Cabinet Construction

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November 21st Written by 

The R630v3 and the R645v3 speaker cabinets have been quite heavily upgraded. The objectives were to improve bass pitch definition, midbass transient response and reduce diffraction effects. These new cabinets meet their design targets very successfully but, as you can see, they are far from simple to construct.

Features of the new cabinets:

  • heavy shelf bracing
  • complete diagonal wall bracing
  • damped wall surfaces
  • damped air volume
  • decoupling pad on top and bottom of cabinet
  • solid surface top
  • seamless, large radius vertical edges

Bottom line: superior construction yielding excellent internal damping and very low wall vibration plus excellent anti-diffraction characteristics. The basic elements of the speaker cabinet construction are as follows:

Vertical Wall thickness - 1" high quality MDF board
Bottom thickness - 1" bottom + 0.07" damping pad +1" MDF base
Top thickness - 1" top + 0.07" damping pad +0.5" Solid Surface polished top
Shelf braces - 2
Diagonal panel wall braces - 9
Vertical Corner Treatment - Heavily radiused (1.5")
Wall Damping
 
- Damped walls
- Multiple layers
Cross Brace Damping - Damped cross braces damped with 0.070" barrier mat
Base attachment
 
 
- Bolt in base
- 4 hex head machine 1/4 x 20 screws screw into internally fixed insert nuts
Top Material
 
 
- Solid surface top (Formica "Black Lava")
- Damped top
- Damped bottom
Brace Material - Baltic birch bracing
Grill Material - Baltic birch grill
Internal Wall Damping Pads
 
 
 
- 18 to 20 triangular pieces glued to interior walls
- Polyester film
0.25" urethane acoustic foam
- 0.07" limp, dense plastic barrier mat
Internal Volume Damping - 1" - 2" urethane acoustic foam damping
Finish - 0.020" black ash Formica laminate
Kits - Bare enclosure
Base
 
 
- Low gloss black paint
- 1" MDF, 0.070" Damping Mat
- Diagonal wall bracing
Grill Finish - Black polyester doubleknit grill cloth
Grill Mounting - Low vibration, strong and flexible pin (in cabinet) and rubber cup (in grill frame)

 

Try the knuckle wrap test. About as solid and dead as a loudspeaker cabinet gets. We will not be responsible for sore knuckles!!

Why damp the cross braces? Cross braces are connected directly to the wall of the cabinet and thus short circuit any damping inside or on the interior wall of the cabinet. A thorough approach to damping requires that any cross braces which go through the air volume of the enclosure must be damped to prevent them from acting as antennae - picking up the soundwaves inside and transmitting them to the walls. Baltic birch is very strong, resilient and very inert and with the damping mat glued to it, quite resistant to the transmission of midbass frequencies. Damping the cross braces is a practice unique to Newform Research as far as we know.

Baltic birch void free plywood is the world standard for professional sound loudspeaker enclosures because of its strength and light weight and "silence". Newform uses high grade MDF for enclosure walls as it is ideally dense and inert. MDF simply would not stand up to being hauled around in trucks and setup 3 times a month for touring groups. Nor would roadies hold up too well setting up loudspeakers made with the much heavier MDF. We use Baltic Birch over the typical MDF for bracing and damping because its qualities of superior strength and resilience are best for that application.

 
 
R630v3 top Solid surface top plate. Exceptionally smooth, seamless baffle to side transition.
 
 
R630v3 Top rear.
 


R645v3 Cabinet interior with baltic birch shelf braces, diagonal wall braces and triangular wall damping pads. Cross braces and 1" - 2" volume damping acoustic foam are added in the final fabrication steps.
 
1" acoustic foam and triangular damping solid mat/foam pads.
 
 
 
Internal view of work-in-process model LineSource Reference cabinet.
 
Read 5574 times Last modified on Monday, 17 June 2013 18:06
Published in Buying Guide
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