4x QCW coils playing MIDI

[Mads Barnkob]

I saw this shared on facebook and it comes from a unknown Russian builder that has quite a lot of videos on his channel, but very little subscribers, definitely worth checking out!

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This should be a teaser good enough for everyone to straight away build multiply QCWs and replicate that awesome show

[Max]

Very interesting! And well done; I really like the arrangement!

When I saw QCW coils for the first time, I thought they would be perfect for playing percussive sounds in addition to a normal DRSSTC playing the notes. But this is even better!

How is the sound here generated? By modulating the bus voltage ramp with an audio frequency? Because the arcs don't look like DRSSTC-like interrupting and they also don't sound as sharp.


Kind regards,
Max

[Hydron]

As you also suspect, I'm almost certain that they are using long pulses (e.g. 10-20ms) and are modulating the bus voltage within each pulse with the note to be played.

This is similar to a normal QCW bus voltage ramp but instead of going for a long straight spark (with a single gradual ramp up/down) they're going for audio modulation instead to play the note - the bus modulator is essentially a class-D audio amp anyway!

The long pulses are what avoid the sharp sound of the DRSSTC - even without modulation pulses in the millisecond region sound _very_ different (much quieter and less "sharp"). In normal DRSSTC music the fundamental tone is from the repetition rate of the pulses (rather than within a single pulse) and then you have a whole lot of other harmonics etc on-top from the rapid heating/cooling of the air from the short pulses involved.

As Mads has mentioned, there are other videos on there worth looking at (I've been subbed for a while) - the "high BPS" QCW videos are especially recommended.

[profdc9]

Watching that video, I think the acoustics of that room helped the sound a lot.  It would probably have sounded much different if those coils were outside.  The echo effect really improves the staccato of the QCW coil and gives it more duration.

Dan

[futurist]

I like his QCW mario song

[Mads Barnkob]

Watching that video, I think the acoustics of that room helped the sound a lot.  It would probably have sounded much different if those coils were outside.  The echo effect really improves the staccato of the QCW coil and gives it more duration.

Dan

You are entirely right on this point, the echo really gives the overall wow effect here, I was so blown away by this video that I just drooled and forgot all about being critical

[Hydron]

They're also doing something funky with the breakout point of one of the coils - it glows much brighter than the others. Might be as simple as a small diameter point getting very toasty hot.

[Max]

The long pulses are what avoid the sharp sound of the DRSSTC

That's true. But I'd still guess, there's some anaolg modulation (which is no contradiction to what you said).

They're also doing something funky with the breakout point of one of the coils - it glows much brighter than the others. Might be as simple as a small diameter point getting very toasty hot.

Could also be some salt. At least the color matches, and it would explain why you can't see any glowing after a breakout at all.

Edit: In case anyone else wondered why there're 4 coils (beside the "because he can"), I guess it's because of the duty cycle; a single coil would probably run too hot. Or what do you think?


Kind regards,
Max

[pentode]

We have all seen and heard MIDI played on DRSSTC's and now
on a  4 piece QCWDRSSTC orchestra at
 

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The bass reproduction is better than DRSSTC.

But I await for an orchestra of QCW PLUS DRSSTC
to give a wider spectrum of sounds combined.
I getting very interested in it on a small scale,  We shall see.

[Teravolt]

does anybody know if they were built using the simple driver board

[flyglas]

I have asked the same question to the creator of the simple driver in this post --> https://highvoltageforum.net/index.php?topic=525.msg3301#msg3301

But he did not answer the question Perhaps he did not read my question or forgot to answer.