something to be concerned about ? - weird speaker phasing

kris Permeke · Post by **kris Permeke** » Tue Jan 31, 2006 9:03 am

This is my first post here. Thanks for letting me in

I have a pair of adams S2A speakers.
This is what I discovered.
I sweeped some sine tones from 20hz to 20KHZ.
Monitor controller is Cransesong Avocet.
In Mono mode , all seems to sound fine.
Phase inverted on Avocet (mono mode), testtone is 100% cancelled through the whole spectrum. Seems fine to me.
Now what happens: when I monitor in stereo(phase normal), at around 111hz, the signal gets almost completely canceled. from 113 hz, everything sounds fine again.
When I flip the phase at the 111hz position, signal is back.

Is this a speaker or an accoustics problem?
thanks for the help.

Post by **kendale** » Tue Jan 31, 2006 9:47 am

Aloha Chris and welcome to the forum!

Before we start, could you please:

Edit your profile to include your location. This is very important, because this is a worldwide resource, and as such, material costs and availability vary widely. For example, masonry is cheaper than gypsum in some parts of the globe, whereas it's the exact opposite in other regions.

Thanks!

A couple of thoughts that come to mind:
The obvious: Have you checked the cable wiring to the speakers?
The not so obvious: Have you checked the cable wiring connectors itself?
Also, could it be that there is a null @ 111Hz? What are the dimensions of your room/listening position, and is the dropout evident throughout the room or only at your listening position?

Hope this helps,

Aloha

kris Permeke · Post by **kris Permeke** » Tue Jan 31, 2006 8:11 pm

Hi there.
I'm absolutely sure my cables are wired the correct way.
But yes , It could be the room accoustics .
Room size is LxWxH= 4.5x4x2.40meter.
I have panel bass traps in the rear corners and on the front ceiling, above listening position.

Post by **kendale** » Tue Jan 31, 2006 9:29 pm

Aloha Kris,

How far is your mix position from the:

a. front wall?
b. side walls?
c. ceiling?

Aloha

kris Permeke · Post by **kris Permeke** » Tue Jan 31, 2006 9:38 pm

mix position: 1.50m from the front , 2m from the sides, 1m from the ceiling.

kris Permeke · Post by **kris Permeke** » Thu Feb 02, 2006 10:24 am

Is this something for the accoustic forum ?
Can someone move the topic overthere?
thanks

Post by **kendale** » Thu Feb 02, 2006 8:00 pm

Aloha Kris,

Sorry for not responding back right away. It's a bit puzzling, but I've been chewing on it. Perhaps someone else has a better understanding?

Is this something for the acoustic forum? Can someone move the topic over there?

You could give a shot and post a thread there. I believe it would take a moderator to move it otherwise.

Aloha

knightfly · Post by **knightfly** » Fri Feb 03, 2006 3:57 am

Moved this to Acoustics, not sure if it'll make much difference though. Can you post a sketch with dimensions, showing your walls, speakers, head and listing exact dimensions from each speaker's woofer cone center to each wall, ceiling, floor, same with your head in all three dimensions?

Also, once you achieve this null can you walk around the room and STILL have the cancellation? Steve

kris Permeke · Post by **kris Permeke** » Sat Feb 04, 2006 6:45 am

Thanks for giving me the attention guys.

Also, once you achieve this null can you walk around the room and STILL have the cancellation? Steve

Yes , there are two spots in my room , besides at the listenin g position, Left and right side, about halfway the room, and approx 3 feet from the sidewalls.

I'm gonna try tomake a detailed drawing.