FrankenWashie's TS-808

This is one of those good news, bad news moments.

First, the good news: the pedal sounds like a tube screamer. No weird noises, bypass works, all knobs do what they should (and in the right direction - not making that mistake twice!). With the gain rolled all the way down it works as a very nice cleanish boost. With the gain rolled all the way up it's not as saturated as my OD-2 which is mostly a tube screamer. I might try a couple of op amps and see if that changes things. It probably won't, but I did have a dodgy opamp last week so worth testing a couple.

The slightly disappointing news: the clipping diode selector switch works, but the effect is not nearly as audible as the same diode combos on my OD-2. I might solder up an asymmetric diode pair to test. I was hoping for a larger sonic difference in the two diode positions.

The bad news: the flat EQ mod sounds bad, at least with my amp. Makes the pedal sound kind of farty. I think it's letting way too much bass through. The mod is a switch that shorts out a 47nF capacitor in a high pass filter that dumps frequencies below 720Hz to ground (or to Vr actually), helping give the circuit its famous mid-hump. Jack's analysis gives a table showing the corner frequency for different cap values. He also suggests a mod that shorts the cap completely, allowing the full frequency range. That's what I have done, but it doesn't sound good in the shorted position.

But wait, there's more good news!

I used a DPDT on-on switch because that's all I had, which means I can mod the mod. Instead of the stock cap and a shorted cap, I can change it so the switch selects between the stock cap and a different cap value. Maybe the same socket idea I used on the diodes will allow swappable caps to tune the bass response of the modded position (with the stock value hard-wired in).

But I am tired now, and I have some Coopers Extra Stout to finish, so modding the mod can wait until tomorrow.

Almost forgot, the disemboweled but fully functional FS-808:
Attachment 35957

Finally time to finish the decal design as well as I need to get this applied and the clear coat on before I can finish assembly. Those cursed DC jacks don't screw in like all the sensible hardware. No, they are entitled and need to be soldered into the enclosure. Selfish custards.

Ahem..<clears throat> Mwa Ha ha ha ha HA HAHAHAHAHAHAHAHAHA!
IT’S ALIVE!!!!!

https://www.youtube.com/watch?v=1qNeGSJaQ9Q

Some new enclosure ideas...

Attachment 35995Attachment 35996Attachment 35997

My favourite is the full Frankie face, but unfortunately I have already drilled the enclosure so I can't move the LED, and Clown-nose Frankie is too sad.

Maybe use a different colour LED?

All good options - I don't even mind the clown nose, though Simon's idea is excellent.

I actually think the middle is my fav of the three

Good idea about the LED colour. I have already soldered a mini board with a RED led, but I can clip that off and use it on another pedal. I have some green ones (although they look slightly yellowish when on) that might reduce the clown nose effect. Here are the updated mock ups:
Attachment 35999Attachment 36000Attachment 36001

I definitely prefer the first still, although the one with Frankie wooing (chasing?) The Bride is growing on me. I am definitely going to swap the LED for green after seeing these new images.

I will wait for FrankenWashie to cast a vote, seeing as he will be the one looking at the pedal.

Also, the modded EQ mod worked a charm. I rewired the switch and added sockets to one side, leaving the other side as an open circuit. I didn't want to disturb the board so I left the 47nF cap in place. Since parallel caps are additive, this gives me the stock setting on one side, and the higher capacitance setting on the other. I tested about 4 different values from 68nF to 1uF and they all sound good, and noticeably fatter than stock. The 1uF cap would probably make this pedal work for bass. It pushed the little speakers on my THR10c a little too hard.

I will send FrankenWashie a collection of caps to experiment with.

And what I like about the mod now is that the original shorted-cap mod is still available, just replace the socketed cap with a link or zero ohm resistor.

Also, does anyone use drive pedals for bass?

Didn't get to experiment with different clipping diode combos because I was having too much fun testing the pedal. It sounds good, even if I do say so myself :cool:

People do use bass drive pedals, but it tend to be on the more aggressive styles. One of those situations where you really want to bypass the low frequencies around the overdrive part of the circuit and just drive the higher frequencies.