I was wondering if anyone was willing to help me out with my 1st vented enclosure build. I've done a ton of reading about it, and have been messing with WinISD for the past couple of days, but I'm still a little skeptical before I start cutting. Sorry if this is too long, but I wanted to give as much details about this as I can.
It's for a friends 4 runner, and his system consists of RE Audio Components up front, Power Bass 5 1/4" in the rear doors and a single RE Audio RFX 10" sub. He's running a MB Quartz 4 channel amp with the front 2 channels powering the compents and the rear powering the sub and the rear doors powered off the deck (Poineer). The MB Quartz amp puts out 300 watts RMS bridged to the sub.
WinISD wants the box to be about 2 cubes of volume tuned down to 25 Hz, but in all I read it should be tuned to 32-35 Hz and more in the range of 1.5-1.75 cubes of volume, so that's the range I've been playing with.
My problem is when it comes to the port length and size. I want to do a slot port that uses the 3 sides of the enclosure as part of the port (can't figure out how to tell WinISD to do this other than messing with the dimensions of both the box and port...is that the right way?). I read that the port area should be 10-15 sq in per cubic feet, but when I do this, it makes the port length a lot longer than the height of the box (the interior port opening would be 12" x 2" in this case).
I was wondering if I just continue the port along the bottom of the box to get the length needed for the correct tuning? I've seen this done, but can't find out of it was for another purpose. I understand that if I do this, I'd have to then make the box bigger to compensate for the loss in volume of the port, but didn't want to start fiddling with that if I'm totally wrong.
Once again, sorry for the long winded post, but here's the specs for the sub from RE Audio's website:
It's for a friends 4 runner, and his system consists of RE Audio Components up front, Power Bass 5 1/4" in the rear doors and a single RE Audio RFX 10" sub. He's running a MB Quartz 4 channel amp with the front 2 channels powering the compents and the rear powering the sub and the rear doors powered off the deck (Poineer). The MB Quartz amp puts out 300 watts RMS bridged to the sub.
WinISD wants the box to be about 2 cubes of volume tuned down to 25 Hz, but in all I read it should be tuned to 32-35 Hz and more in the range of 1.5-1.75 cubes of volume, so that's the range I've been playing with.
My problem is when it comes to the port length and size. I want to do a slot port that uses the 3 sides of the enclosure as part of the port (can't figure out how to tell WinISD to do this other than messing with the dimensions of both the box and port...is that the right way?). I read that the port area should be 10-15 sq in per cubic feet, but when I do this, it makes the port length a lot longer than the height of the box (the interior port opening would be 12" x 2" in this case).
I was wondering if I just continue the port along the bottom of the box to get the length needed for the correct tuning? I've seen this done, but can't find out of it was for another purpose. I understand that if I do this, I'd have to then make the box bigger to compensate for the loss in volume of the port, but didn't want to start fiddling with that if I'm totally wrong.
Once again, sorry for the long winded post, but here's the specs for the sub from RE Audio's website:
- Electrical Q Value -Qes: 0.39
- Mechanical Q Value -Qms: 4.37
- Total Speaker Q Value -Qts: 0.36
- Free Air Resonance -Fs: 21.5 Hz
- Equivalent Compliance -Vas: 75.6 liters
- One-Way, Linear Excursion -Xmax: 12 mm
- Efficiency -SPL 1W/1m: 84.7 dB SPL
- Effective Piston Area -Sd: 322 cm^2
- DC Resistance -Re: 3.4 ohm
- Nominal Impedance -Znom: Dual ohm
- Thermal Power Handling -Pe: 190 W
- Force Factor -Bl: 15.4
Did you contact the manufacturer? If the owner's manual doesn't tell you what enclosures are suitable, tech support should know.
The box says to build a 1 cu ft vented enclosure tuned to 35 Hz...however, I've always noticed that no one builds enclosures to the factory specs typically...so I was thinking that going with the WinISD route would be better. Everything I see/read with the speaker's specs above wants the box to be almost double the volume that's printed.
