Build Your Own Clone Message Board

So what we have below is her OD that my guitar tech neighbor gave me to fix a few things on. To say I'm nervous to not screw it up in some way would be an understatement. It's got a jacked up battery cable that was "hot wired" 10 min before a show as it putzed out. The 9v jack took a Mike Tyson in his prime blow and punched it in which I assume someone stepped on it sideways to accomplish. The more invasive thing is pulling the Vol pot B100k and replacing it. It works but where the solid shaft meets then knurled part you can actually open it up a bit. I would guess that when it was on its side and took the blow the Vol know got bent as well creating this plan in the shaft.

I don't have solder pin pots and was going to order this one pot but is clear that what is out there is too long and the pots in this one are much shorter from end to end of the pin. So I guess I'll take my solder lug and use some solid core wire and solder it end to end effectively creating the pin effect.

Anyone familiar with Moollon from South Korea? I did some research. Interesting stuff on them. It is clear they really don't want anyone poking around at their PCB.

Why would they used a W20k for the tone pot? What's the advantage over more common values?

_________________

Dude, so cool that you're doing this!

Pretty sure the original Tube Screamer used a W20 for the tone pot, so I'm guessing this is a variant of that? As for why, I have no idea.

_________________
Scott

My band, Austin Hollow

Ah, ok, that makes sense but like you why. I would swear I think I've used a W taper pot maybe 2 times possibly just 1 in over 120+ pedals built.

I'm starting to second guess me messing with the volume pot. It moves and the others don't but the question is whether it is worth it to pull it. I'm going to check with him to see if she ever has had an issued with that pot at all.

I looked at that 9v more and whatever fell on it, no way a foot did this, actually cut off an either inch of the hard plastic. That was a heck of a blow with something. I'm guessing that vol knob took a glancing blow or it would have snapped off.

_________________

Thank you for sharing, that is amazing.


From the dusty corners of the Ottawa Valley

Yes, the TS did indeed use a W20K tone pot, and here's why: Because of the rather unique tone control circuit of the TS, if you use a linear pot, the middle portion of the pot sweep will be a large "dead band", i.e. very little effect on the tone occurs there--the useful part of the pot's travel is at both ends of the sweep. So the W taper pot uses a composite taper that changes resistance slowly at each side of the sweep where it has a larger effect on the tone, and quickly in the middle of the sweep, where it's much less sensitive. Take a look at this image that shows how the pot resistance changes across its sweep for four different tapers, including two W types. Note that for the standard W taper shown, the ratio of output voltage to input voltage for the pot increases by only 10% for the first and last 30% of the pot sweep, but by 80% in the middle 40%. This makes the pot substantially more useful since it's sensitive in the areas where the resistance change has more effect, and less sensitive in that "dead band" where very little tonal impact is happening.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Given the owner of this pedal (i.e. the "provenance" as they say), I would only replace that volume pot if you are sure that its function is compromised or that it is in danger of imminent failure. I'm not clear on exactly what's wrong with it from your description. Could you explain that in more detail, or perhaps post a couple more close-up photos that show the cause of your concern?


Sure. They've been around for 20+ years, are very well regarded, and are priced accordingly. Beautiful etched finishes, too, not that it makes them sound any better.

Taking a quick peek on Reverb, it looks like a used example in good condition would go for about $200 or so. But since this is Susan's OD pedal, better add another zero to that....

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Most interesting. So, what and why was this tone control designed that way making it so unique? Should more TS variants use a W pot? ( do they and I've just forgotten?) It's been awhile since I built one of these types of OD's.

_________________

So her guitar tech says she has never had any issues with the Vol pot and I told him let's not touch it. Discretion is the better part of valor on this one.

What piqued my interest was that on the pot shaft where the solid part meets the knurled part there is some play in there. You can rock it a bit or a bit too much. The other 2 pots don't have this. My new pots I checked don't have this. I think like I said below it took a pretty good secondary hit. But if there are not any issues at all then never mind. It won't be this guy that screws up her pedal

He said she has used this pedal for 18 years.

A fun fact side note is that me and my better half go to Destin the end of April beginning of May each year. As luck would have it TTD is playing at a festival there so I snagged some tickets. My wife wanted to see JJ Grey and Mofro the day after instead as we saw TTD at Red Rocks a few years ago but no way can I pass up TTD at the beach. Of course I suggested we see both but she didn't want to spend the dough. At $220/person each day you do the math

But hey, wish me luck as I'm still working on her. I saw JJ solo in Nashville a few years back but that band cooks and I want to see him too.

_________________

I can't definitively tell you why the TS tone control was designed that way, but where most pedals with a single tone control use a passive treble roll-off design, the TS was given an active control that rolls off treble on one side and boosts it on the other. You can read the details of how it works in R.G. Keen's excellent article, "The Technology of the Tube Screamer"; scroll down to the heading "Tone and volume control stages."

I think the reason that so many TS-type effects no longer use the W-taper pot is that they've gotten somewhat hard to find. A lot of us who built BYOC's TS clones over the years would substitute a lower value linear (B) taper pot, typically 2K or 5K, to minimize the size of the dead band. The control functions as a voltage divider, not a variable resistor, so the pot's resistance value is much less important.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Not related to this pedal, but I saw JJ Grey and Mofro open for TTB at the Chicago Theater back in 2018. Great show! Hope you can see both.

_________________
Scott

My band, Austin Hollow

Is the gap you're describing where I've marked on the image below?

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

That's exactly where it is Bob. You can rock it a tad more than what you would want.

_________________

OK, good. I'd say if the shaft still turns smoothly and the pot isn't noisy or causing signal cut-outs, I'd leave it alone.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

I agree. The rotation is very smooth actually. I figure one good kick and I might see that pedal again in the future though!

_________________