Altec 15 inch 3154, or 416 in open baffle any good idea

[MerlinVSM]

Any information how the above woofers would perform in an open baffle (appr. 0,6x0,7m) equalized and active crossover at 5oohz to an Altec 511B horn.


Is the above a good idea ?

[David Yost]

I'll take a shot--

Both of these woofers are low Qt, which means that they will begin their lf roll off at a relatively high frequency -- so if you want to eq them flat into the lower bass range, because of dipole cancellation they will need considerable power and will likely run out of excursion and/or hit their vc power limitations at a relatively low spl. Of the two, the 3154 has a lower fs and higher excursion limits so between them, this would be my pick for OB -- but it would not be ideal.

OTOH, look at the Carver Amazing speakers. They used very high Qt woofers which had huge excursion and were ganged 3 or 4 a side for bass output down to the 20s without eq. Ingenious.

[Old Guy]

If you want to do Altec open baffle best shot is likely 420A

Altec Thiele-Small Parameters

Higher Qts is better for OB

[GM]

From much earlier today: RE: Altec 15 inch 3154, or 416 in open baffle - GM - High Efficiency Speaker Asylum

GM

[Alien_Shore]

GM - you're a damn guru. I swear I need to ready like 10 reference docs to interpret your posts. <respect>

[GM]

Only 10?! I'm slipping in my dotage. I know how you feel though, Some years ago I decided to learn as much about antenna design as I knew about acoustical stuff, so already knowing the TL, horn analogies between the two, I went straight to the advanced designer's forum and most of it might as well have been posted in Sanskrit and Greek since it was loaded with their own specialized lingo and higher math intensive; plus it was obvious that they didn't suffer fools graciously and the mods would ban anyone that was there to get free design theory info that could be found searching the beginner, etc. forums. A really tough crowd compared to the audio/HT forums.

Consequently, I didn't learn much, but ultimately the 'crew' did what I wanted to do, which was design an OTA digital TV antenna for 'problem' areas like mine, though I have no clue how it was done since they declined to publish its design details.

GM

[cradeldorf]

GM - you're a damn guru. I swear I need to ready like 10 reference docs to interpret your posts. <respect>

He's a smart cookie alright.

[GM]

I wish! If I was, I'd of been able to do more than just lurk for ~ a year on that forum before giving up.

GM

[Altec Best]

GM - you're a damn guru. I swear I need to ready like 10 reference docs to interpret your posts. <respect>

I just call him "The Man" And a damn generous one at that too !

[Panomaniac]

I agree that the X-max of the 416 could be a problem. You don't get much bass efficiency out of an OB (that's why they put woofers in boxes) so you have to push the cone farther. That said, I've run across a number of 416s that had a Qts of 0.4 to 0.6 and that means more of a bass bump than factory specs would indicate. But less efficient, so it's a trade off.

Another thing hard to get right is the crossover. Mating an open baffle woofer and a horn is no easy task - I speak from experience! It can be done, but won't look anything like a textbook crossover.
See attached my Selenium 15" + Altec 811 Obee. It later had wings to help the bass.