未分類 - SnapBeat | the simple Lo-fi sampler for fun

2023年11月28日2023年11月28日 By Hiro Akihabara

New version will be available on January 2024.

Now, I’m preparing for production of new version SnapBeat. The new version has MIDI IN (via MIDI-TRS type A cable) capability and back light for sound pads (users can turn it ON and OFF).

Unfortunately, there is not only what was added but also what was lost. Because of the lack of program memory space of Arduino Nano controller chip, there was trade-off between adopting MIDI IN function and built-in sequencer program.

After the first sales of SnapBeat, I had many requests of adding MIDI capability for connecting it with other musical instruments. And I thought that it’s better choice to adopt MIDI capability and use external commercial sequencer via MIDI.

Next lot will be 50 sets and available on January 2024.
Same as the first lot sales, it will be available on Tindie.

I will announce on this blog as soon as it will become available.

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2023年8月26日2023年8月26日 By Hiro Akihabara

The 1st lot was sold out

The first lot 20 pcs of SnapBeat was sold out on Tindie. Thank you very much for people who gave me warm support. Also I’m sorry for the inconvenience of being unavailable on Tindie for a while for who want to buy it.

After the first sales, I got many comments and requests about MIDI interface for connecting SnapBeat to external audio devices. Since I was just an electrical engineer and newbie of electro music, I thought MIDI was something complicated technology. But after I searched it on internet, I realized that it was very simple technology using serial communication protocol which was very popular among MCUs such as Arduino which is used also in SnapBeat. I think it’s not so difficult to add MIDI input capability for SnapBeat without much cost.

Before the next production of SnapBeat, I should stop for a while and study about MIDI. I’m going to try to modify design and add MIDI input capability. Since currently I do everything from design, manufacturing, marketing and shipping by myself, I can’t produce the second lot sets and improve design at the same time.

I will share progress about MIDI implementation on this blog.

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2023年8月10日2023年8月10日 By Hiro Akihabara

A hack of ISD1700 voice recorder chip to improve recorded sound quality

What is Hi-fi sampling mode and how does it work?

SnapBeat is the simple Lo-fi sampler. Yes, it’s really Lo-fi as the name. It uses Nuvoton ISD1700 voice recorder chip for sampling and playback sounds. The chip’s patented MLS (Multi Level Storage) can record analog sound signal directly without Analog to Digital conversion. Thanks for the great technology, the recorded sound is very smooth.

Problem

From the point of frequency range, the chips sampling frequency is limited up to 12kHz as table below. It’s really narrow for a musical instrument purpose.

The sampling frequency is determined by external register called Rosc. And interesting usage of the chip is changing pitch of playback sound by controlling the Rosc. For example, if the chip played recorded sound with 12kHz speed setting and its actual sampling frequency was 6kHz, the sound was played with higher pitch than actual pitch.

After thinking about the method for improving sampled sound quality, I found simple but effective solution which can extend the sampling frequency range.

Solution

The solution I implemented a kind of hack which enhances ISD1700 chips recording quality a little bit. The physical limitation that sampling frequency is up to 12kHz can’t be changed. But what if SnapBeat sampled sounds which was played with x0.5 speed and played back it with x2 speed? As a result, the sampled sound is played with normal speed, but its frequency range is extended (shifted, more accurately) to approximately two times higher side.

The schematic below is ISD1700 recorder chip circuit of SnapBeat. You can find analog switch (74LVC1G3157) and two 56k ohm registers connected to Rosc pin. When the analog switch turns on, Rosc becomes 28k ohm (56k//56k). When it’s off, Rosc becomes 56k ohm. By switching the Rosc value dynamically, ISD1700 chip can change it’s sampling and playback speed independently.

Test result

To verify the the effect of this solution, I compared frequency range of actual sampled sound with Lo-fi mode and Hi-fi mode (Hi-fi mode sounds to be weird. I should think better name for the mode).

For the test, I used free beat downloaded from SampleRadar. The wave form below is of DMX Beat 09 (85BPM).wav.

