addSpec doesnt work for Ndef anymore? (Beginner)

Im starting to change from using SynthDefs to using Ndefs. Mainly because of the Ndef mixer gui. I see in alot of help files something like Ndef(\a).addSpec(\someParam, [10, 20, \exp]); I assume thats for adding\changing a slider for the NdefMixer. However when i compile this.

Ndef(\test, {
	arg freq = 100, amp = 1;, 0, amp);

Ndef(\test).addSpec(\freq, [50,200, \lin]);


It gives the error message addSpec not understood. Did it become deprecated or something?
Anyway the NdefMixer automatically makes the sliders for you, ive noticed. But i dont know how to change the minimum and maximum values of these sliders. If the addSpec doesnt work anymore, can anyone tell me how to set the bounds of the NdefMixer sliders?

addSpec is part of an extension. So you learn something new everyday…