TAD TD-2001 cross over frequency

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I did some measurements on my TD-2001 + 350Hz tractrix horn (new set up) and besides I am amazed by the excellent response curve I feel the temptation to aim for the lowest possible high-pass crossover frequency. The spec mentions a frequency range from 500Hz on but the recommendation is to use 800Hz (2nd order). Odd specification actually, but nevertheless it makes sense with a measured resonance F of 360Hz...x2 gets it close to the recommended 800Hz.

Spec:
Frequency range: 500 - 22,000Hz. Maximum input power: 30 watts (800Hz, -12dB/oct.)

Now...the curve without filter looks very nice and shows a low drop of just below 400Hz (must be de resonance point so it seems to match the logic)

Pushing the boundaries (without damaging this nice driver and while using a SET 300B that will never exceed 7-8Watts):
Efficiency of 109/1W results in max 118dB and for 30W it would be 124dB.
The SPL at 500Hz (measured) is dropped only 2dB compared to the max so with the 8W driving it it would top at 116dB for 500Hz

The question, what would be the maximum power the driver can stand at 500Hz?
 
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30 watt is likely rated with the 800hz/2nd order filter short time (not hours).
Low frequencies need very little power to cause big excursion.
Few watts in low freq. can quickly kill a tweeter.
Beryllium doesn’t like mechanical stress.
That driver increases distortion below 1k.

I dont own it but these are some facts. Be careful.
Living Voice crosses that one at 5k 2nd order ;) highpass.
Ok that’s horn related.
But in my experience 1” driver quickly get and sound stressed at 1k already.
I don’t understand the “crossing low as possible” attitude everyone has.
What about high as possible? :) Also has advantages
 
Here it is.

This shows curves with:

No HP filter
2nd Order HP filter around 850Hz 3.9mH 15uF
HP 15uF (1.3kHz), for the simpel reason the 15uF was already connected for the 2nd order measurement
 

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  • TD2001HP No 1storder15uF 2ndorder 15uF3_9uF.pdf
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The FR graphs do look good indeed! While I understand the desire to cross as low as possible, my experience with large horns has led me to cross where it works the best - and that often ins't the lowest point. With a large horn of course you want it to play low, but sometimes that's not good for the sound.

How to determine the crossover point? Look at the FR, of course, bit also the distortion and the directivity. You can often hear where it integrates best, so don't ignore that.
 
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