Hello, I am new here. I am interested in horn-loading, particularly with regards to increased sensitivities (by this I mean greater SPL/watt ratio) I understand that for lower frequencies, a larger horn must be used. Is this why no one puts bass horns in their cars? I know Bill Fitzmaurice designed a horn enclosure called the AutoTuba
I read on Single Driver Website about a system suffering from impedance spikes if the horn is cut off prematurely. I do not know enough to understand why that would be a bad thing. Couldn't a lower impedance speaker be used?
I read on Single Driver Website about a system suffering from impedance spikes if the horn is cut off prematurely. I do not know enough to understand why that would be a bad thing. Couldn't a lower impedance speaker be used?
some thoughts:
1) A horn is a quarter wave resonator. For instance, a horn with a pathlength of 84" will resonate at 40hz. (speed of sound / 40hz / 4)
2) The dimensions of a car basically make the entire cabin resonate like a quarter wave resonator
THEREFORE
If you want the efficiency of a horn in a car sub, you're going to get most of the benefits of a horn sub by simply placing a sealed box in the typical car cabin
Having said that, I've published a pile of a horn subs for the car. Just google some of my threads.
The main reason that I build horn subs for the car isn't to get horn loading at low frequency, it's to get horn loading at midbass frequencies. For instance, the typical car cabin will give you a lot of boost below 60hz, but there's a lot of 'bass' harmonics that occur from 60 to 240hz.
The Autotuba is a good example of this. Below 60hz the autotuba is no more efficient than a sealed 8" sub. But *above* 60hz it's very efficient and can take a lot of abuse.
1) A horn is a quarter wave resonator. For instance, a horn with a pathlength of 84" will resonate at 40hz. (speed of sound / 40hz / 4)
2) The dimensions of a car basically make the entire cabin resonate like a quarter wave resonator
THEREFORE
If you want the efficiency of a horn in a car sub, you're going to get most of the benefits of a horn sub by simply placing a sealed box in the typical car cabin
Having said that, I've published a pile of a horn subs for the car. Just google some of my threads.
The main reason that I build horn subs for the car isn't to get horn loading at low frequency, it's to get horn loading at midbass frequencies. For instance, the typical car cabin will give you a lot of boost below 60hz, but there's a lot of 'bass' harmonics that occur from 60 to 240hz.
The Autotuba is a good example of this. Below 60hz the autotuba is no more efficient than a sealed 8" sub. But *above* 60hz it's very efficient and can take a lot of abuse.
Hello,
it is necessary to differentiate between acoustic impedance and electric impedance in this context. Unfortunately on a forum like this it is hard to know if somewhat asking a question has a phd in engineering or didn't have an electrics class in high school, so apologies if I'm telling you something you already know.
The electric impedance is the resistance of the speaker, the lower the resistance, the more current can flow through it for a given voltage. However you can't just lower the speaker's electric impedance indefinitely, it needs to match that of the amp for ideal transfer of power from amp to speaker.
Acoustic impedance is a similar concept, but not affected at all by the electric resistance (Ohms) of the speaker. The air around us has a certain acoustic impedance. The lower the acoustic impedance, the more sound can "flow" through it. Unfortunately short of listening underwater, we can't really change the air's impedance around us. However same as with the electrical impedance, the acoustic impedance of the speaker has to match the acoustic impedance of the air to transfer power from the speaker to the air.
For most regular speakers the acoustic impedance of the air is far too low, meaning bad power transfer from speaker to air, meaning low efficiency and quiet speakers. What a horn does is adjust the acoustic impedance of the speaker, making the power transfer to the air better, and therefore the speaker louder. A full size horn will do this all throughout the frequency range it is designed for (determined by the horn dimensions).
If you make the horn undersized, it may only optimize the impedance, and therefor how loud the speaker sounds, at certain frequencies - meaning your frequency response will not be flat, but peaky. Unfortunately, a full size horn for bass frequencies is huge - if the car you drive is a camper van, you could consider putting one in, otherwise it's probably not realistic.
Can an undersized horn still work? Sure it can, but you need to be aware it won't be as efficient (and loud) as a full horn, and you need to simulate to see where it falls short, and if those compromises work with your overall system design (for example the loss of horn function at low frequencies may be counteracted by the SPL gain due to pressure vessel effect in the car, aka cabin gain).
In my opinion a horn can make sense even in an automotive context, but you need to figure out for yourself whether the trade off is right for you.
It can be done and I have it (2 horn tweeters at desk, 2 competition midranges in the door and one folded sub that takes up about 1/3 of the trunk. All powered just by the head unit, so about 18 unclipped watts peak. I have a Volkswagen Golf 3.
Sounds a lot better with the engine off. Once driving there is noticeable low freq noise from tires etc, so you lose some detail and end up using the bass boost function to beef it up. Also due to standing waves the bass sounds a lot more deep when you move your head forward. With front windows down the reflections from the tweets are also gone and the soundstage sounds incredible just in fromt of you. (Not in the current weather possible) Bass is more even then, so this is the preferred way for me.
I made the mistake to use midranges in the doors and they should have gone down lower so I wasn't forced to go up in freq and get some cues from the sub in the back VS less peak SPL.
If I would redo it, I'd probably use a minimal amplifier (https://en.wikipedia.org/wiki/MOT_test is rediculously strict here in Belgium) and also use 4 bass drivers in the doors to even out standing waves in the car.
Pros: If I stay within clipping of the head unit, everything is incredibly clean. (Hard)Rock can be blasted in my face like a private concert. 115dB with no amps or everything and no distortion. Ample headroom to adjust for driving conditions (see above). Passes our MOT without additional "tuning fees". Deep and controlled sound that surpasses the expense of the components. Satisfaction of a personally and unique soundsystem.
Superior imaging of the soundstage, even more so with the front windows down.
Cons: 26 kg is heavy to remove from the trunk if you need the space. In a light car like this the (removal of
) added weight is noticeable during full acceleration. Standing waves for the bass. Lack of distortion/compression makes listening more difficult with road noise. Need for adjustment/custom curve while driving, so not the flattest responce curve. Sub needs to be run a little bit to high for my taste to not stress the front midranges too much. Doesn't sound so loud as it actually is. Lose 1/3 of trunk space.- Status
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