Spatialist Arachnid V2 - low volume and thin sound

[JoeGuitaro]

Hi all,

I already worked on some very easy pedals and wanted to start with something more difficult now.
Since I was soldering the FV-1 by my self, I had a lot of troubleshooting with that, but now I have the feeling that all the effects work mostly as they should.
My main Problem ist now, that the dry sound of my guitar has a very low volume and the sound is super thin. I'm playing a Les Paul and it sounds like I would be playing a Strat with low volume on the bridge pick-up...

I also have attached a picture of my soldering. Is there anything you can see directly? I thought about a wrong resistor or capacitor that maybe kills my sound but my electric knowledge is not so profund.

Thanks in advance and best regards,
Jona

 

[Stickman393]

C6: you've got a 1nF cap in there. That's about 1/1000 of what it should be (1uF).

 

[JoeGuitaro]

Sometimes you get blind, if you look to long at those PCBs...Thanks a lot! That worked

 

[Stickman393]

Stickman. Hell yeah.

That's what were here for. Sometimes ya need a second set of eyes on something.

 

[serhay]

How was the problem solved? I have the same problem, what should I do? In the diagram, you call it C6, which is C11 in my diagram, and I set it to 1uf, but I still have low sound in both dry and wet signal. The sound from my instrument is very low.

 

[Cybercow]

How was the problem solved? I have the same problem, what should I do? In the diagram, you call it C6, which is C11 in my diagram, and I set it to 1uf, but I still have low sound in both dry and wet signal. The sound from my instrument is very low.

We could probably be of better assistance if we could see some good, clear photos of your build - front & back of the PCB and wiring.

 

[phi1]

I don't know that this will affect the volume, but I believe the 47R in the power input is too high for this circuit.

The FV-1 pedals I've made draw around 60~65mA.

V=IR, so the voltage drop accross the 47R is 0.060 * 47 = 2.82V. So after the 47R, you'll be down to ~6.18V.
P=IV, so that resistor is dissipating 0.060 * 2.82V = 0.169W. This is much less than the typical 1/4W rating, so probably ok in that regard, but probably warm.

I had my own design build with that exact 47R and measured the near 3V drop. I've since switched to 10R in that spot (only 0.6V drop), and most pedalpcb circuits don't have any resistor and seem to work just fine.

 

[serhay]

I don't know that this will affect the volume, but I believe the 47R in the power input is too high for this circuit.

The FV-1 pedals I've made draw around 60~65mA.

V=IR, so the voltage drop accross the 47R is 0.060 * 47 = 2.82V. So after the 47R, you'll be down to ~6.18V.
P=IV, so that resistor is dissipating 0.060 * 2.82V = 0.169W. This is much less than the typical 1/4W rating, so probably ok in that regard, but probably warm.

I had my own design build with that exact 47R and measured the near 3V drop. I've since switched to 10R in that spot (only 0.6V drop), and most pedalpcb circuits don't have any resistor and seem to work just fine.

I'm using a 78L33 SMD regulator that provides 3.3 volts, and I've noticed something: this regulator gets very hot, and so does my 1n5818 diode. They're getting hot enough to heat the PCB. Is this heating normal? Could the regulator be the problem? However, what I don't understand is that the PCB still shows 3.3 volts, as if there's no problem. It's strange.

 

[phi1]

Short downstream? Or bad 78l03? Measure the current draw of the pedal.

 

[Cybercow]

I'm using a 78L33 SMD regulator that provides 3.3 volts, and I've noticed something: this regulator gets very hot, and so does my 1n5818 diode. They're getting hot enough to heat the PCB. Is this heating normal? Could the regulator be the problem? However, what I don't understand is that the PCB still shows 3.3 volts, as if there's no problem. It's strange.

That sounds like "thermal runaway". A small regulator like that can cook itself, even while still delivering it's intended 3.3V. There could be an extra load on the 3.3V rail. I think @phi1 nailed it with a current draw measurement.

Personally, of the few dozen FV-1 pedals I've built, not one of them drew more than 76mA. And the regulators merely got warm after hours of use. In my opinion, the three most prominent candidates for having the ability to create 'hot' conditions on the 3.3V rail would be the regulator, the EEPROM and/or the FV-1 chip.