Looking for ideas for a small amplifer for a set of component speakers

[xtremerevolution]

I would never port an enclosure. I am a fan of sealed.

 

 

all that porting does is take a high pitched bass note and distorts it to sound lower than it was actually recorded at. I consider it distorted.

 

That is 100% incorrect.

 

Its not distortion, its port tuning. When done properly, it will yield a much higher efficiency at a given frequency than with a sealed box, the only disadvantage being size. It will sound just as good if not better. Anyone who tells you ported box distorts and sounds lower knows absolutely nothing about box design and port tuning.

 

It doesn't change the frequency *AT ALL*. Its not an equalizer, it accentuates certain frequencies which would otherwise roll off more sharply in a sealed box. It just so happens that most ported boxes are very horribly built and tuned to be one note wonders, so even though all frequencies are being played, there is a peak frequency range that is played much more loudly and makes everything sound like shit. This is why buying pre-fabbed sub boxes are an absolutely terrible idea. Combine that with the fact that cars have a signfiicant amount of cabin gain, and you get a very, very bad frequency response that sounds like absolute garbage.

 

Let me show you what my IDQ's frequency response looks like in the box I designed for it, and this was designed around the T/S parameters of this specific sub:

 

 

The above chart shows a frequency response in yellow for a sealed box, and a frequency response in green for a ported box for my specific sub, tuned to my specifications. Notice its not peaky or boomy, it is a nearly flat frequency response all the way down to 23hz. By comparison, the sealed box would have needed a great deal of equalization. It would require more power and more excursion to reach the same frequency response. In short, its very inefficient. You'll also notice that it does not take a high pitched bass note and make it louder. It accentuates the lower frequency range (or "pitch" as you put it) of bass notes to make a more linear frequency response. Even people who think they know what they're talking about don't factor in cabin gain when designing a car sub.

 

Another problem cars have is most people can't build a proper ported sub box because it won't fit in the trunk. The above graph is modeled for ONE 15" sub that takes 400W RMS and uses 6 cubic feet. My newest design uses 4 cubic feet and 100% fiberglass fill to achieve an even more linear frequency response with even higher power handling before xmax is reached. With the the 4 cubic foot box, I don't reach xmax till I give the sub 150W more than its rated for. That's called proper ported box design.

 

Oh, and fyi, my newest box design was designed for me by none other than Matt Borgardt, the lead engineer behind Image Dynamics, who designed the very sub itself.

[Garrett Powered]

if you have a w7 you will not need a ported enclosure.

[Garrett Powered]

http://mobile.jlaudio.com/support_pages.php?page_id=147

[xtremerevolution]

if you have a w7 you will not need a ported enclosure.

 

You will for a home theater if you want a linear frequency response.

 

Honestly, the w7 elitism is getting a little much. Yeah its a great sub and handles power nicely, but it still follows the rules just like any other sub. Its still entirely dependent on the box you put it into and the environment its playing.

 

Sealed or ported isn't just about output, its about frequency response and tonal accuracy. The w7 has a pretty sharp roloff in the frequency response due to being designed as a car sub with cabin gain in mind. Don't believe me? I can model it in the JL recommended box and show you why it would do terribly as a sealed sub in a home theater. Sealed might be fine for automotive, but that specific sub won't be linear in a large room.

 

Sent from my HTC Awesome using Tapatalk

[xtremerevolution]

http://mobile.jlaudio.com/support_pages.php?page_id=147

 

That article confirmed exactly what I said a couple posts above.

