How to SEAL...?

[Din61]

I meant that, if I was in your shoes, I'd build 2 separate cabinets. I'm in Canada, Could you imagine the cost of shipping 2 boxes weighing more than 150 lbs each?



As for the car audio woofer, I doubt that you would be able to get a sub that has a true Hi-Fi performance.

Ah, I just got confused reading that BUILD, I know the shipping cost would be sky-high...

But, I've listened to some great-sounding car audio subwoofers made for homes (cos no home audio builders here).

 

[Din61]

What T/S parameters would indicate a "car" sub is insufficiently "hi-fi" ? Your Dayton could be considered a car sub, too, couldn't it?

True, unless specifically made for a certain purpose (like for PA builds), in a proplerly-made enclosure, low-freq transducers (especially like the particular Dayton) can really score HI-FI no matter whether it's for your White House or Limousine.

 

[Din61]

But that peak (usually more of a rise, really) isn't as severe as it can be with the Q of a vented box in the 1.5+ range- I don't remember seeing a sealed box model with such a high Q. I didn't write that it can't happen to have any peak, I wrote that it's impossible to have a large peak with a sealed driver but should have added 'if the driver is designed to be in a sealed enclosure'. I should have included something about a leaking enclosure, too- I have seen systems with a peak when the builder wasn't careful about sealing.

In a SEALED enclosure .707 is always the perfect number but 1.2 or higher is under-damped and both fr and tr would suffer.

I'm sure you have been unfortunate enough to be in the area of a car that was playing a narrow range of bass notes with the license plate frame and other parts vibrating for all to hear. Those systems are often designed specifically for that one note/narrow range and it's easy to do. You would hate seeing the response curve in the software.

That's why bandpass is a winner at most car audio competitions over any other type (especially 6th order).

 

[Din61]

It's common if the person using the software doesn't make sure to avoid it. It's easiest to make the peak disappear in a sealed box by increasing the internal volume and in a vented box through a combination of increasing the box and changing the port tuning to flatten it. If you're using WinISD, pick a subwoofer driver and let the software model it for 'optimum'- change the internal volume and watch as the response changes and once you have gained some experience with that, go back to the smoother original curve and change the length and diameter of the port to watch how the tuning frequency changes the response. If the box volume is too high and the port's tuning frequency is too low, the area between the tuning frequencies will sag and it can look a bit like the Golden Gate Bridge.

Agree, with enough stuffing it's a lot easier in SEALED.

 

[Din61]

You need to hear some well-designed car systems- you would be surprised by the sound quality.



I never built systems for 'MORE!!!!!!!!!!!!!!!!!' if the customer was interested in real sound quality. The cars I mentioned were able to play any kind of music, although some of the cars we did were specifically for Rap. Since cars are irregularly-shaped and many have cloth covering most surfaces, the acoustics are much better than most listening rooms in the sense that multiple reflections don't occur and the low frequencies aren't contained by the vehicle, so they don't cause the same problems.

Yes, with sufficient cabin gain a SEALED box would flat-respond at 10hz, a pair of over-ear headphones for example, everything in the nominal range of 20hz-20khz can be heard lossless, no reflections/absorptions, sound hits the eardrum right away, conversely, sound from the speaker comes to you at a distance, in a vehicle cushioned seats and carpets act like passive diffusers, so that it's a better hi-fi ambiance than a listening room in reality.

 

[Din61]

As for this debate btw, something I noted is that HO in general has a higher xmax in comparison to HF.

 

[highfigh]

In a SEALED enclosure .707 is always the perfect number but 1.2 or higher is under-damped and both fr and tr would suffer.


That's why bandpass is a winner at most car audio competitions over any other type (especially 6th order).

Bass determines the max output and competitors get more points with that type of box fed by huge amplification.

 

[Din61]

Bass determines the max output and competitors get more points with that type of box fed by huge amplification.

Just spl, quality isn't there...

 

[Din61]

@Verdinut

I had a misconception on what you were telling me about the Dayton I linked, I thought you told me qts between .40 and .45 is better for SEALED (as I already know .4 to .7 is the SEALED range in general, but more critical would be QTC when built) and someone at somewhere had recommended that Dayton the ultimate-kind for SEALED long ago I barely remember, but it was about PORTED.

However, that driver is rated @ 500w rms, would a SEALED cab (or 2 with 500w*2 rms powered) be enough (just wondering to know cos SEALED is said to be much power-consuming but that driver seems to be very popular in SEALED cabs)?

