System objective: Sure TA 2024 amp and Zilched Minimus 7 drivers in OWI-202 cabs for mini system
I thought I had all of the parts and pieces on hand, picked an appropriate amp cabinet and began. The top started life as a square bamboo bowl. I also obtained a pair of cooked OWI-202 speakers which are just different enough from Minimus 7 cabs to build a one off speaker system.
The assembly began with installation of threaded spacers epoxy-glued into the top which secures a Sure TA-2024 board. Design did not include a BT01 Bluetooth but added flexibility, made it more desirable and I had one. A simple two-position switch selects BT or line in. The stiffening capacitors were hot-glued in place; an Alps volume control, 5-way posts, silver RCAs, power connector and 22 AWG OFC Teflon wires completes the amp’s infrastructure. Most electrical connections are mechanically secured then soldered.
Assembly was straight-forward but an appropriate base eluded me. After electronic and brick & mortar searches the bamboo cutting board of similar dimensions was located, a local cabinet shop cut the board to match the top’s dimensions (one cut). A woodworking supply store recommended red dye application to match the top’s color. Feet are cedar, secured with three screws each, also dyed and distressed, used only to retain brass footers.
The completed amp was hooked-up to a pair of Cornwalls and house 12V power supply (PS); sound was about what was expected. Plenty of clarity, a little tinny (over-emphasized extreme high frequencies) and bass authority did not match my 2024 reference. Bluetooth was noisy at full volume. I’ll look into these issues later.
While testing the amp, speaker assembly phase started. Searching through my Minimus 7 odd parts I couldn’t locate matching pairs of drivers so a pair of silver, early model, MIJ Minimus 7s donated their guts. A local plastics store cut the Plexiglas tweeter frames and I cut the speaker plate and crossover parts boards from an ABS sheet. The OWI cabinets were test-fit for driver compatibility and painted to match my (red) intentions. Painting sux, it took six cans of Duplicolor Cardinal Red to cover the white.
Outside of woofer cones was covered with two coats of thinned PVA glue and basket frames were damped with duct seal. Crossovers are PZ 2.1 Minimus 7 Loudspeakers - Measurements - AudioKarma.org Home Audio Stereo Discussion Forums and shoehorning the completed boards into the OWI cabs was a challenge. After the layout and wiring was completed, fiberglass insulation was added in (as close as possible) accordance with Pete B’s recommendations: Fiberglass was laid loosely around the crossover and the entire upper cabinet; the bottom of the cab was only lined with a half-inch around. The output of the 1mh inductor was connected directly to the positive terminal of the woofer and double strand 22AWG Teflon wire was used to make remainder speaker connections.
Before testing speakers the issue of a noisy BT had to be addressed. 5V is supplied from the 12V rails through a deconstructed lighter/usb power adaptor, physically and electrically connected to the BT. The PS was moved away from the BT and secured to capacitor bank. I checked all terminals and connections, reassembled the amp and put it back into my system.
Bass sounded the same as my reference amp and excessive sibilance was gone. I could listen to either amp interchangeably. BT had a little less noise and seemed louder.
For a system, speaker wires are required. On hand were two six-foot sections of original white Woods cord and a quantity of Multi-Contact bananas. 6moons audio reviews: DIY*Cables - The White Lightning Moonshine How 'out adding a pair of six-foot White Lightnin’ Moonshine speaker wires. Only difference between these and 6-Moons’ prescription is the pair of wires is red (not black) so one could hook them up backwards (on both ends)…if one cared.
Compared to the Cornwalls, I didn’t want to listen to the (now) red IMOs. After a week of burn-in the IMOs still sounded weak. Maybe OK for an office or TV system; will work great with a sub and lots more power but this system does not align. Sound became acceptable; clarity was flawless except there was no bass. Enough volume in my environment was achieved at close to max settings…with no bass. Listening in a larger environment exacerbated poor results. Subwoofer required for bass impact.
Reconnecting the little (red) amp to the Cornwalls was re-enlightening. Ref-amp will stay in place but if I didn’t have it, l’il red would do fine. Using the Samsung 4A SMPS brick power supply, this amp sounds fantastic on high efficiency speakers.
