I would welcome your help to understand wavetable synths.

I thought I had them sorted in my mind but now I am not sure

I have a 12 bit Akai S900 , max bandwidth 12Khz.

I sampled a 6Khz triangle wave and truncated it to one cycle and looped it, 

It sounded like a square wave buzz.

I sampled a 6Khz sine wave and truncated to one cycle , looped and ,

It sounded like a square wave buzz.

I went on to do the same with more complex wave forms sampling 1Khz wave forms and......

You-get the idea they all sounded like a square wave buzz.

I wondered if the looping frequency was dominating the sound so I lengthened the looped wave form a little to no improved effect.

I tried a low pass filter to cut the looping frequency and it sounded like a more dull buzz.

Why

How do wave table synths manage to sound as they are described.

Thanks for you help