Keeley's TS808 Mod .. Anyone try it ???

[Melanhead]

Just noticed it's pretty much posted on his site .... On his TS808 page. From the picture and his notes it's pretty obvious as to what he's doing.

http://www.robertkeeley.com/product.php?id=31


I bought a TS808 reissue before I got into modding my other pedals ( yup, silly me!!! ) ... Anyways, just curious if anyone's has tried the mods.

Not that it really needs modding but hey, Why not! ... It's fun

......

[80k]

go for it  I love my Keeley modded Rat, and i have heard great things about his TS808 mod.

YOu can always change it back.  My homemade tubescreamer is pretty mangled, pads have fallen off, and half of it is point to point now, but it still works great, and i can't even remember the current "configuration" at the moment.  it's a great pedal to mess around with.

[cd]

More bass response my eye.  Let's look at the RC combination from the - input to ground.  If you double the cap value and halve the resistor value, the frequency response (bass rolloff point) STAYS EXACTLY THE SAME.  Try it with the right formula (1/6.28*R*C, with R in megohms and C in uf), you'll see.  All the other HPFs in the TS circuit have rolloff points well below the range of guitar so you won't see any other benefit there either (i.e. input cap).

Halving the resistor value does increase the gain slightly at one end of the DRIVE control (to say SD-1 levels) BUT lowering the 51k to 24k does NOT lower the gain levels (i.e. you won't get less gain with the DRIVE all the way down).  Remember the 4.7k resistor you halved before?  It sets the minimum amount of gain - before the mod, it's 1+51k/4.7k, or approximately 11.  After the mod, it's 1+24k/2.4k, or approximately 11.  The ratio stays the same so no "less" gain.  You will get more drive though, however I personally don't like to do this since it stops sounding like a Tubescreamer with the DRIVE all the way up, though you may like that sound.

[Melanhead]

hmmmm ... Interesting points! ... thanks guys.

I may just replace the electros with metal film just for fun  ...

I like the sound of the pedal but some little voice inside me keeps saying "it can be better"  

nothing is reversable ...

I ordered a batch of violet LED's, I'm sure that'll make it sound way better too!

too much fun...

[LP Hovercraft]

Having just built a TS-808 clone from scratch with the said Keeley mods, I'll vouch for the fact that both the bass and treble response is wider.  It offers buckets more drive (Cleans up better, too) and sounds way better to my ears than stock.  There is a little bit of a tradeoff, however, in the fact that it is more noisy this way.  I'm thinking of changing from the JRC4558D chip to a Burr-Brown Chip and see if that improves matters as it is reputed to do just that.  If you can get a hold of some green LEDs-the kind in the clear case that truly emit green color at the NP junction.  They are LOUD and CRUNCHY to the ear.  Try them in place of the 1N914's.  You can get quite a bit more gain that way.   If you're careful with your hands, all those mods are reversible.

[Melanhead]

Cool thanks! ... I forgot about using LED's as a clipping diode, I meant using the Violet LED's as on/off indicators ....

Meant it as a joke but it can be taken both ways