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Scott Hamlin

Casio RZ-1 Drum Machine

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Anyone have this little guy? A sampling drum machine was very rare at the time of release, and the individual outputs for each sound is still very rare on modern drum machines. This would be a cool one for Casio to update and re-release! 

 

rz1.jpg

 

Casio-RZ-1-Trap-Hip-Hop-Vintage-Drum-Mac

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I've never had one, though I wouldn't mind one to add to my collection. They're quite collectible now and no longer go for bargain prices. From what I've read/ heard, the samples are the same as found on the HT series keyboards rhythm sections. Of course, the RZ allows the user to load in their own samples, which is one of the major selling points of the unit. However, I understand that the samples are very short and might be quite low resolution. For the prices that RZ's go for, you could probably pick up an FZ sampler for similar money, which also had 8 line outs. Then get the RZ samples, load them into the FZ and have all the FZ features as well!

147582275_bbec10610a_b.jpg

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I'd pick up either if they were in good shape and going for a good price. :lol:

 

As far as the low-fi samples... Yes they are indeed, but that is a plus is much of the music I do. In fact I have an effect that simulates low-res to make my sounds more grainy. 

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In physics there is a thing called the Observer Effect: The act of observing or measuring something unavoidably affects what you are observing or measuring. This is kind of like that. In this case, releasing a video on YouTube about vintage gear that is "under the radar" brings that gear into enough prominence that it is now detectable by radar (to continue the analogy), increasing demand and driving prices up.

 

Now, concerning twelve-bit samples being "lo-fi". It's not nearly as bad as they are making out. Twelve bits doesn't have to sound "grainy" (or "crunchy" as they claim in the video). Any grain or crunch heard in sampled sounds is likely due to aliasing from using an overly-low sample rate for the input audio. Filter the audio coming in to the analog-to-digital converter in order to adequately remove frequencies above half the sampling rate and all will be well (assuming proper post filtering as well). If the result is overly dull, use a higher sampling rate if you can. A sampling rate of 48kHz generally does the trick. Unfortunately, the RZ-1 is restricted to a single sampling rate that is probably no higher than 20kHz (according to this site - the RZ-1 manual doesn't specify).

 

But 12-bit audio does obviously have a lower signal-to-noise ratio (SNR) than 16-bit audio (CD quality), which you can hear as a hissy (white) noise floor. The maximum achievable SNR in dB of a digital audio system is approximately 6 times the number of bits. So, 8 bits is about 48dB (objectionably noisy), 10 bits is about 60dB (noticeably noisy), 12 bits is about 72dB (about the same as FM radio and the same as old 1/4-inch reel-to-reel tape decks that were considered audiophile-grade Hi-Fi back in the day!) and 16 bits is about 96dB.

 

The "lo-fi" aspect of the RZ-1's sampled sounds are primarily because of a restricted frequency range, not a limited bit depth (although according to this site, the samples are eight bit not twelve, which means they are noisy). You probably won't hear anything much above 8kHz out of the RZ-1's outputs, which is about half what you need at a minimum for sounds containing high frequencies (like snare drum, hi-hats and cymbals). Other sounds like kick-drum and even tom will probably be okay.

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Snares and cymbals in classic drum machines with low sample rate are (unlike other drums) often output unfiltered, i.e. the samples will not sound dull, but the overtones you hear are fake (stair steps of the waveform). I haven't checked if this is done in RZ-1 (service manual can be found online). The same percussion IC however is also used in Casio CZ-230S. This is what I wrote about it.

The percussion generator "NEC D934G" (64 pin SMD, pins count anticlockwise) is a percussion sound IC with external sample memory, that was used in some Casio keyboards from mid of 1980th and (2 of them) in the RZ-1 drum computer. Percussion samples can be in ROM or in RAM for a sampler function, but sampling has to be done by the controlling CPU (e.g. " NEC 7811G-120" in RZ-1). The samples seem to be only 8 bit, but can be magnified by 2 additional volume control bits (pin DB6, DB7) from the CPU for accents. Percussion sound is output at 20 kHz through an external 10 bit DAC. Its analogue waveform then has to be routed through 4 sample & hold circuits to separate the 4 multiplexed analogue percussion channels (synched by the 80 kHz CLOCK output). The D934G can output 2 percussion sounds on each channel (named 'alpha' and 'beta'), those apparently can be separated further by 2 trigger signals from the CPU. The CZ-230S uses more pins than RZ-1 - likely due to larger address space.

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12 hours ago, CYBERYOGI =CO=Windler said:

Snares and cymbals in classic drum machines with low sample rate are (unlike other drums) often output unfiltered, i.e. the samples will not sound dull, but the overtones you hear are fake (stair steps of the waveform). I haven't checked if this is done in RZ-1 (service manual can be found online). The same percussion IC however is also used in Casio CZ-230S.

 

That makes sense. It's probably why the resulting sound is often described as "crunchy" and explains the appeal of low sample rate drum machines for certain types of music.  

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On 1/3/2017 at 11:35 AM, AlenK said:

 

Now, concerning twelve-bit samples being "lo-fi". It's not nearly as bad as they are making out. Twelve bits doesn't have to sound "grainy" (or "crunchy" as they claim in the video). Any grain or crunch heard in sampled sounds is likely due to aliasing from using an overly-low sample rate for the input audio. 

 

I'm not sure about the RZ-1, though the FZ-1 (plus 10M and 20M) are known for their "crunchiness". In fact, many find that it  adds a unique character to the samples. Now, I've no idea if it's the filter (analogue) that causes this, or if it's the way the FZ processes its samples. It's supposedly 16 bit (and advertised as such), though some speculate that it samples at 12 bit. Or as you said earlier, perhaps it's the frequency range that does it, though I do also know that the FZ has selectable variable rates for sampling.

When my FZ-20M finally arrives here from the UK (it's currently with the shipping company along with all my belongings) I will be eager to test it out!  

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