I know this is an old thread, but I’m about to try this… I’m going to take a guess that your input signal is overpowering your LD20. Those typically have 1.6V input sensitivity, and the DS-300 input is around +/-7V according to the post by Eva. I would measure that input at high volume and see what you’re piping into that board. Also, to simplify install, I’m going to see if I can design a 3D-printed adapter plate to just snap onto the main board.
That's a great idea! I have a 3d printer and just ordered the LD20 to fix my t500. If possible could you please share your design?
Sure, however I’m getting the feeling, from everything I’ve read about these amplifiers thus far, that heat dissipation is a concern, so it may be more important to find a board that has a heat sink that can be coupled with the exterior of the speaker. I don’t think these will last long radiating inside the cabinet.
Also, I’ve been looking at L25D’s instead of the 20’s. Anyone know why that would be a bad idea?
There's something about the T300 and T500 worth mentioning. One of the controls is for tuning a gyrator for what is essentially a parametric EQ. If the pot wiper lifts, the circuit becomes an oscillator. I believe the solution was to put a high value resistor from the center leg of the pot to one end. This damped the Q a little but prevented the thing from turning into an oscillator.
At the end I got a pair of these amplifiers: https://www.osdaudio.com/amplifiers...ass-d-digital-subwoofer-amplifier-smp100.html. At 3/4 volume they already overpowered the high section. They have bypass line for the amplified line coming from the receiver, so I can connect the L/R output of my receiver to the sub amps, then get one connection for the lower section (with phase and crossover control) and one for the high section using the existing high section plate connection on the back. In this way the receiver will see this a "full speakers". This is convenient if you have another dedicated subwoofer (in my case a p1000). I drilled a hole in the panel close to the positive connection of the high section since there was no track in the existing board so in theory I can decide to fix the existing board in the future. Super happy with this setup and with the ability to have crossover and phase control.