The three pictures are frequency range of the original source (the left), of the sampled beat in Lo-fi mode (the center) and of the sampled beat in Hi-fi mode (the right). You can see that the original beat contains frequencies up to about 15kHz. But frequency range of the sampled beat in Lo-fi mode is up to only 5,000Hz. It’s because the sampling frequency determined with Rosc 56k ohm is about 12kHz (by theory, up to 6,000Hz frequencies can be sampled correctly). On the other hand, in Hi-fi mode, frequency range became up to about 10kHz which means that sampling frequency in the mode was about 20kHz (which is nearly two times better than original).

In Hi-fi sampling mode, we must always input x0.5 speed sound source. Fortunately, Spotify (only web browser version) and Windows Media Player have playback speed control. And in Hi-fi sampling mode, it becomes easier to truncate (trim) sampled sound more accurately because minimum step of controlling start and end address becomes finer.

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2023年7月29日2023年7月29日 By Hiro Akihabara

How to assemble 3D cases of SnapBeat

Here is procedure of assembly 3D cases for SnapBeat.

The LCD is attached onto PCB with 3D printed LCD holders.

Place the back panel.

Put pre-soldered board into the bottom case.

The bottom and top cases have enough strength with rib structure.

Put the top case.

Fix the bottom and top cases with screws at two corners.

Place the top front case.

Fix the bottom and top front cases with screws at two corners.

Put rubber feet at the four corners.

Assembly is completed.

Now, SnapBeat has two color variations (left : gray, right : bone white)
On 7/29 today, only pre-soldered board is available on Tindie, but I’m going to list these two colors finished product with cases.

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2023年7月29日2023年7月29日 By Hiro Akihabara

SnapBeat, finished product with cases will be available on Tindie soon.

Currently, only PCBA (pre-soldered board) of SnapBeat is listed and available on Tindie. But now I’ve completed adjustment and tuning of my 3D printer so that I can produce 3D printed case with quality. I’m going to list the finished product with 3D printed cases on Tindie. Firstly, the two colors, gray and bone white are available.

Now, the product on Tindie is available from various countries although shipping method is limited to e-packet (tracking available, delivered within 12 to 20 days).

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2023年6月19日2023年6月19日 By Hiro Akihabara

Some times simple thing is better and fun

There are two types of product. One is a high-end professional product and the other is simple affordable product. For example of camera, a SLR (Single-Lens Reflex) camera is professional product and a point ‘n’ shoot camera is simple product.

I think that not always professional product is better especially in terms of fun. Of course professional products have many functions and are high quality, and often simple products have limited function and inferior quality. But the limitation of the simple product forces or encourages us to compensate the weakness with our creativity. And thanks to the limitation, you aren’t be worried with many choices.

SnapBeat is the point ‘n’ shoot camera of sampler or drum machine. It doesn’t have many functions such as filters. But simply it makes you fun!

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2023年6月19日2023年6月19日 By Hiro Akihabara

OpnBeat changed the name to SnapBeat

OpnBeat, the simple and fun Lo-fi sampler changed its name to SnapBeat.

When I started development the simple DIY sampler, I wanted to name it as OpenBeat because it was open-source project. But because someone had already used the brand name online, finally I named it as OpnBeat. But this was not good idea since it’s simply not able to read.

Later, I understood that the convenience and handiness is the most strongest point of my product. So, I re-named it as SnapBeat. From Cambridge dictionary, the word Snap (noun) has meaning below.

something that can be done without any difficulty:

Like this word’s definition, you can sample any sounds easily and quickly by using SnapBeat. And most importantly, It’s really fun!

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2023年6月1日2023年6月19日 By Hiro Akihabara

The first production for test marketing

Yesterday, I visited our manufacturing partner to prepare the first production of SnapBeat’s board. We will produce 25 pcs of pre-soldered board for design verification and test marketing purpose. By now, I’ve made the board one by one by my hand, but from now I can make it a lot by the power of automation.

There are two purposes of this small volume production.

The first is to verify final design of the board. Because I changed some components for optimize productivity and cost for mass-production, it’s necessary to confirm that the final design works as intended.

The second is for test marketing. I want to know whether SnapBeat is actually accepted in market or not. And I want to understand who actually is the customer of this product.

After verifying quality of these 25 pcs boards, I start test marketing of SnapBeat online.

(*Note : OpnBeat changed the name to SnapBeat)