Patches and discussion for Ensoniq VFX family

Hi Folks

It was me that posted the comment some months ago that a technician 
friend of mine upgraded the output stage op-amps in my VFX to make it 
noticably quieter.
I'm sorry I can no longer supply the part number in question, because 
unfortunately I no longer have that keyboard (I upgraded to an SD-1) nor 
the friend in question (he died of bowel cancer). 

At the time we had a stack of NE5534AP chips on hand for a mixer of mine 
that we were building, and  I have a vague recollection that he decided 
they were compatible,
HOWEVER, PLEASE DO NOT take this as a recommendation.  Can some-one who 
is qualified please confirm the compatibility and suitability of this 
chip before anyone starts soldering some in and blows up their keyboard 
because my memory of an event 15/18 years ago was wrong????!!!! 

_IF_ the NE5534 _/IS /_a match, do not use "N's", the "A's" were the 
MUCH higher spec, and MUCH lower noise.

Over-all this exercise is definitely worth pursuing, the chip change 
made the VFX a LOT quieter, and also made it noticably cleaner as well. 
(i.e. not just less noise but a cleaner crisper more transparent tone as 
well.

That and the discovery that the volume pot was not if fact an attenuator 
sitting at the end of the signal path as you would expect it  to be (and 
there-fore ride the noise level down with the signal level),  but was 
infact an analog controller used to ride the final VCA levels down 
BEFORE their output got fed into the final output stage, there-fore 
making the noise the output stage constant and un-attenuatable - made my 
VFX come ALIVE!!  Running the volume pot as high as your mixer inputs 
can handle was a MAJOR discovery!!

If no-one can work the chip out,  email me or post the number of the 
chip that is in there, and I'll try another local tech that I trust to 
know what he is talking about.

Regards

Roger Campbell