DIY "Keeley"-TS9 mod questions

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A while back I bought a new Ibanez TS9 reissue pedal, but I ended up not liking it that much - it was OK with my humbucker Les Paul guitar (which had a lot of low and high end), but it didn't do much with my Telecaster or Les Paul Jr (which are already mid-heavy). The pedal also didn't go so well with my tube amps, and after selling the Les Paul with humbuckers, I had no place for the TS9 pedal.

That is, until a week or so ago, when, lucky for me, a potential buyer tried the pedal out, didn't like it, and said if he'd ever buy one he'd have it modified Keeley-style. And then it hit me: I know how to solder, I know what a capacitor is, what a resistor is, and so on! So I got all the information I could from the Internet (I live in Romania so sending the pedal over to Keeley is really not an option, it would more than double the price of the pedal in shipping and customs taxes alone), and what I did was:

1. changed the 0.047uF cap to 0.1uF for more low-end.
2. swapped the JRC4558D IC I had in the pedal for a TI RC4558P.
3. replaced a couple of 1uF electrolytic capacitors to WIMA metal film.
4. replaced the 0.22uF tantalum capacitors to WIMA metal film (I'll change the one in the tone section to 0.18uF later).
5. changed the 4k7 resistor to 2k4 and the 51k to 20k (Keeley's "more/less" distortion).
6. the TS9 to TS808 mod: changed the 470 resistor to 100 and the 100k to 10k in the output section.

The pedal is very different, it's great-sounding and needless to say it's off the market now.

Now, my questions are:

1. especially when I turn the DRIVE knob almost all the way up I get pretty audible noise. It's not so bad that it doesn't get drowned in the actual playing once that starts (kind of like the 60-cycle hum of single coils - or 50-cycle hum, like we have in Europe). I've seen suggestions on the net that I should swap the input transistor (2sc1815) to a MPSA18. However, from the data sheets I found on the Internet, the 2sc1815 is "E C B", and the MPSA18 is "E B C". Should I just try to bend the legs on the MPSA18 until I can reposition "B" and "C" in each other's place?

2. which one is the input transistor exactly? I can solder and pick up a capacitor, but I'm not really competent enough to know just by looking at the board, if there's more than one component with the same specs on it. I'm assuming that the input transistor is the one in the upper-left corner of the board, near the IC:



Is that correct?

3. I managed to find a picture of a Keeley-modified TS808 on the Internet, and it looks like he also changed the 0.02 input capacitor to something else (I can tell because there's a red non-polarized film-type capacitor there instead of the original see-through plastic greenish-ones that you can still see a couple of in the picture). I'm talking about the cap in the lower-left side of the picture, under the IC chip. Now, I didn't change that cap, and Keeley doesn't mention anything about changing that cap in the promotional talk about the TS808 Mod Plus on his website. So what value is that cap, and why was it changed?



4. Also in that picture, you can see that he changed 5 resistors to the metal-film type. I've only changed 4 of them: 2 for the more/less mod, and 2 for the TS9 to TS808 mod. The blue one in the low-center area of the picture, I have no clue why he changed that, and to what value. On my board, that seems to be an 8k2 resistor (if I've computed the value right by the color code). What's that resistor for, and why would it be interesting to swap it for some other value?

Thanks for reading, and thanks in advance for your replies!

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I might be wrong, but from this post in another forum it looks like the extra resistor is connected to the LED. So it's probably a "brighter LED" mod.

I'm still extremely curious about the other questions.

[Suhnton]

According to a schematic I have (which is for a TS-808 clone, but it should be very similar), the input transistor has a 10K resistor and 1uF cap off the emitter. Going into the base is a 510K and 1K resistor. The collector goes to the +V rail. Have a look for those parts and you should be right.

I used 2N3904 transistors in mine, I don't get any noise issues with it.

[red]

Thanks! I think I found the input transistor - it should be the one in the upper-left side of the pictures in my post.

