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Old 3rd September 2013, 12:47 PM   #1
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Default Folded horn sound quality?

Where in order would a folded horn's sound quality fall?

1-sealed
2-transmission line
3-ported
4-passive radiator

I've never heard one.
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Old 3rd September 2013, 12:56 PM   #2
gedlee is offline gedlee  United States
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If you are talking about bass in a room, i.e. the modal region, the sound quality of the above would pretty much all be the same, the room being the dominate factor. Then if you use several of them and properly EQ them, the sound quality would be independent of the type of sub.
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Old 3rd September 2013, 03:42 PM   #3
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I could see how it would be true if a lot of constraints were imposed on a system. If I tried to EQ a ported 15 to play at 10hz as opposed to the same 15 sealed (bottoms out) or if I tried to get a sealed woofer to match the spl of the ported one at its vent tuning frequency (bottoms out), or if I put a 15 with specs that called for a sealed system into a vented box, I can pick them apart each and every time.

My question had to do with certain FH subs being called one note boomers. You feel thats just an EQ issue?
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Old 3rd September 2013, 03:54 PM   #4
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The thing that comes to mind is that in my truck it took building 5 boxes to get the TC sounds LMSr12 to sound decent. The last were were all sealed with each on dropping the system Q from .71 to .65, to .60. Each one was a dramatic change and I switched back and forth all night some boxes 3 times. I can pick any one of them out 10 out of 10 times. Its hard to believe that was an EQ issue going from a 1 cubic ft box to a 1.4 then to a 1.75....all sealed. The first 2 boxes were ported and sounded really bad. I could see the ported ones boosting the vent tuning frequency 10-12db causing that issue but the sealed boxes? Not so much.

I respect your education so I will chew on it.

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Old 3rd September 2013, 04:00 PM   #5
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Without generalizing, I would say 5th. A folded horn SUBWOOFER ONLY is meant to facilitate a superbly efficient transfer of bass energy to the room/space. Of course, with exceptions, they are not intended for subtlety or nuance like a sealed or transmission line enclosure is. They also must be designed bang on, otherwise you end up with what you're describing: your horn cuts off far above where you expect it to because it's either not long enough, or was improperly flared to the correct cross-section. This has little to do with EQ: you cannot EQ a horn subwoofer to perform beyond its capabilities below its cut off frequency. You can add as much as you want down there, but you're just squeezing the stone harder to get more water. That said: if you design a horn properly, it can be made to fit your application be it sound quality or simply impact and extension.
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Old 3rd September 2013, 04:55 PM   #6
gedlee is offline gedlee  United States
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Quote:
Originally Posted by SpinMonster View Post
My question had to do with certain FH subs being called one note boomers. You feel thats just an EQ issue?
Putting all the subjective perceptions aside. as far as I can tell from all my investigation into LF sound in rooms, the source type just washes out when you use multi-subs and EQ. The excursion capability and power handling of the driver is all that matters in that part of the equation. The box type has very little impact on either of those parameters. At some frequencies a resonant system, like ported, TL and/or horn may have some excursion enhancement, but at other frequencies it might be degraded. The simple closed box is very hard to beat when one has good drivers (excursion and power handling), enough amp volts and DSP capability. Everything else is just bigger for the same resulting SPL in the room.
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Old 3rd September 2013, 05:40 PM   #7
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Originally Posted by SpinMonster View Post
The thing that comes to mind is that in my truck it took building 5 boxes to get the TC sounds LMSr12 to sound decent. Each one was a dramatic change and I switched back and forth all night some boxes 3 times. Its hard to believe that was an EQ issue going from a 1 cubic ft box to a 1.4 then to a 1.75....all sealed.
Each box would have a different frequency response, and the location in the trunk and size of the car's cabin affect frequency response quite a bit.
Why is it hard for you to believe that the difference in sound was not an EQ issue?

As far as the sound quality of various types of subs, I have found the difference between sealed, ported, TH and FLH to be fairly hard to detect if they are equalized to the same response, properly phase aligned at the crossover point and run below Xmax.

That said, a "one note" version of a sealed, ported, TH or FLH enclosure can be made, and EQ won't be enough to correct the problem.
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Old 4th September 2013, 04:38 AM   #8
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Originally Posted by weltersys View Post
Each box would have a different frequency response, and the location in the trunk and size of the car's cabin affect frequency response quite a bit.
Why is it hard for you to believe that the difference in sound was not an EQ issue?

As far as the sound quality of various types of subs, I have found the difference between sealed, ported, TH and FLH to be fairly hard to detect if they are equalized to the same response, properly phase aligned at the crossover point and run below Xmax.

That said, a "one note" version of a sealed, ported, TH or FLH enclosure can be made, and EQ won't be enough to correct the problem.
You had the red sentence backwards. I didnt think it was an EQ issue because I agree with the blue sentence

The sub's location in my hummer was exactly the same and the external size of the box wasnt all that much different. The driver was always 4" from the side in the rear in all boxes as its distance from the side was with a wooden spacer.

No I dont think EQ makes up for poor alignment choices. I think Earl's statement applies to a properly designed example of each alignment. A sealed box with a Qtc of 1.1 is never going to match the articulation of a Qtc of .57 with just EQ.

Last edited by SpinMonster; 4th September 2013 at 04:45 AM.
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Old 4th September 2013, 05:01 AM   #9
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Quote:
Originally Posted by weltersys View Post
... As far as the sound quality of various types of subs, I have found the difference between sealed, ported, TH and FLH to be fairly hard to detect if they are equalized to the same response, properly phase aligned at the crossover point and run below Xmax.
...
If equalized to similar response, I would mostly agree. But then that would have to take into account phase and orientation of the port for a BR or whatever you choose. If you have several well designed systems placed throughout, it is probably very hard to detect any differences at all, because the locations of the woofers and the phase disturbances made by the room would most likely even out. But if you have few sources and they are not well designed, it would not be a big challenge to pick out any differences. That is the advantage of closed systems IMO, phase predictability.

At least I find that when taking phase into account of the design, it sounds a lot better than if aiming for frequency goals only.
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Old 4th September 2013, 05:38 AM   #10
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EQ will not correct for improper damping or group delay. Also, the sound from a port is delayed from the initial waveform of the driver. They dont happen at the same time. Ringing (resonance lack of damping) is not just an issue of amplitude where cutting a freq fixes the problem, its in the time domain too as on a waterfall plot. Lack of damping is when a feed signal stops but the speaker continues on with inappropriate sounds rather than decreasing the waveform over time. Yes adjusting EQ flattens the freq response on a graph but EQ squashes initial signal to. You're supposed to have an initial attack followed by an appropriate decay. Killing some frequency kills it during the attack too.

Last edited by SpinMonster; 4th September 2013 at 05:41 AM.
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