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TS9 Upgrade?

8/11/1999 11:18 PM
Mike TS9 Upgrade?
I have a TS9 reissue with a 7550 chip in it. I was going to install a 4558D in its place. This is my first time doing this and I need to know how you can tell its turned in the right direction or does that even matter? Second will the changing of the chip make that much difference? Third, is there anything else that is different between the reissue and the original? Thanks in advance.  
8/12/1999 3:00 AM
Mark Hammer
There has been MUCH dialogue in this forum about replacement chips for TS-9's that produce a sound that appeals to more ears. I'm not sure what happened to those threads, but you can find much of that information summarized very nicely at both RG Keen's site ( and at Jack Orman's site (  
The short version is that there are a number of dual op-amps besides the now legendary JRC4558D that appear to have promising characteristics. Jack Orman has speculated about why this is, and what can be done to simulate that characteristics, regardless of what op-amp one is using.  
A simple way to identify the proper orientation of an op-amp on the PC board is to simply look for the ground pin and V+ pin. Most FX use a single-ended +9V battery supply, with the #4 pin going to ground, and the #8 pin going to V+). If you do decide to yank the dual op-amp from your reissue TS9, the smart thing to do is to solder in an 8-pin IC socket so you can try out different op-amps. The socket itself will have a little notch between pins 1 and 8,.
8/12/1999 9:11 PM
I don't see any numbers on the pins of the chip. How do I know which is which?  
8/12/1999 11:05 PM
pin 1 is...
If you look at you chip there will be a U shaped notch in one end (if no notch look for a dot on one corner). If the notch is there orient the chip so the notch is at the top and pin 1 will be the pin in the upper left corner pin. The pins are then in numerical order counter clockwise. If no notch but it has the dot. The dot is pin 1.  
Does that make any sense?  
Good luck,  
8/13/1999 3:45 AM
Yes....thanks Jason. The one I am taking out has a notch at one end and the one I am putting in has a dot. Appreciate the help.  
8/15/1999 2:31 PM
Thanks for the help guys. I put in the chip and the pedal is clearly better. The tonal qualities moved up a notch especially the tightness of the bass and total harmonic overtones. I can see why this is a good mod for the TS9. I played it next to a reissue without the mod and with the settings the same there was a noticable difference. I muxt admit that the reissue sounded good too but just not as good as the one with the 4558D chip. Every little bit helps in the quest for tone.  
8/20/1999 10:46 PM
ts5 mod
Just took my TS5 and modded it with a 4558 chip, 10k, and 100 ohm resistor...changing it to an 808. Great sound!!! I recommend this one. It took that cheap pedal and turned it into a great sounding one. I was going to sell this one but now I think I'll keep it for a gigging spare. Plastic box still sucks but the sound is there.  

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