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Nano Bassballs Trimpots Mod

Discussion in 'Effects [BG]' started by MagicMan_841, Oct 15, 2009.

  1. Ok, so I just got a new Bassballs Nano pedal and would like to do the external trimpot mod. I have ordered a pair of 10K linear 9mm pot (smallest I could find) from Small Bear Electronics and I am hopeful they will fit. It's been done before, I've seen it on TB.

    So, yeah, I did do a search, and came up with a few threads that have been of some help :

    Bassballs External Frequency pots mod?

    Bassballs external trimpot mod? Anyone know how?

    Also Bassballs related are these two websites:

    Topopiccione Electronics - Electro-Harmonix BassBalls (schematics and other stuff)

    L'atelier de Basstrya (French how-to mod the old version)

    But I'm still a little confused of how to execute this mod. I just want to make sure I get everything right. And in the process I could write a nice little write-up on how to mod your Nano Bassballs. But I need your help! Here are some pics I took of my Balls (!).

    This is the back, i.e. you see this when you pop out the rear cover:


    This is the top. You can clearly see two trimpots at the top right.


    Here is a close-up of the back, right where the trimpots are.


    So all the threads I have seen say to remove the 5k trimpots and the 4,7k resistors in series with them (which, if I understand correctly, are R28 and R29 on the PC board, right?) and replace them with 10k linear pots.

    Question 1 : do I have to fill the gap left by the removed resistors? If you look at this picture from the French site, you will notice that he's left the gap. If I understand correctly, the R28 & R29 resistors are linked on one side to the filter circuit, on the other side to the ground. So leaving the gap makes sense. And connecting the common ground from the new external pots to the "left" pin of R28 (the one above the R of R28) will work?

    Question 2 : Am I getting this right : Middle lugs of new pots (pinkish wire on French site) each go to the "lone" pin of the old trimpots on PCB (leading to R24 for 200Hz and R25 for 800Hz). Left lugs of the new pots (blue wire on French site) each go to PCB pins that are linked together on the Nano (the one above the 2 of 200Hz and the one below the z of 800Hz).

    Help much appreciated!
  2. Funkinthetrunk

    Funkinthetrunk Registered User Supporting Member

    Just use 5K pots and leave R28 & 29 intact...that's all I do. Question #2...yes, that's it.
  3. Hi - Thanks for the comments.

    Well apparently the theory behind removing R28 & R29 is that they limit the action of the 5K pots. Most literature I have read on the subject said that the 10K pots give a greater degree of control on the filters, which makes sense. But it seems that both options will work.

    I just received my shipping confirmation for the pots. So this is to be continued some time next week!
  4. So I got my pots from Small Bear in the mail today! I immediately set to work...

    I started by drilling two 9/32" holes in my casing about 15 mm above and below the distortion switch (center of switch to center of pots). It's actually a little less than 15 mm below the switch... more like 13 mm. It's not exact science, so make your own test-fits and measurments before drilling!

    Then on the the PCB -- I removed the trimpots as well as R28 and R29. I used an unsoldering braid which was real handy. I did burn the PCB a little, nothing too bad.


    Then I took both my 9mm Alpha pots and soldered overly long pieces of solid 20-gauge wire with the plastic insulation removed. It is necessary to use solid wire so the pot won't move around as much as with stranded wire, yet you will have some "wiggle room". I also filled flat the little notch on the base of the shaft. You need every mm you can spare in this mod!


    I then fitted the new pots to the board and soldered them. Of course, you have to cut the overly long leads afterwards!


    I also soldered a set of jumpers where R28 and R29 used to be. Small pieces of solid 20-gauge wire did the trick.


    Re-assembly, test run, knobs -- here's how it looks now.



    I've seen this mod done otherwise. One person here on TB had the pots on either side of the LED. This works too, but I wanted my new knobs to be as far as the stomp switch as possible! It does make the top of the pedal a bit crowded, however. Might not be that good an idea if you have really big fingers... lol!

