Can a DIY Sealed Subwoofer Beat Mass Produced Models?

[lovinthehd]

Thank you very much for your input, I am going to be building a couple of subs, they are the Q-power deluxe, 2200 max 1100 rms dvc. I will definitely be checking in with you quite often. I am going to try and use with my 3 ohm 1000 watt home theater system. So I think everything will work out. Please keep me in your prayers!? Lol if you have any information I should have, please feel free to contact me. My email address is available I believe. Thank you again for your information.

HTIB amps usually don't make for good sub amps....what make and model is your "3 ohm 1000 watt" set?

 

[Steve81]

If double the displacement equals double the amplitude, a 6db increase in amplitude is 4 times the amplitude so 4 times the amplitude has to equal a displacement multiplied by a factor of four.

If you don't want to take my word for it that 6dB = 2x driver excursion, you can read it from JL (among others) as well:
https://jlaudio.zendesk.com/hc/en-us/articles/217201737-Doubling-Power-vs-Doubling-Output

Here is a handy summary table which also lists the change in voltage and speaker excursion for each change in level:
......
4.00 x power (watts) = 2.00 x voltage/excursion = +6dB

http://www.baudline.com/erik/ht/dB_laws_etc.html
http://www.globalrph.com/multiple_speakers_distance.htm
etc...

 

[Verdinut]

If you don't want to take my word for it that 6dB = 2x driver excursion, you can read it from JL (among others) as well:
https://jlaudio.zendesk.com/hc/en-us/articles/217201737-Doubling-Power-vs-Doubling-Output


http://www.baudline.com/erik/ht/dB_laws_etc.html
http://www.globalrph.com/multiple_speakers_distance.htm
etc...

I'm sorry for the misunderstanding. I have been confused by what was written in an old book "How to Build Speaker Enclosures" by two ex-engineers at Altec Lansing.
In their book, I quote textually what is printed: "If the excursion is doubled, the acoustical power is doubled". By that sentence, I understood that doubling cone excursion only doubles the SPL which means an increase of only 3dB.

So, the cone displacement is directly proportional to the current going into the driver rather than the amp power going into it. I found the more relevant info on the Baudline website.

Sorry for the all the questioning.

 

[Verdinut]

Double the displacement equals double the amplitude, so the driver only has to move twice as far to achieve a 6 dB increase. Maybe you are thinking of maintaining the same SPL for an octave lower in which the excursion increase must be a factor of four (so long as ports or passive radiators are not involved).

My apologies for the misunderstanding.
I had been confused by a book by ex-engineers at Altec Lansing. In that book, I quote textually what was written:
"If the excursion is doubled, the acoustical power is doubled". I understood that doubling SPL meant an increase of only 3 dB.
Sorry for the questioning.

 

[shadyJ]

My apologies for the misunderstanding.
I had been confused by a book by ex-engineers at Altec Lansing. In that book, I quote textually what was written:
"If the excursion is doubled, the acoustical power is doubled". I understood that doubling SPL meant an increase of only 3 dB.
Sorry for the questioning.

The confusion seems to stem from the difference between amplitude and power intensity, where amplitude is a field measurement that uses a log base of 20 and power whereas a power ratio uses a log base of 10. Amplitude works on a different scale that is equivalent to voltage.