CategoriesTips & Tricks
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Mod. / enabling pitch controls

In this blog post, I’ll explain about how to enable pitch control function by simple modifications.

Pitch contol

The pitch control function was locked as default because the original concept of SnapBeat was simple sampler and I thought that the combination of recording sound quality setting (Lofi/Hifi) and the pitch controls makes it complicated. But you can unlock the function by some simple modifications.

How to enable pitch controls

You need to remove and add some components on the main PCB. Please prepare items below.

  • soldering iron
  • potentiometer B50k (50k ohm, B curve) x 3 (if you add pitch controls to the all eight channels, you need eight potentiometers)
  • hex wrench
Soldering iron
Potentiomenter
SnapBeat with hex wrenche.

Please prepare hex wrench.

Unscrewing the bottom case of SnapBeat, the simple lo-fi sampler

Unscrew the top two screws.
(no need to unscrew the bottom two screws) 

removing rubber feet of SnapBeat, the simple lo-fi sampler

Unscrewed the screws and rubber feet was removed.

Open top case of SnapBeat, the simple lo-fi sampler

Open top case.

modification points of pitch control

Remove the chip resisters on the main board. 

  • R76 : Pad 6
  • R91 : Pad 7
  • R92 : Pad 8
  • R82 : Pad 1
  • R81 : Pad 2
  • R80 : Pad 3
  • R83 : Pad 4
  • R78 : Pad 5
Pad1 – Pad 5 can be modified as same, but it’s a little bit harder because there isn’t enough space on the main board.
removed 0R resisters

Removed resisters.

Cut leg of potentiometer

Cut the first leg of potentiometers.

Soldered potentiometer for pitch control

Solder the two legs of potentiometers on the test points. 

Completed modification, pitch control

Pad 6, 7, 8 are modified.

Top case with holes

Drill three holes on the top case.

The 3D data of top case with holes will be available for download soon.

Screw the rubber feet and bottom and top case

Screw the rubber feet, top and bottom cases. 

Important notice

Operation of pitch control
Edit menu_1, SnapBeat, the simple lo-fi sampler

When the potentiometer is rotated clock wise, the playback speed of the sound becomes closer to its normal speed. On the contrary, when it’s rotated counter clock wise, the playback speed becomes slower. 

When you sample new sound, please not to forget to turn the potentiometer up to clock wise direction completely.
And please always use Hi-Fi mode sampling for the modified channels (Please don’t forget to record sounds with x0.5 speed).

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2nd lot 50 sets are in stock on Tindie

SnapBeat HW1-1 backlight ON
SnapBeat 3D printed cases waiting assembly

It’s already past about six months since the first sale of SnapBeat and it was sold out. After that I got many comments and request from people and they were very helpful to improve the product.

I had to do two things before I restarted selling it. One is to improve the product itself such as adding MIDI IN capability based on user’s feedback. The other is to improve its production facility such as 3D printers. For the first lot production, I had and used only one 3D printer to producing cases. But, now I’m using three 3D printers. In addition, I totally modified cases 3D design for optimizing printing time. Finally, I could improve productivity so much and it became about 1.5h to produce one set of SnapBeat at my room.  

I’ve also modified its firmware. Because this new version doesn’t include built-in sequencer instead of adding MIDI IN function, the system and menu become simpler. This time, I wrote a code almost from scratch and the menu and display became simpler and more useful than the first lot product.

Finally, the new version is ready to ship with new functions below.

  • MIDI IN (3.5mm TRS MIDI cable)
  • Back light for Pads (ON/OFF)
  • Pad responses (DRUM/GATE/TRIGGER)

Please be noted that from this new version, it doesn’t have built-in sequencer function due to the rack of program memory of Arduino micro controller.

SnapBeat website top here photo
SnapBeat HW1-1 with MIDI keyboard
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2nd lot 50 sets

PCBA of 2nd lot SnapBeat, the simple Lo-fi sampler
a close up of a PCBA of SnapBeat, the simple Lo-fi sampler for fun

Before I announced that the SnapBeat 2nd lot will be available on January 2024, but since I had been busy with another project, I think I can start selling it from the end of February.

Now I’ve already gotten 50 sets of PCBA as above photos.
From now on I have to modify blender 3D data for cases and code firmware for the MIDI-IN function.

I apologize for the delay.

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New version will be available on January 2024.

PCB of SnapBeat the simple Lo-fi sampler with MIDI IN

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.

I sell on Tindie
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The 1st lot was sold out

SnapBeat ship out, the simple Lo-fi sampler

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

photo of displaying Lo-fi and Hi-fi, snapbeat, the simple Lo-fi sampler

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.   

schematic diagram, Rosc and analog switch, SnapBeat

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.

wave form of DMX beat

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.

playback speed control in Spotify
Speed control of Spotify
window media player, playback speed control
Speed control of Windows Media Player
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How to assemble 3D cases of SnapBeat

Assembly instruction of 3D cases for SnapBeat.

Here is procedure of assembly 3D cases for SnapBeat.

Pre-soldered board of SnapBeat, the simple Lo-fi sampler

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

photo from back of SnapBeat, the simple Lo-fi sampler

Place the back panel.

photo of SnapBeat PCB and bottom case
photo of SnapBeat PCB in the bottom case

Put pre-soldered board into the bottom case.

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

photo of SnapBeat PCB, bottom and top cases

Put the top case.

photo of screwing SnapBeat bottom case

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

photo of SnapBeat, top case front

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.

photo of SnapBeat, gray and bone white color variations, the simple Lo-fi sampler

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.

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

photo of 3D printed cases of SnapBeat, the Lo-fi simple sampler

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).

I sell on Tindie
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SnapBeat Pre-soldered PCBA becomes available on Tindie

SnapBeat_PCBA_onTIndie

Today, SnapBeat’s pre-soldered PCBA is listed and becomes available on Tindie, the DIY electronics hardware market place.  Now It’s offered with promoted price for early adopters because it’s software would have some bugs and need further improvement. 

Buy on Tindie

I’m sorry for that currently only pre-soldered PCBA is available and product with cases are not listed.  The 3D printed cases take time and I can produce them only 1 set a day. I’m thinking to outsource manufacturing of cases with another material such as sheet metal to improve productivity.

Also I’m sorry for that now product is only shipped to US. This is because of lack of my knowledge about international shipping. I will survey delivery methods for other countries and add the shipping options as soon as possible.  

3D printed case of SnapBeat, the simple Lo-fi sampler
3D printed cases
Full assembled product
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Some times simple thing is better and fun

SLR_vs_snapshoot_camera
SLR vs point and shoot camera
Professional sampler vs SnapBeat

 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!