Gyrators can be used to replace inductances in electronics circuits. The advantages are large inductance values and predictability of parameters. The disadvantage is a limited frequency range . Gyrator circuits with resistive feedback are very common circuits
This was an enjoyable video and your analysis was pithy and well done. Worked on an integrated gyrator in the early part of my career which simulated an 8 H inductance. Compared to a 6 H real inductor at my bench, the size difference between the IC and bulky inductor was obvious, but the frequency response performance of the gyrator circuit was similar to the real inductor.
I came across gyrators a while ago back in JR year of uni. Was so cool to see that I could have a completely parameterized inductor for audio circuits. Currently have a WOOOSSH pedal im working on that is basically just a 1 band parametric EQ.
Some further thoughts after looking back over some more schematics that use gyrators (in addition to the four you brought, Nobels ODR-1 and Boss XT-2): it seems like R >= 25RL and in most cases >= 100RL. Do you think that’s a design guideline to ensure we can disregard the effect of parallel impedance Z2? Or are there other factors at play? Also seems like all the gyrators are configured as notch filters and then use an op amp to cut/boost the band that is notched. Is that correct? And are other topologies possible? Speaking of the Boss XT-2, its EQ is quite interesting. This video th-cam.com/video/gC6a8tdzzyU/w-d-xo.html does a great analysis and suggests some mods. The HM-2 has two gyrators on the same pot (mid and high), and it’s a relatively simple nod to break out the mid onto its own knob for more control (on my BlackBender, I used a switch for user choice of 2-knob or 3-knob control). Of course, the most popular HM-2 mod is to hardwire all three gyrators to the non-inverting input, since “everyone” just dimes all the knobs anyway 😂 (see, e.g., TC Electronic Eyemaster). Finally, Electric Druid has an amazing analysis of the MT-2 EQ - there’s *a lot* more going on there than it seems at first blush: electricdruid.net/boss-mt-2-metal-zone-pedal-analysis/ (Also worth mentioning ESP has a characteristically thorough essay on gyrators in audio circuits: sound-au.com/articles/gyrator-filters.htm)
*The metal zone is probably still the most widely used pedal on tube amps by shred players such as myself, but I'm not running one.* It's also just a very common pedal for soloists and instrumentalists on Mesa Boogies, 5150's etc. I've never worked with gyrators because I'm still stuck with perfboard builds ATM lol. The BJT is more applicable than an op amp in this regard. I bought the CNC mill and laser etcher for mfr. my own "PCB's", but still just hoping to get started with them this year. *It's 10 tons of work to take on all these technical trade skills coupled with a science education for one person in a DIY environment.*
Gyrator circuit, i learned something new. Thank you. This math you doing, should probably be executed 20.000 a second to produce something meaning full. 10:33 these look kinda like Butterworth filters or so, but a bit differently applied.
Uh! A video about gyrators. Fun little circuits, rather useful for filters. Thanks for making this video! :) I have a question: Does the opposite of a gyrator circuit exist?
Is it possible that the backward transistor in the Bad Monkey schematic is being used in the reverse-active region on purpose? I'm curious what that would do for the frequency response and sound.
I bought a metal zone pedal in university, and it sounds like crap. 22 years later and it costs the same price haha I hear the new waza one sounds better.
Guitarists are embarrassing at times. I never understand how people think that a given capacitor of a given value, provides different tonal qualities of tone depending on the material it's made from. Surely it doesn't matter if it is a tiny modern one or a vintage orange drop if the capacitance value is the same. It's like talking about tonewood for a solid body electric guitar or the finish being bare wood or lacquer.
In a 9V environment that may-be true but if you are talking High-Voltage things change. A shitty ceramic sounds definetly different then a good film cap in certain places. And that is due to material properties, no voodoo involved.
@@Pentode3000 I can't see why, you may be right, but I would have thought that ceramic might be for lower voltage applications? I've only made low voltage stuff, so forgive my ignorance.
@@kentl7228 All good. Ceramic Caps are available in many different voltages. Ceramic caps and those old Allen Bradley brown Carbon Comp resistors have a nonlinear behaviour under high voltage and thus create distortion. Voltages like present in tube amps and that is where the myths come from. If people then use Carbon Comp in a 9V environment for the magic mojo i have to laugh too.
@@Pentode3000 I am amused too. People want THE pedal, THE guitar, THE amp as used by some idol player to get the sound. But where did they play along the string length? Where was the microphone? By the centre of the speaker or somewhere else? What did the engineer cut at the mixing board? No, just get the sprague orange drop or oil filled paper capacitor on the tone pots then I will be identical to Hendrix. Of course, people get these capacitors and just run the tone pots at 10 anyway... I searched TH-cam just before and found an interesting proof of our thoughts... th-cam.com/video/dEr-66DR8PM/w-d-xo.html
Finally somebody is talking about the actual electronics.
Thank you for your kind words!
This has been my obsession over the past few months - thanks for covering this topic!
Gyrators can be used to replace inductances in electronics circuits. The advantages are large inductance values and predictability of parameters. The disadvantage is a limited frequency range . Gyrator circuits with resistive feedback are very common circuits
This was an enjoyable video and your analysis was pithy and well done. Worked on an integrated gyrator in the early part of my career which simulated an 8 H inductance. Compared to a 6 H real inductor at my bench, the size difference between the IC and bulky inductor was obvious, but the frequency response performance of the gyrator circuit was similar to the real inductor.
This brings back memories. In the 80's I built my own guitar preamp and used such circuits in the tone control.
