Author Topic: Stupid old man with a few good ideas.  (Read 41930 times)

Offline DeonC

  • Trade Count: (+8)
  • AVForums Grandmaster
  • *****
  • Posts: 1,438
Re: Stupid old man with a few good ideas.
« Reply #210 on: April 20, 2015, 11:23:38 AM »
AFAIK the only disadvantage of aperiodic as compared to sealed is that aperiodic rolls off at 18dB/octave below Fs, whereas sealed rolls off at 12dB/octave. However I still think it is better. From what I have read, aperiodic gives some of the best rise-time (or is that transient response? I cannot remember) measurements of just about any alignment.
Life is not measured by the breaths you take, but by the moments that take your breath away.

Offline Timber_MG

  • Trade Count: (+2)
  • AVForums Grandmaster
  • *****
  • Posts: 6,380
Re: Stupid old man with a few good ideas.
« Reply #211 on: April 20, 2015, 11:29:31 AM »
AFAIK the only disadvantage of aperiodic as compared to sealed is that aperiodic rolls off at 18dB/octave below Fs, whereas sealed rolls off at 12dB/octave. However I still think it is better. From what I have read, aperiodic gives some of the best rise-time (or is that transient response? I cannot remember) measurements of just about any alignment.

That is all down to the HF behaviour of the woofer. Once filtered, the LP filter function will determine that.

Offline DRNB

  • Forum Moderator
  • Trade Count: (+6)
  • *****
  • Posts: 2,920
Re: Stupid old man with a few good ideas.
« Reply #212 on: April 20, 2015, 12:07:39 PM »
That is all down to the HF behaviour of the woofer. Once filtered, the LP filter function will determine that.

Martin, I think DeonC refers to the HP function of the driver box combo, and not the LP filter on the x-over side. I've had it that a sealed box is a 1st order alignment though  :thinking:
But I'm rusted with this, so will have to check again.
"There is no shame in not knowing; the shame lies in not finding out." (Russian Proverb)

Offline DeonC

  • Trade Count: (+8)
  • AVForums Grandmaster
  • *****
  • Posts: 1,438
Re: Stupid old man with a few good ideas.
« Reply #213 on: April 20, 2015, 12:37:54 PM »
Martin, I think DeonC refers to the HP function of the driver box combo, and not the LP filter on the x-over side. I've had it that a sealed box is a 1st order alignment though  :thinking:
But I'm rusted with this, so will have to check again.

Yes, my apologies. :facepalm:

A sealed is a 1st-order (and vented I think is 2nd-order?). Aperiodic is somewhere between them. It rolls off faster in the bass than a sealed alignment, but not as fast as a vented alignment.

For an interesting article about a variation, read this:

North Creek Music's new MAPD (Multichamber Aperiodic Progressive Damping) driver loading
Life is not measured by the breaths you take, but by the moments that take your breath away.

Offline Timber_MG

  • Trade Count: (+2)
  • AVForums Grandmaster
  • *****
  • Posts: 6,380
Re: Stupid old man with a few good ideas.
« Reply #214 on: April 20, 2015, 12:45:19 PM »
an order is 6dB/oct so sealed classically is 2nd order, vented 4th order and so on. Electronicaly assisted alignments are sometimes given one aditional order nominally, like a EBS vented would be called 5th order.

Offline DeonC

  • Trade Count: (+8)
  • AVForums Grandmaster
  • *****
  • Posts: 1,438
Re: Stupid old man with a few good ideas.
« Reply #215 on: April 20, 2015, 11:15:09 PM »
an order is 6dB/oct so sealed classically is 2nd order, vented 4th order and so on. Electronicaly assisted alignments are sometimes given one additional order nominally, like a EBS vented would be called 5th order.

That is what I meant. An aperiodic has a 3rd-order roll-off (half-way between sealed and vented).

AFAIK the only disadvantage of aperiodic as compared to sealed is that aperiodic rolls off at 18dB/octave below Fs, whereas sealed rolls off at 12dB/octave. However I still think it is better. From what I have read, aperiodic gives some of the best rise-time (or is that transient response? I cannot remember) measurements of just about any alignment.
So I was correct saying 18dB/octave, IOW, 3rd-order roll-off. :boring:
Life is not measured by the breaths you take, but by the moments that take your breath away.

Offline DeonC

  • Trade Count: (+8)
  • AVForums Grandmaster
  • *****
  • Posts: 1,438
Re: Stupid old man with a few good ideas.
« Reply #216 on: July 04, 2018, 10:19:31 PM »
Hm, nice, but the Little 4" Faital actually has a Little sister, the 3FE30, what to do?



What, a rear loaded horn for a 3" driver, ridiculous, he cant do that!

Unfortunately, seems he can.



Ingvar

Ingvar, will the FaitalPro 3FE22 also work in the Hilding horn?
Life is not measured by the breaths you take, but by the moments that take your breath away.