It’s occurred to me, probably a bit subtle for a guitar pedal.
Here’s where to get the pedal parts
https://lovemyswitches.com/?srsltid=AfmBOoqL0SJrFrBOW7ZxiMcNYQAear3bAEv1Z92cOy0_yaq6yAYJS1-5
Here’s where to get the pedal parts
https://lovemyswitches.com/?srsltid=AfmBOoqL0SJrFrBOW7ZxiMcNYQAear3bAEv1Z92cOy0_yaq6yAYJS1-5
Look at the circuit I posted in reply 505 of this thread. You'll need an input buffer but a single dual pot will let you dial in as much H2 as you need.
@Loudthud oh that’s dope. The only complaint from my perspective is that there’s a bunch of suggested improvements to the circuit in the replies but not an updated schematic, so I’d have to puzzle through them and update it myself (with my limited abilities). In any case right now this is far future, I just got the board and am waiting on some parts to make a standard variety unit to see how it sounds…
(It occurs to me looking at the thread again that the replies are actually to something else and not your circuit, which looks great. Though pass thinks you're using a potentiometer with too much resistance lol)
Forgive my ignorance, but this isn't clear to me. Does this mean you can change the positive to negative phase by adjusting the trimmers on the board? It's not clear to me how to do that and still maintain the sweet spot of Vds per the documentation
If I'm adjusting the trimmer, what should I be looking for in the output voltage to know that I've succeeded (I don't have equipment more sophisticated than a multimeter)? If it's not adjusting the trimmer, how do I change the operating point?
Has anyone used an op amp to switch the phase back to match the input phase on one of these? I apologize in advance for my lack of understanding as I am not an electrical engineer at all. Just a broke audiophile with soldering skills. I would love to find out how to get the phase of the output to match the input and I have a handful of silicone op amps laying around.
No.
The trimmers set the amount of of H2, not the polarity. Polarity is changed at the speaker connections.
To change from positive to negative: "reverse the phase on the speaker connections to the amplifier. You don't
have to though - it would also give you a chance to hear the positive phase 2nd harmonic."
@elwood625 Right except above @Nelson Pass said:
Saying that there was some way to change the operating point to change the polarity without changing the speaker connections.
The B1 Korg nutube circuit allows the polarity change via the trimmer, all of the H2 circuits are positive H2, to achieve negative H2 the speaker connections are changed.
"It's important to note that this circuit actually generates a positive phase 2nd harmonic, but
after you invert the output (to get absolute phase correct) you will find that it is now a negative
phase 2nd harmonic. I know this might be confusing – I have occasionally awakened in the
middle of the night and thought “That can't be right.” But it is, and if you turn the above
pictures upside down you should see it. If not, just invert the phase at the speakers anyway.
If you invert the phase of the signal before the circuit, then it will keep the positive 2nd."
after you invert the output (to get absolute phase correct) you will find that it is now a negative
phase 2nd harmonic. I know this might be confusing – I have occasionally awakened in the
middle of the night and thought “That can't be right.” But it is, and if you turn the above
pictures upside down you should see it. If not, just invert the phase at the speakers anyway.
If you invert the phase of the signal before the circuit, then it will keep the positive 2nd."
Ah, I see. The problem being, I am using powered speakers. To complicate things further, I am converting the output of the H2 to the speaker plate amp inputs which are XLR. It seems I may need to build a second unit to output a true balanced signal. I was hoping to avoid that. I'm not sure I have the mind to properly wire two units to the balanced outputs. Thank you gents!
Wiring the two units is very easy, the hard part is adjusting the distortion, I used a laptop with REW and a sound card to set the distortion for L+ & L- along with R+ & R-. This is because a balanced signal cancels H2, I've found adjusting H2 on a balanced signal is challenging, it can be done. I've built an H2v2 which is balanced and a balanced B1Korg preamp.
An Elliott Sound Products differential amplifier circuit will covert single ended to balanced, or balanced to single ended. It will also take the XLR balanced input and covert it to differential balanced. I would think taking the H2 outputs to the ESP Differential amplifier and then output balanced XLR to your speakers would be easier. His website is very detailed along with the instructions to build and wire his projects.
Then again, the differential amplifier may cancel the H2.
Interesting. I am not familiar with his products. I will dive head first down that rabbit hole immediately. Thank you!
I see, he was referring to a different design.
My main issue is that I’d like to use the H2 as a buffer for a headphone amp, where switching the speaker connections is not a thing one can do. If there were even a second circuit I could add to the H2 to flip the phase, that would be useful.
I wonder if I could stick an op-amp in an inverting amplifier configuration to the output of the H2 to invert the signal.
This is exactly what I believe Mr. Pass mentioned could be done in a long ago post that I once found, when I read through the entire feed, looking for answers. Now I can’t remember how far back to look to reference it.
Looks like a BJT in a Common Emitter Amplifier configuration would also invert the phase: https://www.electronics-lab.com/article/common-emitter-amplifier/
The trick I suppose would be doing the math to find the resistor values to get it in a unity gain (unless you wanted to use the BJTs as an amplification stage).
The trick I suppose would be doing the math to find the resistor values to get it in a unity gain (unless you wanted to use the BJTs as an amplification stage).
Welp assembled my H2 finally:
However, when I plug it in between my DAC and headphone amp all I get is very faint music and loud whirring sound, both only from the left channel. Not sure what I did wrong, any pointers appreciated. (I'll be the first to admit my wiring and soldering skills aren't top notch.)
However, when I plug it in between my DAC and headphone amp all I get is very faint music and loud whirring sound, both only from the left channel. Not sure what I did wrong, any pointers appreciated. (I'll be the first to admit my wiring and soldering skills aren't top notch.)
There wasn't really room on the board for the screw terminals, they may not be seated properly in the board and that's what's causing the issue. I may have to take them out and just solder the wires directly.