TS808/El Griton 808 TONE Control Issue?

[desertofice]

Hi -
This is my first post in this forum with regards to the second pedal I've built.

On Monday, I finished building a TS808 clone called "El Griton", design courtesy of tonepad.com
I never actually played a TS808, so maybe I'm missing something here.
The tone control seems to do very little to the effect. Should it be fairly dramatic or is it a more narrow/natural tone control?

I've already checked the 20k Tone Pot to make sure it isn't shoddy. Ohms out fine. (purchased the specified 'W' pot at Small Bear)
Checked the board, no signs of damage.
Checked the pot wiring, connectivity is good.

One thing that has had me a bit concerned from the get go is the 0.22uF tant cap. I purchased them at Small Bear (here's the link to the cap that I ordered http://www.smallbearelec.com/Detail.bok?no=560).
Unfortunately, there is no pic and my cam will not focus on the cap - so I'm hoping someone is familiar with this type of cap.
It is listed as a dipped tantalum cap...rated at 16V, looks like a purple teardrop, radial leads, looking closely there appears to be a + designation on one of the leads.
However, the tonepad schematic shows it as -||- and I'm assuming it's supposed to be non-polarized. Would the orientation of these caps cause an issue with the tone control?
Thanks in advance for your help!

[Projectile]

Yes, that would make a difference. You are using a polar tantalum cap, so it must be oriented in the right direction. The + side should be pointing towards the signal source, the negative side toward ground. Also, tantalums HATE to be reversed biased, so there is the possibility that your cap is now bad if you had it oriented in the wrong direction. If it was backwards, then flip it around to the other direction and see if the tone control works. If it still doesn't work, then swap it with a film cap of the same value.

It doesn't matter whether you use a polar tantalum or a nonpolar film cap there. Both will work. Some people use tantalum for the "mojo" factor because that's what the original pedal used. Some people prefer film because it is a more "hifi" choice. Some people can't hear the difference.  I never use tantalums for audio because they are expensive, fragile, and have poor tolerance. They provide very few benefits for stompbox circuits other than their small size, so I just generally avoid them.

The tone control on the TS is pretty drastic, especially towards both ends of the knob's rotation. It doesn't do a whole lot in the center though, which is why it's popular to use a W taper pot.

[desertofice]

Thanks for the advice. I'll check the orientation on the polar tant caps! I'm also gonna pick up some film caps to check out the difference between the two.

[desertofice]

After thinking it over, I said screw it in regards to the polar tantalum caps. I removed them and put in .22uF poly film caps.
Problem solved. Tone control is working perfectly...definitely diggin the tones from 3 o'clock and higher!
Thanks again Projectile!

[John Lyons]

Put in a 5K-B (linear) tone pot. Sounds good about 12 o'clock.
The original tone pot pretty much sucks. All the good stuff is
between noon and 3 o'clock on the original as you noticed.
With the 5K pot your 3pm will be 12 noon...

John

[Projectile]

Put in a 5K-B (linear) tone pot. Sounds good about 12 o'clock.
The original tone pot pretty much sucks. All the good stuff is
between noon and 3 o'clock on the original as you noticed.
With the 5K pot your 3pm will be 12 noon...

John

Funny, I haven't tried the 5K pot yet, but I ordered one a week ago specifically for that purpose. I was looking at the frequency response of the TS tone control and thought a lot smaller pot value would be more useful there. I agree that the normal tone control sucks and is only useful for about a third of it's range. Glad to see other people coming to the same conclusions. I just have to get this baby on the breadboard now so I can try it out. Thanks for the tip.

[Projectile]

Okay I had a chance to try a 5K pot, as well as a bunch of other values.

Conclusions: the 5k linear pot is a good replacement for the original 20K 'W taper' pot. If your parts supplier doesn't have 'W taper' pots available, then the 5K linear pot is a perfectly satisfactory replacement, much better than a 20K linear pot, which is usually the suggested replacement for 20k 'w taper' pot in this circuit. The 5k linear pot is a far better choice IMO.

As far as the 5k pot being superior to the 20K 'w taper' pot, that will have to be for your ears to decide. They sound remarkably close. I decided to leave the 20K "w taper' pot in my pedal because I slightly preferred it's smoother taper. The 5K has a bit of a different sweep, which I found to be a bit harder to dial in the sweet spot. I could see how they someone else would prefer it the other way around, but I didn't find the difference to be all that drastic. To each his own. Note that, contradictory to what John Lyons said, I found both pots to sound almost identical at noon position. I did a blind test where I randomly flipped back and forth between the two and could hardly tell which one was which. For comparison, I found the 3:00 position on the 20K W taper pot to correspond to about 2:30 on the 5k linear pot.  They both work appropriately in the circuit and they both sound good. Linear pots with a value higher than 5k performed miserably in the circuit IMO. Try it and see for yourself. I recommend putting them on a switch so you can flip back and forth between them.

[Toney]

Dont forget yo can always custom do your own taper by adding resistors to the lugs.

For a W pot, you would start with a linear and add equal values to both the 3-2 and 1-2...that's my reading anyhow.

I have had good success with this method for making reverse audio tapers. Start with around 10% of the pot value.

You can always use another pot temporarily, in place of the resistors, while you dial it in.

[Projectile]

Dont forget yo can always custom do your own taper by adding resistors to the lugs.

For a W pot, you would start with a linear and add equal values to both the 3-2 and 1-2...that's my reading anyhow.

I have had good success with this method for making reverse audio tapers. Start with around 10% of the pot value.

You can always use another pot temporarily, in place of the resistors, while you dial it in.

Wouldn't that create the opposite of a "w taper" pot? My math skills aren't that great, but it seems like the resulting curve would be even worse than a linear pot. It seems like it would create a pot that has an even bigger dead spot in the middle, but eh, I could be wrong.  I don't think it's as simple to create a "w taper" pot as tacking on some resistors like you can to make a standard log or reverse log pot. I'm willing to give it a try though.

[Mark Hammer]

I encourage anyone interested in tailoring their TS clone to their tastes to look at the article on the TS tone control over at www.muzique.com