The sound produced by any given electric guitar is shaped not just by the instrument itself but by the amplifiers chosen to make that sound audible. Plenty of musicians swear by the warm sound of amplifiers with vacuum tube circuits, but they do have some limitations. [Collin] wanted to build a reactive load for using tube amps without generating a huge quantity of sound, and it resulted in an interesting project that also taught him a lot about inductors.

The reactive load is essentially a dummy load for the amplifier that replaces a speaker with something that won’t produce sound. Passive loads typically use resistor banks but since this one is active, it needs a very large inductor to handle the amount of current being produced by the amplifier. [Colin] has also built a headphone output into this load which allows it to output a much smaller quantity of sound to a headset while retaining the sound and feel of the amplifier tubes, and it additionally includes a widely-used tone control circuit as well.

There’s a lot going on in the design of the circuitry for this amplifier load, including a lot of research into low-frequency inductors that can handle a significant amount of current. [Collin] eventually ended up winding his own, but the path he took to it was long and winding. There’s a lot of other circuit theory discussed as well especially with regards to the Baxandall EQ that he built into it as well. And, if you’d like to learn more about tube amplifiers in general, take a look at this piece which notes one of the best stereo amps ever produced.

And then there are gyrators: Would save a lot of pain in making monster inductors. Though a gyrator to handle that kind of power brings its own headaches too, since it would require a heatsink.

The so called ‘warmth’ that’s omniprescent in audio homeopathy, usually turns out to be distortion in the form of overdrive / gain+soft-clipping.

People love distortion. And total RMS output wattage. Most of the audioheads who claim to want to eradicate distortion and listen to things at a reasonable volume are just lying. If your set can reproduce music at close to concert levels without hard clipping and fuzz, it’s a good set.

“the path he took to it was long and winding”

I used to work in telecomms and a colleague told me that back back in the dawn of the era of HiFi one of their colleagues was waxing lyrical about distortion-free perfectly linear amps and whatnot, so eventually they offered to build him one (baseband audio being not much of a challenge compared to the HF analogue transmission gear they were working with).

He was incredulous, but they built it and used their lab test gear to positively demonstrate that it had an absolutely flat linear response across the full range (and then some) – and it sounded awful, and was never spoken of again!

Bob Carver, purveyor of audiophile gear popular in the 1970s and 1980s was maker of “magnetic” power amplifiers. Snooty audiophiles looked down their noses at Carver’s amplifiers. There are apocryphal stories of Carver’s standing challenge that he could make his equipment sound exactly like any arbitrary fancy audiophile device. Supposedly Caver would be presented with a piece of gear at a conference, go back to his hotel room and after adding some analog components to his own device, emerge in the morning having met the challenge. At least to the limit of golden ears’ ability to discern any difference.

When “audiophiles” are wiling to spend up to $300 on special AC wall sockets with exotic metal contacts in order to supposedly get a better sound in spite of the fact that the wall socket is on the other side of the power transformer and filters I tend to not pay much attention to whatever they think is a better sound.

Google “audiophile wall sockets”, and then especially check out this link … https://www.enjoythemusic.com/magazine/equipment/0114/audiophile_ac_outlets.htm

Soon, they will only pay their music during certain phases of the moon….

I suspect that they only drink biodynamic wine, too. Hey, if it works for t POhem…

My favourite was the equally expensive custom-machined volume knobs that were claimed to greatly improve the sound.

Honestly if I were devoid of ethics I could make a fortune in the audiophile world.

There’s nothing unethical in parting an audiophool from his money. You’re not running a monopoly, your customer has the freedom of choice and will usually be happy with his purchase. Not much different from selling luxury cars or expensive timepieces.

I generally just play my vinyl with my body as the conduits between the mains outside my house. You would likely not believe how crisp the highs are when your body is convulsing at the same frequency. If you don’t do the same you don’t deserve to be called an audiophile. C’mere let me grab my oxygen-free 2 gauge jumper cables, I’ll show you…

Next up a dedicated powerplant Shielded dedicated powerlines And obviously 44khz to avoid that 50/60hz Hum

Why hasn’t anyone tried to error .. market (yeah yeah that’s it, ‘market’) DC powered amps to them?

“No hum in this power!”

“This is DC so there’s no skin effect to worry about”

“Zero frequency power doesn’t generate harmonics”

“Non reversing current, so no copper grain hysteresis to worry about”

.. or whatever other buzzword driven nonsense sounds enticing to those with money burning holes in their pockets.

Not to mention the possibility of recurring sales of hideously marked up custom battery packs

“but since this one is active”. Is it?

It’s inductive, which means the load changes over time, but it’s not active in the “is it driven by electronics” sense.

Is this similar to the Power Soak designed by Tom Scholz from the band “Boston“?

Many but not all amp power attenuators are resistive in nature. They use arrays of resistors to soak up the power. There was one some years ago that actually looked like a toaster inside.

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