 

Sent from my HTC Awesome using Tapatalk

[Garrett Powered]

its not a rule, its a law. "Hoffmans Iron Law" I love it

 

If I was truly close minded JL fan I would not be buying two other 1000 watt systems and testing them in real life. home and car, not with varying factors like enclosure design, but with fiberglass reinforced sealed enclosures built with the right amount of airspace, airtight suspension, and no flex. so you HAVE tested the W7 as a home sub? ...oh

 

I want you to read this article. http://www.salksound.com/wp/?p=56

[xtremerevolution]

its not a rule, its a law. "Hoffmans Iron Law" I love it

 

If I was truly close minded JL fan I would not be buying two other 1000 watt systems and testing them in real life. home and car, not with varying factors like enclosure design, but with fiberglass reinforced sealed enclosures built with the right amount of airspace, airtight suspension, and no flex. so you HAVE tested the W7 as a home sub? ...oh

 

I want you to read this article. http://www.salksound.com/wp/?p=56

 

You think I don't know anything about hoffman's iron law? I design speakers buddy. I design complex crossover networks and model baffle diffraction and box alignment to achieve a linear frequency response with complete tonal accuracy and phase alignment. You don't have enough knowledge on the subject to even know how a ported speaker box works.

 

Hoffman's iron law doesn't refer only to subwoofers, it refers to the cabinets in which they're built. This is arguably irrelevant to the topic at hand since we were talking about the JL w7 and how you think it doens't need a ported box. Apparently its some Godlike sub that does everything perfectly? Only you know what you meant by that. Hoffman's iron law can also be bent to a very great degree in car audio due to cabin gain. You can have your cake and eat it to; to install a 6.5" comp in a sphere that contains as little airspace as possible to control excursion, because you know that cabin gain will accentuate the frequencies you're reducing by making such a small enclosure to start with, and the remaining peaks can be controlled with a good active crossover and EQ.

 

I want you to start actually proving to me that you know something about home and car audio or stop talking like you do.

 

I would never port an enclosure. I am a fan of sealed.

 

 

all that porting does is take a high pitched bass note and distorts it to sound lower than it was actually recorded at. I consider it distorted.

 

The above quote demonstrates you know next to nothing about how sub enclosures actually work and destroys any credibility or authority you might have had on the subject.

[white4d96]

I was gonna say, my ported box doesn't seem to "distort" frequencies to lower than what they are. Play a 35hz tone it doesn't become 33hz

[Garrett Powered]

if its my word against yours, then lets talk about who experimented with which enclosures first. If I have no credibility on the subject, how come I had a custom transmission line enclosure in my cavalier back in 1992. while it was not designed by a actual scientist, the guy was an eccentric that loved to get the most out of a driver.. any driver. he has this crazy sounding enclosure that made a 4" krako car speaker sound like a 12" woofer. when he got done with my 15 box I ended up just blocking off the hole and using it as sealed.. it was way better after that.

[Garrett Powered]

I was gonna say, my ported box doesn't seem to "distort" frequencies to lower than what they are. Play a 35hz tone it doesn't become 33hz

 

 

maybe not, but it will fart if you dont use a subsonic filter

[xtremerevolution]

maybe not, but it will fart if you dont use a subsonic filter

 

Subsonic filters should be used in *any* ported box to prevent the sub from unloading if ever played below the tuning frequency. The port design and the box controls excursion at frequencies above the tuning frequency, but below that, its basically free air and subs (aside from ones optimized for infinite baffle configurations) will reach their xlim real fast and potentially destroy the coil.

 

I say should because not everyone is too careful with the kinds of frequencies they send through a sub, although I will honestly say I've never heard a song that played below 20hz. I've heard movies that have, but even those are very few and far between. I have enough digits on my fingers and toes to count the number of movies that exist that hit below 15hz.

 

if its my word against yours, then lets talk about who experimented with which enclosures first. If I have no credibility on the subject, how come I had a custom transmission line enclosure in my cavalier back in 1992. while it was not designed by a actual scientist, the guy was an eccentric that loved to get the most out of a driver.. any driver. he has this crazy sounding enclosure that made a 4" krako car speaker sound like a 12" woofer. when he got done with my 15 box I ended up just blocking off the hole and using it as sealed.. it was way better after that.

 

Transmission lines are very difficult to get right, and require very large enclosures. In addition, tuning them is difficult and your frequency response will be very peaky and booby. Combine that with cabin gain and you have a recipe for pure SPL and SQ disaster. It will be a one note wonder and nothing more. If you've seen frequency response charts for bandpass and transmission line boxes, you'll know exactly what I'm talking about. Part of the problem is a very sharp rolloff before and after the tuning frequency, which makes integration with the rest of the system very difficult. Overall a bad idea.

 

Because it worked better sealed meant nothing except it was not designed for SQ by any means and had a very boomy and peaky response. A properly designed ported box will sound just as good as a sealed box when done properly.

 

Let me give you an example of what I'm doing right now. I'm designing a slim wall mountable tower with 4 3" TangBand drivers:

 

https://www.madisound.com/store/product_info.php?cPath=45_241_282&products_id=8781

 

These run out of xmax REAL fast, which is why I'm using a 1.5L (~ .01 cubic feet) sealed box, at which point they barely exceed xmax by .2mm at a short range of frequencies. This will allow them to take their full rated 12W each of power without distorting due to xmax. I'm crossing them low at 2200hz with a 1" Vifa tweeter with a 3" waveguide to prevent any excursion-related distortion on the more sensitive high end, and to eliminate combing and lobing due to driver spacing from the tweeter.

 

These drivers at their maximum 48W thermal power handling will 108.4db SPL per cabinet and a very smooth and shallow rolloff at around 150hz. The reason for the smooth rolloff is the sealed box alignment, whereas ported boxes will have a sharper roloff. A smooth and shallow rolloff is generally better for stereo speakers than a sharp and steep rolloff due to being able to more easily integrate a subwoofer. The subwoofer's low pass crossover combined with the shallow rolloff of the stereo speakers will create a pretty flat summed response.

 

Its a little more complicated than just buying a prefabbed box, stuffing a sub that matches the cutout size, and putting power through it. Its extremely easy to make a sealed box to the manufacturer's specs, and its another thing entirely to make something sound linear, accurate, and efficient.

Edited June 3, 2011 by xtremerevolution

[Garrett Powered]

and what are you doing when you apply a subsonic filter? you are dropping the lowest of the bandwidth that was recorded by the artist and recorder of the piece.

 

what are you going to do to replace this in order to reproduce the piece accurately as the artist and recorder intended? throw one of (these)

 

in your trunk with a 8.5 cubic foot box in order to make up for what you threw away?

 

 

when I use my 1000/1 and w7 together in a sealed enclosure, I have the subsonic filter defeated and the floor drops out.

[xtremerevolution]

and what are you doing when you apply a subsonic filter? you are dropping the lowest of the bandwidth that was recorded by the artist and recorder of the piece.

 

what are you going to do to replace this in order to reproduce the piece accurately as the artist and recorder intended? throw one of (these)

 

in your trunk with a 8.5 cubic foot box in order to make up for what you threw away?

 

 

when I use my 1000/1 and w7 together in a sealed enclosure, I have the subsonic filter defeated and the floor drops out.

 

Holy shit dude, are you just trying to be an ass or do you really not know anything about this? A subsonic filter does exactly what I said it does, to prevent the sub from unloading at frequencies below its tuning frequency. That tuning frequency is more of a range than anything, and a graph will show you that its a general estimate. A W7 for example tuned to 30hz will start unloading at around 18hz and get worse as the frequency range drops.

 

A subsonic filter does not completely cut out that frequency, but rather creates a slope in which its output decreases by a given db per octave typically 6, 12, or 24db depending on what order filter is used in order to protect the cone's excursion.

 

It doesn't take out the lowest frequency or lowest bandwidth, it attenuates the frequency below the port tuning. My 15" sub will be tuned to 23hz as noted earlier with a subsonic (technically called a high pass) at 20hz. Why? Because nobody records at 20hz. In fact, the lowest notes on a bass guitar, drum, or mostly any recorded instrument doesn't go below 40hz.

 

http://www.recordingeq.com/EQ/req0400/OctaveEQ.htm

 

The first usable octave for most recording is the 40 - 80 Hz range, with equalization settings centered around 50 Hz. This range of frequencies is often referred to as "Low Bass"

There is sound between 20 Hz and 40 Hz but little or no sound from instruments. The lowest pipes of a pipe organ will get into this range but more "ordinary" instruments like Bass Guitar, Upright Bass and Foot Drums do not. The lowest pitch on a bass guitar or string bass is at 41 Hz.

 

You'll only get down to maybe 16hz on some pipe organs, so unless you're listening to that kind of shit, you won't need to worry about it. Everything else that goes down to 20hz is synthesized.

 

But to answer the OP's question, very rarely do you need extension down to 20Hz.

 

The low "E" string of a standardly tuned 4-string bass guitar is tuned to ~41.2 Hz.

 

The low "B" string of a standardly tuned 5 or 6 string bass guitar is tuned to ~30.9 Hz.

 

The low "A" key of a standardly tuned 88-key piano is tuned to 27.5 Hz.

 

Of course, there is synthesized bass, but it very, very rarely drops as low as 20Hz. 30Hz is usually low enough for the artist to get his/her point across.

 

What's the volume of your W7? I'll show you exactly how bad your response is. You don't even need a subsonic filter; your sealed box attenuates those frequencies by design. Luckily for you, cabin gain helps fix it, but it would sure as hell not be ideal for a home theater.

 

You will not lose any usable low bass extension with a subsonic filter at 20hz and no subsonic filter at all, because rarely will you run into a synthesized "recording" that goes below 20hz.

[white4d96]

Not quite.

 

With sealed boxes, the lower you go, the lower the output goes, as the woofer has to fight the air in the chamber more. I have never heard a sealed box that played well below 30hz and all the way up to 60-70hz. (Nothing against you Andrei, but one song wasn't really enough to tell me what that puppy could do) My ported box, on the other hand, will play down to 26hz easy, and if you could care less about port noise, will play all the way down to 5hz (Yes, I have a song with a 5hz note in parts of it) without unloading and smashing the formers. Is it ideal? No way, but it's worked so far.

 

 

 

 

...With that being said, I have waaaayy too small of a port and that chokes output down low as well, just not to the degree of a sealed box. Of course, that also helps with playing below tuning without launching cones

[xtremerevolution]

Not quite.

 

With sealed boxes, the lower you go, the lower the output goes, as the woofer has to fight the air in the chamber more. I have never heard a sealed box that played well below 30hz and all the way up to 60-70hz. (Nothing against you Andrei, but one song wasn't really enough to tell me what that puppy could do) My ported box, on the other hand, will play down to 26hz easy, and if you could care less about port noise, will play all the way down to 5hz (Yes, I have a song with a 5hz note in parts of it) without unloading and smashing the formers. Is it ideal? No way, but it's worked so far.

 

 

 

 

...With that being said, I have waaaayy too small of a port and that chokes output down low as well, just not to the degree of a sealed box. Of course, that also helps with playing below tuning without launching cones

 

Like I said, cabin gain fixes that in cars, which is why people can get away with sealed boxes and still have a relatively low frequency response. I've recorded nearly linear down to 25hz. I have the xmax to do it. One song definitely wasn't enough, I agree, so if you want, I'll let you bring a test tone CD (or we can run them off my laptop with WinISD) and listen to a few more tones or songs side by side when you come to the meet later this month.

Edited June 3, 2011 by xtremerevolution

[xtremerevolution]

Not quite.

 

With sealed boxes, the lower you go, the lower the output goes, as the woofer has to fight the air in the chamber more. I have never heard a sealed box that played well below 30hz and all the way up to 60-70hz. (Nothing against you Andrei, but one song wasn't really enough to tell me what that puppy could do) My ported box, on the other hand, will play down to 26hz easy, and if you could care less about port noise, will play all the way down to 5hz (Yes, I have a song with a 5hz note in parts of it) without unloading and smashing the formers. Is it ideal? No way, but it's worked so far.

 

 

 

 

...With that being said, I have waaaayy too small of a port and that chokes output down low as well, just not to the degree of a sealed box. Of course, that also helps with playing below tuning without launching cones

 

Oh, btw, send me your sub's specs (or I can look it up for you), including your box specs and port dimensions, and I'll tell you exactly how much of an effect its playing on your output and what your frequency response, what your xmax is at max thermal power handling, and what you pre-cabin gain SPL is.

[white4d96]

I have the T/S param's saved on WinISD on the home comp, I just remember that the Fs is 28hz on them.

 

As for the box, it's 1.3 cubes per tuned to 33hz with a 4" round port per chamber. It will be getting tossed soon as I need to build an enclosure that will clear the RSTB

[xtremerevolution]

I have the T/S param's saved on WinISD on the home comp, I just remember that the Fs is 28hz on them.

 

As for the box, it's 1.3 cubes per tuned to 33hz with a 4" round port per chamber. It will be getting tossed soon as I need to build an enclosure that will clear the RSTB

 

What sub is it?

 

I stopped using WinISD a while ago. Unibox is sooooo much better.

[Garrett Powered]

I am happy with being an ass. as long as I am included and not dismissed as a fool. I am still trying to find an excuse to build a concrete foundation for a home with some 18" or larger subs so please continue trying to alter my perception on the topic. It is doing nothing but fueling my thoughts for when I win the lottery.

[xtremerevolution]

I am happy with being an ass. as long as I am included and not dismissed as a fool. I am still trying to find an excuse to build a concrete foundation for a home with some 18" or larger subs so please continue trying to alter my perception on the topic. It is doing nothing but fueling my thoughts for when I win the lottery.

 

I have the feeling you don't know what a 15hz or 10hz test tone "feels" like (technically because you can't hear it). I invite you to pull up a laptop, install WinISD, and play a 10hz test tone through your sub.

 

I happened to find a WinISD graph of *TWO* JL 13W7's, ported of course, in a 10 cubic foot box tuned to 17hz. Keep in mind, this is not an ideal alignment as you have very little in the way of cone excursion control due to having such a large box, and you reach xmax in this case long before you reach your maximum thermal power handling.

 

 

Now that's two JL W7's in a home, ported because sealed would have too sharp of a rolloff to be any good below 20hz.

 

With 1000 watts input a high pass filter would be needed at 14 hz to stop the sub from bottoming out at 15 hz and lower.

Read more: Build 2.0 of my JL 13w7 - Home Theater Forum and Systems - HomeTheaterShack.com

 

There turns out to be a long list of movies that hit below 20hz.

 

http://audioaficionado.org/home-theater/2086-ht-20hz-below.html

 

Given that configuration, you can plainly see that even two JL 13W7's in a quite large box are barely enough to keep up with special effects in home theater below 20hz, hence my statement that you need 2-6 18" subs to move enough air to play those frequencies linearly. Even at 15hz, there's a -10db drop. If you want to dig really deep in home theater, you need cone area, and even two JL 13W7's aren't enough to cut it.

 

Here's another graph comparison of a sealed vs ported single JL 13W7:

 

[xtremerevolution]

Just got the box specs for white4d96's subs and modeled them.

 

Your two 12" subs actually don't run out of excursion till you reach 20hz. Anything after 20hz is a very serious increase in excursion. You will literally destroy that sub if you play anything lower than that. I hope your high pass filter has a steep slope. I'd even bump it to 22hz just in case.

 

Your box is quite peaky, with a +5.11db peak at 30.76hz. A lower tuning frequency would do wonders for your box for SQ and for SPL at 20-30hz. An option to improve the response would be to get a 90 degree elbow inside the box and make a longer port. Port nose won't matter too horribly much in a trunk, and 4" ports don't choke a 12" sub by any means.

 

As it sits, my 10" IDMax in .9 cubic feet delivers almost the exact same SPL (1db difference) at 20hz as your two ported 12's do (hence my recommendation to make the ports longer), and if both sets of subs are in sealed or ported alignments, they nearly exactly the same SPL within 2db of each other depending on the frequency. The difference from then on comes in cabin gain and how the rest of the car is set up.

 

I can send you the two unibox spreadsheets if you want to play with either one of them. You'd need Microsoft Excel 2003 or 2007.

[Garrett Powered]

I have the feeling you don't know what a 15hz or 10hz test tone "feels" like (technically because you can't hear it). I invite you to pull up a laptop, install WinISD, and play a 10hz test tone through your sub.

 

I happened to find a WinISD graph of *TWO* JL 13W7's, ported of course, in a 10 cubic foot box tuned to 17hz. Keep in mind, this is not an ideal alignment as you have very little in the way of cone excursion control due to having such a large box, and you reach xmax in this case long before you reach your maximum thermal power handling.

 

 

Now that's two JL W7's in a home, ported because sealed would have too sharp of a rolloff to be any good below 20hz.

 

 

There turns out to be a long list of movies that hit below 20hz.

 

http://audioaficionado.org/home-theater/2086-ht-20hz-below.html

 

Given that configuration, you can plainly see that even two JL 13W7's in a quite large box are barely enough to keep up with special effects in home theater below 20hz, hence my statement that you need 2-6 18" subs to move enough air to play those frequencies linearly. Even at 15hz, there's a -10db drop. If you want to dig really deep in home theater, you need cone area, and even two JL 13W7's aren't enough to cut it.

 

Here's another graph comparison of a sealed vs ported single JL 13W7:

 

 

 

 

 

 

 

You said in your above statement that QUOTE :"Now that's two JL W7's in a home, ported because sealed would have too sharp of a rolloff to be any good below 20hz." Now I am getting not only conflicting data on YOUR GRAPH YOU POSTED. ! how the bass output AT 10 Hz. and below start outdoing the ported! How can you just keep proving yourself wrong 3 or 4 times a post. the JL enclosure discussion on the website suggests a sealed enclosure for better transitions anyway but you can see also there the sharper rolloff *AGAIN YOU WERE WRONG STATING THAT* my god. CLEARLY the sharper rolloff is on the red ported curve! can't you see that?

 

sorry didn't mean to go off, just saying.

 

 

 

can't you see on your lower graph that the sub 10 Hz. tones are louder? now add that with better transitions in that range it does not seeem that bad now. especially once you actually experience it in your car. Not sure about home, but I would really suggest sealed for home use if you want the advantages of it. knowing what I know.

[xtremerevolution]

You said in your above statement that QUOTE :"Now that's two JL W7's in a home, ported because sealed would have too sharp of a rolloff to be any good below 20hz." Now I am getting not only conflicting data on YOUR GRAPH YOU POSTED. ! how the bass output AT 10 Hz. and below start outdoing the ported! How can you just keep proving yourself wrong 3 or 4 times a post. the JL enclosure discussion on the website suggests a sealed enclosure for better transitions anyway but you can see also there the sharper rolloff *AGAIN YOU WERE WRONG STATING THAT* my god. CLEARLY the sharper rolloff is on the red ported curve! can't you see that?

 

sorry didn't mean to go off, just saying.

 

 

 

can't you see on your lower graph that the sub 10 Hz. tones are louder? now add that with better transitions in that range it does not seeem that bad now. especially once you actually experience it in your car. Not sure about home, but I would really suggest sealed for home use if you want the advantages of it. knowing what I know.

 

I was typing quickly and I meant sharp not as in slope, but sharp as in heavy. I was also comparing the two graphs. From 50hz to ~18hz (the range that used in 99% of music and movies) the sealed box does have a sharper rolloff (comparatively). My bad choice of words there, I should have been more specific. I honestly don't care much what a sub can do below 10hz. I posted those to point out the differences in ported and sealed, and the fact that even a W7 can't reproduce a 10hz test tone with any reasonable amount of volume.

 

I don't know what you're smoking, but the vented/ported box in these instances outperforms the sealed box in every instance, with the obvious exception of frequencies below ~12hz. However, the advantage of having more linear frequency response at the frequencies that actually matter for 99% of music and movies outweighs that heavily.

 

The JL website suggests sealed for transitions because in a car, it sounds better with most subs. The additional air suspension controls the cone of the sub. JL's recommended ported box would also sound like shit and be very peaky. However, given the T/S specs of that sub, I'd be willing to bet it would sound perfectly fine with regard to transitions in a ported box, as there is still plenty control on the cone above the porting frequency. One of the reasons I like Image Dynamics subs is they can be configured as sealed, ported, or infinite baffle and sound excellent doing any of those.

 

In addition to the JL site you posted, read the link. Its for the mobile site.

 

In home audio, that transition isn't half as important as you usually blend a sub that large at a relatively low frequency because you have speakers that can hit down to 60-90hz at loud volumes. Also in home audio, as I mentioned, that would never work. I've said it before, cabin gain makes an incredibly large impact.

 

I can clearly see that sub 10hz tones are louder. I can also know that sub10hz tones are limited to a handfull of movies that most people will probably only watch once. Sub20hz is a different story, but once you get below 12hz, you're pretty much never going to play anything that plays that low.

 

Seriously, stop this bullshit, get a laptop, install WinISD, and play a 10hz test tone through a sub because its clear to me you have no idea what it "sounds" like. You won't be able to hear anything below 20hz.

 

I'm assuming you meant "not sure about home, but I would seriously recommend sealed in a car."

 

Just a typo like I made above. In any case, I would agree with that statement, for one very important reason. Cabin gain. If you had that linear of a frequency response, it would be come very un-linear due to cabin gain. If you recorded a frequency sweep of a sub outside on the ground, then recorded it again inside your car, you'd notice a very large increase at certain frequencies. In addition, you couldn't build a ported box big enough for a JL W7 to sound good unless you had an SUV with a large trunk. It would sound like garbage, so yes, if you own a normal car and a W7 and you want sound quality, sealed is your only option. However, transitions were referred to not between one frequency. When people refer to transitions in subs, they refer to its ability to play a wide range of frequencies and play them accurately. A loose sub will hit a low frequency (30hz) tone very well, but when you add in some 70-80hz beats, it would muffle them out because it cannot control the cone enough to play those frequencies at the same time. Its quick transitions between different frequencies. Its another reason why some people are crazy over ID's older V2 subs, with lower xmax and high sensitivity. They won't play very low frequencies particularly loudly, but they will have extremely fast and accurate transitions due to having a lighter moving mass and a lower xmax. Combine that with a sealed box that further increases cone control, and you can see why these things win SQ competitions so easily.

 

Seriously, I HAVE to know though, how have you experienced 10hz in a car. Tell me what song or test track it was, because I'm dying to find it.

Edited June 4, 2011 by xtremerevolution

[xtremerevolution]

For the record, fast forward to .25.

 

 

That's a 5hz test tone.

 

 

That's a 10hz test tone.

 

No, you cannot hear those frequencies, and no, you cannot reproduce them at reference volumes without at least 2 very high powered 18" subs.

[Garrett Powered]

I see an improvement!

 

you went from "I really don't care", to "Whatchu smokin'?", to "I am dying to know".

 

 

this is what I like to see.

 

 

two very high powered 18"s? sounds like something I would be into but that would obviously not be very practical in your car. w-7 in a sealed box would be your best shot. you can't JUST use wood though. the monoleaf is not strong enough and will soon break (even without all that weight) so I would suggest using a Birchmount steel spring, along with a fiberglass braced, thin walled, sealed box, with heavily fortified 2 to 3" faceplate (I use a 5" faceplate ). a clean transitioning sealed box relies on the air suspension to get that low. be careful with yours when you get it, some poor kid had his crappy particle board box explode inside his trunk.

 

 

 

now with the bass curve discussion going on, there seems to be a little confusion. the vocabulary term sharp roll off when talking 12 vs. 24 dB roll off's for the same given sub. 24 would be the sharper because the signal dropped 24 whole dB's in the same amount of time it took for the sealed to only drop 12. with ported you want it to drop sharply because without suspension the sub IS going to fart if you do not. and when it does it is NOT pretty. with a sealed box you want the opposite. the smoother the roll off, the better, because the shallower, the lower the bass extends to (glad you see that now, it is true with all subs, home or car). and the more you will experience if your amp actually plays that tone, and if the recording plays that tone.

 

now cabin gain is another topic that I do not find significant in the discussion of a sealed enclosure for a car. orientation of the sub does not matter at frequencies that low. the bass wave will not fully expand unless you open your windows/sunroof and let it. bass is non-directional and the cone just shoves air around. open the window and it will fluff up your girlfriend's hair and get you in trouble