A small audio amplifier based on NE5532.

A small idea, by the way. Why not build a small, compact linear audio amplifier?

In fact, I had the opportunity to test a small amplifier based on an operational amplifier of the TL074 type during the development of the audio part of a Drumulator.

This concept of amplifier exists, obviously. I have only taken examples that can be found on the Internet.

32 circuits equivalent to 64 AOPs are placed in parallel. Push-pull type topology therefore 128 AOPs in service. This should provide enough power for more than adequate rendering. In addition, this circuit does not require any adjustment.

An example of how the circuit can be rendered:

I have some finalizations of track sizes to do and I think I will make this little prototype.

Attempt to clone an SP12 (3)

I just received the SP12 PCB.

Another circuit to build and test. However, this becomes quite difficult due to the lack of components.

Fortunately, I will be able to test the majority of the functions of the board thanks to a few tips. Some of the components will only be available from April or May next year: terrible situation!

MIDI SWITCH(2)

The final production version of the PCB has arrived.

Finally, the printed circuit is very small. I have gathered the MIDI ports in packs of four, which will make it easier to cut out the front panel of the case. I brought back the micro-usb power socket on the front panel.

It is planned to be able to connect a PC equipped with a small software to facilitate the configuration of the switch. I don't have a MIDI ID so I decided not to use the MIDI interface for this.

This possibility, like that of also serving as a USB/MIDI interface, is planned for the next version. 

Attempt to clone an SP12 (2)

Construction of the SP12 core continues. I routed the board and sent it to manufacturing.

Preview of routed faces. 

Both sides:

Front face:

And the back :

Finally, a 3D representation:

I just have to wait for the reception of the printed circuits to begin its assembly and the first tests...

Attempt to clone an SP12.

Creation of a digital core module for the SP12, with the audio conversion system:

The components are placed. Now I have to route the board!

MIDI SWITCH

The basic functions of the MIDI switch prototype work well. I'm still developing the system but at the same time, I'm redesigning the printed circuit board. 

The prototype was developed from an Intel OEM FPGA module placed on a motherboard that I created myself. On this motherboard, four connectors connect four small printed circuits each supporting four RJ45 sockets, for a total of sixteen ports.

This way of doing things was perfect for a prototype but not at all suitable for a finished product.
What I particularly appreciate is making it as simple as possible. And since the study from the prototype I experimented with a new type of FPGA more practical to use than Intel circuits, I took the opportunity to redesign the entire switch on a single printed circuit :

The circuit used will allow me to route the MIDI ports but also to perform some processing on the MIDI data. Everything will be programmable using, I hope, a small software running on PC and potentially on MAC.

MIDI SWITCH

It's been two months since I posted anything. After the holidays, I strongly put myself in the development of two projects. One of them consists of a 16-ports MIDI rack designed to facilitate the management of the MIDI network within a small music studio.

Although I'm still at the prototype stage, the hardware design is finalized and stable. I am now in the development of the software system. I am progressing step by step in order to create a system offering the essential functions. Subsequently, I will expand the operation by various functions that can be implemented depending on the computing resource that will remain available to me.

This is what the rack looks like:

The challenge is a little bit complicated. A reliable and practical device must be produced at an acceptable cost. And with the current problems of component shortages and rising prices, it really isn't easy!