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FIXED- Crumar Bit 99 - should it Sound this way?

Posted: Fri Jul 12, 2019 2:15 am
by kawaiicroc
First post! I just got a Bit 99, and all seemed fine at first, but I noticed when I have a sound with ramp or triangle added, there is a ringing sound over top of the note played. The ringing is actually in tune with the note played and is only apparent on the lower notes.

At first I thought maybe this was normal, but I don’t hear it in any other demos that I’ve listened to. Can other Bit 99 users attest to this?

Re: Crumar Bit 99 - should it Sound this way?

Posted: Sat Jul 13, 2019 11:24 am
by madtheory
Welcome here! Yes they do this, kinda sounds like aliasing on a sample. If you could post an audio example, just to be sure, that would clear things up right away.

Re: Crumar Bit 99 - should it Sound this way?

Posted: Sat Jul 13, 2019 5:17 pm
by kawaiicroc
madtheory wrote:
Sat Jul 13, 2019 11:24 am
Welcome here! Yes they do this, kinda sounds like aliasing on a sample. If you could post an audio example, just to be sure, that would clear things up right
Aliases is exactly what it sounds like. I will post a clip, but I think you nailed it.

Re: Crumar Bit 99 - should it Sound this way?

Posted: Fri Aug 23, 2019 2:16 pm
by kawaiicroc
After listening to a lot of online examples, my suspicion is that the aliasing on mine is more present in the oscillator than it should be. I will post some sound clips tonight. I wonder if it's the kind of thing that a replacement of caps might smooth out?

Re: Crumar Bit 99 - should it Sound this way?

Posted: Fri Aug 23, 2019 9:41 pm
by kawaiicroc
Here is the audio example. As it starts I am adding the pulse waves. No problem here. Then as the ramp and triangle waves are added you can hear the aliasing come in strongly. It almost sounds like a 2nd oscillator being added in at a higher ocatve.


Re: Crumar Bit 99 - should it Sound this way?

Posted: Sat Aug 24, 2019 12:58 am
by Big Gnome
(Disclaimer: I am unfamiliar with the Bits)
It's definitely not aliasing, as that would produce enharmonic partials that move contrary to the base pitch, and you wouldn't be hearing it triangle waves if you weren't on pulse waves, which produce louder harmonics by a power of 2. It sounds distinctly like truncation distortion to me (think NES music...), which would make sense: according to Gordon Reid, the bits' oscillators, while technically DCOs, produce their waves by dividing down a high frequency square wave master oscillator and summing the lower frequency squares for its output (kinda like how the Korg Poly 800 does), which is more or less analogous to how purely digital oscillators work; so you might end up with a "triangle" or "saw" wave composed of, say, a dozen or so stair-steps, which would definitely manifest this kind of artifact. My $0.02 is it's probably just the nature of the beast and not something wrong with your unit.

Re: Crumar Bit 99 - should it Sound this way?

Posted: Sat Aug 24, 2019 8:09 pm
by madtheory
Yes, it sounds like a normal Crumar Bit synth, and Big Gnome has just explained really well, exactly why it happens. It's also why sometimes, especially in Unison mode, the harmonics can cancel a lot a notes get quieter randomly. That's a "problem" on the MiniMoog as well when you use three oscillators as sound sources (more often it's two osc with one for modulation).

Re: Crumar Bit 99 - should it Sound this way?

Posted: Sun Aug 25, 2019 9:40 pm
by SEM
It's a great synth- too big and heavy though. Anyway, mine does this too. I have a Siel Mono Synth which does something similar on the low notes. DCOs all the way.

Re: Crumar Bit 99 - should it Sound this way?

Posted: Mon Aug 26, 2019 2:49 pm
by kawaiicroc
Thanks everybody. I'm going to go ahead and mark this is fixed.