What eclosure for Visaton BG20

L = 26.93" (68.4cm)

So/SL = 187.38"^2 (1208.84cm^2)

I prefer to use golden ratio dims where practical since the sim assumes a round pipe, so FWIW: w = 17.42" (44.24cm), d = 12.75" (32.38cm)

vent dia. = 3" (7.62cm)

vent length = 1.5" (3.8cm)

driver down 14.63" (37.17cm)

For FR drivers I prefer to mount them off center in a golden ratio when the baffle is wide enough, or 10.75" (27.3cm)/6.67" (16.94cm). This of course requires mirror image baffles. Orientation in-room is a personal preference.

stuffing = ~9oz (~255g)

All dims are inside. Distribute the stuffing from below the driver upwards and place the vent near/at the bottom. This is a max flat alignment (F3 = Fs in this case), so if placed near a wall or corner it may be a bit boomy, so you may need to experiment with longer vents in 0.5" (1.25cm) increments to 'tighten' it up. Also, you will need some form of baffle step compensation to balance out the highs to lows if not up against a wall or corner.


Drivers want to 'feel' a certain amount of compliance around them as well as total Vb based on their electro-mechanical properties. This limits the pipe's Vb, therefore its length for best performance. Also, the longer the pipe, the lower its resonance, so once it becomes longer than what's required for the tuning, a peaking at Fb occurs, with the attendant underdamped dip in the response above it, which gets worse with increasing length.

Many folks find it sonically acceptable, but I'm after the most accurate reproduction I can get within a driver's limitations for a given cab type so I don't recommend them, and I believe once you've listened to a well damped pipe for awhile you won't either.

Since pipes have high aspect ratios and more acoustic energy to dissipate than a typical rectangular cab, I recommend making it whatever height is required to get the driver up where you want it and filling the cavity below it with a massive material such as sand, etc.. I prefer kitty litter as a good compromise between mass/damping/cost. If you don't mind the added height or extra cost, either adding a mass loaded cavity above the pipe or a heavy marble/slate/whatever decorative top helps performance a bit also.