You have to realize that much of the information you get on the internet (including this) is not necessarily from someone that knows what they're talking about. Did the people recommending larger enclosures perform tests (with test equipment) to verify that the larger enclosure performed better? Subjective testing is generally useless because people hear what they want to hear.
The manufacturer wants your system to perform as well as possible. They generally give 3 enclosure sizes (for sealed and vented enclosures) that produce varying types of frequency response.
Email is free. Contact them to see if they can help.
The manufacturer wants your system to perform as well as possible. They generally give 3 enclosure sizes (for sealed and vented enclosures) that produce varying types of frequency response.
Email is free. Contact them to see if they can help.
Here's the the recommendations from the RE Audio site:
10"CompactOptimalSealed:0.40.6Ported:0.7@35Hz1.1@35Hz
I went to contact them on their website right now and just noticed they have a box builder tool...pretty neat and easy to use...it basically gives the dimensions that you need to cut only though.
It's still just weird to me that everything I read about building a vented enclosure says that you use the specs of the speaker to determine the box volume and port length, but this doesn't match the recommended volumes of the manufacturer...guess I just hafta email them.
10"CompactOptimalSealed:0.40.6Ported:0.7@35Hz1.1@35Hz
I went to contact them on their website right now and just noticed they have a box builder tool...pretty neat and easy to use...it basically gives the dimensions that you need to cut only though.
It's still just weird to me that everything I read about building a vented enclosure says that you use the specs of the speaker to determine the box volume and port length, but this doesn't match the recommended volumes of the manufacturer...guess I just hafta email them.
Enclosure volumes typically published by manufacturers are designed to provide the most "acceptable" output in the smallest box that is easiest to build. In regard to ported enclosures, you can build a .4cuft box tuned to 35hz and you can build a 4cuft box tuned to 35hz. The woofer T&S parameters help determine the ideal port freq, and the internal volume is something you can tune to your preference really. With WinISD play around with multiple vented boxes. Build one to the smallest spec and build one to the largest spec, you can change the colors of the graphs to be able to distinguish between the two and start looking at the various graphs provided. You should see a pretty clear difference in the freq response, how smooth or steep it is around the tuning freq, the overall output levels, and even the time delay by freq (what can make a vented box sound " sloppy" ) Then open a third enclosure and start tweaking things to see what works & what doesnt work, and see if you cant find something that suits your desire. Personally I prefer small volume low freq tuned enclosures to get a smooth freq response curve and very accurate (minimal delay) bass, and the sacrifice is port construction is a nightmare because the box ends up being 75% port and the overall output is not as high as it could be. The inverse is a larger enclosure volume with a much shorter port, and a bass bump around the tuning freq several times louder but at the cost of accuracy and vehicle space.
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Thanks a ton, audiophyle247! That makes a lot of sense. RE Audio emailed me back saying they put 1.1 cubes on the specs for safety reasons to prevent over excursion.
Got a few questions for you if you don't mind audiophyle247:
1. What's a "low" freq to tune to in your eyes? I was tuning to ~32 Hz
2. When looking for the minimal delay in bass on the graphs, are you saying that the smoother the graph is, the more accurate it will be or is there something else I should be looking for?
3. Where do I find the F3 reading? I've read about looking at this, but don't see it.
4. How do I build 2 or more boxes on the same graph? (if that's too hard to explain, don't worry...I'll just keep messing with it)
This isn't some huge system...just a simple daily for a friend, so the box should be built for SQ rather than SPL...I'm open to all suggestions since I've only built sealed enclosures in the past. I'm trying out the vented on this build, to be honest, cuz it ain't my money and I've always wanted to try!
Got a few questions for you if you don't mind audiophyle247:
1. What's a "low" freq to tune to in your eyes? I was tuning to ~32 Hz
2. When looking for the minimal delay in bass on the graphs, are you saying that the smoother the graph is, the more accurate it will be or is there something else I should be looking for?
