816 or 817 Internal Volume & Fb

[Earl K]

Hi Altec Fans,

- Does anyone know the internal volumes of either the 816 or 817 enclosures ?

- Also, does anyone know their respective stock box tunings ( or Fb ) ?

Thanks <> EarlK

[GM]

Greets!

Haven't bothered to 'do the math', but factory plots show the 816/817 with a ~61Hz/~52Hz Fb.

GM

[Earl K]

Thanks for the quick response, GM .

- Have you ever heard of anyone successfully retuning these enclosures to better suit a specific driver ?

- ( or is person committed to working with the usual suspects ? ie the 416, 421 or 515 ? )

Thanks <> EarlK

[GM]

Greets!

Due to their ducted vent design utilizing the cab's walls, changing their tuning would be more trouble than it's worth except for aperiodically loading them via damping if the cab alignment is particularly high Q, though I guess you could board them up and install new round ones easily enough.

Really though, these designs are so generic that probably any 15" driver can be made to work with some form of EQ and/or vent damping since the CR is ~1:1 and the 416/417 only loads over a ~1.0/~1.5 octave BW.

If you want it to be optimum for one specific driver then best to DIY from scratch IMO unless you already have some cabs you don't mind modding.

GM

[GM]

Greets!

Due to their ducted vent design utilizing the cab's walls, changing their tuning would be more trouble than it's worth except for aperiodically loading them via damping if the cab alignment is particularly high Q, though I guess you could board them up and install new round ones easily enough.

Really though, these designs are so generic that probably any 15" driver can be made to work with some form of EQ and/or vent damping since the CR is ~1:1 and the 816/817 only loads over a ~1.0/~1.5 octave BW.

If you want it to be optimum for one specific driver then best to DIY from scratch IMO unless you already have some cabs you don't mind modding.

GM

[Earl K]

Thanks GM

- I appreciate your comments

- I found a construction drawing for the 816.

- I calculated it's internal volume at 5 to 5.5 cu'
depending on bracing / fibergalss effects / etc.
This calculation included all of the ducted port .

regards <. EarlK

[GM]

Greets!

You're welcome! Yeah, that seems about right. I forgot to mention that if you DIY your own, I recommend you go to the extra effort to slope at least the bottom horn plate like the 825/828 cab if they are for home use since the standing waves that develop between the parallel sides 'colors' the sound if a >800Hz XO is used on the 816 or >400Hz/817. I never could completely damp out these modes on the 210s so swore I'd never have parallel horn walls again in a home app if its modes were in the passband.

GM