    So yeah, there you have it. External pots on a Nano. It's a simple mod that makes this pedal a lot more versatile. Some settings are pretty useless, and at some positions there is a slight volume drop. But it does make tweaking this puppy a lot easier!

  5. Bassmike62

    Bassmike62 Punch'n Ooomph Provider Supporting Member

    Salut Mathieu,

    I was thinking of bringing it to a shop and have it done, but after reading your post, I've decided to give it a shot.

    Merci !
  6. Ça fait plaisir! :bassist:

    It's indeed a lot easier to do than it looks at first.
  7. kevteop


    Feb 12, 2008
    York, UK
    Can I ask what the benefit is of this mod? I would've thought the trim pots would be set to the best setting for bass at the factory, no?

    I'm not being negative I'm just curious to hear what sort of benefits people are seeing from doing this. Clips would be nice too of course. ;)
  8. Well, I don't know about the factory setting, but the mod does make experimenting the Bassballs a lot easier. Some people might prefer to find a setting they like with the trimpots and leave it like that all the time. There is however quite a few different sounds you can get by messing around with them. I don't think there is one "best" setting, factory or not. Besides, why would EHX have put trimpots there rather than just regular resistors if not for you to mess around with them? Like on any other pedal, everybody have settings they like to accomplish what they want.

    I'll look into making a clip tonight.
  9. Well done, thanks a million for your details and pics. I will be performing this mod soon.
  10. This is exactly what I have been wanting to do to my Nano Soul Preacher, which is a great pedal, but has one of these smaller pots for gain trim. Thanks for the pictures and walkthrough, I am going to take the SP apart tonight and see if this same process is viable. How badass of a screw driver did you need to punch the pot holes in the top of the case?
  11. actually, most internal trimpots are there for factory calibration. many manufacturers warranties are voided if you mess with the trimpots! the trend of "user-tweakable" trimpots is a fairly recent development and to be honest, such controls should be external IMO
  12. Modded my Bassballs today per the French instructions. I'm having trouble posting pics from photobucket. I'll try later. External trimpots and a Boss style jack. Kind of tweeked the hole for the Boss jack so I trimmed it out with a washer.

    Attached Files:

  13. IMG_0313.
  14. kugelspot


    Jun 8, 2009
    lol :p

    Normally, trim pots are for doing minor tweaking to thinks like gain or how certain knobs function, or even minor changes to the tone. And you're right, most companies that use trim pots have standard factory settings that should give you a good starting point, assuming you change them at all (though some companies don't, leading to the confusion of many customers who aren't aware of the trim pots *cough* MXR *cough*). However, EHX decided to put the control for the 2 filters in the pedal as trim pots. Really stupid decision, IMO
  15. Bassmike62

    Bassmike62 Punch'n Ooomph Provider Supporting Member

    Can't wait to get my BB modded. Wanted to do it myself, but I have no patience, talent or time to do it. Found a shop in Montreal that would and for a decent price. So I'm getting a new pedal for less than 50 $.
  16. Funkinthetrunk

    Funkinthetrunk Registered User Supporting Member

    I think the "badass of a screw driver" is called a drill bit.
  17. soothsayer86


    May 5, 2010
    anyone have experience doing this mod to a russian made bassballs? is it similar or the same as the mod to the american made version? thanks in advance!
  18. soothsayer86


    May 5, 2010
    bumpity bump

    anyone have the answer?
  19. It's pretty much the same. On my Russian I think EHX butchered the pcb layout so they had to solder a resistor directly to one of the pot leads. It also has a funky double sheet metal pot/ switch mounting system that you will have to work around a little bit. I rehoused mine so that I didn't have to worry about that.

    It has knobs now, but:

  20. soothsayer86


    May 5, 2010
    any way you could post some pics of the guts of your rehoused bassballs? I think I'd like to do that.... less space consumed= more pedals on my board!

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