Monday, January 7, 2013

Xanu XA-80

Well hello there!

So, as you may know, I have a pseudo company called Xanu Guitars and Music. It's not totally legit, mainly because I don't have the tools to start it up. Sounds like I should head on over to, eh?

Anyway, along with guitars and audio equipment, Xanu does simple synths (the ones I blog about, like the Triple Fiver). Well, in my journey to building the KereMAX, I have started a new project: the XA-80!

If you don't know, the Yamaha CS-80 was essentially a total badass. It was beautiful-sounding, thick, warm, and analogue (and used by Vangelis! And heard in Blade Runner! Which Vangelis did music for! With his CS-80!), not to mention weighed like 200+lbs and was a pain to move and keep in tune. Oh, and nowadays it runs for around $14,000.

Enter the XA-80. It started as an idea to sort of 'recreate' the CS-80's controls and structure and its general sound, but on a more doable level for me and with some slight moderisations and helpful additions. And, before the thought even crosses your mind, no, I can't just sit down with components and faithfully recreate it. This will end up being a cheap hardware emulation that is somewhat similar to the CS-80 but actually a totally different instrument.

What's inside the XA-80:
-Control: the XA-80 will have a 4-octave duo-phonic (maybe) keyboard and an adjustable-range ribbon controller, both adjusting pitch. I'll also have an overall pitch adjustment.
-Modulation: I'm not THAT awesome, so for modulation the XA-80 will only have exponential portamento and tremolo affecting the primary VCAs.
-Voices: 2
-Oscillators: It will have 4 individually-tuned ultra-stable oscillators outputting saw and square waves and noise, but I'm thinking everything dealing with pulse width will have to be kinda scrapped. Either that or I develop/find a totally new oscillator that has square waves with VC adjustable pulse width and saw waves. Either way, it's two oscillators per voice.
-Filters: the XA-80 will feature two 12dB filters, one high-pass and one low-pass, for each voice. They may or may not be resonant, it all depends on if I can actually make a resonant filter or not. It will have an ADSR for control of the LPF (which is an improvement over the original CS-80).
-VCAs: the XA-80 will have two, like the original, except the second one will simply be an amplifier, not voltage-controlled. The first will have input and output levels, a sine wave attenuator (from the oscillator), and an ADSR, just like on the original VCA sections. The second is just an amplifier with a level control, like the CS-80's Output control.
-LFO: this multi-waveform oscillator was labelled sub-oscillator on the CS-80. Really, it was an LFO with attenuated outputs to the VCA, LPF, VCO, and had a separate speed control. The XA-80 will have the same thing, but wider ranges.
-Ringmod: This I'm completely changing as the original was really more of an FM oscillator (but still way cool). The XA-80's will be a transformer-and-diode-based ringmod with two attenuated inputs and an attenuated output. It will use the two individual voices as the inputs. I may also put a crossfader on it to cross between the RM and the normal voices.
-Voice mixer: just like the original, a crossfader.

As for things I'm probably totally scrapping:
-Brilliance: Just because Yamaha can make an analog velocity sensitive keyboard affect levels, doesn't mean I can. Just set the ADSR's D a little higher, same general effect :)
-IL and AL controls: they would affect the level and voltage of the filter's ADR, but I will simply have an attenuator on the ADSR.
-2nd voice detuning: given that I'm using individually-tuned oscillators, this is kinda pointless.
-Octave/Footing controls: I'm using very wide-range oscillators, so these are also pointless.
-Presets: Yeah, ok, so I'm scrapping one of the main features of why the CS-80 was awesome, but you know what? I'm not about to even think about how to do analogue presets. You want presets, go digital or expensive :) Besides, I feel a synthesizer should be played and used as a synthesizer, not an instrument that plays like a piano but with different sounds.

Things I'm adding:
-External Input: the XA-80 will have no external control (not like the CS-80's was very useful anyway), but it will have an audio input which uses the 2nd voice's VCF and VCA.
-Other previously mentioned items.

So overall I'm doing what I can, but there's really no way I can faithfully recreate the mighty CS-80. As you can see, though, I'm recreating a lot of what the CS-80 was, as well as adding some useful features, so I just really hope it turns out well. Obviously I'll blog about my progress.

Oh, and if you are a CS-80 or perfectionist fan, please don't hate on me for leaving out important features. I'm simply not capable of doing them yet. This is a totally different instrument anyway, it'll just be kinda similar.

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