I’ve been working on this for the last couple weeks. The box was originally lazer cut for another purpose, but is applicable to this project. A pair of RS100P-8 are serving as widebands, surface mounted, and a front trim ring and aluminum grill are then mounted atop of them.
To get “some” bass out of them, the baffle was originally also cut for a TB W3-1750S, and would have been a 2.1 setup. The former used a different and better W3 woofer, so the 1750 sat on my shelf. FFWD to a couple weeks ago, I decided to use it as passive radiator with brake assist. I measured it with an Lpad attached until I got a Qmp of 2.0, and that is a 20 ohm resistor value in this case. The concept I likely first saw in the Sonus Faber Extrema, and thought it eould work in this application better than a sub with its limited xmax.
Box is about 3 ltrs. It uses the AcoustaBlue damping, and currently the tentative network shown.
I should be able to mount the amp and test it in a day or 2.
I do not comprehend the circuit, but I will continue to check on this thread because I am intrigued. Also I first thought your speaker case looked like it was made from sugar wafer cookies.
Had to figure out how to allow the blue pairing/power LED to show while looking at the boombox, and this is what I came up with. It also allows replacement of the amplifier should something go wrong. (Not shown is the black sealing gasket that goes under the amp puck.)
I decided to use 2 strips of Neoprene tape in the gaps on the top due to lack of time, as this is to be finished by Saturday. (Yeah, cutting it close again.) Top gets glued on shortly after I post this, then maybe a coat of polyurethane before the night is over on the wood panels.
I stained the rear panel to finish it, just a brushed on coat of the same stain on MDF. I may leave the btm naked with a seal coat of glue and call it good.
Tomorrow I test and glue on the back if all goes well.
Sonically, balance is warm without being dark. It has decent kick- if you have enough juice! It seems honestly that currently (pun intended) this booger wants a strong power supply. Both the 19V/3.3A linked above, and a 16.5V/4.6A PSU led to clipping from the amp after a second or 2. Until the clipping starts, it sounds great.
So- i overnighted an Amazon 24V/6A floor wart and solidly glued the back into place. This means I’ll be able to get the PR bass evaluated better tomorrow morning with the better PSU in tow.
I should say, played quietly, neither previous PSU led to clipping. The “where I want it” output isn’t there without more though. The board also sends a message to the source saying “there is only 10% battery life remaining”, and I don’t even use a battery here. 24V PSU has arrived, will be testing shortly.
When I built the OSFA speaker, I never felt that I could not get the output I desired with the older KAB 30x2 amp.
Did some digging, and the ZK502L I’m using in this build is apparently either a Fosi made board, or a clone of it.
Okay, found the clipping cause was something I did. If you use the board as marked, the polarities are correct and it should function well. Just hook up drivers and go. I checked it with a YouTube (L/R/Stereo in phase/Stereo out of phase) test.
I found the 24V/6A supply to work the best.
Turns out, it has the L and R channels reversed currently, but that is an easy fix and likely my fault too. I used a 4 terminal strip for connections to the amp, drivers, and filters.
However, it sounds pretty good as it sits. The bass with the damped driver in the center works rather well. It has enough impact and depth. At -2 on the phone and 3:00 on the knob, the RS100 move pretty good, but not overly so. Thank you 500uF caps!
Treble is what it is from the 3” drivers, but it’s lacking a bit up top.