Does anyone know why the old 0.02 cap has been changed? Does it have a different capacitance value, or was it just changed to metal film for better quality? Aren't the see-through yellow plastic ones also metal film?

Thanks for the transistor suggestion, I'll see if it's available around and try that one too.

[Suhnton]

I think the yellow ones are mylar caps. As for the 0.02uF cap, if you're talking about the one at the base of the input transistor, then it's about right. The value I have is 0.027uF (close enough).

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I think the yellow ones are mylar caps. As for the 0.02uF cap, if you're talking about the one at the base of the input transistor, then it's about right. The value I have is 0.027uF (close enough).

The 0.02 cap I'm talking about is the yellow one right above the numbers 12 and 13 (12 is where the red wire connects) in the picture labeled "TS-9 Modifications". Yes, in the schematic it looks like it's connected directly to the input transistor.

Anyway, yes, I know the value is 0.02uF, both from the schematic and from reading what it says on the capacitor in my TS9 reissue pedal, my question was: do you know if the Keeley mod uses the same value for that capacitor (if you look at the second picture I've posted in my initial post, you can see that the yellow cap has been replaced with a red metal film cap), or if the mod uses a different value for the replaced capacitor?

[duhvoodooman***]

I doubt the transistor change would have an audible effect. You'd be better off changing all the higher rated resistors (anything 100K or higher) to metal flim. Carbon films at high ratings tend to be a little hissy.

Keep in mind that you've doubled the pedal's gain with that change of the 4.7K resistor to 2.4K, and that doubles the noise, too, when the gain is dialed up. So you're fighting physics, to some extent.

I wouldn't worry about that 0.02 cap. It's at the start of the input buffer and I've never seen any mention of it being tonally important.

Can't comment on that 8.2K resistor; that's not a rating I've encountered in a TS.

BTW, your bass didn't increase with that switch to a 0.1uf cap--it just compensated for the 2.4K resistor. The two form a frequency filter, and when you cut the one in half, you have to double the other to keep the bass response the same. If you really want more low end, increase it to 0.22uf.

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I doubt the transistor change would have an audible effect. You'd be better off changing all the higher rated resistors (anything 100K or higher) to metal flim. Carbon films at high ratings tend to be a little hissy.

I don't expect to completely cure the noise, just cut it down as much as possible. I found this article that stated:

"Note that in going to higher gains, you will inevitably increase the noise in the output. This may be curable to a degree by changing the input transistor to a quieter part (MPSA18 or 2N5089 is good) as well as swapping to a more modern and quieter opamp like the LM833 or both."

The Keeley Baked Mod page also specifies:

"I also change the input transistor to a MPSA18 for lower noise operation."

Now, I like the RC4558P very much, so I won't be changing that, but I though I'd give the transistor swap a try. It might not cure all of the background noise when going to higher gain, but it if cures some of it I'll be happy.

I wouldn't worry about that 0.02 cap. It's at the start of the input buffer and I've never seen any mention of it being tonally important.

Well, this is where I've seen a mention that it might be tonally important. I've also tried it out - I put a 0.1uF cap there and I got more bass than I had bargained for. But I really like the 0.02uF cap, and I don't think mr. Keeley changes that value, so I'll just swap it for a 0.022uF metal film for better quality and leave it at that.

BTW, your bass didn't increase with that switch to a 0.1uf cap--it just compensated for the 2.4K resistor. The two form a frequency filter, and when you cut the one in half, you have to double the other to keep the bass response the same. If you really want more low end, increase it to 0.22uf.

Indeed you are right, sir. I did try a 0.22uF, I thought the pedal got too muddy though and went back to the 0.1uF.

Thank you for your reply!

[sumitomo]

This will be cool I just got one of these ts9's today with a blues jr I bought and next week I should be getting the Rodent Vood is making so I should have a fresh opnion of these pedals because I mainly just plug in an amph.Sumi