First Shaka 5 build

[mat]

Hi,

I've read a lot of the raving comments of the Shaka 5. I built it but the overdrive is quite shrill and little barky. Obviously I've made some kind of mistake.

I have the J201's in a right way + tried the BS170's on both ways. I also bought IRF510's + other mosfets + several germanium diodes. The TL072 gives voltages:

Pins 1 & 2 = 8.4V
3 & 4 = 0V
5 = 4.3V
6 & 7 = 4.5V
8 = 8.9V

J201 (Q1)
D = 4.7V
S = 0.22V
G = 0V

J201 (Q2)
D = 8.9V
S = 4.7V
G = 4.3V

How does these seem to more advanced builders than me 

Thanks,
Mat

[aron]

If it's working it sounds more like a wrong component (capacitor?) more than anything else. Or maybe the tone stack is wired incorrectly.

[mat]

If it's working it sounds more like a wrong component (capacitor?) more than anything else. Or maybe the tone stack is wired incorrectly.

I'll recheck the wiring (again). I think You are right because the tone pot gives really huge range from muffled to an icepicked variations. I twigled the pot and it is almost like a vibe pedal  I'll measure the caps again and report back tomorrow.

Btw. I borrowed my friends Zendrive and it is a fabulous pedal ! I hope to get somewhere near same kind of dynamics from the Shaka 5 that I got from the ZD. Here is a clip of the ZD+ DIY amp:

http://media.putfile.com/zendrivehrmbm

Thanks,
Mat

[aron]

I listened to that clip and yes, it will be possible to get that kind of dynamics. If you want even more dynamics the Shaka HV+mods can be even more dynamic than the Shaka series.

Final note, you are really good!

[mat]

I listened to that clip and yes, it will be possible to get that kind of dynamics. If you want even more dynamics the Shaka HV+mods can be even more dynamic than the Shaka series.

Final note, you are really good!

After I get my Shaka5 running properly, I will definitely build the Shaka HV ! Btw. does the voltages seem right ? Is it normal to have more than 4 volts of DC on the pin 5,6 and 7 of the IC ? I checked the wiring + measured components (in the circuit) and cannot find the problem. Tone pot gives a really dark to very bright sweep. Actually when tweaking the tone pot back and forth the sound is very close to vibe pedal sound    My friend had really good time when he came in and checked my new 'overdrive' pedal 

Thanks Aron for the nice comment, I wasn't consentrating to the playing, just listened how it sounds and reacts to the picking dynamics. When I get my Shaka5/HV pedals ready, I will post clips 

I have tried to search suggested voltages of the Shaka 5 without success.
Matti T.

[aron]

What layout did you use? I'm wondering why pins 1&2 have 8.4V on them.

However it sounds like you are using input 2 of the dual op amp.

From R.G.

For an opamp to be working as a linear amplfier, both the inverting and noninverting inputs and the output pin must be within a few millivolts of the voltage on the noninverting input.

[mat]

What layout did you use? I'm wondering why pins 1&2 have 8.4V on them.

However it sounds like you are using input 2 of the dual op amp.

From R.G.

For an opamp to be working as a linear amplfier, both the inverting and noninverting inputs and the output pin must be within a few millivolts of the voltage on the noninverting input.

It is Jack Ormans (2000) layout and schem. I cannot get to the page anymore for some reason but I have them on my PC. I am lost too why pins 1 and 2 are so high V because they are not connected anywhere but to each other ? I will check that part again !

[aron]

Matti,

I should point out that I have never built the Shaka 5. I stopped at the Shaka III. :-)

Doug Hammond had the Shaka 4 and Jack whipped out the Shaka 5.

[stumper1]

Aron,

What are the differences between the 3, 4 and 5?

[PerroGrande]

Jack Orman's Shaka 5 Circuit only uses one side of the dual op-amp. The "A" side of the op amp is wired such that the non-inverting input (pin3) is grounded and pins 1 & 2 (output and inverting) are wired together.  I would expect to see right around 4.5v (quiescent) on pins 5, 6, and 7.  The non-inverting input is biased to Vref through a bypassed voltage divider.  The drive pot controls the gain in this portion of the circuit.   When quiescent, the op-amp is going to have stable biasing at DC right around the Vref point.  In other words, the voltages look pretty good.

You could try the recommended alterations to C5 (220pf cap to ground) to reduce some harshness. This may be all that is required. 

