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Subwoofer with resonator tube?

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Subwoofer with resonator tube?

Postby scottherbert » Tue Aug 15, 2017 1:43 pm

I posted this question in another topic and got no response, so here it is again. If a subwoofer like the Tuba HT goes low, but is slow because of it's folded horn design, what about a sub with a small box and a large resonator like the Teres subwoofer?

It uses 2 sub drivers directly radiating out of a small cube, with a large cylinder out of the top to resonate the sound lower, somewhat like an (extremely) oversized tuning port. The tube is about 15 inches wide by (approximatly) 5 feet long. I am probably way off on the dimensions, I'm only going by memory, but you get the general idea.

~S
"Life is just a dream, it is in death that we truly awaken!"
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Re: Subwoofer with resonator tube?

Postby 1961TC4ME » Tue Aug 15, 2017 5:30 pm

Hi Scott,

I saw your post about this in the other topic I started, but didn't get a chance yet to throw in my 2-1/2 cents worth. My thinking (and maybe I'm wrong here) would be to have a sub that develops the lows a bit slower than faster as I'd maybe assume a sub that belts them out quickly may be a bit too boomy or inaccurate to what actually happens? Just a guess though. I do know or have at least heard that for the very lowest notes of a given organ the notes generally take some time to fully develop as they interact with the surroundings.

I was at an organ demo up in the loft a number of years back at the local very large Cathedral here in St. Paul, MN and when he hit the very lowest 32' on the pedal you really didn't hear anything at first, then just a rather faint, slow fluttering almost like a slow pulsing wind going past you.

Marc
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Re: Subwoofer with resonator tube?

Postby scottherbert » Tue Aug 15, 2017 6:23 pm

It's not about those lowest notes where the speed is the question, it's all the harmonics and higher notes. I know we all want a sub that can reach 16 hz, but there is so much more above that. I have seen so many designs that claim each is the best, I just get dizzy! :roll:

~S
"Life is just a dream, it is in death that we truly awaken!"
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Re: Subwoofer with resonator tube?

Postby scottherbert » Tue Aug 15, 2017 6:32 pm

Thanks Marc, for your consideration;
If a sub is slow and is re-creating the slow speech of a pipe, does the sub add slowness to the speech?
If a sub is fast and the slow speech of the pipe is accurately sampled, would the fast sub be better for reproduction of that same slow speech?

~S
"Life is just a dream, it is in death that we truly awaken!"
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Re: Subwoofer with resonator tube?

Postby murph » Tue Aug 15, 2017 6:41 pm

Part of the problem with long horns is the time it takes for the sound to arrive at the mouth. Unless the supporting speakers are delayed by as much (if not more!), the horn will always sound "slow". (Upper harmonics should not be coming out of a bass-horn!!! EVER!)
When it comes to HW, deliberately adding another 8+ms delay is not always desirable just to integrate things to the lowest frequency transducers. Then everything sounds distant!
A better approach, for large spaces, is to only send the 32' stops to the long horn and delay the sound of it's upper harmonic producing speakers back to the horn. This will sound just like a real pipe developing it's speech in a real room.
For smaller spaces/sound systems, compact front-loaded subs are easier to integrate.

My 2c.
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Re: Subwoofer with resonator tube?

Postby 1961TC4ME » Wed Aug 16, 2017 11:29 am

One thing I have always wondered is, overall how accurately am I reproducing the sound of the real thing with the sample set? You take a given organ in a given acoustic, it's recorded from a given position and or positions, these recordings are then combined and created as a sample set that we then bring into our own space to play. Even in the given church depending on the listening position I have no doubt the response time of certain notes, harmonics, etc., will all vary just depending on where you're listening from. Realizing all this, and yes as things go on the quality of the sets are getting better and better, more realistic, almost to the point of being unbelievable, but no matter the set I purchase it at best is still going to be a very good rendition of the actual instrument, but not a perfect one because of all the variables involved.

