2" vs 1.5"/1.4" vs 1", what compression driver size should I use?
As we see upper, the throat size will dictate the top end control of the horn, so the CD behavior. larger the throat size is, lower the top end control we will have, but there is some tricks, like on our bi-radial horn.
1" compression driver: They are relatively cheap, they cannot go very down, the best of them have a limit of 950/1000hz (BMS and 18Sound), the throat is tiny so the radiation control is high in frequency.
2" compression driver:
It’s an historic size, the control in high frequency is limited, today we continue to see some of these throat size for very specific usage : Have a high SPL, low end device (for replace a tinier compression + medium couple) without taking account of top end control.
These needs find an use case Line Array, so for a very far distance, it’s typically the usage of the Celestion Axi2050, it’s have been create for this very specific purpose.
The usage of 2" is not recommended for our usage.
1.5" or 1.4" compression driver:
It’s an ideal, they goes down and the throat size is not too big. In fact some 2" inch driver are just 1.5" driver with build in adapter, like the JBL 2450 or TAD TD4002. For the perspective of the horn it’s way more efficient to use an 1.5" version of a driver rather than the 2".
1.4" drivers have a 3" diaphragm, so the break-up is upper. 1.5" drivers have a 4" so better max SPL capacities and lower THD at the bottom range.
On our 1.4/1.5 Bi-radial horn we use a smooth pinch for push the control like it’s an 1", this way we have all the advantages.