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Joseph Crowe

DIY Plans for Speaker No. 1786 --- Large DIY 15" 2-way Monitor using SB Audience Products

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By purchasing these plans you will automatically receive via email detail and assembly drawings to construct speaker system No.1786.

Introdiction Video click HERE.

Technical deep dive video click HERE.

Update (November 2022): We've added the option of using the ES-600 Biradial horn and included a dedicated passive crossover schematic for this particular horn and driver combination. Details on this can be found here. This variation is called No.1815 which is included with the original No.1786 plans listed on this product page. 


Plans No.1786 includes 

  • High Sensitivity (95dB@1w) 
  • 15" 2-way design using 600Hz crossover (3rd order slopes) 
  • SB Audience Bianco 15OB350
  • SB Audience 65CDN-T 1.4" compression driver 
  • SB Audience H280 1.4" Horn 
  • Compact physical size including corner placement option
  • Aesthetically pleasing 
  • Off the shelf components that are easily available 
  • High output SPL and low distortion 
  • Suitable for audiophile two channel or high end home theater as L/C/R 
  • Crossover optimized to audiophile listening and flat frequency response 
  • Clean, tight bass that is free from 'boxiness'  or 'boominess' 
  • Easy to construct 
  • Crossover schematic including suggested part numbers 
  • Assembly and detail drawings (.PDF format) in metric and imperial units
  • $80 CAD for the plan set (approx. $62 USD)  
  • NEW! Bonus Plans No.1815 (introduced November 2022)
    • 3D CAD files for ES-600 Horn No.1076 (1.4" throat)
    • CAD file formats are .iges and .STL 
    • Passive crossover schematic 
    • 1st order crossover slopes for textbook perfect step and phase response 
    • For details click here

A more detailed blog post on this product can be found HERE

Speaker Plans 

There are multiple configurations depending on your skill level. The HF horn can be mounted into the enclosure, or the horn can be positioned on top of the cabinet. There are two variations for top mounting the horn. The first is a basic support frame. The second is a more elaborate frame. Chose the design that fits with your visual preference and capability. 

Configuration 1 with the horn mounted into the enclosure is shown below. 

The second configuration (shown below) is with the horn mounted on top of the enclosure. This method eliminates the need for the support stand and positions the listening height at 90cm. It also allows for the compression driver modification I mentioned earlier. 

The third configuration is shown below. This adds thick solid hardwood bezel to the horn similar to a picture frame. This is just an esthetic choice and has no affect on sound quality. The picture frame is a little more difficult to construct but may be preferred visually to some people. 

 

The plans include assembly and detail drawings to construct each version, along with the passive crossover schematic to construct the crossover. 

I chose a corner cabinet design so that the speaker could be placed well into the corner of the listening room. This maximizes bass response however it is not necessary. I found great bass response even with the speakers placed 70cm from the side walls and 15cm from the rear wall. If using the speaker in the corner of the room, the speaker only protrudes from the corner by 40cm (15.75")

The render shown below highlights how discreet the speaker can be in a normal living room. 

For aesthetic purposes the woofer is rear mounted into the enclosure. This requires that the side panel be removable on the cabinet. This is optional of course. The driver can be front mounted if you'd like and simplifies cabinet construction even further, but means an exposed driver frame and doesn't look as clean as the rear mounted configuration. 

The instruction package includes both assembly drawings (shown above) and detail drawing (shown below) for each component of the assembly. The assembly drawings only show the arrangement of the components. The dimensions for construction of each component is shown on the detail drawings. 

The Bill Of Material (BOM) is located on the assembly drawings. It highlights the list of detail drawings associated with the cabinet. For example, cabinet 1786-04 is made up of seven components or parts numbers as shown below. 

The specific detail drawing number in shown in the drawing title block shown below. 

Cabinet Material

The cabinet material is standard 18mm thick birch plywood. You can also use marine ply or apple ply as well. If you decide to use MDF, please double the wall thickness or use use substantial internal bracing and account for the bracing for the internal volume. It is recommended to avoid MDF if at all possible for this reason. 

Cabinet Stuffing 

The cabinet is to to be stuffed 100% full of polyfill (pillow stuffing). The pillow stuffing should not be compressed in any way. It must be loosely filled in the enclosure enough to fill all the voids. 

 

Crossover 

The crossover schematic includes suggested part numbers which have been optimized for the best sound quality. The final tuning of the crossover was based on extensive music listening to a variety of tracks. Acoustical measurement was used to verify a flat frequency response, but it was not the end goal, even though the response is very flat, the end goal is excellent subjective sound quality. 

 

 

I measured the in-room frequency response which is shown below. Because of the normal room reflections introducing peaks and dips in the response, I applied 1/1 smoothing so that you can understand the general trend.