So, it seems to me anyways the trick then is to set things up that sound best to you, speaker choice, sub choice, how many channels and so on are just parts of the overall picture. Some of the things mentioned here, harmonics, low note reaction time, and I'll throw in clarity, stereo field image, clashing of harmonics (and there's probably a bunch more we could mention), is the exact reason early on I played around endlessly with rank routing, speaker positioning and so on until I got things 'as real as it gets' for me.

Marc
Last edited by 1961TC4ME on Wed Aug 16, 2017 3:16 pm, edited 1 time in total.
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Re: Subwoofer with resonator tube?

Postby jkinkennon » Wed Aug 16, 2017 2:11 pm

On the subject of a sub being fast or slow I don't think we need to get caught up in that issue. If we put a console and speakers in the center of a wall and place the sub, any sub, in a corner then that sub is already slow since it is farther from the organist than the regular speakers. Figure the slowness as roughly one millisecond per foot. Compensation for that delay may not be practical, but organ music does not typically require the kind of phase aligned impact that one would want for a kick drum or bass guitar.

Are we talking about a residential room? Then the sub's power is not an issue. Pick a quality sub sized at 12" or 15" that uses some kind of servo feedback from the driver so that it can extend gracefully down to 16 cycles. The most musical designs are likely sealed enclosures, not ported, for the smoothest response rather than the most power out. Avoid PA subs as they are intentionally rolled off at higher frequencies.

My choice would be something from Rythmik Audio, but there are others that use fancy servo or equalization compensation to get similar results. I'd expect this sort of sub to go for about $1500 or more depending on how much hype is included in the price.

Lots of sample sets have slow attacks in the pedal which I imagine is how the real organs respond. Attack delays that are noticeable are way longer than the delays in a particular sub design. Isn't it something like 25 to 30 ms that can actually be heard as "late"? I believe that to be the case.
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Re: Subwoofer with resonator tube?

Postby 1961TC4ME » Wed Aug 16, 2017 3:27 pm

jkinkennon wrote:On the subject of a sub being fast or slow I don't think we need to get caught up in that issue. If we put a console and speakers in the center of a wall and place the sub, any sub, in a corner then that sub is already slow since it is farther from the organist than the regular speakers.

Lots of sample sets have slow attacks in the pedal which I imagine is how the real organs respond.


I agree on both counts, to me it's more a matter of how you're getting there than anything else, and if the sub design you use does the job that's 3/4th of the battle. Part of the issue is the size of the enclosure, and for the average 'Joe' here, me included in that, I don't have the room for a monster sized cabinet or some long tube object occupying a large part of the little space I have. If my set-up was out in a pole barn, well sure, then I'd go all out and not worry about cabinet size and I'd probably be rattling the screws right out of the siding and roof! :lol: It seems the newer servo style subs are one of the answers, I am also a fan of the larger 12" and 15" passive radiator designs, both of which still have the more reasonable footprint size, but aren't cheap unless you can obtain the parts and build yourself, which still won't be inexpensive, but will be far less than buying completed.

Marc
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Re: Subwoofer with resonator tube?

Postby jkinkennon » Thu Aug 17, 2017 1:34 pm

1961TC4ME wrote: If my set-up was out in a pole barn, well sure, then I'd go all out and not worry about cabinet size and I'd probably be rattling the screws right out of the siding and roof!


Marc, that reminds me that for anyone building their own cabinet they need to be careful about what fasteners they choose. The Tuba HT that I built vibrated the screws out of the first plate amp I tried. Not just my mounting screws but the manufacturers machine screws that held the plate amp together. Use Loctite or a similar thread locker for any machine screws, even when they have lock washers. It's tempting to use "T" nuts and machine screws in a sub, including for mounting the driver itself and they work fine so long as extra care is taken to keep everything locked tight.

On the original question about resonant extensions to a small cabinet I'd imagine they work fine just like a sonotube subwoofer. I don't see where that saves space though perhaps it allows a smaller footprint. While a conventional 15" enclosure is approximately a 21" cube, I've been able to use them to hold lamps or electronics so the space they occupy need not be completely wasted.
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