I'd like to do some experimenting with subwoofer enclosure design . Can I use automotive speakers with my house amps ? I have a QSC CX 302 that I don't use anymore and I could use that to power car subs . The reason I want to use car subs is that I can get small ones , like 8 or 10 inch that put out a solid low end and they'll be relatively inexpensive . The enclosures would also be cheaper as they'd be scaled to a smaller speaker . What kind of voltage and current requirements are there for PA speakers and car speakers ? Any help you can give me would be much appreciated .
Automotive subs ?
- Thread starterwhaleboat
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Just make sure that your Ohms and Watts match. Don't hook up your 3000w amp to a 12w car speaker. Most stock car receivers max out around 30w-50w. On the other hand, PA amps can easily go to 3600w at 8 ohm, and if you drop that down to 4 ohm you're looking at over 5,000w.
If you're going to experiment and not 100% on the specs, just be willing to lose both the speaker and the amp.
If you're going to experiment and not 100% on the specs, just be willing to lose both the speaker and the amp.
It will work, just watch your amp/speaker matching at was noted above. Be aware though, car audio speakers are designed to really just move air and rumble. They are not really intended for any real audio reinforcement. If you are looking for that, get a real speaker. If you just want to shake some speakers in a black box... go nuts.
Not sure what they use currently, but the Mirage Volcano used to use these or similar from the same company, in bathtub- sized and shaped enclosures partially buried.
DiscoBoxer
Active Member
This has been a general rule of thumb, but advancements in today's car audio sub market have really challenged this statement, but you will pay for it and it may not be the most economical solution. There are many car subs that provide excellent sonic quality and many of them can get as low if not lower than popular "standard house" subs. I am a big fan of 10" subs as they are more accurate than a typical 18". An example for reference may be JL Audio 10W7 series, with a freq response of: 20-250 Hz. I have built 2 single subs that I use for my home theater setup and I couldn't be more pleased. I have also built 4 boxes with three of these 10's in them for a nightclub installation in Atlanta many years back that performed exceptionally well.
If you are aiming for accuracy/SQ than build a sealed box. If you want more SPL out of the sub with some loss of accuracy, than port the box. Not all speakers work well in the same enclosures and this is true for all speakers, not just car subs.
Do as mentioned above, by verifiying that the amp, your subs, and your wiring technique (parallell vs. series, etc) mate properly. Then you will want to check the speaker manufacturer specs on enclosure volume and porting if you choose to port.
They may do that with the right application for a listener a car, doing the same thing for a larger environment and/or in a different enclosure is not the same.
You really have to look at how a driver and enclosure work together. When you think about it there are multiple ways to move the same amount of air. You could use a larger driver, use one that moves a greater distance, use the motion of the driver in both directions, use an enclosure that couples more effectively to the environment, etc. Each approach has advantages and disadvantages and it's the speaker designer's role to decide which to try to employ in order to best serve the application. In car audio the smaller listener space, limited physical space and so on may greatly impact those decisions. In large scale sound reinforcement the larger listener space and other factors can impact the decisions.
The JL Audio 10W7 noted is an interesting example. It has a free space resonance of 30.6 Hz, so you could run it lower with the right enclosure but 20Hz would be below its natural resonance. But where the real difference arises is in the sensitivity and output. For comparison, let's look at the JL Audio 12W7 driver and the JBL 2206H 12" driver. The 12W7 has a lower free air resonance, 27.2Hz versus 52Hz, at almost four times the excursion with an Xmax of 1.15" versus 0.3". SO the 12W7 can provide lower frequency response and probably do so with a smaller enclosure. On the other hand, the 12W7 has the warranty voided if run with more than 1,000W 'RMS' and has a sensitivity of 86.2dB@1W/1m while the 2206H has a 600W continuous, or 2,400W peak, power rating and a sensitivity of 95dB@1W/1m. So with the recommended 750W for the 12W7 and the 'rule of thumb' 1,200W for the 2206H the outputs at 1m would be 115dB for the 12W7 and 126dB for the 2206H, an 11dB difference or just over twice the perceived volume. The enclosure could impact the actual response and output but the point is that the drivers are designed for different goals.
