited to 0.45 but shouldn't be below 0.35 for sure, because that would make it more difficult for a sub to efficiently reach infrasonic frequencies.

'A sub', yes- it's difficult but with more subs, enough power and some equalization, it's not terribly difficult.

You're referring to the driver's QTs, right? I was talking about the Q of the system. A correctly designed sealed box will be in the .5 to .707. .5 is considered 'dry-sounding', .707 is more typical and the slope is more gentle than ported, but it's very easy to miscalculate when designing a ported system and cause a large peak, which is impossible with a sealed design. A sealed design can work with the room to extend the response, but it will likely need some EQ for the bass to be considered 'strong', unless its output is higher than the midbass/midrange and tweeter(s).

I have built car systems with sealed enclosures that absolutely sounded amazing and with 4 10" woofers, there was no lack of output. The response from that system was also among the flattest I have ever seen and I judged IASCA events for 4 years. One of the cars I did for an IASCA event scored 37/40 using the same model of RTA that I used for the other and it wasn't as good, although I didn't have an RTA to see the response when we dialed it in because they had been moved to the event as I was finishing the car. The car with the 4 woofers was one of the smoothest-sounding systems I can remember and yes, they were sealed.

Audio Control made a piece called 'Epicenter', for creating a subharmonic to reinforce low frequencies that were lacking and the guy with the 4 woofers had bought one before I reworked his system. It was also the reason he killed some woofers, which was the reason I reworked it. Once it was done, he never used it and it was removed, so be sold. I never had a chance to really tweak it in great detail because he really liked it. One Saturday, he came into the store to say he was going to the IASCA event in Gray's Lake, IL. Without dialing it in, he took 3rd Place in the 501-1000 Watt class which was always the largest group of cars.

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fhometheaterhifi.com%2Fvolume_5_2%2Fimages%2Fdamping.gif&f=1&nofb=1

 

[highfigh]

I have 3x18 and a 2x15 dual opposed box in that room....been procrastinating on replacing the 2x15 with my last two 18"s in a dual opposed box. 20hz isn't a problem. Have no idea about the 4th order thing let alone combining it with other designs (unless perhaps you can find someone who has done a successful design and build for such with a driver you can obtain)..... As was mentioned, you'll pretty much have to rely on sufficient amplification and eq with sealed designs for lower bass.

4th order is less sensitive, so you would need some power- I would model it, but watch the power handling spec.

 

[Din61]

It's impossible to reach down to 20 Hz with sealed subs without any EQing. In addition, that would require powerful amplification as every 3 dB boost means doubling of amp power. To produce a frequency one octave lower than at 40 Hz, the cone displacement has to quadruple. Infrasonic frequency production requires a lot of air displacement and this where the ported design has the real advantage.

I would suggest that you try having hold of a subwoofer having a Qts of 0.40 to 0.45 and a Fs around 20 Hz, with which you could build at its recommended box volume, the proper enclosure.
With the good driver in a properly tuned ported cabinet , you shouldn't expect any poor transient response. You need to have adequate knowledge about the complexity of building speaker enclosures. The following books are good starting guides:

Designing, Building, and Testing Your Own Speaker System with Projects: Weems, David: 9780070694293: Amazon.com: Books

Designing, Building, and Testing Your Own Speaker System with Projects [Weems, David] on Amazon.com. *FREE* shipping on qualifying offers. Designing, Building, and Testing Your Own Speaker System with Projects

www.amazon.com

Speaker Building 201: Ray Alden: 9781882580453: Amazon.com: Books

Speaker Building 201 [Ray Alden] on Amazon.com. *FREE* shipping on qualifying offers. Speaker Building 201

www.amazon.com

Also, some online stores sell kits including the appropriate cabinet where you have no calculations to do, just assembling.

I totally agree on everything you stated, acoustic suspension in a room as big as mine would obviously be problematic even after EQd and loads of AMPing would be a compromise too, I was seeking if there's any chance but it seems none, "for every 3dB increase watts should be multiplied in powers" is a rule of thumb, I know.

This by far is the best-suited for my application with.43 Qts and 19.5hz Fs plus 14 xmax, but where to purchase Dayton in our country...? I'm helpless dear...

Home

Dayton Audio RSS390HF-4 15" Reference HF Subwoofer 4 OhmThe Dayton Audio Reference Series RSS390HF-4 15" speakers take the quality and performance of the much acclaimed RS line into the subwoofer realm. As with the rest of the Reference Series, the main focus of these subwoofers is...

www.parts-express.com

Thanks for book links btw...