3. Where do I find the F3 reading? I've read about looking at this, but don't see it.
4. How do I build 2 or more boxes on the same graph? (if that's too hard to explain, don't worry...I'll just keep messing with it)
This isn't some huge system...just a simple daily for a friend, so the box should be built for SQ rather than SPL...I'm open to all suggestions since I've only built sealed enclosures in the past. I'm trying out the vented on this build, to be honest, cuz it ain't my money and I've always wanted to try!
An externally hosted image should be here but it was not working when we last tested it.
Picture is just for reference
I am an addict of vented enclosures and it happened shortly after building my first soooo many years ago, so prepare yourself. lol
1. Low in my eyes? My last ported enclosure was an 8" Audiopulse Epic that I had tuned down to 28hz with a .3cuft volume. The port length was ridiculous and snaked back & forth countless times, but wow did it sound great. My goal is to extend the low end for much more output than a sealed box is capable while trying to stick with the accuracy & smooth response a sealed box has. This will make perfect sense to you once you start exploring ideas while mapping multiple projects.
2. Group delay tab shows how accurate the bass will be and graphs the delay by frequency and milliseconds. Graph a sealed enclosure next to a ported enclosure & it will make perfect sense. The gain tab shows you the freq response curve, and how loud/quiet each freq will be. Imagine playing a sine sweep, a smooth curve will have little change in volume level across the sweep, where a freq response with a steep peak will sound like the volume is changing. If you want a lot of bass, a high peak will give that impression, if you want SQ a flat or smooth curve will provide the most balanced output.
3. F3? Are you sure its not Fs which is the resonant frequency of the driver, you have it listed above and is a pretty important aspect of a woofer.
4. The graph is always there, and you notice when you build a new enclosure you are working in a smaller separate window. Simply click to open another project and another window will show up, the plot tab in every project window allows you to adjust the line color & width for each project shown in the graph window. All open projects will automatically plot across the graph window, its just confusing at first because they always open as the same color. Every time you change something on a project window the graph will instantly update to reflect those changes.
Man...thanks for breaking this down into much simpler terms for me! So I'm guessing all the youtube vids are of these massive boxes in order to obtain that peak in the tuned Hz.
That explaination of the gain and group delay really helps. I can't wait to start plotting a few more designs when I get home!
With the .3cuft box, was the overall box still fairly big since you have to consider the port volume separate from the box volume? My friend actually wants a smaller sized box, so this actually is a plus!
That explaination of the gain and group delay really helps. I can't wait to start plotting a few more designs when I get home!
With the .3cuft box, was the overall box still fairly big since you have to consider the port volume separate from the box volume? My friend actually wants a smaller sized box, so this actually is a plus!
Ok...so I've been playing with this for a while now, but no matter what I do, the best graphs show the box tuned to ~25Hz with 1.8 cu ft of volume (basically what the WinISD came up with 1st). Now, this is doable as far as building and room in the 4 Runner...but is it ok to tune to such a low frequency?
With this tune, the gain graph has NO peaks an platos to 0 at about 35 Hz, the Group Delay graph peaks at 23ms about about 25Hz but then smoothly drops faster than any other. Also the SPL graph shows smoothness but at 26 more dB's.
All of this seems too good to be true, especially when i read that I should be tuning in the 30-35 Hz range. Any suggestions?
With this tune, the gain graph has NO peaks an platos to 0 at about 35 Hz, the Group Delay graph peaks at 23ms about about 25Hz but then smoothly drops faster than any other. Also the SPL graph shows smoothness but at 26 more dB's.
All of this seems too good to be true, especially when i read that I should be tuning in the 30-35 Hz range. Any suggestions?
Are you taking into account the vehicle's transfer function?
