I hate math

[b_force]

Some might argue that Bessel response [Q = 1/sqrt(3) -- maximally-flat delay] is superior. Depends upon circumstances.

Both arguments are totally useless without knowing ANY context, goals and constraints.

There is NO perfect.

 

[AllenB]

It has been described in terms of whether or not there is overshoot of the impulse, and whether or not there is ringing.

 

[planet10]

Bessel response [Q = 1/sqrt(3)

With a sealed box it is my typical target. 0.58 rounded off. Also a good starting point for an optimal miniOnken vented alignment.

dave

 

[Ixnay]

Dave, I am trying to resist the temptation of building these miniOnken guys, but you are not helping. I may give in after all.

 

[gberchin]

With a sealed box it is my typical target. 0.58 rounded off.

Unfortunately, Bessel highpass filters do not share the excellent transient response of Bessel lowpass filters. They're still good, though.

 

[witwald]

Yeah, though I grew up with critically damped = max flat/0.707; 0.5 = transient perfect.

And which of the following step responses is "transient perfect"?
The plots show the step responses of second-order high-pass filters with values of Q = 0.7071, 0.5, and 1.0. Note that each of the high-pass response functions have the same a –3dB point: 50Hz. In this comparison, the Q = 0.7071 response has the shortest settling time, but it has the second-largest oevershoot in the negative direction, but not by a very great amount.

 

[b_force]

Omg not this discussion all over again 🙁

 

[Booger weldz]

So what’s a ‘critically damped’ box for this? Probably one of the lowest Qts in all of subwooferland.

https://www.parts-express.com/pedocs/specs/294-6028--bc-18ds115-4-spec-sheet.pdf

 

[gberchin]

According to WinISD, 28.2 liters will give Qtc = 0.500. That's really tiny for an 18" woofer.

 

[planet10]

According to WinISD, 28.2 liters will give Qtc = 0.500. That's really tiny for an 18" woofer.

Expected for such low Q_ts. What is F6/F10?

dave

 

[gberchin]

What is F6/F10?

About 70 Hz and 59 Hz, respectively.

 

[planet10]

Not impressive for a sub. Good for an uppercase, lower mids in a PA.

dave

 

[gberchin]

WinISD recommends vented Extended Bass Shelf 6 alignment that drops 3 dB below the shelf at around 32 Hz.

 

[planet10]

Not a fan of tha kind of alignment.

dave

 

[gberchin]

With 1700W power handling capability, you could EQ the snot out of it, if you don't mind it doubling as a space heater.

 

[Booger weldz]

According to WinISD, 28.2 liters will give Qtc = 0.500. That's really tiny for an 18" woofer.

Yeah, that’s not useful unfortunately . can you even dsp it into More neutered bass? Edit: you said ‘space heater already ’. 😝👍🏼

 

[Booger weldz]

Best I could do was a 300cm long tapped pipe (600cm2)

 

[gberchin]

Best I could do was a 300cm long tapped pipe

A 10' tapped pipe only gains a couple of dB and a few Hz over a 74 liter vented box, below about 50 Hz.

 

[Booger weldz]

How big is the port In crossection?

 

[GM]

And which of the following step responses is "transient perfect"?

None actually since there can't be anything below the line according to both a local Altec engineer and an old local curmudgeonly E.E. that worked at W.E. in the early days of cinema sound circa '66 that noted the best we can do 'perfect' in sound reproduction was a 'euphonically' distorted response, which IME 0.5 is my 'perfect' transient response based more on the much better hearing of young females than my then youthful hearing already damaged from game hunting, auto racing and several other hearing damaging hobbies/endeavors.