 

[lovinthehd]

I totally agree on everything you stated, acoustic suspension in a room as big as mine would obviously be problematic even after EQd and loads of AMPing would be a compromise too, I was seeking if there's any chance but it seems none, "for every 3dB increase watts should be multiplied in powers" is a rule of thumb, I know.

This by far is the best-suited for my application with.43 Qts and 19.5hz Fs plus 14 xmax, but where to purchase Dayton in our country...? I'm helpless dear...

Home

Dayton Audio RSS390HF-4 15" Reference HF Subwoofer 4 OhmThe Dayton Audio Reference Series RSS390HF-4 15" speakers take the quality and performance of the much acclaimed RS line into the subwoofer realm. As with the rest of the Reference Series, the main focus of these subwoofers is...

www.parts-express.com

Thanks for book links btw...

Call it sealed, you're not going to find acoustic suspension drivers....and it's that you need to double power for each 3dB spl....

 

[Din61]

Ported designs are a better design than sealed by almost every measure. There's 1 reason to consider sealed and that's if it absolutely has to be as small as possible. That's it, full stop. You've been reading uneducated, subjective accounts on this. Go with a ported design.

No, box size doesn't matter at all, I have enough space, I'd be happy even if you suggest me a horn-loaded, but I doubt a horn-loaded can go down to 20hz, was planning for a parallel 6th order before that would easily get my job done, but then I learnt 6th order has a poor group-delay, so gave up the below design I sketched.

 

[Din61]

I have 3x18 and a 2x15 dual opposed box in that room....been procrastinating on replacing the 2x15 with my last two 18"s in a dual opposed box. 20hz isn't a problem. Have no idea about the 4th order thing let alone combining it with other designs (unless perhaps you can find someone who has done a successful design and build for such with a driver you can obtain)..... As was mentioned, you'll pretty much have to rely on sufficient amplification and eq with sealed designs for lower bass.

Oh! That's 5 altogether... I'm willing to use 2 at most (not a bass-oholic, just in hope of covering up the 20hz-20khz range), there are some 21" B&Cs here but again they can't go beyond 30hz (not sure if possible inside of a 4th order or any other type of enclosure than SEALED when tuned) as they're for outdoor in general.

 

[Din61]

'A sub', yes- it's difficult but with more subs, enough power and some equalization, it's not terribly difficult.

You're referring to the driver's QTs, right? I was talking about the Q of the system. A correctly designed sealed box will be in the .5 to .707. .5 is considered 'dry-sounding', .707 is more typical and the slope is more gentle than ported, but it's very easy to miscalculate when designing a ported system and cause a large peak, which is impossible with a sealed design. A sealed design can work with the room to extend the response, but it will likely need some EQ for the bass to be considered 'strong', unless its output is higher than the midbass/midrange and tweeter(s).

I have built car systems with sealed enclosures that absolutely sounded amazing and with 4 10" woofers, there was no lack of output. The response from that system was also among the flattest I have ever seen and I judged IASCA events for 4 years. One of the cars I did for an IASCA event scored 37/40 using the same model of RTA that I used for the other and it wasn't as good, although I didn't have an RTA to see the response when we dialed it in because they had been moved to the event as I was finishing the car. The car with the 4 woofers was one of the smoothest-sounding systems I can remember and yes, they were sealed.

Audio Control made a piece called 'Epicenter', for creating a subharmonic to reinforce low frequencies that were lacking and the guy with the 4 woofers had bought one before I reworked his system. It was also the reason he killed some woofers, which was the reason I reworked it. Once it was done, he never used it and it was removed, so be sold. I never had a chance to really tweak it in great detail because he really liked it. One Saturday, he came into the store to say he was going to the IASCA event in Gray's Lake, IL. Without dialing it in, he took 3rd Place in the 501-1000 Watt class which was always the largest group of cars.

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fhometheaterhifi.com%2Fvolume_5_2%2Fimages%2Fdamping.gif&f=1&nofb=1

I'm willing a pair at most, that's another story, but you're absolutely right, I've also heard people got that 20hz with plenty of subs (and kilowatts of input).

Yep, .707 is considered a perfectly damped (not over/under) enclosure with the smoothest roll-off, room-gain is critical for SEALED as opposed to my room volume of of 4000 cu. ft. and that's why SEALED go down to 10hz with the cabin-gain of vehicles I think.

Congrats on your old work, and that exact same reason is why I like SEALED, once in my life I've listened to a 8" SEALED nearly 5 years ago, that was on demo in a car audio shop, a 10*10 space may be, hit a proven 28hz and, to be honest, the cleanest bass I've ever listened to, unbelievable for a moment it was an 8" woofer, that was heavenly.

