New Mid Bass (mod rod pt. 2)

[Steve Mac]

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with grille cloths(marshall bluesbreaker gray)


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I’m witholding judgement until the system gets moved to its new home later this year but:
-it sounds great
-i wonder what larger altec sectoral horn would get me safely down to 300hz...

[Old Guy]

329A or 311-90

[Steve Mac]

329A or 311-90

Thanks, will these horns properly couple the 288 down to 350hz?
Would I still need to consider a higher filter than 12db?
Didn?t you have a pair of the 311-90s?

[GM]

It depends on the max power it will likely 'feel' since these horns at a ~220 Hz cutoff are way too short for true 300 Hz loading and barely long enough for their 500 Hz measured ratings [1 WL effective path-length]. Ditto 300 Hz multi-cells.

In short, the 300 Hz rating is about pattern control [polar response] over a wider bandwidth [BW] to a lower frequency [Fc].

Edit: My [failing] memory caught me out. Went back and pieced together the [assembled] dims and all the [3] suffix multi-cell horns have sufficiently long path-lengths for the claimed 300 Hz rating.

[Old Guy]

It depends on the max power it will likely 'feel' since these horns at a ~220 Hz cutoff are way too short for true 300 Hz loading and barely long enough for their 500 Hz measured ratings [1 WL effective path-length]. Ditto 300 Hz multi-cells.

In short, the 300 Hz rating is about pattern control [polar response] over a wider bandwidth [BW] to a lower frequency [Fc].

Spot on that you will lose some pattern control. 24 Db/octave helps. The octave down is 150 Hz, should be around 12 Db down at 220.

[GM]

Another option is the one I PM'd awhile back, i.e. a horn baffle large enough to support 300 Hz that combined with reduced power should suffice.