Table Tuba build!!

[digital_chris]

Well, I may or may not have popped the Dayton driver. Tonight was the 2nd night I think I bottomed it out. How? I don't know but while playing the DVD version of Matric Reloaded, definitely heard many whomps during the scene when Trinity jumps out of the window firing auto's at one of the agents. The first night I heard the whomp was during the original Matrix at one of the explosion scenes. So, I turned it down a little and all was good. These DAMN MATRIX MOVIES!!

These aren't even DTS versions and my volume wasn't THAT loud, my mains sounded just fine, no stress, just the sub stressed out. I know the amp has a 29hz cutoff, but maybe that's not enough? Maybe I need to lower the Low Freq DB setting in the AVR? I haven't ran it hot either, I just let Audessey set it. Before I bought that amp, I purchased some 30hz FMOD's, think I should install one of them as well?

I think I will try the FMOD and finally get my butt in there and adjust that curve, the "right side of the room" bass is killing it for me

Wish me luck and if any recommendations come to mind, jot them down

[Rune Bivrin]

The only thing I am still worried about is pushing the woofers in my mains to hard. I few scenes in I, Robot made the cones move quite a bit, I can't tell if it's close to x-max or not.

This statement really caught my eye. I may be thick as a brick, but for the life of me I cannot figure out how you can an idea of cone movement in a finished cab.
Isn't the driver in a sealed chamber? Did you use glass for access hole covers?

[SeisTres]

I cannot figure out how you can an idea of cone movement in a finished cab.
Isn't the driver in a sealed chamber? Did you use glass for access hole covers?

The tt has no access cover when finished.

Chris, if you have already moved your TT around and still aren't getting the results you want, you might try raising it up and fire it into the the roof and see if that does anything and then maybe you could mount it if it helps. Also, you could raise it just enough and downfire it. Also, turning it different ways as to have the open access space firing into some different places.

[Rune Bivrin]

I cannot figure out how you can an idea of cone movement in a finished cab.
Isn't the driver in a sealed chamber? Did you use glass for access hole covers?

The tt has no access cover when finished.

Now, I don't have the plans for the TT, but I surmise it has no access cover because the table top covers up the hole. I still don't see how you would estimate cone excursion visually?

[SeisTres]

Now, I don't have the plans for the TT, but I surmise it has no access cover because the table top covers up the hole. I still don't see how you would estimate cone excursion visually?

No, the hole is not covered up by anything; it has no access cover. And yes, this is the only horn cab from Bill does is designed this way.

[digital_chris]

The only thing I am still worried about is pushing the woofers in my mains to hard. I few scenes in I, Robot made the cones move quite a bit, I can't tell if it's close to x-max or not.

This statement really caught my eye. I may be thick as a brick, but for the life of me I cannot figure out how you can an idea of cone movement in a finished cab.
Isn't the driver in a sealed chamber? Did you use glass for access hole covers?

I'm sorry I had you scratching your head over this. I was referring to the woofers in my mains (front L/R speakers), not the TT. I'm surprised that no one else picked up on that, lol.

As for not getting the sound dispersion I was hoping for, unfortunately, the TT will have to sit where it is, in the configuration it is in because of the way I made it/dressed it up. I guess I will just have to try the crossover trick in the amp and hope for the best.

[digital_chris]

Ok, so that didn't work out too well. As far as I can understand, even thought I don't understand the graph for the Foster too well, I adjusted VR603 full CCW. After that setting, I really didn't notice any difference in the directional bass. I then proceeded to change the crossover frequency in the AVR to 60 hz instead of 80 hz and that didn't do anything either. The amp's LPF is also set at 60hz. Man, I guess I'm just screwed. Why can I pin point my subwoofer so clearly? It MUST be the room and seating. I really don't think I can take this anymore, to the point where I want to build something else that can fit up front... what a stinker this is

Even with my AVR volume set at a moderate level (-10 db), the sub still burps during one bassy scene in Matrix Reloded.. (Shakes head).

[Bill Fitzmaurice]

Why can I pin point my subwoofer so clearly? .

Something is just plain wrong with your low pass filtering. My TT is six inches behind me and I can't pinpoint it.

[SeisTres]

Why can I pin point my subwoofer so clearly? .

Something is just plain wrong with your low pass filtering. My TT is six inches behind me and I can't pinpoint it.

+1. I know I had problem with nulls and hot spots but nothing this bad. Also, today i watched some youtube videos of the matrix to see what you were talking about, but compared to other movies of the day, is nothing else my TT hasn't seen. I really don't have an idea of whats going on with your TT. And from reading the thread some time ago, I remember you already played with the settings on your receiver and all that so I guess there's no point in recommending that either.

[digital_chris]

Is there a good possibility that it's just my room and seating? Maybe the sectional is causing this? I just hear all the time of people not being able to pinpoint their sub, and that anything below 80hz really should not be localizable.. So, just for safe measures, I drew up a sketch pretty much to scale or my living room setup... Let me know if you see any negatives in there... Bill, is there anything I can do to see if it is my filtering that is causing this? Maybe run test tones at certain frequencies and see how localizable they are or any settings in the AVR I should play with? I know the settings are simple and I shouldn't have this much of a problem but man, it's racking my brain..

