Hello folks, been registered here for a while but now need some help.
Just bought a cheap Magnat Xpress 15. I know its not the best sub there is but this IS diyaudio and i like doing things on the low budget side so i think this is the best place on the internet to seek help.
Anyway i would like if you guys could help and guide me with box design and parameters. Here are the screenshots of subwoofers specifications to make it easier for you guys.
I like music with really low bass sometimes hitting 30hz and lower so whatever you guys think would be the smartest thing to do please let me know.
Id like to mention that i have a box that is 146x56x31 cm (57.5x22x12.1 inches) measured from inside so that gives about 253 litre of volume, made from good quality wood and im ready to repurpose it whole just for this enclosure. It would be preferred if i could leave the box as is and just port it or put a horn or something.
I would really like it to go as deep as possible and im not expecting miracles from that sub but it would be nice to hear a boost in that part of the bass feels nice instead of that cheap crap that only rumbles in your ears.
Anyways guys, be it closed, ported, horned or whatever things exist that i havent even heard of please give me ideas, links, plans, opinions or whatever else, im all ears and im very excited to read your posts tomorrow!
Im probably in a different time zone than a huge majority of you guys and going to sleep so i cant wait to see your responses in 15ish hours.
Thank you guys!
Just bought a cheap Magnat Xpress 15. I know its not the best sub there is but this IS diyaudio and i like doing things on the low budget side so i think this is the best place on the internet to seek help.
Anyway i would like if you guys could help and guide me with box design and parameters. Here are the screenshots of subwoofers specifications to make it easier for you guys.
I like music with really low bass sometimes hitting 30hz and lower so whatever you guys think would be the smartest thing to do please let me know.
Id like to mention that i have a box that is 146x56x31 cm (57.5x22x12.1 inches) measured from inside so that gives about 253 litre of volume, made from good quality wood and im ready to repurpose it whole just for this enclosure. It would be preferred if i could leave the box as is and just port it or put a horn or something.
I would really like it to go as deep as possible and im not expecting miracles from that sub but it would be nice to hear a boost in that part of the bass feels nice instead of that cheap crap that only rumbles in your ears.
Anyways guys, be it closed, ported, horned or whatever things exist that i havent even heard of please give me ideas, links, plans, opinions or whatever else, im all ears and im very excited to read your posts tomorrow!
Im probably in a different time zone than a huge majority of you guys and going to sleep so i cant wait to see your responses in 15ish hours.
Thank you guys!
This is not a very good driver, it has limited usefulness.
Simulated here in both ported and sealed 250 liter boxes. Hornresp says qtc and f10 are both a bit higher than predicted by P10 in the previous post. I had to guess at Sd and Le. And I'm not sure if the xmax is rated for one way or peak to peak, so I've assumed one way which is the best case scenario.
Shown at 125 watts (which is enough to drive the sealed box several mm past xmax, while the ported box stays within excursion limits as long as a 16 hz 4th order high pass filter is used).
The sealed response is not bad and will blend ok with room gain but it's not going to be loud at all even at it's limits. The ported box will be pretty boomy in room unless you eq since the room gain will boost the already boosted lows. It would require a MUCH larger box with lower tuning than shown to get a better response with a ported box, but for a cheap driver like this a box like that is a waste of money and space. If you had 20 or 40 of them and used them in infinite baffle that would be another story ... that could work really well.
This kind of driver is meant for car audio infinite baffle, or seriously boosted response in smaller boxes. There's a 100 liter ported box recommendation in the manual for the driver, as you can see it's got a seriously boosted low end that doesn't go much lower than 30 hz.
Here's the manual - http://www.magnat.de/media/image/articles/datenblatt/f/Xpress_10_12_15_Manual.pdf
Here's the sim -
Simulated here in both ported and sealed 250 liter boxes. Hornresp says qtc and f10 are both a bit higher than predicted by P10 in the previous post. I had to guess at Sd and Le. And I'm not sure if the xmax is rated for one way or peak to peak, so I've assumed one way which is the best case scenario.
