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previous: John Greene One more time:NJM i... -- 11/17/1999 6:34 PM View Thread

Re: I thought NJM4558's were plagued as well

11/18/1999 2:00 AM
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Re: I thought NJM4558's were plagued as well
John,  
 
Interesting to see this thread.  
 
I remember corresponding with you about a year ago on this subject.  
 
I did my own taste tests using several of the opamps listed and came to the same conclusion. I tested the various opamps by plugging them into a socket on a TS-808 clone.  
 
My test was simple and highly subjective :-)  
 
Using the same guitar and amp settings, I cranked the drive on the TS wide open.  
 
With each opamp I would play a series of chords and listen to the decay of distortion. Then I would do the same thing playing a series of single notes and double stops, finger picking only, at various select positions on all strings over the entire range of the guitar neck. I did the same patterns repeatedly for all contenders. Again, listening for attack and transition from distortion to clean.  
 
The JRC4558D, new or old, won hands down as sounding the most natural. (I yanked some old ones from and old Japan Boss Chorus.) True, it genereated a little more noise than some of the other chips but not enough to make me go with anything else. And I couldn't tell the difference between the old vs. new JRC4558D.  
 
Many of the other opamps would of fizz towards the end of the decay like a shorted circuit. Not really that noticable on hard hitting chords but on the sublte stuff, it was quite noticeable.  
 
I use to be a components buyer in the 80's and early 90's for several high tech companies and I concur with your explanation about die changes etc.  
 
I find it highly unlikely that JRC revised the actual circuit design or layout.

 
Replies:
JR IMHO, I really don't notice much d... -- 11/19/1999 6:38 PM