Optimized impulse responce of subwoofer; Horn VS Vented box - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 21 Old 03-05-15, 05:23 AM
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Re: Optimized impulse responce of subwoofer; Horn VS Vented box

This sounds like a valuable discussion here because accuracy in subs is not easy to attain. If I can comment on LLT enclosures: If you tune your enclosure low enough the worst part of the group delay is located under 20Hz. The peak of the delay may be very high but (with music at least) you wont hear it because its typically much lower by 25HZ and up. So as a ported enclosure goes this may be a good choice?
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post #12 of 21 Old 03-05-15, 06:12 AM
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Re: Optimized impulse responce of subwoofer; Horn VS Vented box

Quote:
phazewolf wrote: View Post
Off topic how low can you get while still having a flat response and what size room are you working with?
The native response of the subwoofer sytem in my rough;y 24'x19'x10' vaulted ceiling room extends to the low teens with the inherent eoom gain. The overall response is slightly down-sloped, falls about 4 db by 18 kHz and is very linear when measured at the listening position using 1/12 octave smoothiing.

Last edited by rkeman; 03-07-15 at 07:15 AM.
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post #13 of 21 Old 03-05-15, 01:40 PM Thread Starter
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Re: Optimized impulse responce of subwoofer; Horn VS Vented box

Here is the output of the horn and the vented sub for 1W input and for 1000W input.
The RCF LF18X400 speaker is used as driver in both examples.
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Optimized impulse responce of subwoofer; Horn VS Vented box-freq-horn-vs-.sub.jpg  

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post #14 of 21 Old 03-05-15, 01:45 PM Thread Starter
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Re: Optimized impulse responce of subwoofer; Horn VS Vented box

My room will be about 9m x 7m. It is not built yet.
The subwoofer will be built into the front wall. The idea is a critical listening room/studio control room.
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post #15 of 21 Old 03-05-15, 01:52 PM Thread Starter
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Re: Optimized impulse responce of subwoofer; Horn VS Vented box

My problem with subwoofers is that I really dislike them!
In most cases I would rather not have the bass extension instead of turning the sub on.
I think most sub-woofers on the market just smear the music and sound terrible.
A lot of it has to do that in general the only parameters that are specified is the wattage and the frequency response. But these parameters say extremely little on how it will sound when playing music.

I believe that transient response is the most important parameter for a sub. If it is not quick a bass drum beat will sound the same as a bass guitar note and the music will just be a general blur below 60Hz.
That is why I want to build a super fast subwoofer, so that I can finally enjoy the lowest octaves in music!
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post #16 of 21 Old 03-06-15, 12:48 AM
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What are you using for your mains and if you don't like subwoofer's have you thought about using a full range speaker?
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post #17 of 21 Old 03-06-15, 03:47 AM
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What is the purpose of this system? Is it for 2 channel music a home studio for mastering?

What kind of treatment is in the room as of now? Many subs have sounded very bad when placed in a room that did not have proper bass traps setup.

Also just a other thought what subs have you played with and we're they in a well treated room and properly setup and aligned with the mains and was this confirmed with measurement software?

Besides just bad subs and they are out there a lot of issues seem to be room related placement or poor matching to the phase of the mains. If the bass from the sub lags behind the mains it is going to sound slow.
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post #18 of 21 Old 03-07-15, 03:41 AM Thread Starter
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Re: Optimized impulse responce of subwoofer; Horn VS Vented box

The room is going to be used for two channel stereo material. The "subwoofers" will actually be part of the main stereo setup, so there will be one sub on each side supporting a large studio monitor with the lowest 2 octaves.
So it is a bit like a PA system where a stereo setup is supported by multiple boxes.

It will be used mainly as a critical listening room to judge recordings and changes made to equipment. It will also be used as a studio control room for mixing and recording.

I think my main complaint with subwoofers is that they are usually made to get the most bass out of a as small as possible box volume. This usually lead to some bandpass design or a high Q tuning vented box. This usually means a boomy ringing bass. Even most of the "professional" subwoofer such as Genelec and KRK have this problem. On the Hi-fi side I have tested one of DynAudios bigger subs and was very disappointed. I think most subs that I have tried suffer from "one note bass" to some degree.
I also do not like long throw woofers. When you see a speaker moving like crazy already at normal listening levels you just know that that speaker will run out of headroom fast when there is a transient and there will be distortion as a result and the music will sound compressed and boring. I like large subwoofer, more like PA subwoofers where the cone is almost standing still for most of the playback, but this type of speaker is very rare in a domestic enviroment I think, largely due to it's size.
For some reason fullrange speakers do not suffer as much from this problem, maybe because bass extension is not the primary design goal, so a roll off may be accepted as a good compromise when it comes to over all performance.

My goal is kind of to have PA sound levels with Hi-fi performance. PA speakers are usually very efficient, but few of them play good bass below 30Hz, and they usually have a bit more distortion than Hi-Fi speakers. I want to go all the way dowmn to 20Hz and still be able to support peaks of 120dBSPL without ringing and a lot of distortion.

I would love to try a large overunder damped subwoofer tuned to a Bessel response. But these are mostly found in big cinemas where they do sound very good indeed. Ironically I think that some cinemas are the only place left to hear real audio quality for music playback. Even concert PA systems seems to be designed for a lot of other things than sound quality. A good cinema is still a place were you can hear a wide dynamic response at high SPL with low distortion.
To bad they mostly show movies there...
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post #19 of 21 Old 03-07-15, 04:10 AM
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If the goal is high output with low distortion then a few well designed horns would do what your looking for.

No need to tell you that horns for 20 hz will not be small and as long as your fine with such I don't see a issue hitting that spl with a few of them depending on how far you plan on sitting from them.

Do you have the equipment to offset the proper delay for your mains sense the horns will will have a larger latency then the mains will.
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post #20 of 21 Old 03-07-15, 05:59 AM Thread Starter
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Re: Optimized impulse responce of subwoofer; Horn VS Vented box

My thought exactly!

Yes I know they will be big...
I will get a digital delay line for the other drivers, since the horn will add up to 20ms of delay for the lowest frequencies.

But back to my initial question; I thought horns would definitely be the way to go, but when simulating, the horns actually have worse transient response then a vented cabinet, and I do not want to start building anything before I am happy with my simulation results!

This simulation result does not really add up to my subjective experience with horns as being very fast and direct, and not having a lot of overhang, so now I'm confused...
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