Ibanez TS-10 to TS-808 conversion.

The circuitry on the TS-10 is 95% identical to the supposedly better-sounding TS-808, so some feel it's worth making the TS-10 100% identical. I am not suggesting that a TS-808 is a magically wonderful item. I'm just telling you how to make one. You can make a TS-10 99% identical to a TS- 808 in about 40 minutes, given the correct IC. The switching transistors are different, but the audio path ends up the same.

I'm using the component numbers from the pcb on my TS-10. Other TS-10's may use different numbers for all I know.

1. There is an extra transistor in the signal path when the effect is in the OFF position on the TS- 10. I removed the 10K R40 and ran a jumper from the end of the R39 1K resistor furthest from Q6 to the end of C15 nearest Q6. I then removed transistor Q6. This introduces a "switch on squawk" problem if you crank up the volume.

2. IC replacement: Since my IC was a JRC4558D (same as the TS-808) it did not need to be replaced. JRC 2043DD and NJM4558 IC's are said to sound really bad. According to  John Greene , the NJM4558 sounds identical to the JRC4558D, and can be had from Mouser at about 3 for a dollar. Since he has compared the two chips side by side, I am inclined to believe him. The TA75558p is said to be "OK". The JRC4558D is the best chip, don't try to remove that one. If it had been a bad type, I could have snipped its legs off, and removed all traces of its existence, replacing it with a better IC.  GEO  - IC removal  You can buy the JRC4558D at www.guitarkit.com.

Or then again I might have very carefully solder braided it off the board for later comparison purposes (there is a good chance of destroying the IC in the process, but I did it successfuly on a TS-5 by blowling the solder off while using a screwdiver as a lever). An 8-pin DIL IC socket would allow you try different IC's. It also stops you from frying the new IC with your soldering iron. If you put the IC in the wrong way around, you will destroy it instantly. TL072, TL082, LM385, LM833, LT1124 , TI RC4558 and OP227 are IC's reported to work well in the Tube Screamer. TL072 is "low noise" , readily available and sounds fine to me.

There are a lot of brand new opamps with JRC4558D stamped on them, so don't go paying big bucks for a 35-cent item.

3. I replaced the output resistors. The 470R resistor (R21) connected to the output socket via a 10uF capacitor gets changed to 100R. The 100k resistor (R22) from the output to ground is changed to 10k. This is the TS-9 to TS-808 conversion.

When the guitar amp's input vacuum tube grid is driven positive by the peak of the pedal output it can leak current to ground through the R22 (now a tenth of its original value). This gives you soft clipping on the signal's positive peaks. If the tube screamer output does not go directly to the plate of a vacuum tube, this can't happen. Many tube amps have a 68k resistor in series with the grid which will reduce this current flow. So you can only hear the difference with certain tube amps. I think.

Some people moan, groan and complain that reducing the 100k resistor reduces volume on their amp. So don't throw the old parts away.

--- I could have stopped at this point, the remaining changes didn't seem to affect the sound --

4. I shorted out R6, and C11. I removed R17. (none of these exist in the TS-808).

5. The input section before the first transistor is biased to +4.5V through a single 510K resistor on the TS-9 and 808.

Easy way: Replace R2 with a 22k resistor. More Accurate way: Remove R2 and R3. One end of the 510K resistor will now not be connected to anything. Now you must connect it to 4.5V. The PCB 4.5v tracks are labeled "4.5v" (I know I need to explain this better).

Steps "1" and "2" made an audible difference. Step "3" is subtle, but many regard it as essential. Steps "4" and "5" don't seem to make an audible difference. "4" is easy to do, though. Steps "3" and "4" may reverse some circuit protection Ibanez added. Perhaps this might reduce the life expectancy of your pedal, perhaps not.

A TS-10 converted to "TS-808 standards" has a switch-on squawk problem which the TS-808 lacks. I have no idea why, the switching FET's aren't the same for one thing.

No, I don't think the TS-808 is the greatest thing since sliced bread. What was the greatest overdrive pedal before sliced bread?