Mellotronists

<< The high frequency of a bias signal simply ensures that the domains are 
always kept in motion, negating the effect of inertia at audio frequencies. >>

that's the one. that's the version I was looking for- I sort of knew all that 
but I've never been able to sum it up so neatly. cheers for passing that on. 
so, how much does one have to slow a 'tron down to hear a whistling noise? I 
mean average cloth-eared musicians, not hyper-tense alsatian puppies or bats. 
martin, what sort of deck are you making the new tapes on?

the uhers I have don't specify a bias frequency, the revoxes say 120kHz and 
my old ferrograph is a mere 63kHz. interesting that this latter still blows 
the others away on a good day, with the big a810 not far behind and then the 
g36 and one of the uhers. 
bias voltages presented to the record head are typically an order of 
magnitude greater than the accompanying audio signal, which is why we have 
bias traps- to stop the bias getting into the record amplifier and 
overdriving it. on the playback side, if they're present, bias traps are 
there rather optimistically to protect the output stages from being saturated 
at supersonic frequencies; this is more likely to happen through flux linkage 
than via tape (! chance'd be a fine thing), especially on multitrack 
machines...... and is presumably why there doesn't appear to be an rf trap in 
the 'tron's pre-amp. john?

I know. I should get out more.

duncan/m400nr1098 and a load of 1/4" machines

> I know. I should get out more.

Then who would we ask?

Jon E Salley
MiloJohnson@...
M400 #886