 

[Din61]

4th order is less sensitive, so you would need some power- I would model it, but watch the power handling spec.

Friend, have you repiled me that you'd model a 4th order? Then I can sketch something to help you in advance.

I can power like 1000*2 for my 2 subs if necessary, and no box size limitations as well.

 

[lovinthehd]

Oh! That's 5 altogether... I'm willing to use 2 at most (not a bass-oholic, just in hope of covering up the 20hz-20khz range), there are some 21" B&Cs here but again they can't go beyond 30hz (not sure if possible inside of a 4th order or any other type of enclosure than SEALED when tuned) as they're for outdoor in general.

The data-bass.com site has some diy B&C 21 measurements in a dual opposed as well as single sealed box....they can go fairly low it looks like

 

[lovinthehd]

Just what country are you in?

 

[Din61]

Call it sealed, you're not going to find acoustic suspension drivers....and it's that you need to double power for each 3dB spl....

True, acoustic suspension drivers aren't available in the real world (now).

 

[Din61]

The data-bass.com site has some diy B&C 21 measurements in a dual opposed as well as single sealed box....they can go fairly low it looks like

I haven't checked that bro, will see by evening (GMT +5.30)...

 

[Din61]

Just what country are you in?

Sri Lanka, a tropical island in the Indian ocean, a tourist hub, a historical paradise, but a sociopolitical mess however...

 

[lovinthehd]

Sri Lanka, a tropical island in the Indian ocean, a tourist hub, a historical paradise, but a sociopolitical mess however...

My father's best friend married a gal from Sri Lanka (from his trips as a trans-pacific sailboat racer) altho never was able to visit myself. Looks beautiful from what I've seen. I can imagine the differences in availability better now

ps I'm near the west coast of the US, in Oregon.

 

[Din61]

My father's best friend married a gal from Sri Lanka (from his trips as a trans-pacific sailboat racer) altho never was able to visit myself. Looks beautiful from what I've seen. I can imagine the differences in availability better now

ps I'm near the west coast of the US, in Oregon.

Ah really, is the couple now in SL? Bro, we have a nature-balanced climate, seasonal impact is non-specific, the tropical advantage, you might've heard of "Ceylon tea", that's our pride, we have a few NASA scientists as well, a literate nation we are. But, as you imagined, the economy is pretty bad here, which is why everything is cheap, all because of dirty politics.

 

[lovinthehd]

Ah really, is the couple now in SL? Bro, we have a nature-balanced climate, seasonal impact is non-specific, the tropical advantage, you might've heard of "Ceylon tea", that's our pride, we have a few NASA scientists as well, a literate nation we are. But, as you imagined, the economy is pretty bad here, which is why everything is cheap, all because of dirty politics.

No, retired to US after sailing for many years around the world. She may have returned to SL or stayed in California where they had a ranch....he died a year or so ago but I'd have to ask my sister who was more in touch. We're all about to join you in some funky economies I think due Covid....

 

[Verdinut]

I totally agree on everything you stated, acoustic suspension in a room as big as mine would obviously be problematic even after EQd and loads of AMPing would be a compromise too, I was seeking if there's any chance but it seems none, "for every 3dB increase watts should be multiplied in powers" is a rule of thumb, I know.

This by far is the best-suited for my application with.43 Qts and 19.5hz Fs plus 14 xmax, but where to purchase Dayton in our country...? I'm helpless dear...

Home

Dayton Audio RSS390HF-4 15" Reference HF Subwoofer 4 OhmThe Dayton Audio Reference Series RSS390HF-4 15" speakers take the quality and performance of the much acclaimed RS line into the subwoofer realm. As with the rest of the Reference Series, the main focus of these subwoofers is...

www.parts-express.com

Thanks for book links btw...

It is a darn good performer. Did you notice that I'm using three of those subwoofers in my home theater?

https://forums.audioholics.com/forums/threads/my-7-channel-system.111234/

Where do you live? You could verify with Parts-Express to see if they would ship to your home place. The shipping cost might be prohibitive though:

Home

Dayton Audio RSS390HF-4 15" Reference HF Subwoofer 4 OhmThe Dayton Audio Reference Series RSS390HF-4 15" speakers take the quality and performance of the much acclaimed RS line into the subwoofer realm. As with the rest of the Reference Series, the main focus of these subwoofers is...

www.parts-express.com

Otherwise, it might be good of you to tell us what raw driver brands are available in your country, so we could see what are some alternate possibilities.