DiscoBoxer
Active Member
Excellent challenge Muse. On the JLAudio 12W7 my memory served me that they had a peak of 2000W "RMS". After your post I looked a little deeper, and the peak is stated@2000 on their spec sheet, but you are correct in that they void warranty at 1000. I find this to be very interesting as it's more like a statement of the sub can do this, but not recommended. I could not find an equivelent statement for the JBL sub that expressed maximum tested vs. maximum recommended.
If we take enclosure options out of the equation and look at the speakers as they have done in their specs, what is the relationship of increased power once the drivers are operating below their natural resonant frequency? Having a FS of 27.2Hz vs. 52Hz, wouldn't that mean that the JBL sub is working harder to produce the same frequincies in that difference, than the JL version?
The JBL sub may be able to handle more power, but this could also have a marketing element to it as well.....same as JL. JBL may state the sub tested at a higher peak and will warranty such to "lead the pack" in capability as a sales tool, but do they also host the same standards as JL when it comes to acceptable failure rates. Understand that I am not pitching either company here as they both make fantastic products, it is just a great opportunity to learn with the exercise.
I consider myself intermediate on these type of details and genuinely appreciate your expertise to teach me something.
If we take enclosure options out of the equation and look at the speakers as they have done in their specs, what is the relationship of increased power once the drivers are operating below their natural resonant frequency? Having a FS of 27.2Hz vs. 52Hz, wouldn't that mean that the JBL sub is working harder to produce the same frequincies in that difference, than the JL version?
The JBL sub may be able to handle more power, but this could also have a marketing element to it as well.....same as JL. JBL may state the sub tested at a higher peak and will warranty such to "lead the pack" in capability as a sales tool, but do they also host the same standards as JL when it comes to acceptable failure rates. Understand that I am not pitching either company here as they both make fantastic products, it is just a great opportunity to learn with the exercise.
I consider myself intermediate on these type of details and genuinely appreciate your expertise to teach me something.
There are standards for testing many aspects of speakers and it would be nice if manufacturers followed them and reported the information in a form that really allowed directly comparing them. But there are also times that the standard procedures don't relate well to the intended use. And you are right that the marketing becomes a numbers game just as it does for many things. FYI, the power rating on the JBL 2206H is stated to be per AES standards with pink noise band limited to 60-600Hz. The JL Audio power handling is "Thermal Power Handling" which as far as I can tell is somewhat analogous to continuous power handling but I do not know how it is actually defined or what signal is used. Obviously both have some limitations in defining the power handling for a subwoofer.
Sensitivity is also an often abused value. Is what is reported the average sensitivity, the minimum sensitivity over the stated operating range or the peak sensitivity at any frequency? I've seen some subwoofers with claimed sensitivities that relate to a peak in the response at a frequency well above where the sub would normally operate, meaning that in actual use the sensitivity might be much less. Then add in whether the sensitivity was measured free field/whole space or half space, the latter is common for many low frequency drivers and subwoofers. On top of that, factor in power compression. Power compression is one of the issues also often not addressed in power specifications and in simple terms is that a speaker tends to lose sensitivity due to voice coil heating and other factors when run hard for any length of time. The reality is that when all these are factored in two drivers or speakers with 'identical' sensitivity specifications could actually differ by 10dB or more in their effective sensitivity and without knowing what the numbers really represent you have no way of being sure.
Sensitivity is also an often abused value. Is what is reported the average sensitivity, the minimum sensitivity over the stated operating range or the peak sensitivity at any frequency? I've seen some subwoofers with claimed sensitivities that relate to a peak in the response at a frequency well above where the sub would normally operate, meaning that in actual use the sensitivity might be much less. Then add in whether the sensitivity was measured free field/whole space or half space, the latter is common for many low frequency drivers and subwoofers. On top of that, factor in power compression. Power compression is one of the issues also often not addressed in power specifications and in simple terms is that a speaker tends to lose sensitivity due to voice coil heating and other factors when run hard for any length of time. The reality is that when all these are factored in two drivers or speakers with 'identical' sensitivity specifications could actually differ by 10dB or more in their effective sensitivity and without knowing what the numbers really represent you have no way of being sure.
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