Table Tuba build!!

[Radian]

I still don't freakin' understand.... how come I can clearly tell that my sub is in the corner, ESPECIALLY during music. What am I doing or not doing that is causing this?

Turn the sub off completely. Then play some music. Does it still sound like there's bass coming from that area? Maybe it's just a room mode at some higher frequencies there.

[NCDaveD]

Chris, for the last year I have been listening to, and tweaking my TT for pretty much the same reason as you. What I have noticed is that at my current settings, there are still frequencies that seem to be localized to the corner, but the really low stuff seems to be all-encompassing. As I shift the crossover frequency, the localization seems to change a bit, but never leaves the corner entirely. Bill is right in that if you run it hot, that exacerbates the situation.

At one time, I thought I had it licked, but the very next movie, the localization came back, and I"ve never been able to repeat that one experience. That's why I'm buidling another TT to see if this will help eliminate it for sure.

I'm too lazy and too cheap to buy and learn how to use REW and it's support equipment.....

NCDaveD

[88h88]

I'm too lazy and too cheap to buy and learn how to use REW and it's support equipment.....

So you chose the manly way of dealing with it. Building another sub.

[Bill Fitzmaurice]

there are still frequencies that seem to be localized to the corner

That usually has nothing to do with the sub. Bass traps are often employed to tame room modes in the corners, and the thing is that bass traps don't affect bass. They damp midbass, the source of which is the mains.
I know that TT has no directionality issues because mine is located directly behind my chair, the horn mouth 16 inches from my head. My mains are 14 feet in front of me, and I can't directionally located the TT.

[NCDaveD]

It is quite possible that the frequencies I am hearing are midbass from the mains. Further experimentation will be underway! That is...once I finish my other TT.

Anyways....that is the excuse I used to sell the wife that I had to build another. If you can't sell them with logic....baffle em with bullsh*t!

This also means if the new TT doesn't work, I may be able to finagle a new Omnimic setup....... "Thats right dear, I need to be able to MEASURE what is going on to fix it"....yeh, that sounds good

NCDaveD

[Tom Smit]

This also means if the new TT doesn't work, I may be able to finagle a new Omnimic setup....... "Thats right dear, I need to be able to MEASURE what is going on to fix it"....yeh, that sounds good

NCDaveD

[digital_chris]

Thanks for the recent thoughts guys, I still think something is amiss with my setup. I did a quick run with REW, a sweep from 30hz to 150hz, mains disconnected. Some of the folks on another forum think the roll off should be steeper with the two x-overs inline (AVR and sub amp), what do you guys think?

[Tom Smit]

I am going to guess that the crossover is set at 50hz, and that there is a roughly 10db/octave rolloff..not much.

[el_ingeniero]

I still don't freakin' understand.... how come I can clearly tell that my sub is in the corner, ESPECIALLY during music. What am I doing or not doing that is causing this?

Because the low pass filter on it is crossing over too high, and there's too much output over 100 Hz.

[digital_chris]

Here are two more I just took, purple graph is 60hz x-overs and blue graph is with 80hz x-overs.

[Gregory East]

No pic as yet...

The next octave up from 100Hz is 200Hz, which is locatable, so you want the slope to knock it down to inaudible, 10dB down is just half as loud, that's still audible.At 20dB down, probably still a pretty decent sniff of bass, I don't actually know what you need to get to inaudible, I just use 48dB /oct because I can, problem solved.

[digital_chris]

Both the AVR and sub amp have x-overs set at 60hz and 80hz relative to the two graphs I posted. From what I gather, with two x-overs inline, the drop off should be significantly steeper than what is shown.

[Gregory East]

10 + 10 is 20dB which makes 1/4 "loudness". That's all I know.

[Gregory East]

I still don't freakin' understand.... how come I can clearly tell that my sub is in the corner, ESPECIALLY during music. What am I doing or not doing that is causing this?

Turn the sub off completely. Then play some music. Does it still sound like there's bass coming from that area? Maybe it's just a room mode at some higher frequencies there.

iHow did this test work out?

[digital_chris]

I've listened to the system without the sub plugged in before and no bass comes from that corner.