Shown at 125 watts (which is enough to drive the sealed box several mm past xmax, while the ported box stays within excursion limits as long as a 16 hz 4th order high pass filter is used).
The sealed response is not bad and will blend ok with room gain but it's not going to be loud at all even at it's limits. The ported box will be pretty boomy in room unless you eq since the room gain will boost the already boosted lows. It would require a MUCH larger box with lower tuning than shown to get a better response with a ported box, but for a cheap driver like this a box like that is a waste of money and space. If you had 20 or 40 of them and used them in infinite baffle that would be another story ... that could work really well.
This kind of driver is meant for car audio infinite baffle, or seriously boosted response in smaller boxes. There's a 100 liter ported box recommendation in the manual for the driver, as you can see it's got a seriously boosted low end that doesn't go much lower than 30 hz.
Here's the manual - http://www.magnat.de/media/image/articles/datenblatt/f/Xpress_10_12_15_Manual.pdf
Here's the sim -
An externally hosted image should be here but it was not working when we last tested it.
Planet10 Thank you for the quick response!
Could you perhaps point me towards wiki of sorts so i can understand what you guys actually mean when you answer?hah sorry!
If you don't understand his response your best bet is probably to put the driver in the 250 liter box you have without a port and try it out - also put lots of fiberglass or polyfill or pillows in the box.
If it doesn't have enough low bass for you, you can try to add a port. The port shown in the sim above is 100 sq cm and 25.1 cm long. This will give fairly high port velocity, so if you are not using a high pass filter you might want a bigger port.
I listen to music mostly on my headphones connected to a usb DAC and AMP, with that setup i can easily hear 24 Hz sine but the speaker system im using isnt even audible under 50. Those have really nice mids and tweeters do great job as well but i just have to literally shake some things up in order to properly enjoy it.
I apreciate every each one of your responses guys, id just like it a lot if i could learn what i "Q=0.707", "F10 <20 Hz." or "P10" actually meant.
Thank you just a guy for the simulation, I did see their box plans in the PDF but i figured you guys would know
what to do to get it to play lower notes than that crappy 50hz car boxes i assumed they put there.
I want to mention that im not that scared of going a bit over Xmax.
One more question, would it be okay to mount the woofer facing forwards, roughly at the height of my head sitting in the chair?
Kinda like this.
Still not sure if its smarter to keep it sealed and be quiet or port it low but play with equalizer and crossover to kill it slowly over 50hz?
Thanks a bunch guys.
I apreciate every each one of your responses guys, id just like it a lot if i could learn what i "Q=0.707", "F10 <20 Hz." or "P10" actually meant.
Thank you just a guy for the simulation, I did see their box plans in the PDF but i figured you guys would know
what to do to get it to play lower notes than that crappy 50hz car boxes i assumed they put there.
I want to mention that im not that scared of going a bit over Xmax.
One more question, would it be okay to mount the woofer facing forwards, roughly at the height of my head sitting in the chair?
Kinda like this.
Still not sure if its smarter to keep it sealed and be quiet or port it low but play with equalizer and crossover to kill it slowly over 50hz?
Thanks a bunch guys.
Q = .707 - this means the calculated sealed box qtc with that driver in that box. You can study up on sealed box qtc if you like but here's the quick breakdown. .7 qtc gives you the flattest response to the lowest frequency that is possible with a given driver. .5 qtc is usually called "critically damped" and will usually blend nicely with room gain to give a flat(ish) in room response. Qtc higher than .7 will give a humped response above fs.
Here's a quick graph I made a few years ago. It shows 4 theoretical drivers that are all the same except they have different values of qts. They are simulated in infinite baffle, so driver qts = sealed box qtc. As you can see, different values of qtc give wildly different response shapes. Most people like to shoot for .5 - .7 qtc when designing a sealed box, sometimes that isn't possible since the box has to be too large, and you can't ever have qtc less than driver qts.
