Not getting powerful sound out of Tuba HT LP

[DaveMacKay]

As noted here viewtopic.php?t=398

can DSP help much in dealing with a room’s shortcomings?

Not much. If you fill a major dip at one listening position with EQ it will result in a peak at another position. If you and everyone else sit in one small area that may not be a problem, but over a large area it will.

Thanks for the reply, and for the pointer to the other thread.

One other question … is the direction that the THTLP “mouth” faces important? Currently both of my THTLPs stand vertically, as close to (diagonal) corners as possible, with their mouths pointed to the ceiling.

[Bill Fitzmaurice]

Probably not, although in some circumstances it could result in a floor bounce cancellation.

[Jan-Kees]

Okey, I did new measurements on different distances from the back wall. Red is 30 cm from back wall, green is 60 cm from back wall. Purple is the current listening position at 2,27m. I have to say there is a window in the back wall, like 17cm deeper then the wall itself, the measurements are from the window...
The 40hz notch is less deep. And it looks like there is not much difference between 30 or 60 cm from the back wall. It even looks like 60 cm from the back wall is giving a flatter bass overall. But the 40hz notch is not completely gone...
And I always thought that the back wall was the worst listening position because of bass build up (slow bass) / standing waves and reflections? I have a window there with blindings. And the surround speakers are hanging on the back wall, there will be a lesser surround effect, I know that, because I once had the couch there! And the screen is a lot smaller..
Some recommendations says like 1 meter al least from back wall...I did some more measurements and the further away from back wall, how deeper and sometimes wider the notch around 40hz became.

[Bill Fitzmaurice]

Now move the sub to the back wall and see what happens.

[Jan-Kees]

On a good day I will test the sub in the back and do new measurements. But my wife never gonna except a big sub like the Tuba HT there. So I'm already looking for other solutions. Will it make any sense and difference to put the smallest Table Tuba in the back corner or next to the listening position? (see picture) The one that roll-off after 38hz?

[Jan-Kees]

it's woolly sounding.

Sounds like an EQ issue.

Can you explain what you mean by that? Because I have set the EQ on bypass now, and the woolly sound is practically gone. Did I have too much EQ corrections?

[Bruce Weldy]

it's woolly sounding.

Sounds like an EQ issue.

Can you explain what you mean by that? Because I have set the EQ on bypass now, and the woolly sound is practically gone. Did I have too much EQ corrections?

Well, if it sounds better than it did before, then I'd say yes. 90% of the time EQ should be used to subtract the frequencies that are causing a problem, and occassionally a small amount of increasing a frequency or two. If turning off the EQ made it sound better, then whatever curve you had was causing your problem.

When you use the word "wooly", I tend to think about frequencies in the 100-250hz range. But, since I doubt that you are running the sub that high - I'm not sure what your definition is. Of course, if you don't have the sub low-passed and it is getting into the same range as your main speakers - that is the problem most likely.

[Jan-Kees]

The sub is crossed over at 80hz. And by wooly I mean kinda muddy, lacking definition and tightness. Before I had the sub out of fase and with EQ, it was terrible. The dynamics of the whole sound was gone.

[Bruce Weldy]

The sub is crossed over at 80hz. And by wooly I mean kinda muddy, lacking definition and tightness. Before I had the sub out of fase and with EQ, it was terrible. The dynamics of the whole sound was gone.

Ok, are your tops high passed at 80hz also? What slope are you using for the crossovers?

[Jan-Kees]

Yes, every speaker is high passed at 80hz. I have set them in the Lexicon MC8 surround processor, so I don't know what slope it is using.

[Bruce Weldy]

Honestly, we're just shooting in the dark here. Since we all have different definitions when we describe what something sounds like, it's hard to nail down the problem.

My suggestion is to get the sub in the best possible position that your wife will allow, then start with the EQ flat and begin cutting one frequency at a time and try to locate the offending frequency that causes the wooliness. There may be more than one. Most likely the problem is going to be between 80-400hz. Try not to boost any frequency unless you have everything sounding really good and it just needs a little bump somewhere to make it better.

[Radian]

Yes, every speaker is high passed at 80hz. I have set them in the Lexicon MC8 surround processor, so I don't know what slope it is using.

That’s the bulk of your problem right there. LaScala high pass filter set too low….and THT low pass set too high. The mains and subs are walking all over one another in your space.

According to the manual, the MC8 filters are 24 dB/oct…although analysis of their charts indicates more like 12-18 dB/oct in application….which would be inline with THX standards.

Set any EQ to flat first.

Then set the sub (the low pass filter) to 30-50hz, then go back and raise the output of the sub back up +12 dB SPL

Then set the remaining speakers (their high pass filters) to 100-110hz.


That should yield a crossover @ approximately 80-90 hz confirmed by using a tone at either freq and checking phase there, and a helluva lot better transient performance of the entire system.

After that, go back and EQ to taste only pulling down any obvious peaks to taste. Won’t take much

[Jan-Kees]

If I select THX crossover setting in the MC-8 processor, it sets all speakers to 80hz. So all speakers above the 80hz and sub below 80hz, the Lexicon takes care of the crossover transition right? With a overlap, which is normal.

[Bill Fitzmaurice]

by wooly I mean kinda muddy, lacking definition and tightness.

Below 80Hz there's no such thing as definition and tightness. You have to go up another octave to hear that. Below 80Hz even pitch is difficult, if not impossible, to hear.

So all speakers above the 80hz and sub below 80hz, the Lexicon takes care of the crossover transition right? With a overlap, which is normal.

Overlap isn't normal. Summing to the same level at the crossover frequency is, but not overlap. Show us RTAs of the sub alone by turning off the mains amp, then of the mains alone by turning off the sub amp.

[Jan-Kees]

From the MC-8 manual...
"When a THX speaker setup is selected, the MC-8 applies a THX 80Hz crossover point with a 12dB-per-octave filter to the Front L/R, Center, Side L/R and Rear L/R output connectors. The MC-8 applies a THX 80Hz crossover point with a 24dB-per-octave filter to the Subwoofer output connector."