Newbie's latest project

[gfinlayson]

Hi all,

Just joined today, and put my first post in the introductions forum. Cal Weldon asked me to post up some pics of my current project so here goes:




Panels for second speaker

Front view
The sections in between the middle four braces have still to be routed out and there's a 25mm outer panel to go on.

Rear View
As with the front, the inner rear panel will be routed out between the middle four braces and there'll be an additional 25 mm rear panel.

Top, bottom and sides are all 25 mm, bracing and inner front and rear panels are 18 mm.

The braces still have to be routed out. The cabinets have been partly dry-assembled to cement the port into the base.


This bad boy is the 2.2mH Intertechnik air cored inductor for the bass driver.

Drive units are Scan-Speak 18W/8531G00 and D2905/930000.

Internal panels will be lined with 2mm bitumen with 10mm foam atttached. There will also be some Monacor MDM-3 behind the bass driver. The cabinets will sit on a 30mm thick plinth on 50 mm spikes to give the port room to breathe.

I was initially going to build a ProAc 2.5 clone, but after reading Troels Gravesen's extensive paper on the 2.5 clone I opted to go with the 9300 tweeter as the 8513 doesn't work well with the newer 18W/8535. After some further thought I decided to go with the 18W/8531G00 Revelator instead of the 8535. I wanted to bottom port the cabinet to make placement less fussy, and use a big port to minimise noise. It just so happened I had a length of 102mm ID soil stack pipe lying around as well. For a 33 litre cabinet at 33 Hz, the port comes out at about 400 mm.

I'm using Troels Gravesen's SP98 series crossover as a starting point. Depending on how my drivers measure, I may have to tweak a little.

Thanks are also due to Finn Dahle for the cabinet construction idea from his 2.95 Clome. Unfortunately I don't have access to CNC routing, so all of my recesses and cut-outs had to be hand routed.

Incidentally, I read a post earlier today regarding difficulty in finding 25 mm MDF in the UK. I got mine at my local Travis Perkins, about £25 for an 8' x 4'. The guys in the wood yard were also kind enough to cut it into 4 sheets of 4' x 2' on their table saw for free.

Veneer will be bubinga, although I haven't decided how I'm going to stick it on or finish it yet.

[gfinlayson]

Photos are OK now. Long day, late night and messing about with websites don't mix.

[gfinlayson]

Some more progress -


Bracing cut outs finished, T-nuts for plinth in place.


Dry fit of panels, T-nuts for rear panel in place.


Bitumen/foam damping added, panels ready for assembly.

[Vikash]

I love pitchures. Keep 'em coming with your progress

[gfinlayson]

Latest progress report:


Assembled skeleton


Front 25mm panels and small rear panels added. Nail holes filled, ready for sanding. Grill frames cut.


Removable rear panels and plinths with first coat of primer sprayed.

[69stingray]

What is the diameter of that port? What Freq. is the enclosure tuned to?

[gfinlayson]

The port is 102 mm ID (4") and 400 mm long (15 3/4"). If I've got my sums right, it should be tuned to about 33Hz. I didn't want to use a smaller diameter port. Because the port flare is only 80mm from the floor, I was concerned that using a smaller port might cause chuffing. Once I take delivery of the woofers, I'll fit the drivers and do some impedance measurements to see exactly where the tuning frequency has turned out. If it's too low, I can trim the port back a bit.

[Cal Weldon]

Looking really good so far. Can't wait to hear the results and see the veneering.

[gfinlayson]

Thanks Cal. They're getting there slowly. I'd forgotten how long it takes to build a pair of speakers.

It'll be a few weeks before I get round to the veneering. Since I'm using raw veneer, I'll need to let it flatten for at least a week before I can use it. It's my first veneering project, so I'm straight in at the deep end, but Bill Martinelli was kind enough to give me some advice. The man is a god when it comes to veneering. If you look down his home page a bit, the curved veneer cabinets are simply stunning!

[gfinlayson]

Slightly more progress:



Cabinets after sanding



Cabinet with finished grill. The grill design has been shamelessly plagiarised from the ProAc D25.