F10 < 20 hz - this means the frequency at which response is down 10 db relative to the mid frequencies is under 20 hz. Check the sim I posted. For the sealed box in my sim the F10 frequency is about 17 hz (I was mistaken when I said f10 was a bit higher than P10 claimed, I should have looked a bit closer).
P10 = Planet 10 = the author of post #2.
If you put this driver in a sealed box of any size it won't go very loud and it won't play low notes with any authority at all. If you put it in a ported box you might need a bit of eq to bring down the low frequencies or it might sound boomy (or you might like the low frequency boom, a lot of people do like it). This is a cheap driver and it won't perform very well regardless of what you do with it. As I mentioned, the best bet would be 20 or 40 of them in infinite baffle.
Here's a quick graph I made a few years ago. It shows 4 theoretical drivers that are all the same except they have different values of qts. They are simulated in infinite baffle, so driver qts = sealed box qtc. As you can see, different values of qtc give wildly different response shapes. Most people like to shoot for .5 - .7 qtc when designing a sealed box, sometimes that isn't possible since the box has to be too large, and you can't ever have qtc less than driver qts.
An externally hosted image should be here but it was not working when we last tested it.
F10 < 20 hz - this means the frequency at which response is down 10 db relative to the mid frequencies is under 20 hz. Check the sim I posted. For the sealed box in my sim the F10 frequency is about 17 hz (I was mistaken when I said f10 was a bit higher than P10 claimed, I should have looked a bit closer).
P10 = Planet 10 = the author of post #2.
If you put this driver in a sealed box of any size it won't go very loud and it won't play low notes with any authority at all. If you put it in a ported box you might need a bit of eq to bring down the low frequencies or it might sound boomy (or you might like the low frequency boom, a lot of people do like it). This is a cheap driver and it won't perform very well regardless of what you do with it. As I mentioned, the best bet would be 20 or 40 of them in infinite baffle.
just a guy, got it! Looks like i have nothing to lose to try it closed first to see how i like it, if i do not like it if i understood correctly i could try building a port in it of 100cm2 area that is 25.1cm long. (hope dimensions dont have to be THAT precise) It might be worth the mention that the total RMS of the rest of my system is 100W total and from the specs i looked at they actually go 48Hz at -16db. Unusable for music with low notes so ill be optimistic with this build.
That is the ABSOLUTE MINIMUM port size I'd consider, and even then I'd only use it if I had a proper high pass filter included and roundovers on both port ends, otherwise velocity would be way too high. You might want to consider a larger port (which would have to be longer to maintain the same tuning) and you might even want to consider tuning lower (which would require a longer port). If you tune higher you'll get a bump in response above tuning like the design in the driver manual. But it's up to you. Try it sealed and if you want more low bass put a port in it.
Thanks just a guy, Just give me the port area you think would be perfect to hit lowest and hardest and ill get on planning in sketchup, it could make my job much easier later on if i would know PERFECT preferred dimensions. Why not just make whole port like a horn going like a labyrinth through the box. Of course i dont know whats the smartest option but i just want that low notes shaking my room that these speakers i have cant hit.
Thanks!
Thanks!
I can't recommend a tuning for you, you have to chose for yourself. What I can do is recommend a port size for you chosen tuning. If you don't mind large ports that makes it easy. But I need to know your desired tuning, whether you will use a high pass filter and whether you intend to do roundovers on the port ends.
I will make it easier for you and say i dont inted to use a high pass filter and i dont intend to round over the ports.
I see quite a few of these subs shaking the whole car or at least shaking windows if they are installed in a home. I would love it ported as low as it would make sense. If it was too low to be audible because of its power and just the way the sub it then i dont see the point. I would love if it could hit 20 and make my chest vibrate but im also down to earth enought to know it wont happen. At least i can try spend my time and money productively by learning something building the box and hopefully enjoying the fruits of labor.
