Tube synth diy

It sounds really soft and creamy, and a magnet is not really necessary, 
it works great with only hands, because the 2d21 is nott hot at all...
But i got problems to listen to it, as it is the first module i can 
only hear it when plugged on he phono input of an old Scott hifi 
amplifier, even thee there is a lot of hum, but from the amp... i 
tryied to plug it in my preamp/compressor, but all i had was hum ant 
tried all my differentamps and inputs and it is all the same... (i 
still didn't try in a mxer cause i have none now where i am, i lend 
mine to a friend for few days... but the preamp/comp is a kind of mixer 
channel)
I am building the  VCF, to run the noise source in... hope it will be 
easier to hear it.
if anybody got tips or suggestions, i am waiting for it...