Table Tuba 11 inch panels, humming sounds at 20 hz

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Bill Fitzmaurice
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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#16 Post by Bill Fitzmaurice » Sun Nov 14, 2021 12:02 pm

Extension is based on horn length, but sensitivity is based on mouth area. A 36" THT is more sensitive at 20Hz than a 24" THT. It's not a huge difference, to get 3dB you'd need to double the mouth area with a 48" width. That would result in throat area too large for one driver.

JensToft91
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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#17 Post by JensToft91 » Sun Nov 14, 2021 12:12 pm

So I'm 3 db down at 20 hz, compared to a 22 inch TT? And then a 10" would probably help, because 20 hz is below the horn "tuning". Have I understood correctly

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Seth
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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#18 Post by Seth » Sun Nov 14, 2021 12:58 pm

JensToft91 wrote:
Sat Nov 13, 2021 12:57 pm
Right now it's running on a digital board amp 100w. Tpa-something. Input is RCA from the phone. Tone generator.

Got the same sound from the avr (chromecast-youtube-20 Hz tone video-rca from subwoofer out-tpa Amp)
Have you tried using one of the AVR channels instead of the board amp?
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#19 Post by JensToft91 » Sun Nov 14, 2021 1:48 pm

I believe i fixed it, but i will try this tomorrow.

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#20 Post by JensToft91 » Tue Nov 16, 2021 4:26 am

I ended up disconnecting the TT, and reconnecting my SVS PC12-NSD, because it goes deeper. But rehearing the cannons in Greyhound left me disappointed.

SPL is SPL, and I doubt that the SVS doesn't have enough dynamic range for my listening level (-25 -> -30db) with dynamic EQ (10db setting in Audyssey). Subs +5db.
Can it be true that a horn has more of an impact-feeling to the sound? A more aggressive "attack"?

I'm not trying to use fancy "audiophile" terms here.

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Seth
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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#21 Post by Seth » Tue Nov 16, 2021 11:46 am

Are the cabs EQ'd at all? Individually, or same settings for both? With an RTA or just by ear?
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#22 Post by JensToft91 » Tue Nov 16, 2021 12:11 pm

Both Audyssey EQ'ed. Multi XT32.

I may have eq'ed the SVS with a boost down low- possibly lowering the 30-80 hz to much. This is where the impact sound is, as far as I've understood.

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#23 Post by Seth » Tue Nov 16, 2021 7:46 pm

If they weren't EQ'd to the same target curve, that makes sense. Even with the two EQ'd to the same target curve, they'll not sound identical. Also, the port and driver location on the SVS could contribute to it having slightly different acoustic characteristics in the room, compared to the TT (or any other sub).

That said, with the three horn subs I have made, they all seem to have a special quality to them that direct radiators just don't match. Even if the horn's not as loud (measured or perceived) they just seem to sound better and switching back to a direct radiator hasn't been satisfying in my experience.

I don't know what it is, but I think I understand where you're coming from. I'd give up some sub 30Hz sensitivity in exchange for the smooth, tactile, effortless sounding bass that horns seem to exhibit any day of the week.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#24 Post by JensToft91 » Wed Nov 17, 2021 5:40 am

About the horn-sound: Thank you Seth. This is exactly what I felt. There's a different feel to it - And I think i'll end up doing the same as you. Give up sub 30HZ response for the horn-sound.

About EQ:
I beginning to hate the whole Audyssey-deal. I've never really liked the sound of an EQ'ed speaker. It doesn't sound natural to me.
I've been using Bypass L/R, but the surrounds are still EQ'ed.

Just yesterday, when I wanted to equal the system after your answer (Are they EQ'ed the same), I ran Audyssey again with the TT connected. I then measured the frequency response of my front right speaker, and then the sub. The sub was 5 db lower than the speakers bass response. I've been so frustrated about boosting the subchannel 10 db after calibration, and kept holding back, because it was "technically wrong". Now it makes sense. I like it 5 db hot, atleast.