Gyrators are interesting elements in classical electrical network theory. Fun fun fun .
Wow, blast from the past. Almost totally forgot this from EE school in the late 80's, since I somehow wound up in software all these years.
I came across gyrators a while ago back in JR year of uni. Was so cool to see that I could have a completely parameterized inductor for audio circuits. Currently have a WOOOSSH pedal im working on that is basically just a 1 band parametric EQ.
IIRC the API 560 Graphic EQ used gyrators. I have a schematic around here somewhere…
Great video!
Some further thoughts after looking back over some more schematics that use gyrators (in addition to the four you brought, Nobels ODR-1 and Boss XT-2):
it seems like R >= 25RL and in most cases >= 100RL. Do you think that’s a design guideline to ensure we can disregard the effect of parallel impedance Z2? Or are there other factors at play?
Also seems like all the gyrators are configured as notch filters and then use an op amp to cut/boost the band that is notched. Is that correct? And are other topologies possible?
Speaking of the Boss XT-2, its EQ is quite interesting. This video th-cam.com/video/gC6a8tdzzyU/w-d-xo.html does a great analysis and suggests some mods.
The HM-2 has two gyrators on the same pot (mid and high), and it’s a relatively simple nod to break out the mid onto its own knob for more control (on my BlackBender, I used a switch for user choice of 2-knob or 3-knob control).
Of course, the most popular HM-2 mod is to hardwire all three gyrators to the non-inverting input, since “everyone” just dimes all the knobs anyway 😂 (see, e.g., TC Electronic Eyemaster).
Finally, Electric Druid has an amazing analysis of the MT-2 EQ - there’s *a lot* more going on there than it seems at first blush: electricdruid.net/boss-mt-2-metal-zone-pedal-analysis/
(Also worth mentioning ESP has a characteristically thorough essay on gyrators in audio circuits: sound-au.com/articles/gyrator-filters.htm)
*The metal zone is probably still the most widely used pedal on tube amps by shred players such as myself, but I'm not running one.* It's also just a very common pedal for soloists and instrumentalists on Mesa Boogies, 5150's etc.
I've never worked with gyrators because I'm still stuck with perfboard builds ATM lol. The BJT is more applicable than an op amp in this regard.
I bought the CNC mill and laser etcher for mfr. my own "PCB's", but still just hoping to get started with them this year. *It's 10 tons of work to take on all these technical trade skills coupled with a science education for one person in a DIY environment.*
My question - there are limited ways to create overdrive and distortion. How can we design a new circuit for OD and Distortion?
Gyrator circuit, i learned something new.
Thank you.
This math you doing, should probably be executed 20.000 a second to produce something meaning full.
10:33 these look kinda like Butterworth filters or so, but a bit differently applied.
You forgot the important and one of the first gyrator circuits the Tube Screamer
I don't seem to see a Gyrator in the Tube Screamer?
😊
Uh! A video about gyrators. Fun little circuits, rather useful for filters. Thanks for making this video! :)
I have a question: Does the opposite of a gyrator circuit exist?
Capacitor multiplier?
@@r080 That actually makes sense, Thanks.
s high pass filter.
I would love to take one your classes :,(
Is it possible that the backward transistor in the Bad Monkey schematic is being used in the reverse-active region on purpose? I'm curious what that would do for the frequency response and sound.
Do any wah-wahs use this method instead of an inductor?
Never seen one. Morley and George Dennis have inductorless models but they are active variable bandpasses as far as i know.
Bad Monkey fever… catch it!
What's a gyrator do?
Think of it as a circuit that adds a band of EQ boost, than the usual cutting to sculpt an EQ.
an inductor without an inductor.
I bought a metal zone pedal in university, and it sounds like crap. 22 years later and it costs the same price haha I hear the new waza one sounds better.
Guitarists are embarrassing at times. I never understand how people think that a given capacitor of a given value, provides different tonal qualities of tone depending on the material it's made from. Surely it doesn't matter if it is a tiny modern one or a vintage orange drop if the capacitance value is the same.
It's like talking about tonewood for a solid body electric guitar or the finish being bare wood or lacquer.
In a 9V environment that may-be true but if you are talking High-Voltage things change. A shitty ceramic sounds definetly different then a good film cap in certain places. And that is due to material properties, no voodoo involved.
@@Pentode3000 I can't see why, you may be right, but I would have thought that ceramic might be for lower voltage applications? I've only made low voltage stuff, so forgive my ignorance.
@@kentl7228 All good. Ceramic Caps are available in many different voltages. Ceramic caps and those old Allen Bradley brown Carbon Comp resistors have a nonlinear behaviour under high voltage and thus create distortion. Voltages like present in tube amps and that is where the myths come from. If people then use Carbon Comp in a 9V environment for the magic mojo i have to laugh too.
@@Pentode3000 I am amused too. People want THE pedal, THE guitar, THE amp as used by some idol player to get the sound. But where did they play along the string length? Where was the microphone? By the centre of the speaker or somewhere else? What did the engineer cut at the mixing board? No, just get the sprague orange drop or oil filled paper capacitor on the tone pots then I will be identical to Hendrix. Of course, people get these capacitors and just run the tone pots at 10 anyway...
I searched TH-cam just before and found an interesting proof of our thoughts...
th-cam.com/video/dEr-66DR8PM/w-d-xo.html
@@kentl7228 I hear ya. Brian Wampler did a nice one on Chips. th-cam.com/video/PH2uj9bWfM4/w-d-xo.html