question about placement and wavelengths

[smpsmp]

So I've build myself a little 2-way setup. a 3" woofer and tweeter in a small ported enclosure. Port facing forward.

They sound great BUT....


They sound amazing if I were sitting right in front of them (2 feet way), great midbass and low end.

about 6-8' away sitting on my couch I loose alot of that bass / mid-bass.

14-16 ' away I get that full sound again.



How to I adjust this?? change the port length?? box size?? is there a calculator to figure this out?? (and no, I've decided where I want them and moving the couch back is not an option


Any help would be great.


Thanks.

[Cal Weldon]

Sounds like you are getting cancellations from wall reflections. Only solution is to augment the bass with a dedicated woofer in a different location or move the speakers. I have the same thing in my party room. Right at one of the couches, the bass drop out is enormous so I tell everyone to stand near the rear wall if you want it to thump your chest.

We may be talking about slightly different size drivers but the effect is the same.

[smpsmp]

wall reflections... you mean the back wall probably behind my couch??? what if I put baffles/sound absorbtion material on the back wall to stop this?? maybe help??

[Cal Weldon]

Yes likely the back wall.

You will probably not get satisfactory results from sound absorbing materials but it may help somewhat. Down in the bass, the waves are rather long so it takes an enormous amount of absorbing to be effective. No chance of moving things around a bit to check?

[smpsmp]

No chance, my apartment layout is kinda laid out in it's only configuration. What about changing the enclosure design?? Transmission line? my only thing is that I don't want to seal them up and utilize a sub.

[Cal Weldon]

You have to work with the situation. The cancellations are a matter of distance related to the frequency so changing the enclosure will probably make it sound better but not get rid of the problem.

[boris81]

It sounds like you are having cancellations due to wall reflections. Changes to the speaker and sound absorbance won't do much good. You should try moving the speaker around the room. Distance from the walls will affect where and at what frequencies the cancellations occur.

Here's a quick illustration of what's going on.
wall.PNG


All of us suffer from this issue!
As Cal suggested already, the best solutions seem to be:
- moving the speakers around
- adding subs at certain locations in the room
- well placed EQ

[DrDyna]

Originally Posted by Cal Weldon

Sounds like you are getting cancellations from wall reflections. Only solution is to augment the bass with a dedicated woofer in a different location or move the speakers. I have the same thing in my party room. Right at one of the couches, the bass drop out is enormous so I tell everyone to stand near the rear wall if you want it to thump your chest.

We may be talking about slightly different size drivers but the effect is the same.

Hahaha, I love it. I can see all the guests sitting on laps in one spot. I've had people go into the kitchen to hear a bass note before!

Wavelengths and standing waves are a funny beast.