The thing I can't solve is dynamic range compression. I LOVE Audyssey's DRC - but I can't acces it without using the EQ. Dolby Volume is too aggressive. You can tell when it compresses (ex. a gunshot).

When I come home, I'll setup the system manually. Probably EQ the sub with a miniDSP, Set channel levels by mic, and then finetuning the sub by ear.
Then I'll probably have to settle with Dolby Volume for DRC.

How is your system set up?

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#25 Post by Seth » Wed Nov 17, 2021 2:31 pm

I'm into pro audio, and to a lesser extent, car audio. I'm not into home theater at all. So, I have no system to share with you other than my inexpensive 2.1 computer speaker system. I had never heard of Audyssey and had to google it and read a little to get an idea of what you're talking about. DRC... MultEQ XT... never heard of them before either.

As far as an EQ'd system not sounding natural... if that's the case, something's wrong. Nearly any speaker in any room can benefit from EQ correction and contouring. That said, trust your ears. If you prefer the sound when you bypass the EQ on the mains, then that's the right thing to do.

I don't know the in's-and-out's of Audyssey's functionality, so I can't really provide any insight on setting sub levels. In car or pro-audio, if the sub output is down 10dB, I'd either increase the sub amp signal gain, attenuate the mid/high signal, or a combination of both until they matched up at the crossover frequency. I'm not really sure how that's done in Audyssey.

I'm sure I'm overlooking something obvious. But, what's "technically wrong" about boosting the sub channel 10dB to match the tops? It's the entire LFE channel, isn't it? Not an EQ adjustment, right?

I did a little looking into the "TPA" board amps. It could serve you well to get or try something a little more traditional. All of the YouTube tests I watched indicated their actual performance is about half of advertised at best. If you end up needing a decent amount of EQ to get the desired in-room response from the TT, you may really appreciate (and notice) the extra power.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#26 Post by Rich4349 » Wed Nov 17, 2021 3:22 pm

How did you decide to locate the subs where you did? Visual esthetics? (Wife acceptance factor), sub crawl, only place it will fit?
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#27 Post by Seth » Wed Nov 17, 2021 6:00 pm

JensToft91 wrote:
Sun Nov 14, 2021 12:12 pm
Bill Fitzmaurice wrote:
Sun Nov 14, 2021 12:02 pm
Extension is based on horn length, but sensitivity is based on mouth area...

So I'm 3 db down at 20 hz, compared to a 22 inch TT? And then a 10" would probably help, because 20 hz is below the horn "tuning". Have I understood correctly
I'm not 100% positive and really, this is just a hunch based on my occasionally faulty intuition, but I think since 20Hz is lower than the horns length is tuned for, the mouth area wont have the same effect as it would for frequencies within the horns designed bandwidth.

Could be complete rubish
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

Rich4349
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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#28 Post by Rich4349 » Thu Nov 18, 2021 10:05 am

At or near the bottom end of these horns' performance, the driver in the enclosure itself has some output as a direct radiator, *I believe*. I think I remember this coming from the horse, himself.

If this is so, a larger driver would most likely have a bit more output at the bottom end, below the horn tuning level.
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#29 Post by Seth » Thu Nov 18, 2021 11:51 pm

...or more Xmax. Either (or both) can increase Vd. :idea:
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Re: Table Tuba 11 inch panels, humming sounds at 20 hz

#30 Post by Bill Fitzmaurice » Fri Nov 19, 2021 7:48 am

Rich4349 wrote:
Thu Nov 18, 2021 10:05 am
At or near the bottom end of these horns' performance, the driver in the enclosure itself has some output as a direct radiator, *I believe*. I think I remember this coming from the horse, himself.

If this is so, a larger driver would most likely have a bit more output at the bottom end, below the horn tuning level.
It will, but since its sensitivity below the horn corner frequency is still much less than within the horn frequency there's no point in doing it.

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