My whole audio has lower end set up like this
so im not even worried about hitting too low. Just give me your estimation if it makes any sense to tune it under 30hz, maybe to be able to hit A0 note at 27.5Hz or something. i think you need to know my expectations arent that high, Im running 50rms of **** bass that rumbles at 80to100 Hz and only hurts ears.
Let me know if you think it would be smartest to place the woofer in the middle of the cabinet from my picture or at the top and have the lower part be a port IF needed.
Knowing myself even if i were pleased with the sound id still hack the box up and try a port just to see where im at.
Thanks a lot just a guy! Youre a real champ!
I see quite a few of these subs shaking the whole car or at least shaking windows if they are installed in a home. I would love it ported as low as it would make sense. If it was too low to be audible because of its power and just the way the sub it then i dont see the point. I would love if it could hit 20 and make my chest vibrate but im also down to earth enought to know it wont happen. At least i can try spend my time and money productively by learning something building the box and hopefully enjoying the fruits of labor.
My whole audio has lower end set up like this
so im not even worried about hitting too low. Just give me your estimation if it makes any sense to tune it under 30hz, maybe to be able to hit A0 note at 27.5Hz or something. i think you need to know my expectations arent that high, Im running 50rms of **** bass that rumbles at 80to100 Hz and only hurts ears.
Let me know if you think it would be smartest to place the woofer in the middle of the cabinet from my picture or at the top and have the lower part be a port IF needed.
Knowing myself even if i were pleased with the sound id still hack the box up and try a port just to see where im at.
Thanks a lot just a guy! Youre a real champ!
Bjorno - Thank you very much i took a closer look but cant say i can draw a conclusion from it, my lack of understanding audio theory is getting in our way. It looks like you did most math and research so what is your final conclusion, what would be the smartest move to perhaps hear A0 note 27.5Hz or if it would be a ton easier a B0 which is 30.8677Hz that would make me tremendously happy as well! I see graphs i see you have spent time for a stranger on the internet which is very kind , just dumb it down for me now please.
Honestly i just want deep bass that goes under what we can hear from regular pc speaker sets, however that funny it may sound to you guys when we are talking about a cr*p sub with only 200w of power, it will still be an improvement and an experience for me.
Ron E - Well it was more a figure of speech, 36hz is freq i believe is not so low but not hard on the ears like 60-100 my speakers make currently which i hate.
The Amp im ready to grab is 250w RMS bridged @ 4 Ohm, has a cutoff at 15Hz so just a guy will be pleased to hear that even though im EQ everything under 20 as well as shown in the picture in my last post.
Low pass filter : 40 – 300 Hz, 12 dB per octave
High pass filter : 40 – 300 Hz, 12 dB per octave
Subsonic filter : 15 Hz, 12 dB per octave
Nominal output power: 1 x 250 W @ 4Ohm bridged
Does that sound good? Should i take it?
Cheers guys and many thanks to all.
, just dumb it down for me now please.Honestly i just want deep bass that goes under what we can hear from regular pc speaker sets, however that funny it may sound to you guys when we are talking about a cr*p sub with only 200w of power, it will still be an improvement and an experience for me.
Ron E - Well it was more a figure of speech, 36hz is freq i believe is not so low but not hard on the ears like 60-100 my speakers make currently which i hate.
The Amp im ready to grab is 250w RMS bridged @ 4 Ohm, has a cutoff at 15Hz so just a guy will be pleased to hear that even though im EQ everything under 20 as well as shown in the picture in my last post.
Low pass filter : 40 – 300 Hz, 12 dB per octave
High pass filter : 40 – 300 Hz, 12 dB per octave
Subsonic filter : 15 Hz, 12 dB per octave
Nominal output power: 1 x 250 W @ 4Ohm bridged
Does that sound good? Should i take it?
Cheers guys and many thanks to all.
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Cant edit my post anymore.
Grabbed the amp, it was at a very low price just like the sub was and barely used. not even a scratch on it. Anyway i realized my expectations about how audible this sub could be on such low freq were way over the top, but if someone could dumb down what bjorno wrote and tell me which one would be the best to hit hardest at B0 note 30.8677Hz or similar that would be great.
