[Bumpy]

I now have my 3 way open baffles so that the bass drivers can be powered by their own amp.

I have vintage Altec 416 8 ohm drivers who’s specs claim they can only handle a constant 30 watts. I am guessing I will need to power the drivers with well over 30 watts in order to overcome the OB roll off at low frequencies. So can I damage them?

[Openly Baffled]

I guess it depends if your taste is live rock or chamber music so to answer your question we need a lot more information.
Factors like X-max, efficiency, Fs, Qts and baffle Fc are all important.

30 watts is quite low for an open baffle bass driver, especially considering the bass response will roll off 6dB for every octave below baffle Fc.
I use two 15" / 800W woofers per channel and for me it lacks headroom, even when listening at moderate levels. (maybe 100dB SPL)

[opnly bafld]

I use two 15" / 800W woofers per channel and for me it lacks headroom, even when listening at moderate levels. (maybe 100dB SPL)

I have not heard too many people call 100 dBs a moderate level. 

[richidoo]

Yes you can damage them. They are midrange / midbass speakers from the golden age when there really wasn't musch bass in the recordings because vinyl couldn't handle our modern bass. This is why rap waited until 1990s.

They are designed for low excursion to minimize midrange distortion, so pushing them to big excursion for low bass isn't their strong suit.

The damage would come as over heated voice coil from too much power, and surround and suspension could be damaged too..

There are better choices for OB bass driver that will free the altec for the midrange only, and they are designed for professional use and can take high power.

[Bumpy]

Yes you can damage them. They are midrange / midbass speakers from the golden age when there really wasn't musch bass in the recordings because vinyl couldn't handle our modern bass. This is why rap waited until 1990s.

They are designed for low excursion to minimize midrange distortion, so pushing them to big excursion for low bass isn't their strong suit.

The damage would come as over heated voice coil from too much power, and surround and suspension could be damaged too..

There are better choices for OB bass driver that will free the altec for the midrange only, and they are designed for professional use and can take high power.

This is great info and was what was worrying me.

While I am experimenting with the set up. I am using Eminence Alphas which can take a lot more punishment. At present the bass is pretty good using a dedicated modified Rotel 820AX amp (approx 30wpc).

The low pass filter is at about 100-120Hz. Below this I believe the sound quality of the bass driver becomes less important but the residual slope of higher frequencies encroaches on the lower midband most importantly on the human voice. Its here that a more classy bass driver could show its worth.  I can easily compare the Alpha and the Altec by playing mono and having one of each in the two OBs.

This may be all I need, but if not, Plan B was to use a 1000wpc ICE amp. I think now I will keep this amp away from my valuable Altecs.

[sebrof]

even when listening at moderate levels. (maybe 100dB SPL)

Yikes!! Your amp must go to 11

[Bumpy]

Yikes!! Your amp must go to 11

It wasn't me said I listened at 100dB. My moderate listening level is 70db

[Bumpy]

Yes you can damage them. They are midrange / midbass speakers from the golden age when there really wasn't musch bass in the recordings because vinyl couldn't handle our modern bass. This is why rap waited until 1990s.

They are designed for low excursion to minimize midrange distortion, so pushing them to big excursion for low bass isn't their strong suit.

The damage would come as over heated voice coil from too much power, and surround and suspension could be damaged too..

There are better choices for OB bass driver that will free the altec for the midrange only, and they are designed for professional use and can take high power.

You mentioned much better drivers. Can you offer any examples?