one or two open ports

[cschang]

Just wondering, with the VTF series, what are peoples preferences? One or two open ports?

I have a VTF-3 and I'm undecided.

curtis

[lcotts]

I have the VTF-2 and after listening both ways, I prefer 1 port open. The low frequencies are much tighter in my listening area and is satisfying for both music and HT.

[Sasha_G]

Because the VTF-3 goes so low with both ports open, we often recommend having both ports open, although it is still a matter of preference.

[Consequence]

By the way, with all things equal i.e. subwoofer in the front of listening position, dead centre. Where should the port/ ports face for the VTF2/3. 1) towards the side walls 2) facing the listener 3) facing the front wall as in a rear ported speaker? The ports seem to be directing a lot of energy.

[Sasha_G]

Dr. Hsu designed the VTF-3 ports to face the side or front wall, away from the listeners. It is not critical which way they are faced, since the sound waves reflecting off the wall are 40-60 feet long.

It is a good idea in general to face the ports towards a wall. It is not a huge issue either way if the ports are not facing the wall.

FYI, the deepest notes come from the ports, and the mid bass notes come from the speaker. When you are sitting a few feet away, they blend together.

The main thing is to keep 3 inches of clearance around the ports to prevent port noise. Port noise is the worst because it is usually at some high frequency that draws attention to the subwoofer, making it more localizable in the room.

[Ddavidson]

I think it really depends on personal preferences, the source material, and most importantly the actual room acoustics.

As Robert Deutsch found out in the slightly off putting SGHT review, the room can really change how bass is reproduced. I wished this had been made clearer as I found he did not make things clear enough about what was happening with using deep bass mode (one port).

I use both of mine in deep bass mode and have never gone back to high output mode on either Vtf-2 or Vtf-3. But then again my rooms do not have room modes at either 20 and 25 Hz (or mutiples of either freq).

Dr Hsu's SGHT reply got to the heart of the issue.


I would also like to comment about the response characteristics Robert noted. The dimensions of his room and his seating position would result in peaks at 20Hz and multiples of that frequency, 40Hz being the next strongest peak. This is why setting the VTF-3 to Maximum Output mode helped tame the 20Hz peak, making it smoother. In a different room, the peaks would most likely occur at different frequencies. Measured in half space (against a single barrier such as a wall or floor), the VTF-3 should not have peaks at these frequencies.

Dr Hsu
President, Hsu Research


Ddavidson