It holds an AMP32 plus 2x Monacor-SPH-30X (intertechnik.de, PA-20K/4) and it has a couple of tricks up it's sleeve to make it sound REALLY GOOD! (like notch filters and input transformers...as I did before, but better...)
It sounds incredibly big for the size and it has a nice little green led when it's on [^] Plus it has some really nice cables that should last for years....
The frequencies under 50hz are common low freq noise from traffic and stuff here in the area, the measurements were by no means done in a dead chamber.
Here's what's been done:
- first the voltage is stepped up and the signal is isolated by the Neutrik audio transformer.
- the mid to high frequencies lowered a little and the bass frequencies boosted a little bit (the Monacor drivers can handle a lot of power for a 3" driver).
- I chose to filter all the lowest of frequencies that the drivers can't reproduce anyway by replacing the input caps for much smaller ones. This makes sure the small drivers are not damaged from LF.
- and I set the input gain of the AMP-32 reasonably high (the highest gain with the supplied resistors).
Before anyone is to build one too, let me remind you that the speaker baskets have to be cut off (they're plate steel). This is quite a tricky job because the magnet (neodymium!) is very strong and debris can enter the magnet very quickly. I know this from years of experience so i took measures for this:
I taped off every hole in the speaker and after the cutting I taped on another layer closing up possible debris, than peeled the whole tape off. There can be small debris collected on the front of the cone as well on the dustcap), I removed this by holding a screwdriver near and magnetically attract the debris.
BE VERY CAREFUL FOR THE CONE DOING THIS!!!!
The magnet is extremely strong and can attract the screwdriver moving it through the cone!
I guess I was lucky... but I've had poorer luck in the past..
I just put it on a bicycle, the person who's gonna use this speaker wanted to take it along on the bicycle...
The battery in the bottlecage (in a bottle)