Blue Box (octave down + fuzz) sounding buggy

[perfectsoundforever]

I built a Blue Box the other day, but it's sounding buggy and I couldn't fix it. I hope someone here can guide me a bit, I'm pretty lousy at electronics but I'm trying the best I can.
The link to the project is
http://www.tonepad.com/getFileInfo.asp?id=73
I did the two octaves mod (which connects pins 1 and 2 of the IC2 with a SPDT) and replaced 0.05uF capacitors with 0.047 ones.
The blend pot turned CW ONLY works with the mod on, which causes crazy octave jumps depending on how I hit the strings. When I'm really quiet it stays in the same octave. The blend pot turned CCW gives me a good fuzz, and turning the mod on doesn't make any change at all.
I did some testing and this is what I got:
Battery power (the battery alone as well as the +9v connection on the board)= 8.72 (I hope it's OK to do the testing with just 8.72v)

Transistors:
1
C = 6.78
B = 0.22
E = 0.00

2
C = 0.22
B = 0.56
E = 0.00

3
C = 0.02
B = 0.48
E = 0.00


Diodes:
1
K = 8.72
A = 0.00

2
K = 0.02
A = 0.01

3
K = 0.02
A = 0.00


ICs:
1
P1=4.36
P2=4.46
P3=2.35
P4=0.00
P5=4.1
P6=4.12
P7=1.45
P8=8.66

2
P1=1.39
P2=1.39
P3=5.98
P4=0.00
P5=1.39
P6=0.00
P7=0.00
P8=0.00
P9=0.00
P10=0.00
P11=6.74
P12=0.00
P13=5.98
P14=5.95


I really hope someone can give me a hand with this. Thanks in advance guys, and if anyone wants me to make anything more with the tester, don't hesitate to ask me and I'll post the results.

[Mark Hammer]

Legend has it that when Neil Young finished doing his part on the Canadian equivalent to "We are the World" (called "Tears are not enough", and orchestrated by Brian Adams), on his way out of the studio, the engineer or producer remarked that Young had sung a bit flat.  Young reputedly replied "That's my sound, man".

So, if you find the BB a bit buggy, all I can say is "That's its sound, man".

However, since you only get sound in one direction of the Blend pot, clearly something is amiss, not just normally buggy.

First, are you sure you didn't accidentally zap the 4013 when doing your mods?  Are you sure it was inserted and seated properly into its socket?  Are you sure you have not produced any unintended solder bridges?

[Kinetic]

Like Mark says, the Blue Box doesn't track 100% so you will not get the perfect octave(s) down all the time, it is temperamental.  You get the best tracking if you turn your guitar tone pot all the way down and use your neck pickup.

As for the circuit, did you check the stock version was working before doing the mod, or did you build with the octave mod immediately?

[Quackzed]

it sometimes helps to drive these type circuits with a booster or distortion of some kind. a distorted signal is naturally more compressed and with a bit of added volume it can help to hit the octaver with just the right amount of signal, as well as add sustain and keep it tracking more smoothly. also, neck pickup/ tone rolled down is usually best, so you want to drive it with something that has good bass.

[perfectsoundforever]

After recovering from the laugh at the Neil Young comment, I'll say that

-I re-checked for solder bridges and couldn't find any.
-The IC is in position and all its pins are making contact from what I can see.
-I didn't test the circuit before doing the mod,
-Thanks for the pickup/tone/compression tip. That really helped controlling the octave chaos.

If I have the chance tomorrow, I'll try to dismount the IC and re-re-check all its contacts with the socket. And maybe buy a new one and try it (though we're on some celebrations here in my country, and the next working day is wednesday, so I'll have to wait). If I have any new data I'll post it.
What I don't understand is why the pot just works with the mod on. And the output pot... shouldn't work like a dry/wet pot in terms of fuzz? Because instead of getting a clean signal or a mix I don't get anything.


