The M1 speaker project with ABC switch

[HAL]

Converting a pair of commercial 2-way speakers from the original passive crossover to a dspNexus 2x8 Audio Weaver DSP crossover.

Building an RPi5 driven ABC switch to compare the original passive crossover, a passive crossover with better quality components and the DSP crossover. The user can run a Thonny Python 3 program to switch between all three crossovers after level matching at 1KHz. The Python program is running the GPIO logic now to drive relays for the switching.

Plan to take the setup to CAF2024 in room 702 to demo the system so listeners can hear the differences. But sorry, the subs will not fit in the demo room.

Attachments

[HAL]

Building the ABC Switch relay wiring and testing the drive circuit. Using 8-DPDT replays with silver contacts for the speaker level switching between the crossovers.

Decided on a RPi5 using Thonny for Python 3 coding for the logic drive to the GPIO ports. A ribbon cable to the driver board.

Simple relay switching with power MOSFET VN10KM drivers. Each relay coil is 12VDC@0.203A, so the small VN10KM devices will work without a heatsink.

The SMPS is working and will power the RPi5 and all the relay coils.

Attachments

[HAL]

The first ABC Switch relay box #1 prototype is done. The Neutrik connectors are relay switching signals on the front with the outputs to the speaker drivers.

Rear connectors are the ABC inputs from the different crossovers.

Now to build relay box #2.

Attachments

[HAL]

Built the relay controller boards and wired them to the relay connectors and SMPS.

Next is wiring the RPi5 ribbon cable to the controller boards and start testing the ABC Switch.

Attachments

[HAL]

The ABC Switch RPi5 and Relay control boards are now connected.

Time for some relay testing for channel #1 then swap to channel #2. Then onto both.

Attachments

[HAL]

The M1 speakers ABC Switch System is ready for testing.

This is the original passive crossover, upgraded component passive crossover and inputs for the dspNexus 2/8 DSP crossover system.

Now for system connection and listening trials. Need to level match the 3 crossovers. Cable lengths for each channel are 8ft of Belden 1309A 14awg speaker cable without the PVC jacket.

Then, let the games begin!

Attachments

[HAL]

For the upgraded M1 speaker crossover, the original value of two inductors used is not a stock value. Had a matched pair of aircore inductors made for the new passive crossover for the ABC Switch box system.

I will install these and ready for system installation and ABC crossover trials.

Attachments

[Cogito]

What is the goal of this exercise?

Comparing passive crossovers with active DSP crossovers is not a fair game, as the active DSP crossover optimizes the signal for the listening environment.

Unless, you are trying to show the benefits of active DSP crossover. No?

[HAL]

People have asked how does DSP crossovers compare to original and upgraded passive component crossovers.

I used popular upgrade passive parts so they can hear the differences.

Many people have not heard the differences between what passive and modern DSP crossovers would sound like.

The ABC Switch lets you hear all three with the same music material.

These will be level matched ABC comparisons.

[Cogito]

Sounds good.
Will you be demonstrating it in CAF?