This is very interesting. I think the lack of an output buffer is probably why I'm less impressed with this pedal than with the Orange Burst - I'm assuming that has one, because it has a much cleaner, more sparkly sound, for me, like a good quality clean boost. Without an output buffer, the output impedance is much higher. Some amps don't cope so well with that. Did you check the component values to see whether it was closest to the AC Booster or the RC Booster? I hadn't realised they were so similar. Sorry, I only vaguely understand a tiny amount of German. It's nice to see the through hole components - I could mod it a bit, if I wanted to. I've added an op amp output buffer to my EHX Octave Multiplexer, which is a big improvement. That normally taps the output directly off a 100k pot, which is just a crappy way of designing a pedal - it means it sounds much better with some amps than others.
I see you're showing 4 diodes, under the gain pot. If those are all clipping diodes, that differs from the AC/RC Booster schematic - those use 3 diodes, for asymmetrical clipping.... I guess that's probably what you're saying at 3:25. Presumably, the Pure Sky uses symmetrical clipping, like the original Tube Screamer, but with a higher clipping voltage, from, pairs of diodes, to give softer clipping. I'll pull mine apart soon, and look into it. Watching your video is easier though :)
Hi TooSlow Tube, sorry for my late response......For me the main difference is in the missing In- and Output buffers. This would also explain the less sparkling overall sound. I would not estimate the asymetrical clipping too much.
Agreed. I modified a cheap overdrive (SD-1 clone) with a switch to choose between symmetrical and asymmetrical clipping, and the difference was so subtle I wondered why I'd bothered. The missing buffers would be most of what I'd notice, yes - not that I've tried an actual AC/RC Booster. I'm no "cork sniffer", but that's got to make a big difference to the sound. I haven't pulled my Caline pedals apart fully, to check component values and see how they're wired up, but I have taken the backs off some of them and poked around with a meter, looking at the solder side of the PCB. It turns out the Pure Sky and the Highwayman have a 10 kOhm volume or level pot, with the wiper (middle pin) directly connected to the output jack. The Orange Burst has a 100k volume pot, but it's not directly connected to the output jack. I can see what appears to be a transistor close to it (three small pins in a row, which measure as two diodes with a common anode, so an NPN transitor, presumably), so it does appear to use a transistor output buffer, despite being "true bypass". To be fair, using a 10k pot for the output volume (direct to the jack socket) is a lot better than doing it with a 100k pot, like many of the EHX designs. The output impedance will be low enough for most purposes, but it will change with the position of the volume knob, whereas a transistor output buffer will be constant output impedance. A transistor buffer will definitely sound different though, even if the output impedance is very similar.
This is very interesting. I think the lack of an output buffer is probably why I'm less impressed with this pedal than with the Orange Burst - I'm assuming that has one, because it has a much cleaner, more sparkly sound, for me, like a good quality clean boost.
Without an output buffer, the output impedance is much higher. Some amps don't cope so well with that.
Did you check the component values to see whether it was closest to the AC Booster or the RC Booster? I hadn't realised they were so similar. Sorry, I only vaguely understand a tiny amount of German.
It's nice to see the through hole components - I could mod it a bit, if I wanted to.
I've added an op amp output buffer to my EHX Octave Multiplexer, which is a big improvement. That normally taps the output directly off a 100k pot, which is just a crappy way of designing a pedal - it means it sounds much better with some amps than others.
I see you're showing 4 diodes, under the gain pot. If those are all clipping diodes, that differs from the AC/RC Booster schematic - those use 3 diodes, for asymmetrical clipping.... I guess that's probably what you're saying at 3:25.
Presumably, the Pure Sky uses symmetrical clipping, like the original Tube Screamer, but with a higher clipping voltage, from, pairs of diodes, to give softer clipping.
I'll pull mine apart soon, and look into it. Watching your video is easier though :)
Hi TooSlow Tube, sorry for my late response......For me the main difference is in the missing In- and Output buffers. This would also explain the less sparkling overall sound. I would not estimate the asymetrical clipping too much.
Agreed. I modified a cheap overdrive (SD-1 clone) with a switch to choose between symmetrical and asymmetrical clipping, and the difference was so subtle I wondered why I'd bothered.
The missing buffers would be most of what I'd notice, yes - not that I've tried an actual AC/RC Booster. I'm no "cork sniffer", but that's got to make a big difference to the sound.
I haven't pulled my Caline pedals apart fully, to check component values and see how they're wired up, but I have taken the backs off some of them and poked around with a meter, looking at the solder side of the PCB.
It turns out the Pure Sky and the Highwayman have a 10 kOhm volume or level pot, with the wiper (middle pin) directly connected to the output jack. The Orange Burst has a 100k volume pot, but it's not directly connected to the output jack.
I can see what appears to be a transistor close to it (three small pins in a row, which measure as two diodes with a common anode, so an NPN transitor, presumably), so it does appear to use a transistor output buffer, despite being "true bypass".
To be fair, using a 10k pot for the output volume (direct to the jack socket) is a lot better than doing it with a 100k pot, like many of the EHX designs.
The output impedance will be low enough for most purposes, but it will change with the position of the volume knob, whereas a transistor output buffer will be constant output impedance.
A transistor buffer will definitely sound different though, even if the output impedance is very similar.