 

[Din61]

@lovinthehd

I took a visit to "data-bass", happily there's a SEALED cab with a B&C 21DS115 driver (available in our country) hitting 20hz @ 95dB+ @ 2m distance, see.

Data-Bass: Subwoofer Measurements

data-bass.com

But totally confused of the given output. It's 18000w rms... I mean seriously??? That driver can bear 3400w rms continuously at most.

 

[Verdinut]

@Verdinut

I had a misconception on what you were telling me about the Dayton I linked, I thought you told me qts between .40 and .45 is better for SEALED (as I already know .4 to .7 is the SEALED range in general, but more critical would be QTC when built) and someone at somewhere had recommended that Dayton the ultimate-kind for SEALED long ago I barely remember, but it was about PORTED.

However, that driver is rated @ 500w rms, would a SEALED cab (or 2 with 500w*2 rms powered) be enough (just wondering to know cos SEALED is said to be much power-consuming but that driver seems to be very popular in SEALED cabs)?

No, I never said that Qts between 0.40 and 0.45 is best for a sealed cabinet. Drivers with a Qts of 0.5 or more are best suited for sealed designs. The Qts of a loudspeaker often changes but not by much within the burning-in period. The Q of a specific system is another matter and too complex to discuss here.

 

[lovinthehd]

@lovinthehd

I took a visit to "data-bass", happily there's a SEALED cab with a B&C 21DS115 driver (available in our country) hitting 20hz @ 95dB+ @ 2m distance, see.

Data-Bass: Subwoofer Measurements

data-bass.com

But totally confused of the given output. It's 18000w rms... I mean seriously??? That driver can bear 3400w rms continuously at most.

The amp is capable of such https://www.powersoft.com/en/products/touring-amps/k-series/k20

You can see what voltage he applied in the long term tests (up to 101.4 V).

It is a consideration as to what he can test at vs what your amp can do, tho.....

 

[highfigh]

Just spl, quality isn't there...

Oh, it can be there. It just requires a good design. The RTA test is done with a Real Time Analyzer- it's only an objective measurement, so SQ isn't a factor but the car still needs to be competitive in that if it's going to win or score well.

 

[Din61]

No, I never said that Qts between 0.40 and 0.45 is best for a sealed cabinet. Drivers with a Qts of 0.5 or more are best suited for sealed designs. The Qts of a loudspeaker often changes but not by much within the burning-in period. The Q of a specific system is another matter and too complex to discuss here.

I know you didn't, which is why I've replied it was my misconception.

Q is a generic term counting on QTS (QES+QMS) and QTC altogether, it may lead to a long off-topic discussion here, agree.

 

[Din61]

The amp is capable of such https://www.powersoft.com/en/products/touring-amps/k-series/k20



You can see what voltage he applied in the long term tests (up to 101.4 V).



It is a consideration as to what he can test at vs what your amp can do, tho.....

Ah, didn't notice that my friend, it was 101.4 volts...

 

[Din61]

Oh, it can be there. It just requires a good design. The RTA test is done with a Real Time Analyzer- it's only an objective measurement, so SQ isn't a factor but the car still needs to be competitive in that if it's going to win or score well.

True, any design optimized for a certain application can perform well enough in that environment.

 

[Din61]

Back to life...!

INFINITY KAPPA PERFECT 12VQ 12"
400W RMS
3" VC
22.19hz FS
.47 QTS
16.75mm XMAX

INFINITY REFERENCE 1262W 12"
300W RMS
2" VC
25hz FS
.46 QTS
13mm XMAX

Seem perfect huh...?



Update:

INFINITY KAPPA 122.7W 12"
350W RMS
3" VC
20.6hz FS
.456 QTS
12mm XMAX

 

[lovinthehd]

That Infinity 1262W is still available there? I did build a couple nice little sealed subs for my bedroom with those, but they do have their limits.

 

[Din61]

That Infinity 1262W is still available there? I did build a couple nice little sealed subs for my bedroom with those, but they do have their limits.

Just imagine how outdated we are, 1262W is the latest car audio woofer available here my friend.

Yeah, all these 3 drivers hit 400w rms at most, I doubt my room would be pleased.

 

[lovinthehd]

Just imagine how outdated we are, 1262W is the latest car audio woofer available here my friend.

Yeah, all these 3 drivers hit 400w rms at most, I doubt my room would be pleased.

I think they haven't been available here for a few years now.

What do you mean the drivers hit 400w at most?