I thought I had all of the parts and pieces on hand, picked an appropriate amp cabinet and began. The top started life as a square bamboo bowl. I also obtained a pair of cooked OWI-202 speakers which are just different enough from Minimus 7 cabs to build a one off speaker system.
The assembly began with installation of threaded spacers epoxy-glued into the top which secures a Sure TA-2024 board. Design did not include a BT01 Bluetooth but added flexibility, made it more desirable and I had one. A simple two-position switch selects BT or line in. The stiffening capacitors were hot-glued in place; an Alps volume control, 5-way posts, silver RCAs, power connector and 22 AWG OFC Teflon wires completes the amp’s infrastructure. Most electrical connections are mechanically secured then soldered.
Assembly was straight-forward but an appropriate base eluded me. After electronic and brick & mortar searches the bamboo cutting board of similar dimensions was located, a local cabinet shop cut the board to match the top’s dimensions (one cut). A woodworking supply store recommended red dye application to match the top’s color. Feet are cedar, secured with three screws each, also dyed and distressed, used only to retain brass footers.
The completed amp was hooked-up to a pair of Cornwalls and house 12V power supply (PS); sound was about what was expected. Plenty of clarity, a little tinny (over-emphasized extreme high frequencies) and bass authority did not match my 2024 reference. Bluetooth was noisy at full volume. I’ll look into these issues later.
While testing the amp, speaker assembly phase started. Searching through my Minimus 7 odd parts I couldn’t locate matching pairs of drivers so a pair of silver, early model, MIJ Minimus 7s donated their guts. A local plastics store cut the Plexiglas tweeter frames and I cut the speaker plate and crossover parts boards from an ABS sheet. The OWI cabinets were test-fit for driver compatibility and painted to match my (red) intentions. Painting sux, it took six cans of Duplicolor Cardinal Red to cover the white.
Outside of woofer cones was covered with two coats of thinned PVA glue and basket frames were damped with duct seal. Crossovers are PZ 2.1 Minimus 7 Loudspeakers - Measurements - AudioKarma.org Home Audio Stereo Discussion Forums and shoehorning the completed boards into the OWI cabs was a challenge. After the layout and wiring was completed, fiberglass insulation was added in (as close as possible) accordance with Pete B’s recommendations: Fiberglass was laid loosely around the crossover and the entire upper cabinet; the bottom of the cab was only lined with a half-inch around. The output of the 1mh inductor was connected directly to the positive terminal of the woofer and double strand 22AWG Teflon wire was used to make remainder speaker connections.
Before testing speakers the issue of a noisy BT had to be addressed. 5V is supplied from the 12V rails through a deconstructed lighter/usb power adaptor, physically and electrically connected to the BT. The PS was moved away from the BT and secured to capacitor bank. I checked all terminals and connections, reassembled the amp and put it back into my system.
Bass sounded the same as my reference amp and excessive sibilance was gone. I could listen to either amp interchangeably. BT had a little less noise and seemed louder.
For a system, speaker wires are required. On hand were two six-foot sections of original white Woods cord and a quantity of Multi-Contact bananas. 6moons audio reviews: DIY*Cables - The White Lightning Moonshine How 'out adding a pair of six-foot White Lightnin’ Moonshine speaker wires. Only difference between these and 6-Moons’ prescription is the pair of wires is red (not black) so one could hook them up backwards (on both ends)…if one cared.
Compared to the Cornwalls, I didn’t want to listen to the (now) red IMOs. After a week of burn-in the IMOs still sounded weak. Maybe OK for an office or TV system; will work great with a sub and lots more power but this system does not align. Sound became acceptable; clarity was flawless except there was no bass. Enough volume in my environment was achieved at close to max settings…with no bass. Listening in a larger environment exacerbated poor results. Subwoofer required for bass impact.
Reconnecting the little (red) amp to the Cornwalls was re-enlightening. Ref-amp will stay in place but if I didn’t have it, l’il red would do fine. Using the Samsung 4A SMPS brick power supply, this amp sounds fantastic on high efficiency speakers.