Higher tuning frequencies are used in vehicles because the transfer function boosts the output greatly at low frequencies. If you build an enclosure that is flat (without taking into account the transfer function) and your goal is a system with a flat frequency response, when you install it in the vehicle, the low frequencies will be too strong.
Higher tuning frequencies are used in vehicles because the transfer function boosts the output greatly at low frequencies. If you build an enclosure that is flat (without taking into account the transfer function) and your goal is a system with a flat frequency response, when you install it in the vehicle, the low frequencies will be too strong.
No I'm not...but mainly since this is the 1st time I've ever heard of the transfer function. By flat are you referring the graphs in WinISD?
Also, by too strong are you meaning that the lows will over power the highs?
Also, by too strong are you meaning that the lows will over power the highs?
The bigger the box, the more narrow the bandwidth will be (the fewer notes it will play accurately) but the output will be louder near the tuning frequency. For a daily driver a good rule of thumb is to keep the peak of the transfer function around 3db (I believe that is covered in the WinISD manual). That gives you a nice mix of sound quality and SPL. In small cars tune a little higher, large cars tune a little lower.
I generally build the largest volume recommended by the manufacturer and adjust tuning to create a 3db gain. 6db for a boomy box , 12db or higher and a larger enclosure for SPL (one note wonder box). If I am grossly under powering the subs I often go bigger than recommended as well.
If you build the box larger than recommended it will often perform fine at the tuning frequency but will approach xmax (and xlim) much more quickly below the tuning frequency. So too much power becomes an issue and the subsonic/infrasonic filter must be set higher on the amplifier (you should always have a subsonic filter if you go ported).
Also, F3 is the point at which the transfer function falls 3db below 0. Just run your mouse along the graph until you reach -3db, that's your F3. WinISD Pro uses a purple line to designate 3db down.
I generally build the largest volume recommended by the manufacturer and adjust tuning to create a 3db gain. 6db for a boomy box , 12db or higher and a larger enclosure for SPL (one note wonder box). If I am grossly under powering the subs I often go bigger than recommended as well.
If you build the box larger than recommended it will often perform fine at the tuning frequency but will approach xmax (and xlim) much more quickly below the tuning frequency. So too much power becomes an issue and the subsonic/infrasonic filter must be set higher on the amplifier (you should always have a subsonic filter if you go ported).
Also, F3 is the point at which the transfer function falls 3db below 0. Just run your mouse along the graph until you reach -3db, that's your F3. WinISD Pro uses a purple line to designate 3db down.
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Thanks, m4ick! I read through the short about/tutorial on WinISD I thought...is this something I might have missed or is there a bigger/more in-depth manual you are referring to?
I appreciate you explaining what the graph means compared to sound. Being my 1st build and even for a friend, I don't have the luxory of playing around with different boxes, so I have to do what I can do please him on the 1st shot.
The amp puts out 300 watts bridged in the 3/4 channel and the speaker I believe is 175 watts RMS, but is dual 4 ohm so I'm going to wire it at 8 ohms hopefully making the power at about 150 or somewhere closer to the RMS rating. I didn't do my research on the RE audio subs and didn't realize they had been bought out and making somewhat inferior products now...at least this is just a daily driver and good replacement of blown stock components. Also, this will be the 1st aftermarket system he has ever had, so he should be pleased with almost anything that doesn't clip like crazy.
I'm still waiting on the amp to arive, so I have a little bit of time before cutting happens. I have about 4 different designs now, but will take what you said into consideration and play with it a little more. I'll post up some pics/specs of what I come up with!
I appreciate you explaining what the graph means compared to sound. Being my 1st build and even for a friend, I don't have the luxory of playing around with different boxes, so I have to do what I can do please him on the 1st shot.
The amp puts out 300 watts bridged in the 3/4 channel and the speaker I believe is 175 watts RMS, but is dual 4 ohm so I'm going to wire it at 8 ohms hopefully making the power at about 150 or somewhere closer to the RMS rating. I didn't do my research on the RE audio subs and didn't realize they had been bought out and making somewhat inferior products now...at least this is just a daily driver and good replacement of blown stock components. Also, this will be the 1st aftermarket system he has ever had, so he should be pleased with almost anything that doesn't clip like crazy.
