The Rift - Cool Fuzz, but WTF about the level of signal out!

[Kero55]

Hi guys,

Newbie in DIY stompboxes, but enjoyed to built The Rift Octave Fuzz pedal.
The thing is the signal out is too strong and I do not understand if it is the standard behaviour or not. As when I am plugging in my valve 50W Mesa Boogie Amp, I need to set the volume of the amp to 8:30 (start at 8:00) as when I switch on the Rift, the sound is going crazy loud and the difference between the pedal ON & OFF I have a difference level between pedal ON & OFF.

When I built the pedal, I had no Diode OA70 then, I replaced it by paired 1N34 Diode, could it be linked to the signal out level?

I know I have a Volume button on the pedal but the thing is the FUZZ effect is more important (thus more adapted to my tastes) when the Pedal Volume is set at 12:00 or 03:00...

Could you help me to understand what could be the cause, and anyone could know a solution to reduce the signal level but keeping the effect amount untouched?

Thanks in advance for your help!

[patrick398]

Welcome to the jungle forum!
It would be helpful if you could provide a schematic of the pedal

EDIT: Not sure i totally understand what you mean about the volume button? Do you mean a potentiometer? Different settings on the volume control should not affect how much fuzz you're hearing

[Kero55]

Hi Patrick,

Indeed, I forgot the link to the schematics. Normally, it should work as the link below:
https://www.dropbox.com/s/pw9inud5lfelh21/aion-rift-superfuzz-documentation.pdf?dl=1

So yes, normally, you are right the Volume potentiometer (and not button  )  shall not change the effect sound but it changes it! If you start by switching ON the pedal with Volume = 9 and if you try the same on 4 or 5, then, the FUZZ is more present and more fun too (octave too).

So to give more detail: when I plug Guitar>The Rift>Mesa Boogie, I need to set the amp volume to nearly the minimum if I do not want to have my ears exploding when I will switch ON the Rift. The thing is, on a song, I would like to be able to hear my "CLEAN" sound from my AMP and when I want to switch ON the pedal without blowing my ears.

[patrick398]

From the schematic i can't see why adjusting the volume control would have any effects other than changing the volume, i may be missing something. Unless it's affecting the bias of the Q4 and Q5 but that would mean 2 or 3 (depending on the tone switch) of the capacitors after the trannies are not doing their job or removing DC, unlikely.
Have you triple checked component values?

[anotherjim]

C6 & C14 on the schematic are shown with incorrect reversed polarity. They could be marked correctly on the PCB, but do check. C1 is doing a similar job and is drawn correctly.
The Clip diodes (D2, D3) after the frequency doubler were originally just this germanium pair fixed (no switch). This gives the fuzz section a much lower output level and together with the tone section meant a buffer amplifier (Q5) was added to boost the final output level if required.
This versions extra Clip switch options of none or x4 diodes will give a much higher output that really called for a more sophisticated switching that reduces the amplitude to match the germanium pair.
I would suggest sticking to the original germanium 1N34A clip option. That is what this fuzz is famous for.

[thetragichero]

Projects may be used for commercial endeavors in any quantity unless specifically noted. No
attribution is necessary, though a link back is always greatly appreciated. The only usage restrictions
are that (1) you cannot resell the PCB as part of a kit without prior arrangement, and (2) you cannot
"goop" the circuit, scratch off the screenprint, or otherwise obfuscate the circuit to disguise its source.
(In other words: you don't have to go out of your way to advertise the fact that you use these PCBs, but
please don't go out of your way to hide it. The guitar effects industry needs more transparency, not less!)


i like it!

[Kero55]

C6 & C14 on the schematic are shown with incorrect reversed polarity. They could be marked correctly on the PCB, but do check. C1 is doing a similar job and is drawn correctly.
The Clip diodes (D2, D3) after the frequency doubler were originally just this germanium pair fixed (no switch). This gives the fuzz section a much lower output level and together with the tone section meant a buffer amplifier (Q5) was added to boost the final output level if required.
This versions extra Clip switch options of none or x4 diodes will give a much higher output that really called for a more sophisticated switching that reduces the amplitude to match the germanium pair.
I would suggest sticking to the original germanium 1N34A clip option. That is what this fuzz is famous for.

When you mean polarity reversed, could it have an impact on the output signal level? I am sorry, I have limited level in electronics, so I need a little bit more detail on what could be the root cause and the potential impact of it.

Regarding the "reversed polarity", I checked on the PCB and I confirm that the PCB is the same as in the documentation. For now the pedal works (except this output signal level too high), so if C6 & C14 are reversed, don't you think the pedal would not work at all?

Thanks for the help,

[anotherjim]

Well, if you have 10uF caps in there, in the circuit one lead is to a transistor input that has some positive voltage on it from the biasing resistors. The other lead takes the signal in from a control pot that connects to ground. So the cap should have its negative lead at the ground end. Putting them in reverse is a common error - some people seem to believe the signal always feeds in toward the positive end of the cap, but this isn't necessarily so. The DC voltage across the capacitor should have the most positive voltage to the positive lead, no matter what the signal is doing.
If you put an electrolytic capacitor in backwards (more positive on the negative lead) then it suffers reverse leakage which...
Might not be immediately apparent in some situations.
Slowly reduces the capacitance value until it's zero and then reverses the polarity.
Causes internal breakdown of the electrolyte in the capacitor and it explodes or ruptures.
Causes crackling when control pots are turned due to the reverse leakage current in the caps changing the DC bias.

In this circuit, those caps might only have 2 or 3 volts across them, so can probably survive without damage but I would fix them. It won't have too much impact on the signal level, but it should improve the "quality" of it.

The original pedals that this thing is based on got the polarity of those caps right. Note a different convention for showing the polarity - a flat plate for positive and curved for negative.

[Kero55]

Thanks for your well detailed answer (even if on some part, I do not totally understand all as not as the same level as you!  )

Regarding the Output signal level, any clue to reduce it?

[anotherjim]

Fit a resistor in between the tone switch common (tag2 on the scheme) and the volume pot tag3. That forms a resistive divider with the pot. If you fit a 47k resistor and if the pot is 50k, it will act like a 100k pot turned down halfway when turned fully up.

Incidentally, the scheme you have shows the pots as a "B" type taper (50kB). Those B pots should be Audio or Log taper.  In some countries, a B taper is, in fact, linear taper and those don't give an ideal control sweep as volume controls. Only the Octave control should have a linear taper (its a trimmer pot so only available in linear).
Most brands of potentiometer call the audio/log taper type A and linear type B.
So it is possible you simply have the wrong type of pots. If you have the common 16mm Alpha brand pots, you need their A taper (A for audio, easy to remember).

[Kero55]

Thank you very much for all your answers. I will test it and check also the type of the Volume Pot according what you wrote above. (I was busy with my professional life during last month...)

I bought the same kit from AION for my brother and I am curious if again the C6 & C14 are reversed as posted by anotherjim.

Could you let me know as per the pcb below? It will ease my work when I will built the kit!
PCB is here: https://ibb.co/bs3q2qZ

Thanks for all!

[aion]

I traced an original Superfuzz before the development of the 125B version and can confirm that for both capacitors, the positive side goes toward the transistor base (as in anotherjim's schematic). So if the earlier 1590B version has those reversed then it would be an error, but the 125B version is correct. There are a few schematics floating around out there showing those two caps reversed and I must have based the original PCB off of one of them without cross-referencing the orientation.