Question regarding SEAS 27TBFC/G and 27AFNC/G

[ractis]

Hi, I'm looking at the frequency reponse graphs of the following 2 tweeters from seas..

SEAS 27TBFC/G http://www.madisound.com/pdf/seas/H1212.pdf
recommended range = 1500hz-20000hz

SEAS 27AFNC/G http://www.madisound.com/pdf/seas/h1397.pdf
recommended range = 2500hz-30000hz

My question is, the FR graph for the first drops off at about 2000hz but SEAS suggests it is usable down to 1500hz

whereas for the second tweeter, the rolloff occurs only around 1500hz but it's recommended usage is from 2500hz

So am I missing something here about interpreting FR graphs?

Thanks for any help.. confused..

[BobEllis]

There's more to performance than just frequency response.

Looking at the Xmax numbers, you'd think that the 27AFNC/G would be a good performer at low frequencies. Unfortunately, it must have a stiff suspension or the non vented pole piece is taking its toll - see the bump in the impedance curve at 1200 Hz. or so? That is it's resonance, getting close to that implies increasing distortion.

Zaph tested both and almost across the board the 27AFNC/G has higher distortion, but particularly below 2kHz. Use it where you really need the small size.

Otherwise, consider the 27TBFC/G or 27TDFC, both of which can be used down to 1500 Hz with high order filters and reasonable (ear healthy) SPL expectations.

If you've got more money to spend, it sounds like the new HDS and AirCirc are even better performers.