Better to have it and not need it than vice versa ! 😉 With this huge displacement you can do ELF systems for the subsonic range with generous SPL capabilities.
Regards
Charles
generous...yeah thats the word.
Bogie, in some senses you are my hero, buy two more and do an IB and youll be my hero in ALL senses 😀.
I would have gone with tempests, you can get more linear displacement out of 4 tempests than you can out of 6 quattros.
Simon, are you saying i should get a bigger box and tune lower? -7db at 16hz is pretty good IMO. plus I will be getting ALOT of room gain. Give me an example of what you would tune to with the tempest for some serious lows.
Bogie, in some senses you are my hero, buy two more and do an IB and youll be my hero in ALL senses 😀.
I would have gone with tempests, you can get more linear displacement out of 4 tempests than you can out of 6 quattros.
Simon, are you saying i should get a bigger box and tune lower? -7db at 16hz is pretty good IMO. plus I will be getting ALOT of room gain. Give me an example of what you would tune to with the tempest for some serious lows.
As you tune a vented box lower and lower you start to move towards the response of a sealed box. You may want this, but you start to lose output, until you get to a point where you have a much bigger box and the same response as a sealed box. This is where you are going if you keep tuning lower! To a degree you can extend the bass deeper with EBS by also making the box bigger and you can get the rolloff to mate with room gain, but don't take this too far. IMO it's not worth what you give up, and also you get a big ugly box!
Try this ... model a large vented box tuned at 1 Hz and compare it to a sealed box ... just for interest.
Try this ... model a large vented box tuned at 1 Hz and compare it to a sealed box ... just for interest.
The group delay is much better with a vented box tuned to 1 Hz, that is amazing! 21 ms of delay for the vented box versus 50 ms for the closed box when we look at 2 Hz! About 60% better!
The group delay is way better down to 1,2 Hz except the ugly 3 second (LOL) group delay peak at 0,8 Hz.
But, you are right, frequency response is the same.
In another way, we use vented to produce these frequencies without going in overexcursion...
If we want to use 250W, the closed box (Qtc = 0,5 so 575 liters)will go in overexcursion when you reach 27 Hz and under.
To compare, I tuned a 575 liters vented box to 18,6 Hz, we never go in overexcursion except under 17 Hz. We have also 10 dB more output at 20 Hz.
This 10 Hz extension gain is quite important to me... improved efficiency is good also! 😉
This big vented box is only for testing, it's not a good design except if you want to use it outdoors because it's flat anechoic down to 17 Hz (excursion limit) with 250W. So it will sound boomy in room hehe!
The group delay is way better down to 1,2 Hz except the ugly 3 second (LOL) group delay peak at 0,8 Hz.
But, you are right, frequency response is the same.
In another way, we use vented to produce these frequencies without going in overexcursion...
If we want to use 250W, the closed box (Qtc = 0,5 so 575 liters)will go in overexcursion when you reach 27 Hz and under.
To compare, I tuned a 575 liters vented box to 18,6 Hz, we never go in overexcursion except under 17 Hz. We have also 10 dB more output at 20 Hz.
This 10 Hz extension gain is quite important to me... improved efficiency is good also! 😉
This big vented box is only for testing, it's not a good design except if you want to use it outdoors because it's flat anechoic down to 17 Hz (excursion limit) with 250W. So it will sound boomy in room hehe!
xstephanx, I would tune your 250L box with a 240W amp to 12,1 Hz, you must not go lower than that to prevent overexcursion. You might want to tune it to 12,5 Hz just for safety. Very flat rolloff that will match room gain and won't go in overexcursion until you down lower than 11 Hz.
But, you would need to give me the rumble filter built in your amp. Down that low it will affect the response, so I need to include it in WinISD Pro to see the effect of it, maybe with the rumble filter the FR response will rolloff faster and need a higher tuning, or maybe it will give us a bit more room to tune lower.
The problem is the vent, you might need a folded slot port.
But, you would need to give me the rumble filter built in your amp. Down that low it will affect the response, so I need to include it in WinISD Pro to see the effect of it, maybe with the rumble filter the FR response will rolloff faster and need a higher tuning, or maybe it will give us a bit more room to tune lower.
The problem is the vent, you might need a folded slot port.
BAH! all this is starting to confuse me. I like the sound of a house curve for HT, and a tempest in 250l tuned to 19hz should give me that. The box will be sealable as well, so i can just throw a plug in and voila, sealed box!
Even my hunger for infrasound has a limit, anything below 15hz i dont want. Below 15hz is when the ear starts to actually "hear"( i use quotation marks becuase youre really only feeling the pressure fluctuations in your ear) each seperate cycle of the speaker.
I heard a couple times that tuning lower lowers group delay, but i never knew it lowered it considerably less than a sealed box!
Even my hunger for infrasound has a limit, anything below 15hz i dont want. Below 15hz is when the ear starts to actually "hear"( i use quotation marks becuase youre really only feeling the pressure fluctuations in your ear) each seperate cycle of the speaker.
I heard a couple times that tuning lower lowers group delay, but i never knew it lowered it considerably less than a sealed box!
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