# Full Range Vs Low Frequency Driver?

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#### shank1207

Hi,
The upper limit of Low frequency driver is upto ka=2(k being the wave number and a the diameter of the driver). I want to understand how the full range driver operates above this range, does it make using of decoupling and use just the dome?. And also if anyone knws the advantage of either when the volume is really small( aprrox 200 cm3.)
Thanks

#### shank1207

welcome - E J Jordan Designs

particularly the 7 chapters of the Loudspeaker Manual
Thanks for the reply i was looking for the 1963 book Loudspeaker by Jordon i will have a look at the manual.

#### planet10

Paid Member
The upper limit of Low frequency driver is upto ka=2(k being the wave number and a the diameter of the driver)

An awful lot of simplifications & generalizations to come up with that equation. The actual numbers will have significant range.

dave

#### shank1207

An awful lot of simplifications & generalizations to come up with that equation. The actual numbers will have significant range.

dave
I believe that to be true because when i simulate a driver in infinite baffle the omnidirectional characteristic is above the range of ka=2 but there is a pattern of directivity increasing as radius of driver is increased.

#### planet10

Paid Member
The sim is using the generalized model, so the results are to be expected, but the real-world results will change depending on the actual driver used. ie the sim is of limited usefullnes wrt that parameter.

dave

#### shank1207

Is there a general rule of thumb to the upper frequency limit of the low freq driver for real world situation.

#### planet10

Paid Member
That is the general rule-of-thumb. It is just not very accurate.

dave

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