P.S. I made a mistake when posting, when the blend pot is all the way to the left, I get sound despite the status of the mod SPDT.

[Kinetic]

I'd take the mod out and see if the stock circuit works as intended, work on that, and then readd the mod switch.
With the Blue Box, the blend pot varies the amount of octave/fuzz, it won't mix dry input signal with wet.  So, if the pot is all the way to one extreme you'll get octave effect only, all the way to the other and you'll get fuzz only, and of course, a combination between.  The output pot is just volume.

[plankspank]

Just successfully built one, so this is fresh in my mind. Recheck your solder connections and component values carfully around the collector of Q1: you are measuring around 6 VDC here; it should be in the vicinity of 100- 200 mV.
      The Blue box is basically 2 circuits in one, seperated by the blend pot; one one side you have an op amp generated fuzz, the other side is a decades down square wave generating FF, with the clock being fed by the Fuzz.
      Depending on how you wired lug 1 and 3 of the blend pot, with the knob maxed out one way you will get the classic cartoonish "super mario bros." tone from the FF, maxed the other way you will get just fuzz.. Due to quirks in this circuit, the fuzz side will be louder than the FF output side....

[oskar]

Recheck your solder connections and component values carfully around the collector of Q1: you are measuring around 6 VDC here; it should be in the vicinity of 100- 200 mV.

The voltage on Q1 collector is depending on the output from IC1b. 6V actually looks a bit low to me...

IC2 isn't really driving any loads so it shouldn't pull down V2 at all and V2 should be just a bit lower than the battery...
check the value of R24.
I think IC2b has protection diodes on the input so if it's fed 9V from R1/Q1 this would drop to V2 voltage if it's lower, which it is...
like I don't know...       I'm a bit rusty though...   

[perfectsoundforever]

Well, going to work now, but I just made a couple of tests...

I changed the 4013 for a new one
I changed the Q1 2N3904 for a new one
I replaced R24 and re-checked its value (328 ohms says my tester)
I removed the mod completely

and now this is what I get:


no sound.






Damn.
I'll check some voltages when I get back from work or maybe saturday.

[Angelo777]

Well, going to work now, but I just made a couple of tests...

I changed the 4013 for a new one
I changed the Q1 2N3904 for a new one
I replaced R24 and re-checked its value (328 ohms says my tester)
I removed the mod completely

and now this is what I get:


no sound.






Damn.
I'll check some voltages when I get back from work or maybe saturday.

I used the same schematic to built one for myself for fun and it worked just fine.... Make sure that your wiring is not messed up and that the connections are OK. Then if you soldered it check if when you were soldering you stayed too long at an active component and you burned it. If you breadboarded it the check each connection one by one and make sure that components leads dont collide inside the breadboard... try cut them sort enough... And lower the pot value of the fuzz pot a little bit and put a clean boost at the biggining. Use the values and the schematic from tonepad.com and one more thing. As Mark Hammer said this is a unique kinda octaver.... when i built it everywhere sounded good though when i was playing at the 2nd string i had a bizzard effect beside the octave...

Have fun!
Angelo777

[oskar]

I did the two octaves mod (which connects pins 1 and 2 of the IC2 with a SPDT)

Please link to the mod.
pin 1 and 2 should not be connected. That's a short for sure and can most likely account for the voltage drop across R24. They are both outputs and two digital outputs shouldn't be directly connected/shorted.
If you want to switch between octaves (but wait untill it's working...     ) you can either connect a spdt switch to pin 1 and 3 and tap the signal from the middle lug. Or you could connect a pan pot (~10k - 100k between these pins and tap the mixed signal from the middle lug.)

The blend pot turned CW ONLY works with the mod on, which causes crazy octave jumps depending on how I hit the strings. When I'm really quiet it stays in the same octave. The blend pot turned CCW gives me a good fuzz, and turning the mod on doesn't make any change at all.

It probably was when you turned the mod off that you starded to hearing those crazy octaves...