TBX pot not working in Claptonised strat

[robby]

I recently picked up a nice Mex Strat with the intention of customising it, and proceded to fit a set of Tonerider True Vintage pickups,Graphtech nut,stainless saddles,etc and sent for a Fender Clapton Mid Boost Kit from the US.This is an active system with pots,jack,switch and circuit board. My problem is that the TBX control has almost no effect on the tone/sound, even when moved from extreme left to right the difference is hardly noticible. Is this likely to be a problem with the TBX, the board, or a wiring issue, although I'm fairly confident about my wiring installation, any help here would be appreciated. Thanks Rob

[ChrisK]

Well, a pic would be a start (I can't actually see that far).

The TBX is actually two things.

The first (from "5" to "0") is a regular, normal, boring, passive high frequency cut tone control. It is out of circuit above "5".

The second (from "5" to "10") is a low-tech, boring, passive, increasing resistance/decreasing loading pot that gradually goes to 1 M ohms.

Compared to a 25 dB [10^^25/20 = 17.78 times]active mid-boost circuit, the TBX effect isn't even suBtle, it's just plain subtle.


Of course, there may be a connection or component issue (hence the pic).

[sumgai]

robby,

Hi, and welcome to the NutzHouse! ;D

You've just been indoctrinated by the Doctor in the House, our resident obfuscator himself, ChrisK.

You said that you bought a mid-boost circuit, and by including the part about "pots, jack, switch, and circuit board", one assumes that this is an active device, which is fine (as well as necessary in order for any real "boost" to come about). But then you go on to talk about the TBX control, and that's where Chris and I get lost. You see, TBX control circuits are passive, and are not designed to boost the mids at all. In short, the two circuits are very different, and will yield very different results.

So which is it, did you mistakenly call the mid-boost control a TBX control? Or are you referring to another control within the guitar, separate from the mid-boost circuit? Inquiring minds would like to know.



sumgai

[robby]

Hi
Okay, after posting and waiting for replies, I decided to open up the offending article again and just check my installation against the supplied wiring diagram:



Now, I didn't mention previously but I'm a lefty so I had to make certain changes to my installation to compensate for everything being reversed, this also included turning the pickups round 180degrees in their slots. I did manage to fit the circuit board in the main cavity as you can see in this pic.



As I said I did make some changes, one of these was to solder the resistor on the opposite side of the TBX as there wasn't a lot of room between the pot and the guitar body on the side shown on the WD, this was due to my LH installation. You can see this on the next pic.



Now if you go back to the wiring diagram, it's not terribly clear but you'll see that the resistor is soldered from the case of one TBX pot to the middle tab of the other TBX pot, but it's also soldered to the outside tab of the first one as well, but when I moved it to the opposite side I forgot to attach it to that outside tab! See the previous pic. So I rewired the resistor correctly and what do you know.... my problem has been solved, I haven't had a chance to try it in earnest yet but the difference is very apparent.

Possibly also of interest is the battery placement, I found that the 9v battery is a very snug fit between the block and the body.



This could be a possible placement solution for some of you guys that don't use the trem, it's also simplicity itself to change the battery. This however is a temporary arrangement for me as I'm in the process of making a full size steel block, when I fit that I'll probably have to relocate under the pickguard. Anyway here is a pic of the Claptonised strat now.



I embarked on this as there is very little choice available for us Leftys, either buying new guitars, or buying parts, so in the end it's turned out to be a very worthwhile project which I'm really pleased with, and for a total outlay of around £310 I've got a superb strat which looks and plays a dream, now hopefully it's got the sound to match...!









(Edited by sumgai to turn the textual links into real ones.)

[ChrisK]

Actually, the Clapton Strat has the mid-boost pot and a TBX pot.

Also, the TBX pot is right-handed only. It can't be wired up for left handed orientation (CCW is full hi freq cut).

[sumgai]

robby,

I was just going to say the same thing as Chris, but I was busy modifying your post to show the images.......

I was unaware that your particular circuit has both a TBX and a Mid-boost control. Perhaps if you'd share the source of this project......

And you say this all works, even in "reversed" mode, after finding and fixing the missing connection? Hmmm, that's a bit strange..... Like Chris said, the TBX pot is meant to be used in one orientation only, the resistance elements within it are built just a certain way, and that's all there is to it. Interesting.......

Some pickup makers do put out left-handed versions of their product, others might not mention it on their website, but will do so, if you ask. Could be the usual lefty penaltypremium, though, so it'd pay to ask ahead of time. I mention that because I see that you were forced to make room for the reversed 'righty' pickups. You'll appreciate it when I tell you that I always just automatically haul out the template and the router, and convert that area to a universal pickup cavity - makes installing both the shielding and any pickups so much easier! ;D

HTH

Edited to add:

I forgot to mention...... nice shielding job!




sumgai

[robby]

The continuing saga..!

Thank you for your replies and especially to you Sumgai for the work you did on my post..!

I gather from your comments that you think this ought not to have worked..!
but I may have caused a grey area when I said I'd made some changes to the installation to compensate for it being reversed. I suspected that the TBX might have been irreversable' so rightly or wrongly I decided to do the installation as a RH, the changes' mainly amounted to re-routing the wiring and simply changing the soldering points on the pots, the resistor was moved to the opposite side of the pot, but connected as RH, I made no actual changes to any of the wiring, it's essentially exactly the the same as the RH version.
The volume control works fine, the mid boost appears to work as it should, as does the TBX, with a sort of normal tone control on one side of the detent and further tones available on the other side.
You asked about the 'source' of this project, I simply wanted to make a guitar which appealed to me visually and had a tad more 'range' than my std strat , but without breaking the bank..! The S/H MIM Strat and this circuit appeared to fit the bill, and it can 'drive' my Laney valve amp from the guitar itself.

During my research on this I did find this article. which was of some help.
www.areyouexperienced.net/fender_clapton_mid_boost_kit.htm

I considered routing the body to create a large cavity which would have made fitting the whole kit much easier, but decided to remove as little timber as possible, just enough to allow the pickups to fit.. so retaining the maximum amount of wood mass.

As I mentioned previously, I'm making a full size steel block for this, so I'll keep you posted on it's progress/fitting and effect.