Even if the IP is double as good, this simple sloppy thing I threw together with pin sockets is still pretty impressive. Smooth as mothers milk 🤱make proper Iron Pre , then write about buffers
A bit lacking in the bass, but need to revise the PSU. We’ll see
I seem to like concoctions
I know the PSU is crap. What would you say to a statement about correctly made series regs can compete with shunts?
I have fetishes too. But there is no emoji to express them in this forumyou see series regs in anything I made?
do not count relay PSU, eenyweeny biasing supply etc.
I mean, anyone around is having some Fetish, I'm enough self-important so I'm allowed to have as much Fetishes I want
The idea is totally fine but you will be pulling a lot more current across the first resistor so the voltage drop will be larger than expected.
If that’s driving both channels then something like 470/1500 is probably closer to what you might want.
Even if the IP is double as good, this simple sloppy thing I threw together with pin sockets is still pretty impressive. Smooth as mothers milk 🤱
A bit lacking in the bass, but need to revise the PSU. We’ll see
I know you are already working on this but if you need further encouragement, I will say this: A preamp or buffer is no place to make compromises on the powersupply, we just don't need to, or should make compromises here.
You haven't truly heard the pre/buffer circuit until the supply is at least 10 times better than it.
Thanks! I hadn't considered the draw across the first resistor in calculating. Just used the dumb resistor divider equation.
I can play with some values.
Do you consider this a compromise in power supply (as per your response to Andynor). Seems that a 100-500R and 4700uF have a pretty good low pass filter response across the audible range especially because with the SMPS the 60 and 120Hz components are already way down below -100dB (from previous measurements)
Could do away with the voltage divider and just use a series dropping resistor. Combined with the decoupling capacitor at the buffer pcb will make a nice RC filter.
Thanks! I hadn't considered the draw across the first resistor in calculating. Just used the dumb resistor divider equation.
I can play with some values.
Do you consider this a compromise in power supply (as per your response to Andynor). Seems that a 100-500R and 4700uF have a pretty good low pass filter response across the audible range especially because with the SMPS the 60 and 120Hz components are already way down below -100dB (from previous measurements)
Yeah this is one benefit of a switcher, it's easier filtering out high frequency noise with RC filtering compared with getting rid of 100Hz of rectified ripple.
I would include additional RC filtering per channel - say 5 Ohms and 4700uF per channel after the main supply you have illustrated.
Taking it one step further would be adding shunts or a loaded series regulator per channel after that additional dual mono RC filtering step.
Yes that will also work, but I think it is preferable having less series resistance and more capacitance, rather than more series resistance and less capacitance.
Adding a little extra load on the supply is also beneficial, so I like his idea a little more.
When I powered up and gave a listen, my first thought… “where did the bass go?”A bit lacking in the bass, but need to revise the PSU. We’ll see
I was impatient and used a 24V wallwart.
Good Gemini will be next
What would be the mechanism such that the frequency response would be altered so significantly by a 24VDC wall wart? I understand it might be noisy as hell but how would the bass be impacted, unless it’s was severely underpowered in terms of wattage? I’m genuinely curious, not at all trying to bust balls.When I powered up and gave a listen, my first thought… “where did the bass go?”
I was impatient and used a 24V wallwart.
Good Gemini will be next
Using the IP boards or making yourself?When I powered up and gave a listen, my first thought… “where did the bass go?”
I was impatient and used a 24V wallwart.
Good Gemini will be next
Removed some stuffing from my overstuffed Superpencils yesterday, and fine tuned the F2J’s output impedance, and re-removed degen on the B1R2 boards. Bass is now pretty decent.
Have been having dialogue with Pico lately, and will make some adjustments to the power supply and then add RC filters for both chans, not far from what the original schem calls for. Still, clarity is the best I have had. With no hint of harshness.
My ultimate goal is the Iron Pumpkin. But I really like finding out what this circuit is all about first. Then go to maybe shunt and or other form of dual mono, then inductive attenuator.
Mighty made the ultimate, so can’t reinvent that wheel for that and Iq reasons
But I can still follow the path and experience the steps, step by step.
Last edited:
