Author Topic: 0415 Guitar Synth + Mastadon - Quest for the Ultimate Bass Synth  (Read 157 times)

Mikro93

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Hi guys,

This topic is a review of two effects I recenly built, and some ways to get some sweet analog synth sounds with a bass. It includes soundclips, review and FFT analysis.  ;D

What is it

 - the 0415 Guitar Synth by Parasit Studio, a PLL-based synth pedal that plays a synthesized square-ish wave proportional to the played note. It features (-1 or -2 octave) and (+1 or +2 octave) blended together with a MIX knob. No dry signal, and no square wave at the same pitch than the played note, they are always 1 or 2 octaves apart. Full kit goes for 34 euros including pre-drilled enclosure.



 - the Mastadon by GuitarPCB, wooly-inspired gated fuzz, with knobs for gain (Wool), volume (Vol), equalisation (Eq) and gate (well... Gate). The assembly was quite a challenge despite the small circuit, and my second attempt is still far from perfect (no LED, residual noise...). But practice makes perfect, right? The whole kit clocks in at 32 euros including predrilled enclosure.

Here is a family picture along with a Green Muff Civil War (Blue Muff, aka Musikding clone of the Russian Big Muff) and an Into The Unknown, which is 0415's big, twisted sister.



You'll also hear a Zorg Effects' Love Philter, which is a LP/HP filter made in France, which happens to be available as a DIY kit.

How does it play

With these two effects, I can obtain some pretty rich sounding synth sounds.

Both circuits are gated by nature, especially when running one into the other; this goes along with imitating a synth sound, with very few fret sounds and string sounds.

What's more, both effects tend to compress the sound for a high sustain, at least while the input signal is loud enough. This emulates sort of an ADSR envelope with Attack set to 0, the Decay set to 0, maximum Sustain and Release set to 0.

The 0415 by itself sometimes lacks some bass in its -1 setting. This is a bit frustrating, since the square wave does indeed sound like a square wave, only a bit thin to my taste. I found two ways to get around this: 1) put the Mastadon after it, to bring back some fatness (and also even harmonics, which I'll develop later...) and 2) use a sweeping low-pass filter with high resonance, which can enhance the lowest harmonics when the cutoff frequency sweeps by it. You can hear all that in the sound section.
The 0415 features a trimmer pot to adjust sensitivity of the PLL chip - my guess is that it's just an pre-gain in front of the chip, but I didn't check the schematics  ::). The effect behaves at its best when playing high on the neck, and with the right hand plucking at half of the vibrating string length. This feeds the pedal with a close-to-pure tone which allows for impeccable tracking.

I'm not exactly convinced by the Mastadon, but my kit might not be properly assembled. It is certain that the circuit doesn't lack low frequency by any stretch of the imagination. The EQ is efficient and versatile, covering a wide range of the frequency spectrum, and the Gate knob can really cut the noise and bring out some of that "velcro" character, yet not as much as a Fuzz Factory.

But the chaining of the two pedals, 0415 -> Mastadon, really shines in my opinion. You can hear that below, but I find it very close to the character of a sawtooth wave, with very few interference noise, and close-to-zero latency (since there is no "real" tracking as in digital effects, and no workaround to pass latency off as portamento...).

How does it sound

Here is a soundclip:


I'm playing a Harley Benton B-650 straight into a soundcard, with a bass amp simulation plugin. You can hear :
 - Dry bass
 - Bass -> 0415
 - Bass -> 0415 -> LPF
 - Bass -> Mastadon
 - Bass -> Mastadon -> LPF
 - Bass -> 0415 -> Mastadon
 - Bass -> 0415 -> Mastadon -> LPF

And two bonus clips : Bass -> 0415 -> Mastadon and Bass -> 0415, playing the low B string, hence reaching a B-1, and that's 15 Hz. 15 Hz with a clean tracking, how cool is that?

You got it, I really love that 0415 -> Mastadon sound, and I can hardly wrap my head around the fact that I can get such a clean sawtooth sound for that low amount of money.

There is something interesting going on with that 0415 -> LPF, a square wave can be heard, but it is not exactly an easy task, especially with a musical context around it.

How does it look like

Let's take this a step further and take a look at what the frequency content looks like.

The results presented here have to be taken with a grain of salt, since the FFt analysis (performed with Audacity) is made on only one note (E1) and on 8192 samples. But the sounds are almost stationary, so it should be good enough for all practical purposes.

Here is the E1 of the dry bass:



Few high harmonics, strong 2nd and 3rd harmonics, no doubt, it is a dry bass.

Now, the 0415 alone:



Those lovely odd harmonics are a distinctive feature of a square wave, here with peaks at 41 Hz, 123 Hz, etc. and dips in between. A perfect 41.2 Hz square wave is presented below:



This signal is much cleaner, which is not surprising since the 0415 circuit is  not a proper square wave generator, but it shows the same peaks and dips.

Now on to the 0415 -> Mastadon combo:



This time, all harmonics are present, which is typical of a sawtooth wave. They do stop a bit early, around 10 kHz, which sounds like a slightly filtered swatooth wave. For the record, here is a perfect 41.2 Hz sawtooth wave:



Again, much cleaner, but the two sounds clearly cover the same ground. Of course, we have to keep in mind that the analog synths we all know and love do not provide perfect waves, and that accounts for variety and certain character of a sound.

How to conclude

Once again, I'm blown away by the sounds of that specific combo. Getting such clean sounds for such a low amount of money is an absolute delight. Of course, the combo is not as versatile as an actual synth, since it does not provide the same settings, but nevertheless that stuff is awesome, and I might want to put the two effects in a single enclosure in the near future.

Of course, this approach is purely empirical, we're so far away from the Future Impact and other digital effects.

Do you guys have any sweet synth tones with combinations of DIY boxes?

Thank you so much for reading :)

Cheers,
Mik

bsoncini

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Re: 0415 Guitar Synth + Mastadon - Quest for the Ultimate Bass Synth
« Reply #1 on: August 20, 2017, 01:10:09 PM »
That is quite the build report. Sound and wave samples. Nice work. I've built a few into the unknow's. Fun pedal to mess around with.

Mikro93

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Re: 0415 Guitar Synth + Mastadon - Quest for the Ultimate Bass Synth
« Reply #2 on: August 21, 2017, 01:41:31 AM »
Yeah, I went quite in depth with this one :)

And yeah, the ITU is a fun one! Synth, Theremin, noise box, plus a PWM-like, lots of fun :)