Wednesday, May 1, 2013

DIY Clone of Rogers AB1

While awaiting for the AB1 cabinet to arrive, I found the following DIY info(s) on the net. The cabinet ordered will be made from Birchwood ply as well.

A Quad enthusiast I know made his own DIY AB1 from normal plywood.

One example of a home built subwoofer for the LS3/5A
Example of another home built subwoofer for the LS 3/5A

When I received the cabinets, I was impressed! They looked pretty good and felt solid as well.
Cabinets received
Upon inspection, noticed there were some internal modifications vs the information from the websites above. External dimensions are the same as the original.

One difference is the length of the bass port. The original was 85mm vs 88mm on the cabinet. Another was the insert cutting for the B110 on the original AB1 cabinet - absent from the cabinet I received. And there were no pre-drilled holes on the bottom of the plith for inserting spikes.

After a while, I finally realised the absence of a means for the cabling to flow between the top and bottom chambers??? Looks like I will need to drill or file an insert on the separator - method for creating the inter-cavity punch thru really depends on the gauge of the cabling to be deploy for internal connectivity.

Apologies as I did not take any additional pixs of the AB1 internals as was in a hurry to get it going and forgot to do so! Hence will update the next time I open the AB1 up for maintainence.

The electronics are setup in the following manner. I used the same alternative woofer as per the LS 3/5A as I ordered 2 pairs from the UK. The cross-over inductor was a 15mH with 16gauge coils, and, capacitors were ordered from the US as local prices were simply not realistic.

Connectivity diagram is as per the 1st weblink above. The large inductor was place at the bottom of the lower chamber over a very thin layer of foam. The DIY crossover was placed onto the back panel (which has the banana sockets). Used my defacto standard speaker cables in the internal wiring for the AB1.

For the insulation, I followed the setup as per 2nd weblink above. Monacor MDM-2 were used in the sides of the top chamber. Inner ceiling of the smaller chamber and the sides of the lower chamber were lined with a DIY hybrid insulator which consists of yoga mat (4mm) adhered to a thin felt double layer using the 3M type 77 spray-on adhesive. This resulted in a hybrid insulation-layer which was about 20mm thick - see pix of sample leftover below.
MDM-2 at top and the DIY hybrid insulator created at the bottom

Close-up of DIY hybrid insulator

Monacor MDM-2 packaging

How does it sound?

DIY of LS 3/5A with AB1

Understand there are 2 school of thoughts on the matter. One camp prefer the LS 3/5A as a standalone unit while the other prefers using the AB1.

The DIY AB1 does make a difference to the presentation of the DIY LS 3/5A. You could hear the DIY LS 3/5A breath easier as some of the LF load has been offloaded to the AB1.

For me, the DIY AB1 is well worth the investment.