There are some opportunities to test this circuit in stages.  The gate of Q1 (the lower FET in the minibooster portion of the circuit) is connected to the wiper of a 100K trim pot. 

If you're brave, you can remove the trim pot and test the two stages separately. 

To test the minibooster stage, remove the trim pot.  Temporarily connect the guitar's input to the gate of FET Q1 via a coupling capacitor.  You'll also need to rig a 1Meg resistor to ground to provide a DC return. (connect this resistor on the Q1 side of the coupling capacitor)  You should hear a clean, boosted signal.  If it sounds terrible, your problem is likely in the mini-booster and/or tone stack side of the world.  If it sounds good, then you've isolated the problem to the other side. 

[stumper1]

Aron,

What are the differences between the 3, 4 and 5?

Found it

[mat]

Perrogrande, Thanks for Your help. I will check the circuit as You adviced today.

Aron, Ok I will definitely build the Shaka 3 also 

Thank You,
Matti T.

[aron]

Matti,

Go for the Shaka HV. I can help with some mods.

[newfish]

+1 for your fingers!

Hope you get your Shaka working.

[mat]

Jack Orman's Shaka 5 Circuit only uses one side of the dual op-amp. The "A" side of the op amp is wired such that the non-inverting input (pin3) is grounded and pins 1 & 2 (output and inverting) are wired together.  I would expect to see right around 4.5v (quiescent) on pins 5, 6, and 7.  The non-inverting input is biased to Vref through a bypassed voltage divider.  The drive pot controls the gain in this portion of the circuit.   When quiescent, the op-amp is going to have stable biasing at DC right around the Vref point.  In other words, the voltages look pretty good.

Ok, that is great !

You could try the recommended alterations to C5 (220pf cap to ground) to reduce some harshness. This may be all that is required.

I will try this also but the sound in my home with different amp was just horrible. Something is really wrong on my solderings 

There are some opportunities to test this circuit in stages.  The gate of Q1 (the lower FET in the minibooster portion of the circuit) is connected to the wiper of a 100K trim pot. 

If you're brave, you can remove the trim pot and test the two stages separately. 

To test the minibooster stage, remove the trim pot.  Temporarily connect the guitar's input to the gate of FET Q1 via a coupling capacitor.  You'll also need to rig a 1Meg resistor to ground to provide a DC return. (connect this resistor on the Q1 side of the coupling capacitor)  You should hear a clean, boosted signal.  If it sounds terrible, your problem is likely in the mini-booster and/or tone stack side of the world.  If it sounds good, then you've isolated the problem to the other side.

I lifted the far end of the trimmer and jumpered my guitar plug in to the J201 via 3n3 and 1M to ground before the cap. The volume boost (volume at full) is very light if any and with tone pot cranked there is alots of hiss ! I have checked the J201 orientation few times but I think I will desolder them and put in two sockets to stick them in to.

Will report back soon..

[mat]

+1 for your fingers!

Hope you get your Shaka working.

Thanks newfish, I hope so too.

[DougH]

Nice playing!

IIRC, the shaka 4 was just a "beefed up" shaka 3- a little more bass, shelving tone control instead of the bmp, etc. The shakas are nice sounding overdrives. Aron and Jack did a good job on those.

[mat]

Nice playing!

IIRC, the shaka 4 was just a "beefed up" shaka 3- a little more bass, shelving tone control instead of the bmp, etc. The shakas are nice sounding overdrives. Aron and Jack did a good job on those.

Thanks DougH, Yes what I've heard on the soundclips the Shaka series are very cool OD's.

I did put in the sockets for the J201's but no help. I think I will focus on the ShakaHV next. With my build (how it is now) the mosfets bring more harshness and drive. Without them (just the ge-diodes in) there is more volume and the sound is smoother but not right at all..

[aron]

I think it might be time to build the audio probe.

Check it out:

http://www.diystompboxes.com/wiki/index.php?title=Debugging

This will let you "listen" to your circuit in stages. Right at the output of the op amp, then before the MiniBooster circuit etc....

[mat]

I think it might be time to build the audio probe.

Check it out:

http://www.diystompboxes.com/wiki/index.php?title=Debugging

This will let you "listen" to your circuit in stages. Right at the output of the op amp, then before the MiniBooster circuit etc....

Could I 'inject' the sound from guitar to different spots on the circuit also with the audioprobe ? I have built one and I've always used it in the input of the amp. Started probing from the input of the effect and then moved forward component by component..