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4558 chip

2/5/2003 4:31 PM
Al B. 4558 chip
I'd like to do a tube screamer mod to a TS5.  
What are the choices of 4558 chips on the market,  
and where can I get them.Any help is appreciated.  
2/5/2003 8:36 PM
Contact Small Bear Electronics. He has some chips you may want to try, including the JRC4558.  
You can try different chips easily if you install a socket. I did this to a TS5. It's easy enough to do.  
Good luck!
2/8/2003 6:00 AM

No one can convince me that using a different (IE: the JRC)is gonna make a big difference, and probably no difference at all. If there is one, i'd bet that it'll be mostly a placebo effect, and that once that wears off you'll realize it really didn't make any difference in the big picture. Any real difference will probably be insignificant. That was my experience. Other mods did make a considerable diff in low end and output, but changing to a JRC make no real difference for ma at least. Go ahead and try it tho........maybe you will notice a lot more than me.......who knows. Just saying what i heard.
2/26/2003 10:47 PM
Rick Erickson

"No one can convince me that using a different (IE: the JRC)is gonna make a big difference, and probably no difference at all."
While I can appreciate your scepticism here I can assure you that different IC's can make a very audible difference in the sound of a tube screamer. Not major differences but little things like the harshness of the distortion sound which can make one chip seem to distort more than another. Someone, I think maybe RG Keene suggested that adding a 220 Ohm to 1K resistor in series with the opamp output terminals may virtually eliminate the differences between IC's in this (Tubescreamer) circuit. I think this may work but haven't actually tried it yet. Still have lots of JRC4558D's in stock. :)  
2/9/2003 3:50 PM
hugh jorgan
go on ebay, pick the highest priced one, and double the price so you win the bid.  
remember, the more you pay, the better the chip is.
2/10/2003 1:51 AM
Steve Dallman

A decent bifet sounds better than that cheap, little JRC4558. TL072, LF353...or any number. The JRC4558 is just cheap and available. That's why they were used.
2/10/2003 1:17 PM
hugh jorgan
TL072 is an excellent choice.  
Don't be fooled by all the hype you read here about the fabled JRC4558, the new ones are just as good as the old ones.

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