ATS-4 Drawings and Pics
Copyright 2013 © Troels Gravesen


Before anything else: Any change to the front panel design and you're on your own. You'll need a modified crossover and I can't help.

Cabinets were made from 21 and 18 mm Baltic birch and I used maple fillets for fronts on all cabinet sections. 18 mm was used for mid and tweeter cabs. Making these cabs from Baltic birch takes considerably longer compared to MDF. I know, because the Jenzen ATS were made form MDF and it took a fraction of the time I used for these ATS-4 cabs. The advantage is that I have the final finish at once and handling spray lacquered cabinets gets on your nerves, where Baltic birch and maple fillets can be repaired fairly easy should accidents happen. I added lacquer by a roller and it cost me a fraction of having the Jenzen ATS spray lacquered by a professional.
I often have the question whether Baltic birch is better than MDF and with a good quality MDF + proper bracing, I don't find any difference. The common notion that MDF kills the sound is rubbish. All depends. With soft MDF + no bracing + dull drivers (read low Qm) everything may get pretty muffled up.

I hope the images below speak for themselves and I have added only a few comments. This is not a first-time DIY project and you need a good table saw and you need some experience in woodworking to make this come true.
To cut Baltic birch takes practice to avoid edge ripping. I used a lot 6 mm MDF to put under the sheets before cutting. This way edge ripping can be avoided.

I must be said that you can get exactly the same sound from a much less complicated construction - as long as you stick to front panel shapes and dimensions - and keep internal volume and damping. What fancy shapes are behind the front panels is fully up to you.

Cabinet drawings 

Click image to view large

Port is made from 15 mmm Baltic birch and is 40 mm (H) x 200 mm (W) x 250 mm (D).
Rather than using the foam padding on front you can laminate two panels to male 28-33 mm thickness. You do not have to adjust volume from this.

Click image to view large
Mid cabnet volume ~16 litre, minus bracing, bitumen pads, port and driver.
Tweeter cab can be closed or open to the rear, doesn't matter.
Mid- cab port is 50 x 100 mm and stuffed with a roll of 10x20 cm acoustilux to make cabinet aperiodic.

Also check out Illuminator-4 pics for more construction tips.


I used 4 mm bitumen pads on all internal panels except front. This goes for mid cabinet too.
For the tweeter cabinet this was only to add weight.


1. 4 mm bitumen pads on all internal panels except fronts and braces.
2. 8 mm grey felt on all internal panels except fronts.
3. 2 layers of 30 mm acoustilux at bottom of 10" bass cabinet. 2 layers of 30 mm acoustilux behind 10C77 driver (rear panel). No acoustilux in 23I52 cabinet.
4. Mid cabs: Rear and front parts, 1 layer of 30 mm acoustilux on bottom and sides.
5. Roll a piece 10 x 20 cm of 30 mm acoustilux for the mid cab vent! This makes the aperiodic tuning.

Minor rebate for the 10C77 driver due to 10 mm thick frame. The 23I52 frame thickness fits the foam thickness.

I had some 8 mm foamed rubber, which I used for the bass cab fronts.
If you don't want to use something similar, laminate front panels with another layer of 6-8 mm Baltic birch.

Left: Cover panel for MT crossover.

Stuffed mid port


Tweeter cabs

The tweeter cabs can be made in many ways, this is not the easy one.
As long as front panel dimensions and tweeter placement are kept, you're safe.

To make the rounded cut-out on the top, quite an elaborate set-up was needed. Attach support panels to the sides to eliminate edge ripping when doing the routing.

Tweeter cabinet added bitumen pads to add weight.