New try with question about the Shaka Braddah III behavior.

[solderman]

Hi again
I was probably a bit unclear with my last question about the Shaka Braddah III since I haven't got any replays on the post. I dint men for someone to correct my layout if it deviated from the schematics that's my responsibility. But I am still not sure that it is suppose to sound like mine does. I have understood that a lot of you out there has built this one and might know how it suppose to behave ,So my questions are.

When I plug it in I have to have full volume and full gain on the trimpot for it not to lower the signal too much. It is only at full gain it gives the amp a boost that results in a higher output than the amp clean.



I only added the layout to clarify what components myn contained. If it should behave like this then I don't need to spend more time on it. From the soundclips it sounds really nice and mine don't sound that bad but it acts quite strange to be something that I supposed to be a booster. The clipping sound is quite .OK The switch for the diodes is an  on-(off)-on. My thought was to use this one with the possibility to have a clean booster that had two different types of clipping sections.

Anyone??

link to earlier post
http://www.diystompboxes.com/smfforum/index.php?topic=71029.msg572505#msg572505

//Solderman

[aron]

It sounds like something is wrong with your copy. It should be able to boost easily.

[DougH]

There is a soldering/wiring error, or something is wrong with the layout. This will get well above unity gain easily.

[solderman]

Thanks
The I know it is worth spending time on.

//Solderman

[aron]

You might consider building an audio probe as detailed in the debugging page. This will allow you to hear the signal path and figure out where the problem is.

[solderman]

Hi again
Yes, as I assumed I made a flaw in my PCB layout. I had connected the 0.1uF output cab before the tonestack at the wrong end of the 0.01 Cap so it was directly connected to Ground etc. on Q2. My mistake.

What have I learned? Never do any PCB layout after midnight. Go to bed and get some sleep and you might not screw up next time!

Besides from that it sound nice. It has very little headroom with clean boost tough so the clipping section has quite a small impact on the overall sound. With the 1N914 diodes in, the gain goes down a bit and a slight midrange grittyness is somewhat more pronounced. With the MOSFET section it's both more mid and bass but less loss in gain. All of this is of cause expected. With no clipping section engaged the difference is quite little. Especially on low gain.

I have updated the PCB layout so anyone how wants can try it.

http://solderman.fatabur.se/future_project.htm

Thank for getting my on the right track to troubleshoot the thing.

//Solderman

[aron]

>It has very little headroom with clean boost

I'm not sure why you are not getting a better boost from the FET section. It should be able to boost pretty loudly even with the drive turned down fairly low.

[solderman]

Hi
The boost from the FET section is OK now. It is pretty strong and loud. It's just that I thought that it would be both loud and clean. But I like the tone anyway. I adjusted both the trimpot in parallel with the gainpot (27K) and the trimput at the JFET (0.85K) to a position where I thought that the tone was as clean as it could get in balance to the level.  I exchanged the trimput in parallel with the gain for a 27 K resistor and the gain with a 1M Audio pot witch is way more than I need. But I did not have any 500 or 250K Audio in stock. The important part was to have a logarithmic one to smoothly increase the gain. Now I have tons of gain if I want to. I really like that it has such a wide range, from gritty to heavy dist.

The conclusion is that I have got my self yet another real nice sounding OD-Dist. Now I am going to hunt my self down a one knob clean boost, witch was my original intention, and equip that one with a clipping section wich I can switch in insted of trying to switch off an existing one from a OD pedal. I am thingking of trying the MXR Micro Amp or/and the Runoffgroove Peppermill, both on the bredboard first.  Any other suggestions ? 

//Solderman

[aron]

Search the forum. You can try this:

http://diystompboxes.com/pedals/schems/shakaboost.jpg

and read this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=35054.0

[aron]

You can also lift the diodes from the Shaka 3 OR simply tap into the op amp before the diode clippers. Done.

[solderman]

Hi Aron
Thanks for the tip. After following the links you submitted it struck me that the solution was right in front of me all the time. As my grandfather would have put it, if you want corn plant corn. This gadget is a combo of a clean booster and an OD/Dist. It actually says so on the schematic. What I did was to separate the two with a switch. Then I discovered that the tonestack sucked a lot of gain from the JFET stage. Without the tonestack it gains clean and good. I thought it was a solder bridge or a PCB layout flaw so I disconnected it and made a new "dead bug" tonestak witch I connected instead with the same result. I like the flexibility in tone when the first stage is connected so I didn't want to skip the tonestak. After playing around and testing different guitars and so I discovered that I really didn't need the tonestack in the clean boost mode. So my solution is to use tree switches.

The first one is a foot switch (I don't count the usual bypassswitch)
I added a 3PDT switch to the effect. The two first connectors on the switch switches the IN either as in the schematic or direct after the input cap to the Gate on the first JFET and also cuts the path between the gate and the 33K resistor. This bypasses the first gain stage (might add a 1M resistor to grownd when switched here). This leaves one pad unused and I am planning to put a millennium bypass LED here as an  indicator. Although it is a bit different than usually for the millennium. The last part of this switch switches the OUT to bypass the tonstack in boos mode or as normal in dist mode.

The second one is a SPDT  that switches the clipping between MOSFET and standard 1N914.

The third one is a SPDT that switches the connection point to the signal side of the clipping switch between as in the schematics or a point just before the output cap. This way I can switch the clipping diodes in and out even when the footswitch is in Boost mode. It gives a little bit of extra grit.

The result is that I have both a very nice sounding 3 knob dist pedal that with a stomp on a second footswitch becomes a one knob clean booster with the ability to switch in clipping diodes, just as I intended from the start. All this in one box. I

Right now the thing looks like a cable chaos but as sonn as I have got it strightend out and boxed I will post pictures an updated PCB layout.


//Solderman