I'm still waiting on the amp to arive, so I have a little bit of time before cutting happens. I have about 4 different designs now, but will take what you said into consideration and play with it a little more. I'll post up some pics/specs of what I come up with!
as mentioned, going larger on the enclosure makes the power handling drop due to mechanical limitations. iirc, i saw it was thermal rms rated for like 192, so if you are shooting for 150rms, then you can go a little larger on the enclosure, but i could not tell you by how much. perhaps the engineers have played with them. i know diamond had a chart and several specs giving you a box range with ideal power level accordingly. nearly double the power handling for the small enclosure as for one 40-50% larger
Manufacture "recommended" enlcosures are normally a bad compromise, best to build for what you need-I've seen them recommend enclosures with tiny port diameters that would whistle like a builder on the beach...
I'd go for 2.344cf, tuned to 23Hz, flat out of car response, run one VC off each channel (gives flater response than series). Using 0.75" MDF gives you gross dimensions of 30" width, 13.5" height, base depth 12" top depth 8". Vent 12"H x1"W x 24.86" Length also made out of 0.75" MDF-you can use the 0.75" port material as internal bracing. SSF @ 18Hz (amp probably doesn't feature one though, you can get these: FMOD (Filter Module) High Pass RCA Level Crossover)
Perry is kind of right about cabin gain-your box won't give a flat response in the car, you'll tend to get a 12dB an octave rise from around 60Hz (depends on car's internal dimensions)-BUT it is widely accepted to tune low and EQ down the peak then it is to try and tune high and use the cabin gain to get it flat-for a start you wouldn't want a ported box if you didn't want heavy bass, 2ndly if you do tune a ported box to the 60Hz region and then drop some dubstep you will kill your subwoofer as you'll unload it below the tuning freq. Also consider the Fletcher Munson/Equal loudness curve-bass frequencies have to measure a higher dB to SOUND as loud to us humans...Equal-loudness contour - Wikipedia, the free encyclopedia
Equal loudness contours and audiometry - Test your own hearing
If you really want a flat in car response with little/no EQ then I found the best route is a LT enclosure, using the cabin gain as the EQ circuit, but most people buying an RE Sub and speakers won't be aiming for "flat"-no offence🙂
I'd go for 2.344cf, tuned to 23Hz, flat out of car response, run one VC off each channel (gives flater response than series). Using 0.75" MDF gives you gross dimensions of 30" width, 13.5" height, base depth 12" top depth 8". Vent 12"H x1"W x 24.86" Length also made out of 0.75" MDF-you can use the 0.75" port material as internal bracing. SSF @ 18Hz (amp probably doesn't feature one though, you can get these: FMOD (Filter Module) High Pass RCA Level Crossover)
Perry is kind of right about cabin gain-your box won't give a flat response in the car, you'll tend to get a 12dB an octave rise from around 60Hz (depends on car's internal dimensions)-BUT it is widely accepted to tune low and EQ down the peak then it is to try and tune high and use the cabin gain to get it flat-for a start you wouldn't want a ported box if you didn't want heavy bass, 2ndly if you do tune a ported box to the 60Hz region and then drop some dubstep you will kill your subwoofer as you'll unload it below the tuning freq. Also consider the Fletcher Munson/Equal loudness curve-bass frequencies have to measure a higher dB to SOUND as loud to us humans...Equal-loudness contour - Wikipedia, the free encyclopedia
Equal loudness contours and audiometry - Test your own hearing
If you really want a flat in car response with little/no EQ then I found the best route is a LT enclosure, using the cabin gain as the EQ circuit, but most people buying an RE Sub and speakers won't be aiming for "flat"-no offence🙂
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