Hartke VX3500 question

[metlman72]

What is the difference between the VX3500 A series and B series? Is it made in USA and made in China? Lastly which one (grey head/black head) is which? I have the model with the gray head.

Thanks

[mogpipe]

The one with the grey head are the newer models, i have one as well. Great amp! The black head ones are the older ones. They say 'Transient Attack' on them. The greys don't.