AV8 8" home theatre speaker

 AV8 is a home theatre speaker based on a 1" compression driver, 8" waveguide and 8" midbass driver. Shown here on my measurement turntable where the dispersion performance is tested. The MDF enclosure is rubber lined for vibration damping and it's also sealed with fibreglass resin to resist moisture changes, hence providing a good substrate for the textured paint finish that will be applied. 

AV8 is a 93 dB speaker designed to reach THX reference levels with an ordinary AV receiver. It has an 8 ohm load, 70 Hz extension and a small box. Being an AV speaker, it's anticipated that it will be placed near the wall. This particular pair is designed for a client where it will be placed on a pro audio bracket.

The midwoofer has a clear coating which helps to damp cone breakup. When testing the raw driver with no filters in place, this is audible in comparison to lighter untreated cones. 

This is an alternative driver that was tested, without the treated cone. It has higher sensitivity in the upper midrange, but cone breakup is clearly audible. Although a cheaper driver, the savings are likely lost in a more expensive crossover.

 

Woofer baffle. Neo magnets are hidden in the baffle for grille attachment of woofers. These are machined manually, not via CNC, since they are machined from the rear of the baffle and this doesn't easily suit the CNC process, where all work is done from the top side. This is done with a drill press manually, then what remains is filled with bog. A straight cut bit is used, since a drill bit would not let the magnet get close enough to the surface without breaking through. 

The baffle above is for the surround (AV8S).

CNC panels laid out:

Rubber sheets line the box for vibration damping. 

Front baffle:

AV8S construction. Damping rubber and some of the lining is attached during assembly, as access is limited after.

Woofer baffle is double thickness.

Keyhole brackets allow the box to be installed to the wall. You can also see a recessed section around the speaker terminal cut out. This allows a speaker wall plate to be located here, so all cabling is hidden, and installation is simple, with no need to offset the speaker from the wall.

Top and back of the surround (AV8S). Dual ports fire up out of sight.

Sometimes you just can't have too many clamps!

The compression driver/waveguide for the surround is angled down 15 degrees. 

AV8

AV8S (surround) rear sitting upside down. Here I've used a neo driver to keep the weight down.

AV8 rear:

Dayton Titanic ported sub

The new Dayton Titanic Mk 4 15" sub driver is very appealing. This is a custom sub for a client as part of a home theatre system. In this design, I've used a down firing design to keep things simple in terms of grilles, high driver excursion and little fingers. A key feature of this design is a large slot port with a generous flare at the end.

Good aerodynamics here is the key to ensuring the port does not limit the LFE potential. 

The internals of the port are pre sprayed as there is no chance once fully assembled.

Solid timber feet avoid the weight of this heavy sub bearing down upon the MDF feet. The feet near the port are angled to avoid interference. 

Polyurethane glue is used here for extra strength, along with screws into each solid timber insert.

After complete assembly, the edges were all rounded over with the router and the box is sealed with fibreglass resin to provide a more stable substrate. Often prior to finishing, raw MDF expands and absorbs moisture, resulting in a seam appearing, which then requires more sanding.

Cinem8 with tassie oak veneer

Cinem8 in Tassie Oak veneer. Shown here prior to varnishing.

Clearance - items for sale

S1 - point source horn prototype pair - 60 x 60 degrees, MDF pyramid - raw unfinished box.

Drivers and passive crossover not included.

This is a raw horn MDF shell that works very well with low cost Pyle 6" closed back drivers available from Parts Express and a 1" exit compression driver.

The mouth is 500mm square.
This can be finished in textured black by request.

S3 - point source horn prototype pair - 80 x 60 degree, MDF pyramid - raw unfinished box.

OEM dedicated mids available for the pair (not available without the horn).

The mouth is 900mm wide x 600mm high (approx).

This can be finished in textured black by request.

Bass trap with opening for either S1 or S3

This is a corner bass trap with an opening to suit one of the point source horns. It hides the horn and bass box and fits things neatly into a corner. Grille required (can be added by request).

The idea with this panel is to create a bass trap and also hide the speaker in the corner. The result is very neat and avoids the need to finish the horn nicely.

18" Bass module

60L sealed box ideally suited to either prototype, with an Eminence Magnum 18" woofer and a very well damped sealed box with bitumen lining. 55kg in total!



All these items would best suit someone located in Melbourne aspiring to have a very impressive horn on a budget.

12" Rythmik curved sub

Curve sealed sub (raw MDF) - can be finished in textured black by request.



370w Rythmik plate amp - driver and new servo board can be added but I don't have them currently.



Amp and sub available for separate purchase.

Enquiries >

Building a curved speaker with constrained layer damping - 4

After some sanding and filling:

There is still quite a bit more sanding and filling to come before veneering. There is also a base and a port to install and tune.

Building a curved speaker with constrained layer damping - 3

Project intro >

Part 2 >

Attaching bracing and bottom:

The box lining is attached in place, along with the vibration damping (either bitumen or rubber sheets) prior to assembly. Access will be limited later. A staple gun comes in very handy here. 

Gluing first curved segment:

Many clamps are used, not only to apply pressure but also for adjustment. The use of CNC panels does not make a good result certain. If not correctly assembled, the box may not end up square. The diagonal clamp in this picture is used for adjustment.

Long clamps are required in a project like this. I'm using 1m clamps here:

 The glue ooze is expanding polyurethane glue. It's expensive and harder to work with, but necessary in certain places. Why is it harder to work with? Even getting it out of the bottle needs more effort, firm pressure is required. Gloves must be worn, since it's very difficult to clean off your hands. If you get it on your hands, washing immediately will usually not get it all off.

Dowells added as bracing and the top also goes on:

Building a curved speaker with constrained layer damping - 2

Part 1 >

Test fit of curved segments together with a constrained layer damping sheet:

Not yet attached ...

 Clamping together:

CLD (Constrained Layer Damping) curved segment: 

Ribs are modified so they fit together better:

Priming the bitumen:

Front baffle stoppers - these hold the ribs into position firmly.

Vibration damping applied to the internal surface of the front baffle.

Absorption applied.

First layer of bitumen over primed MDF:

Top walls clamped whilst the glue sets, bitumen applied also. Masking tape is there to keep the bitumen off the middle, where a dowell will be used as bracing.

First layer of bitumen over the first assembled CLD composite segment:

All layers of bitumen applied: