Re: JamMan memory problems, Part 2

["Mikell D. Nelson" <mnelson@dmans.com>]

Dave Trenkel wrote:
> 
> This time, I got a really horrible digital distortion with random 
>crackling
> and bursts of digital noise. Much worse than the original distortion I 
>got,
> in fact it made the random crackling and bursts even with nothing in the
> input. Also, the level LED showed that the unit was overloading, even 
>with
> nothing plugged in. This was bad.
> Swappped the 8 second chips back in, JamSter works fine. Swapped
> 32-sec chips, same as above. For good measure, I swapped the 8-sec's back
> in, all OK.
> 
> And if the order of the chips can create
> these 2 levels of distortion, then maybe there's an order that can 
>produce
> no distortion. Figuring a maximum of 16 different permutations, I thought
> I'd try them all and see what happened.
> 
> On the second permutation, I got the desired effect: 32 seconds of
> glorious, distortion-free looping.

Dave,
  There is a very rational reason for this behavior: stuck bits. After
power up the bits should all be at zero yielding silence on playback,
but one or more of the memory modules has some bits stuck at 1. The
change in noise with module location probably occurs because of the
following. Each module is responsible for storing 4 bits of each 16 bit
sample. If the bad module is in the "most significant" position then it
represents a huge number and you hear a pop. If the bad module is in the
"least significant" position, then the flaw may be completely
inaudible.  In between locations for the bad module should create in
between noise levels. Because you found a very quiet positioning, I'd
say your vendor sold you only one defective module.

Motley