Right now I'm going to go play some test tones and see what I can and can't hear and or localize.

[Steve Regier]

Staining is NOT fun for a beginner

Staining is not fun period.

I have started using an automotive SATA3000 HVLP paint gun with urathane stain. I reduce it and spray it like autopaint after standard prep for staining. I am using this process on my Davids and any other project requiring staining veneer. A bit more hassle but the finish comes out like glass.

Sorry to hear about your performance issues. I have also experienced bass nodes or directional sounding bass.
As far as your room placement is concerned would it be possible to stand the TT on end so that the driver opening is facing the back wall and the bell is facing the other wall in the corner? I would also try standing the TT on end with the bell firing down the long wall towards the room entry with the driver opening against the same wall. I also wonder if since you know the sub location you may be very sensitive to any timing issues in the signal. If you were to watch and listen from a position directly say 2 feet from the TV and mains would the perceived placement effect of the sub decrease. I would also suggest setting your HP and LP to what sounds best and the adding about 20ms or more of delay to the signal. This would place the bass arrival even or slightly behind the mains.

[digital_chris]

I have started using an automotive SATA3000 HVLP paint gun with urathane stain. I reduce it and spray it like autopaint after standard prep for staining. I am using this process on my Davids and any other project requiring staining veneer. A bit more hassle but the finish comes out like glass.

Nice Idea, I might have to try that

Sorry to hear about your performance issues. I have also experienced bass nodes or directional sounding bass.
As far as your room placement is concerned would it be possible to stand the TT on end so that the driver opening is facing the back wall and the bell is facing the other wall in the corner? I would also try standing the TT on end with the bell firing down the long wall towards the room entry with the driver opening against the same wall.

I really don't have many options on cab orientation because of how I designed it, nothing else would look right. One thing I will try now that you mention placement options is to turn the cab 90 deg and have the mouth face the left wall, right now it is facing the back wall. The only issue then is that the mouth will only be about 4-5 inches from the side wall if I choose that placement. But, it's worth a shot. Actually, I do have one more option, that is to put the TT in place of my coffee table, the bass will not be nearly as loud or strong, but I will try almost anything to even out the LFE.

I also wonder if since you know the sub location you may be very sensitive to any timing issues in the signal.

Yes, that is an issue. There have been a couple ( < 3 ) times that the bass was a lot more centered in the room, but 90% of the bass in movies I can hear at the left side of the room, to the point where my left ear feels bass deaf sometimes.

If you were to watch and listen from a position directly say 2 feet from the TV and mains would the perceived placement effect of the sub decrease. I would also suggest setting your HP and LP to what sounds best and the adding about 20ms or more of delay to the signal. This would place the bass arrival even or slightly behind the mains.

No matter how I adjust the crossovers, it always sounds the same to me... The only way I get better sound dispersement is if I set my mains to "Large" and my crossover to 60hz, but, I'm afraid of pushing my mains too hard..

I will let you know how my sound is after I rotate the cab.

[Bill Fitzmaurice]

. The only way I get better sound dispersement is if I set my mains to "Large" and my crossover to 60hz, but, I'm afraid of pushing my mains too hard..

That tells me the problem is your receiver, which probably has insufficient slope on the low pass. Try it this way, if the mains are strained you'll know it. Does your plate amp have a low pass? if you have to set the receiver crossover to 80Hz or higher compensate for it by setting the sub amp low pass at 60 Hz.

[digital_chris]

. The only way I get better sound dispersement is if I set my mains to "Large" and my crossover to 60hz, but, I'm afraid of pushing my mains too hard..

That tells me the problem is your receiver, which probably has insufficient slope on the low pass. Try it this way, if the mains are strained you'll know it. Does your plate amp have a low pass? if you have to set the receiver crossover to 80Hz or higher compensate for it by setting the sub amp low pass at 60 Hz.

I think I'm getting more dispersement only because my mains are putting out more db in the 60-80hz range and my sub is putting out less, is this correct? At this stage, my AVR / sub amp settings are as followed..

Front: Large
LPF / HPF: 60hz
Bass Mix: Mix
Amp LPF: 60hz

Normally and ideally I would have them set as...

Front: Small
LPF / HPF: 80hz
Bass Mix ***
Amp LPF: 80hz

On a different note, I turned my sub 90 deg and that didn't have much change if any and I didn't put it in the center where my coffee table is because I really don't want to wire in that spot so I didn't even bother.

I did play the AVR's test tones to make sure my sub wasn't running hot and they were reading the same DB across the board but when I played the LF tone, it's like I can "see" if coming from the corner, that's how directional it is.

To be a little more fair, I know the movie depends on how the bass will sound but that damn matrix movie is wicked directional. I popped in I, Robot though and played a couple scened in DTS, the bass was spread out a bit more but I still hopeed for better all in all.

[Bill Fitzmaurice]

The problem with insufficient slope on the LP filter is that there's still too much content into the directional frequencies. That's a real issue with horn loaded subs that have higher sensitivity as frequency rises. An 18dB slope is OK, but most receivers are only 12dB, as are most plate amps. But if you cascade the two that's 24dB, and then you can run to 80Hz with no worries.