Altec Beefy look

[Earl K]

That would be my choice.

GM

I too am a firm believer in custom networks ( especially when components have been changed ) .

Let's keep in mind Licorne thought this box was mine ( & to boot, called it a custom-built Valencia ). I think the whole 288 driver ( swap thing ) is best treated as a theoretical exercise .

Having said that ( is the 511E horn swap a deal breaker for this class of network) ?

- A 288-8K on a 511E horn ( vs the 802D on a 511b ) doesn't miss duplicating the dimensional marks by all that much .
- In fact, the difference is around .75" ( with the 288-8K/511E combo coming up the "shorter" of the 2 combos ) .


- Here's bfish(s) work ( for a quick visual reference ) ;



- The 288-8K is @ 4" deep from exit to ( middle of ) top plate while the 802D is @ 2.5" .

- Cutting off say 2.5" from the 511b ( then adding back on a 1/4" deep mounting flange ) leaves one with a 2.25" ( shorter horn ) with 1.5" added back ( accounting for the 288s extra depth ) giving an approx. depth difference of just .75" ( less ) .

- At crossover ( & say it's exactly 500hz ) a quarter wavelength is @ 6.5" - 6.75" . So the .75" difference is well within what I'll call an allowable zone of additive quadrature ( all the while making some pretty broad assumptions, such as Altec having actually "nailed" the phasing of the original crossover ) .

- Assuming my early morning math hasn't failed me [ ( .75 / ( 1130 / 500 * 12 ) ) * 360 = 9.96 deg ] , that .75" represents about a 10deg difference ( in phase rotation ) compared to the original network.

- A 10deg difference ( compared to the original ) wouldn't hinder the goal of achieving proper summing ( within the crossover region ) .


- OTOH, the 288 & the 802 variants differ quite a bit in their sensitivities , their impedance curves ( from 400 to 2K ) as well as their frequency response curves .
- ( If this was my project ) I would proceed to modify the original HF leg of the network based on those factors . And since I really prefer bi-amped woofers ( with passively crossed HF driven by another amp ) the original network would be right out the window .