Your box volume is way too small for 2 woofers vented. At 38 litres only you'll get a midbass peak then quickly dropping off. Vented enclosures need a larger enclosure than sealed. Often driver Vas * number of drivers is a good starting point. Model your tuned 38Hz in only 38 litres with 2 woofers to see what I mean
Likewise try plugging the port and using the linkwitz transform method in a sealed box to try to fix the current sub-bass issue?
That's something I need clarification on - why is vented 65L good and 38L bad for two woofers?
The alignment of a vented enclosure is a balance of enclosure volume and Fb with the driver specs. If you undersize the volume you'll lose bass extension. In the case of the 18W-8531G00, 38 liters is a pretty good alignment for 1 woofer. Adding a second woofer to the same 38 liter enclosure causes the alignment to be undersized.
Blue is one 18W in 38L with Fb at 33Hz.
Orange is two 18W in 38L with Fb at 33Hz. This graph shows the two woofers wired in series so that the efficiency is normalized.
Thanks, bass extension is good enough now - slightly better than ZD5 after installing spikes and adjusting the stuffing in the bottom. I think that 65L would be just too much for such a small room.
Why don't you model your current box volume and vent parameters so you can see for yourself? As I stated. A vented enclosure requires more volume than equivalent sealed to get a flat / extended response
When I am home I'll post a 38L two woofer vented enclosure response. How many ports did you try and what length were they?
When I am home I'll post a 38L two woofer vented enclosure response. How many ports did you try and what length were they?
I am almost ready to pull back all the negative I wrote about ZRT. You might get an idea why from this video:
