Sonotube with 12" Driver, New to Diy - AVS Forum
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post #1 of 69 Old 04-04-2013, 11:58 AM - Thread Starter
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I've been looking for a cost effective way to build a good subwoofer for a small room and it seems i may have found it. I'll be using what appears to be a jl audio Jl12w0 subwoofer driver that came with a used bass amp.

What edge thickness should i be looking for when purchasing Sonotube and what's a good place to buy 14"+ diameter in Canada?
Most appear to be under 1/2" thick, is that enough for durability and keeping the sound in the tube?

It appears some people have had good success with the jl auto subs (mostly higher end) for ht in certian enclosures and i am curious what specs i should know about the woofer to calculate enclosure size through software.

Also is their a huge difference in sound quality and effeciency between the low end and high end Jl's or mostly just power handling?

I would like to hit as low as possible but having never heard much lower than 30hz anything deeper would be new to me.

I'm also stuck between building it shorter and wider with a plate amp on the top or picking up a used power amp and installing a low pass filter in the sub.
Either way i'd like to keep the cost down and i imagine 100 watts+ is a good amount of power for a small room, if the driver is somewhat effecient.

I would prefer a sealed build but i'm not sure how frequency response scales with size in sealed vs ported or wether sonotube is suitable for sealed?

If it could be kept to about 5-6' tall and around 20" wide or less without sacrificing sound quality than i would prefer to go relatively compact as well.

This sounds like an awesome way to jump into diy and I would greatly appreciate help with figuring out what software to use and how to go about putting this together and attaching the top and bottom wood panels to the tube.

This is the tube that got me interested in this build: http://www.avsforum.com/t/1460025/sonotube-build-pics

If it could be about half as tall and a few inches wider it would be perfect, although i'd like to put a basic finish on mine.

Thanks in advance smile.gif
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post #2 of 69 Old 04-04-2013, 02:24 PM - Thread Starter
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I checked out the back of the driver and found out it is a jl12w0-4, xmax and effeciency are readily available but other specs like Q, Fs, and frequency response are nowhere to be found googling...
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post #3 of 69 Old 04-04-2013, 03:00 PM
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You can get the manual with all the T/s parameters from

http://mediacdn.jlaudio.com/media/mfg/9013/media_document/live_1/10_12_15W0_MAN.pdf?1317790098

 

This driver can only handle 125 watts so you're not going to get massive output from it. It seems to model best in a sealed enclosure that is 1.75 cu ft with 100 watts.

 

You can go ported but you would need a 7cu ft enclosure, tuned to 20hz, 75 watts with a 2nd order highpass at 20hz.

 

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post #4 of 69 Old 04-04-2013, 03:44 PM - Thread Starter
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Thanks for the reply and the info, what software are you using there and why is it that such a large box is required for a ported design? Like I said i'm completely new to this and i'm curious what either a larger sealed or smaller ported would have an effect on? Linearity? Spl?

Also Fsc is the resonant frequency of the driver? if so it is quite high (though probably spot on for a car sub from what i've read).

People apparentlly put more along the lines of 200 to 250 watts into these based on the reviews i've read, they claimed rms but i'm not sure if there's a difference between car sub amps and ht amps?

Thanks again, and this is definetly more of a learning project than building a high spl super sub.

Edit: I read the manual and the 22hz resonance sounds a little more reasonable, but i'm still not sure how it fits the big picture?
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post #5 of 69 Old 04-04-2013, 06:09 PM
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The software is WinISD Pro.

The large box is required to keep the response linear and that is determined by the Thiele/Small parameters.

Fsc is the resonant frequency of the driver while in the enclosure.

There is no difference between car and home amps. They both amplify the signal and their output is measured in wattage. It is the intended use of the driver and the material being sent to it. For car audio, it is music and music contains very little low bass. Some old rock songs never get below 50hz. Home theater can dip in to the subsonic (under 20hz) range on a lot of action movies. RMS ratings on speakers are thermal ratings. That is how much power it can handle over a specific period of time before glue starts to melt and the sub just falls apart. That rarely happens in home audio. We have to look at mechanical limits. Let's say your sub moves 4mm when producing a 40hz tone at 90db (all hypothetical). To keep that 90db level and produce a 20hz tone, your sub would have to move 16mm. To keep the level the same and play an octave lower, your excursion quadruples.

You will either find this project tedious and give up or it will become a lifetime obsession. I built my first sub in 1987.
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post #6 of 69 Old 04-04-2013, 07:01 PM - Thread Starter
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"You will either find this project tedious and give up or it will become a lifetime obsession"

Definitely the second one biggrin.gif

So basically i can grab the software, type in some parameters and mess around with the compromises, sounds like a plan.

The wattage to extension makes sense but only for a sealed build right?

What happens to the wattage numbers in a ported build?

The sealed 1.75' cu build doesn't look like it'll dip much below 30hz (although it has more output than i would have thought) not to mention the tube would be much less of a conversation piece at a couple feet tall wink.gif

I'll mess around with the software for a bit and see if I can find a good balance between size and extension, my mains should be good to 40hz as well so sacrifices can be made to higher frequency linearity if that will help the lows.

I've heard of sonotube software as well which i'm guessing will be useful for figuring out the volume of the cylinder.

Other than that i'll probably run this off an old Peavey cs800 for awhile to see how it sounds rather than dropping the cash for a plate amp right away.

The Peavey has the classic pop on startup through the cv pa's though, is that likely to damage the sub?

Also a good soundcard with lfe out is a suitable low pass filter?
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post #7 of 69 Old 04-05-2013, 06:54 AM
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Excursion/wattage is even more important with ported subs as they unload below the enclosure's tuning frequency. That's why you need a subsonic filter.

These simulations don't take into account the room's natural ability to boost the low end. It can't because it is room dependent. The sealed box doesn't look bad and in a small room will supply you with bass much lower than what that sim shows.

Here's the sonosub calculator - http://www.subwoofer-builder.com/sonosub.htm I used it when building three different ones. Two were passive cylinders with older, SVS Plus drivers (OEMed from TC Sounds) and one was an active cylinder with a Dayton DVC 12" and a 275w amp installed in the side like SVS does.

Depends on the voltage from the "pop" and how much mechanical clearance your driver has.

No.
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post #8 of 69 Old 04-05-2013, 09:51 AM - Thread Starter
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What do you think the sealed will get in a 14x10 room? That's a tiny box, my last powered sub was a cerwin vega lw12 ported that probably had around 3-4 cubes and it was good (though overpowering) but i would like to move down in frequency response from it's 30hz if possible.

I've got a multimeter around so i'll make sure to test the pop voltage before making use of it.

Soundcard lfe outputs integrate low pass filters right? I've driven sub frequencies through full ranges from cheap onboard sound lfe without issues.

So far i like the looks of the sealed box at around 3 cu ft, The qtc drops as the box size goes up and i gain more in the lows than i sacrifice in the 60hz and up range but room gain effects the lower frequencies more right?

Does lower qtc=tighter bass?

And why does qtc dissapear under box settings for a vented enclosure?

Edit: Excursion limits surpassed for ported and larger sealed tongue.gif Back to the drawing board
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post #9 of 69 Old 04-05-2013, 12:34 PM - Thread Starter
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Also it appears a ported 5 cu ft option is a little better as 7 put the excursion past it's limits above 20hz at 75 watts?

If i'm dealing with ported should i know more about the available alignments?

Why does vent length decrease when i decrease the vent diameter, shouldn't they balance out instead?

So many questions tongue.gif
Once again thank you for all the help, i'll definetly be sticking around the diy forum in the future to help out newbies like myself after i've done a few builds.
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post #10 of 69 Old 04-05-2013, 05:19 PM
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Smaller boxes control excursion better. Larger boxes are more efficient. Read up on Hoffman's Iron Law.

We really don't use things like EBS or the other "named" alignments. What size box can you live with is usually our biggest question.

No. It's a Hemholz Resonator. The math backs up my statement - http://www.diysubwoofers.org/misc/portcal.htm

As I said earlier, I've been doing this as a hobby since the 1980's and it still brings a smile to my face when I crank up a new sub. I've taken it a step further and I have built my own drivers. Here's one example. No, that's not me in the video. I traded the sub to a friend that likes to post videos. it's a TC-7 motor from TC Sounds, a generic basket that no one can figure out the original manufacturer, a coil and spider from a TC-2000 (TC Sounds) and a cone/dust cap from Sundown Audio. http://youtu.be/kG38EfCnBI8
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post #11 of 69 Old 04-05-2013, 07:09 PM - Thread Starter
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I'm more of a real world scenario guy, I'd be lost in a second reading that stuff biggrin.gif

I'm mostly just stuck on finding a balance now. As long as this driver isn't known to be sluggish in a large ported box i'd probably only use sealed for preliminary testing at this point.

I believe my psb 500's will have better mid bass regardless of the scenario so i'm looking more at the 60hz and below segment making this a home theater sub rather than musical.

I've got it narrowed to around 5 cu ft with a port tune in the 22 hz region, hopefully i can get the graphs up'd tommorow.
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post #12 of 69 Old 04-05-2013, 07:48 PM
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As long as this driver isn't known to be sluggish in a large ported box
Slow, sluggish, etc are descriptions that are technically incorrect. http://www.diy-audio.narod.ru/litr/WooferSpeed.pdf
Quote:
i'm looking more at the 60hz and below segment making this a home theater sub rather than musical.
Why not a sub that will accurately reproduce whatever signal is fed into it? It doesn't know you are watching TV or listening to a CD or sometimes watching a music video.

Why don't you go a little smaller and tune higher? You only have 8.6mm of xmax to work with. Look at 3.5 cubic feet tuned to about 25hz. You will definitely need a subsonic filter no matter what ported enclosure you go with.
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post #13 of 69 Old 04-06-2013, 10:44 AM - Thread Starter
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Alright, how about overall performance in a large ported box vs a sealed.

The article stated the speed of a woofer is actually due to the magnet structure rather than the woofer right?

I have an adjustable subsonic filter built in to my behringer ultragraph pro eq but i'm not sure the exact numbers it can be tuned to other than 25hz

Similar to this except without the feedback detection: http://www.musiciansbuy.com/mmMBCOM/Images/BEHRINGER_FBQ3102.jpg
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post #14 of 69 Old 04-06-2013, 09:19 PM - Thread Starter
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Another issue is knowing where to stop tweaking. For example the sealed build will hit 18hz at 90db in a 1.75 cu' box but for all I know 18hz at 90db could shake the walls or not really do anything at all.

It would be nice to know some examples of what effect diffferent sub frequencies at different sound levels generally have in a 150 sq' room.
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post #15 of 69 Old 04-06-2013, 10:21 PM - Thread Starter
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And while i find this kind of "music" horrible the excursion on this looks far to good to be true?: https://www.youtube.com/watch?v=NdIGRsMiXZk
I wonder how distorted it is, or whether it's even the driver they state it is, distortion cleans up at 45 seconds in.

Here's another but all that's stated is 12w0 not 12w0-4: https://www.youtube.com/watch?v=hzXV4dSiWYE

Seems like more than 0.3 inches, i might have to try this someday when it's time for an upgrade biggrin.gif
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post #16 of 69 Old 04-07-2013, 07:05 PM - Thread Starter
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Here's what i've got so far. I chose the 2nd order butterworth highpass but i'm really not sure what is in the behringer ultragraph pro geq3102 that i have and i'm not sure of the best place for the hipass in the sealed build? Each setup is recieving 70 watts.


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post #17 of 69 Old 04-07-2013, 08:00 PM
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Quote:
Originally Posted by Mik James View Post

It would be nice to know some examples of what effect diffferent sub frequencies at different sound levels generally have in a 150 sq' room.

Mik, it can't be said what kind of effects different freq's will have in a room. Each room is different. Things like furniture, drapes, carpeting, windows, material the floors and walls are made out of, the shape and volume of a room, etc all play a role in effecting sound waves and how they are absorbed or reflected. Also, every thing on this planet has what's called a resonant frequency. This is the natural frequency at which an object resonates, or vibrates, at. Look up the Tacoma Narrows Bridge for a good example. The bridge did this due to the wind traveling over, and under, it at just the right speed. In this case, think of blowing across the opening of a bottle. Except in our case, things will do this at very specific frequencies. I could make my cat vibrate apart if I played the right frequency loud enough. All of these variables effect the acoustics of the listening environment.

Back in the 90's when I worked for a local car audio chain, JL was just cutting their teeth in the industry. Nobody had really heard of them. I bought 4 12w1-8's and put them in the hatch of my Ford Escort in 1.25ft3 sealed enclosures and ran them bridged to 2 ohms with about 500w RMS. After those, only 1 sub I had ever came close to performing as well as the JL's did (Alpine ZR's). The W0 series is what replaced the original W1's. Back then, there were no W0's. Price was about $100 each and they handled 100 or 125w RMS each. If JL still makes subs like they used to back then, even the bottom of the line W0's won't let down. (As a side note, the W7's are what the W6's used to be, top of the line.)

What you get with the more expensive models, like the W7's (and most drivers really), is cast baskets (which won't flex under high power and stress) vs the W0's stamped baskets. Also higher Xmax, (how far a driver can travel in one direction before exceeding it's mechanical limits), larger voice coils to handle higher power, etc. In short, the ability to handle gobs more power. You don't want to run a sub rated for 500+w rms with only 100w rms. Bad things can happen and cause damage to the driver, amp or both. It's actually better to run a sub with more power than it's rated than less.

With a sealed enclosure, aka acoustic suspension, the enclosure is more forgiving when it comes to errors or compromises on internal volume. A ported enclosure, aka bass reflex, must be made to pretty close manufacturer recommendations. In sealed, the air in the box acts to damp and control the driver. Kind of like a spring on a cars suspension. It helps to keep the driver from exceeding xmax and tearing itself apart. In a ported box, you don't have that "air spring" because the box isn't sealed. This is where the term "unloading" that RLJ mentioned comes from. If the box size and port aren't carefully calculated and made, the air in the box no longer acts as a spring to help control the driver. At this point, Xmax becomes exceeded and the driver destroys itself. This is why the box and port size are critical.

On the subject of using a sonotube and the wall thickness. The thickness isn't as critical with a tube as it is with a regular box shaped enclosure. When we put a driver in a box type shape, there are 6 surfaces for the sound waves to reflect off of inside. Remember that bit above about resonant frequencies of an object? Well that comes into play here along with something called standing waves. The super thick (or thicker) 1 inch panels you see standard enclosures made from are that thick for a reason. To keep enclosure resonances down, which have a tendency to make things sound not so great. With a tube, we don't have all of those flat surfaces for the waves to reflect off of, thus not nearly as great a chance for the enclosure to resonate. The exceptions being the baffle where the driver is mounted, and the opposite end panel.

If I'm wrong in any of this in the slightest way, please, someone correct me. It's been a few years since I've built a sub and my knowledge may be a bit rusty.


Mik, what is the freq your mains play down to effectively without struggling? This point and lower is where I would focus. Me for example, my mains (Infinity IL40's) do a great job down to between 30-35Hz. I've been thinking about building a sub and focusing strictly on the 15/20-35Hz region. Some people are obsessed and insist on getting down to 10Hz or lower. This will cost some big $$$$ usually. If this becomes an obsession for you (as it does for most of us), it's inherent that you start reading and learning. Things only get more difficult, confusing, and expensive from here on out.
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post #18 of 69 Old 04-07-2013, 10:53 PM - Thread Starter
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I've actually found there is alot more flexibility with a ported build and this driver which is why i'm leaning towards ported rather than sealed. At this point i'm thinking of bench testing the driver with a ruler taped to the gasket as the excursion in the videos a few posts back looks like more than a third of an inch to me. I'd need a test tone that is easy to hear distortion in but low enough to get it moving.

My mains are probably good to around 40hz before losing output and they start to plummet below 35.
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post #19 of 69 Old 04-08-2013, 06:51 AM
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zagnutty is 100% correct that sealed is more forgiving than ported. Both in design and in use.

Trust JL on their xmax numbers. Measuring them your way is a recipe for disaster because you don't know if xmax and xmech are the same. xmech is when the voice coil starts to hit the back plate or it jumps out of the gap. Neither one are a good thing especially hitting the back plate and you only having a Kapton former. JL either used the (winding length - top plate thickness)/2 method or the 70% BL method to determine xmax. Both are valid methods throughout the industry.

I have some 3" speakers that will play 40hz but they are down 40db from the other frequencies. Bass is about moving air and most of us like to use a crossover between 80hz and 60hz.
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post #20 of 69 Old 04-08-2013, 07:10 AM
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I thought this was a very good comparison between the different systems:

http://www.data-bass.com/data?page=content&id=82
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post #21 of 69 Old 04-08-2013, 12:19 PM - Thread Starter
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In the end i don't need to know the exact excursion numbers, what matters is how loud it will play cleanly. Will a speaker audibly distort at audible frequencies before reaching either xmax or xmech?

My 8" drivers will play 24hz at less than half the volume of 50hz but that's not usable response. I think 50hz +-10hz will be a good place to draw the line to avoid localization.

Thanks for the info cogeng, it's good to know the tradeoffs like group delay, which seems like a good reason for me to tune lower than what i want to use in a ported build, as long as it doesn't negatively effect higher frequency performance by more than a db or 2.
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post #22 of 69 Old 04-08-2013, 01:36 PM
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Will a speaker audibly distort at audible frequencies before reaching either xmax or xmech?
It will. The more excursion, the more distortion. How much depends on the driver design. One reason people liked XBL^2 enabled drivers is that they had very little distortion through the stroke of the sub. The downside is that there was no indication that you were stressing the driver and failure was sudden. I have a fried Blueprint 1001 sub that was a victim of this. It sounded awesome right up to when the wire unwound on the voice coil.

If you aren't familiar with XBL^2 - http://www.acousticdev.com/cms/index.php?option=com_content&view=section&layout=blog&id=12&Itemid=64
The inventor - http://www.acousticdev.com/cms/index.php?option=com_content&view=article&id=44&Itemid=55 Too bad Dan doesn't post much any more. Some of his posts here and at other forums were like attending a physics and acoustic lecture combined.
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post #23 of 69 Old 04-08-2013, 02:45 PM
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Quote:
Originally Posted by Mik James View Post

Will a speaker audibly distort at audible frequencies before reaching either xmax or xmech?

Some will. But I've also seen some that don't give any warning before self destructing.

Pretty much comes down to this - Efficient, good LF Extension, cheap. Pick two.
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post #24 of 69 Old 04-08-2013, 02:49 PM - Thread Starter
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What's used in the 12w0?

Basically i'm going with ported tuned so i know excursion will max out and be similar at around the 15hz and 30hz mark (depending on what i tune to). Then if I ever feel the need to test the limits i know if I test the 28-32hz range for distortion it will ideally reach the same maximum excursion at 15hz.

On the topic of hipass filters does anyone know what's in the behringer eq's? I selected butterworth hipass's for each potential build but i'm not sure if that is any thing like what the eq uses for "low cut".
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post #25 of 69 Old 04-09-2013, 05:03 AM
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What's used in the 12w0?
It's a basic overhung design - http://en.wikipedia.org/wiki/Voice_coil

Underhung speakers like the XBL^2 I linked to earlier have a thicker top plate like this Elemental Designs 13Av.2:



While overhung speakers are known for having a thinner top plate like this TC-9 motor:


Then there is the exception to the rule. Overhung subs with thick top plates. The best example is the TC Sounds 3 HP motor used in the current line of Axis subs but also the older TC-3000, Lightning Audio Storm series and some Eclipse models. The pictures in the link below are from the neodymium version but the measurements are still the same. While the TC-9 has a 1/2" top plate, the 3 HP has a 1 3/8" top plate. They also have long coils which gives them insane motor force and high excursion. I know. I use a pair of 15" TC-3000's in my home theater and I have 4 of those neo motors and parts to make them into 15" subs.
http://www.caraudioclassifieds.org/forum/speaker-accessories-parts/144826-tc-3hp-neo-motors.html
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post #26 of 69 Old 04-09-2013, 11:16 AM - Thread Starter
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I'm looking into using one of these in bridged mode: http://www.amazon.ca/OSD-Audio-AMP120-2-Channel-Amplifer/dp/B0052CHIYC/ref=sr_1_1?ie=UTF8&qid=1365527369&sr=8-1&keywords=osd+audio

Looks to be a clone of the Audiosource amps, they also sell clones of the Audiosource subwoofers that got good reviews. Any step up from Pyle or Pyramid without breaking the bank would be nice.

With free shipping i could sell my cs800 and buy 2. One of the reviewers was running 1.8ohm subs off of them so i suppose i may be able to get away with 4ohms bridged as long as i don't max it out...?

Otherwise i could place a resistor in the tube to increase the load right?

The other option is the 70 watt partsexpress plate amp which would likely cost me 80$ or more to ship from solen.ca

I'll be building a sleek looking amp panel on top of the sub either way unless someone has a sleeker idea.

Something like this (excuse the bad doodling biggrin.gif )

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post #27 of 69 Old 04-09-2013, 12:23 PM
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i suppose i may be able to get away with 4ohms bridged as long as i don't max it out...?
Take your chances but heat kills electronics. Lower impedance generates heat.
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Otherwise i could place a resistor in the tube to increase the load right?
It just turns the wattage into heat. If you want to run this amp into a 4 ohm load then use one channel.
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Any step up from Pyle or Pyramid without breaking the bank would be nice.
Don't judge a sub by its name. A lot of the Pyramid Pro subs were made by Eminence. I have a pair from 1990.
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post #28 of 69 Old 04-09-2013, 12:37 PM - Thread Starter
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I was actually judging an "amp" by it's name.

Resistors turn it into heat where? at the amp or the resistor?

I wonder if i could put an aftermarket fan in there somewhere, or put one above the vent...

Though i suppose i would have to power that fan somehow frown.gif

And of course the amp vents at the top effectively ruling out the enclosure idea.
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post #29 of 69 Old 04-09-2013, 12:48 PM
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I was actually judging an "amp" by it's name.
Same. There was a line of Pyramid car amps made by PPI. Not the PPI of now, but the PPI of the early 90's when they were hand made in Tempe, AZ.
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Resistors turn it into heat where? at the amp or the resistor?.
At the resistor. It's a waste. If you add a 4 ohm, 100w resistor (they are expensive) in series with your your 4 ohm sub so you can bridge the amp then you are sending 60 watts into the resistor and 60 watts into the sub. The EXACT same wattage goes to the sub if you use the sub by itself and only one channel of the amp. You then have a 2nd channel for later when you get a second sub.
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post #30 of 69 Old 04-09-2013, 01:25 PM - Thread Starter
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Oh yeah I suppose it would. I've toyed with the idea of wiring up a car sub amp as well and i have access to a 250 watt low profile computer power supply but i'm not sure how safe, practical, and high quality a solution that would be. They're compact but i'm not sure how i'd integrate both things in a clean way.

If i did wire the sub to the osd audio amp bridged would that just mean i would have to be careful not to push more power than it could with an 8 ohm load or would it heat up more at the same power output?
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