Help with caps for TS 808 "Keeley" mod

[gravityman]

Hey guys, I have a Keeley modded TS9 that I purchased on my recent trip to the US (I live in the philippines), and I'd like to do the same for my 808 reissue. As much as i'd like to support robert's work and purchase a pre-modded one, its still quite expensive especially to have one shipped. I'm an engineering student and I have experience in soldering for pedal mods, guitar electronics wiring, and i've built a few DIY pedal kits as well.

Anyways, I'm aware of these changes  in the keeley 808 mod:

"The bass response is improved to the point of perfection. It is nice and tight and not muddy at all. We
upgrade that cap (C4) from a 0.047 to a 0.1uF and at the same time we increase the gain possible
when the drive control is turned up. That resistor (R7) is dropped from a 4.7k to a 2.4k. We also make
the pedal so it cleans up more. We take the 51k (R6) and lower it to 20k. This is our More/Less mod.
You get both more drive and less drive as well as all the sweet stock spots in the middle of the control.
We also upgrade the 1uF electrolytic caps (C2, C7) to high tolerance, great sounding, more consistent
1uF metal film caps. This type of thing is done in all HI-FI stereo and audio gear.
We upgrade the tone control circuit and take the .22uF Tantalum to a 0.18uF (C6) for better control and
response from the tone control. This allows you to get a more full sound on the lower end of the tone
control"

These are my questions:

1. It is stated that the 1uF caps are replaced with the metal film type, should the replaced C4 (0.047uF to 0.1uF) and the C6 (0.22uF Tantalum to 0.18uF) also be metal film as well? In other words, should all cap replacements be to metal film?


2. Assuming I'm able to find these cap values locally, should the voltage ratings be equivalent to the stock caps? (original 0.047uF is rated at 100v). Or is any voltage that is atleast double of the operating voltage or within the safe range  good?


Hoping that  someone here has done the mod themselves or owns a keeley 808 can shed some light. 

[thermionix]

1.  That will be fine.  "Metal film" is kind of a generic term for "metallized poly____ film" (polyester, polypropylene, whatever).  These days, it's basically any cap that isn't ceramic or electrolytic (aluminum or tantalum).  Sometimes just called "film caps".

2.  The voltage rating just needs to be at least what the cap will be subjected to.  Plus a little safety margin.  Most film caps you'll see are rated for at least 50v, way more than enough for a TS808, even if it's run at 18v instead of 9v.  Caps get larger as the voltage rating goes up, so just make sure you can physically fit whatever you get.

[gravityman]

It seems, that I can't find the 0.18uF tants for the C6 swap. I was able to get film caps, and I was wondering whether this would have an effect tonally? I'm aware that the tants are polarized, but I also read that they might have been used because they were easier to fit due to their size.

[duck_arse]

there are some people claim tants give a grainy or granular sound. no, wait, that's ceramics. funny thing is, these same people never explain "grainy".

put poly, learn to stop worrying.

[karis12]

I have exactly one 180 nanofarad (0.18uF) polypropylene capacitor in my parts bin. If you're anywhere near San Pedro, Laguna (where I live) and are still interested in this by December this year, I can give it to you free of charge.

[gravityman]

I have exactly one 180 nanofarad (0.18uF) polypropylene capacitor in my parts bin. If you're anywhere near San Pedro, Laguna (where I live) and are still interested in this by December this year, I can give it to you free of charge.

Thanks for the offer sir!!  A quick trip to Raon (if you know what i mean) solved the problem 

[gravityman]

By the way, this may be semi off topic but, does anyone know if he alters the current limitting resistor when swapping out the LEDs or does he simply put in a super bright?

[bloxstompboxes]

By the way, this may be semi off topic but, does anyone know if he alters the current limitting resistor when swapping out the LEDs or does he simply put in a super bright?

Since it makes no difference to the sound whatsoever, I wouldn't worry if he does or not but just do it if it makes you happy. If it is too bright then change it, or vice-versa.

[gravityman]

Hi, thanks for the input, but yeah I am going to switch it out for something brighter. I was just wondering if I gotta swap out R131 which is rated at 36k ohm for another value if I install the superbright LED. Current limiting resistors seem to play a role in protecting the LED from currents and they help with the battery consumption. 

[antonis]

I don't know anything about R131 (or any other component w/o schematic) but I'm sure it isn't a current limiting resistor for a conventional LED on 9VDC...
(36k allow less than 200μA working current..) 

[thermionix]

I believe it's actually 3.6K.  Original schematic is blurry.