modifying TM into MTM or TMM

[ultrachrome]

Assuming a tweeter's efficiency is about 3dB higher than the woofer, can the same crossover be used when converting a TM into a MTM or TMM?

Obviously, the tweeter won't need to be attenuated as much or at all but will the distance between the bottom woofer in a TMM cause any audible anomolies? Or would the lobing be screwy with either configuration?

 

[sreten]

Tweeter efficiency only has to ~ = the woofer, depending on BSC.

However you are correct in the sense the tweeter to be used
in a MTM or TMM must be attenuated back by the amount of
BSC used in the MT.
If it has no attenuation it will only work if the TM has no BSC,
in this case a TMM 2.5 way is the easiest as you can keep the
c/o as is and add the extra bass driver with its BSC inductor.

Generally a TM crossover cannot be used for a 2.5 way as
some BSC is included which must be removed, it cannot be
used for an MTM 2 way as the driver impedance is now half.

sreten.

 

[ultrachrome]

Forgot about the impedence change although for the design I was thinking about modifying I could get a 16ohm version of the driver.

By TMM 2.5 way you mean each woofer has it's own crossover point? One at the tweeter's crossover frequency and one at the baffle step frequency?

Well, in any case it sounds like I would end up having to start from scratch which is what I am trying to avoid due to time constraints. I'm not sure I even want baffle step due to the speakers being placed close to the walls.

Thanks.

 

[Bill Fitzpatrick]

I would get the new drivers in the same impedance you already have and wire them in series. Except for the tweeter, divide all capacitances by 2 and multiply all inductances by 2.

I guess you know that by adding a driver you will need to increase box size and change the vent.