Ground Sound

Equilibrium Jr with Coolback II 600

This DIY project was inspired by another Danish forum member loudspeaker project
- The Equilibrium Project by "AKSA"

Thomas F's forum friend "AKSA" has a close relationship with the Austrailen DIY amplifier module manufacturer ASPEN Amplifiers
Both Equilibrium projects started out as passive loudspeaker systems, but ended up being actively controlled by Ground Sound digital crossovers. Whereas "AKSA" of course chose the ASPEN amplifier modules and "only" the DCN24 digital crossovers from Ground Sound, Thomas took a short-cut by investing in the optimized and very popular solution Coolback II 600 - which is more or lees "plug & play". So eventhough "AKSA" started some time before Thomas, Thomas was up and running sooner than "AKSA".
Thomas only had to remove the original passive crossover and mount SpeakOn connectors on the back of the loudspeakers. After preparing the loudspeakers and two wooden external boxes for the Coolbacks Thomas "invited" me (Robert GS) to make the final installation and initial measurements and setup.

Links to the Danish forum threads:
Thomas's Equilibrium Jr project
AKSA's Equilibrium project

The drivers in the Equilibrium Jr project is:
Tweeter - Scan Speak R2904/7000 - ring radiator
Mid-range - Focal Utopia 6W - modified
Bass - Peerless HDS205 - 2 pcs

At the time of installation of the Coolback II 600, Thomas already talked about upgrading the drivers...
Maybe new mid-range... Maybe new tweeter
- this I have experienced quite often when a customer sees how easy it is to make
the setup via the Ground Sound digital crossovers...
Inspired to do more


The inner structure is finished	Damping material between driver baffle and enclosure


First steps toward active drive	The passive crossover before it is removed


Installing the 8-pol Neutrik SpeakOn connector	Now only cables from the connector to the drivers

The Coolback II 600 and the external wooden enclosure ready for assembly

Ohh - that's me, Robert, soldering the SpeakOn connector with Thomas's tools

A bit of chaos when the measuremets were made, analyzing the results and making the setup

Above is the simlated response of the setup - pretty nice.
Now it's up to Thomas to fine tune the sound to his taste

The Active Equilibrium Jr loudspeakers
- as they look today unless Thomas has upgraded with new drivers...

active@groundsound.com