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FredT300B  > Hobbies > Building the FredArray
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The just-completed Fredarrays playing for the first in the upstairs listening room, driven very nicely by my Assemblage 300B amp. With 95dB sensitivity and a 9 ohm impedance they are easily driven by my 3.5 watt Bottlehead Paramours too.
The FredArray incorporates a ten driver midwoofer line array with a point source tweeter. The ten midwoofers are 5.25" Silver Flutes with cast metal frames and treated wool cones. After trying several tweeters I selected an MCM 1" titanium dome driver. Each enclosure is 72" high, 10" wide, 14" deep. The enclosures are rear-ported with two 4" ports. F3 is in the low 50's. Sensitivity will be about 95dB. The nominal impedance is a tube-friendly 9 ohms.
One enclosure in clamps while the glue is drying.
The other enclosure in clamps. Bracing between every other driver seems to work well in these tall enclosures
Mounting shelf for the back panel being glued into place.
The next step after the enclosures have been glued up is to smooth the seams where the mdf panels meet. This is done with a trim bit in the router. HINT: When cutting the panels, cut the front panel about 1/32" wider than it should be. Then, when you put everything together it will protrude about 1/64" on either side, so you can trim it flush to form a perfect seam which will not show through the paint or veneer finishing.
Here's one after trimming.
Next you do a roundover to the front edges. It's partially completed in this picture. There's some disagreememt about whether a small radius roundover reduces diffraction, but there's no doubt it looks better.
Edge trimming and roundover completed. I also apply a 50/50 glue/water mix to the entire exterior with an especially heavy application to the rough mdf edges. This will be sanded when dry to form a non-porous base for the paint. If you don't do this the edges will drink up several coats of paint and still look rough.
The just-completed Fredarrays playing for the first in the upstairs listening room, driven very nicely by my Assemblage 300B amp. With 95dB sensitivity and a 9 ohm impedance they are easily driven by my 3.5 watt Bottlehead Paramours too.
The just-completed Fredarrays playing for the first in the upstairs listening room, driven very nicely by my Assemblage 300B amp. With 95dB sensitivity and a 9 ohm impedance they are easily driven by my 3.5 watt Bottlehead Paramours too.
The just-completed Fredarrays playing for the first in the upstairs listening room, driven very nicely by my Assemblage 300B amp. With 95dB sensitivity and a 9 ohm impedance they are easily driven by my 3.5 watt Bottlehead Paramours too.
Original size: 1152x872 |
Current: 800x606 |
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