Consider im starting with a 146x56x31 cm (57.5x22x12.1 inches) box measured from the inside and am able to do pvc pipe port if necessary, just need to know perfect length and its diameter or surface area.
If it would be better it could be possible to do a 56cm wide "labyrinth" through the box as a port i just need to know how much sense that would make. Im afraid im too dumb to understand what bjorno data is telling me.
Btw i also hope the box would be louder and lower than the woofer does in free air.
Grabbed the amp, it was at a very low price just like the sub was and barely used. not even a scratch on it. Anyway i realized my expectations about how audible this sub could be on such low freq were way over the top, but if someone could dumb down what bjorno wrote and tell me which one would be the best to hit hardest at B0 note 30.8677Hz or similar that would be great.
Consider im starting with a 146x56x31 cm (57.5x22x12.1 inches) box measured from the inside and am able to do pvc pipe port if necessary, just need to know perfect length and its diameter or surface area.
If it would be better it could be possible to do a 56cm wide "labyrinth" through the box as a port i just need to know how much sense that would make. Im afraid im too dumb to understand what bjorno data is telling me.
Btw i also hope the box would be louder and lower than the woofer does in free air.
There's not enough information to give a real recommendation.
1. It looks like you are eq'ing everything below 20 hz down by 48 db/oct or so.
2. In addition, you say the amp has a subsonic filter (high pass filter) of 12 db/oct at 15 hz.
3. Also in addition, the amp has another high pass filter with 40 hz lowest setting, 12 db/oct.
Hopefully #3 is defeatable, otherwise you may never achieve your goal. I assume #2 is not defeatable, and #1 may not be necessary.
So can you turn the subsonic and high pass filter on the amp on and off or are they always on? This is the kind of stuff you need to know before you buy things.
Are you using this sub in a car or in a house?
1. It looks like you are eq'ing everything below 20 hz down by 48 db/oct or so.
2. In addition, you say the amp has a subsonic filter (high pass filter) of 12 db/oct at 15 hz.
3. Also in addition, the amp has another high pass filter with 40 hz lowest setting, 12 db/oct.
Hopefully #3 is defeatable, otherwise you may never achieve your goal. I assume #2 is not defeatable, and #1 may not be necessary.
So can you turn the subsonic and high pass filter on the amp on and off or are they always on? This is the kind of stuff you need to know before you buy things.
Are you using this sub in a car or in a house?
Hello just a guy, glad to hear from you again!
1. i can eq and tweak my eq-ing however i like software wise
2. yes sub does have a subsonic filter which i believe is hardware made
3. the manual if i understand correctly states that if i use it in one of the 3 modes it provides, for example "subwoofer mode" it only uses low pass filter and high pass is "infinite".
Im planning on using the sub and amp in my house.
These kind of components were at least 20 times cheaper than even crappy "home hi-fi" grade ones trust me.
It will be tons easier for me to power it from 12v than buy mains powered equivalent amplifier.
1. i can eq and tweak my eq-ing however i like software wise
2. yes sub does have a subsonic filter which i believe is hardware made
3. the manual if i understand correctly states that if i use it in one of the 3 modes it provides, for example "subwoofer mode" it only uses low pass filter and high pass is "infinite".
Im planning on using the sub and amp in my house.
These kind of components were at least 20 times cheaper than even crappy "home hi-fi" grade ones trust me.
It will be tons easier for me to power it from 12v than buy mains powered equivalent amplifier.
Ok, here's one way to do it.
Put a port in the 250 liter box that is 180 sq cm and 20 cm long. That can be a slot port or round. If it's round you can use a 6 inch port or four 3 inch ports. That should be big enough to keep velocity at an acceptable level with the filters used here.
Use the amp's 15 hz subsonic filter AND the amp's high pass filter set at 40 hz. You don't need to use your eq to cut anything, these two filters will give the response and displacement shown with 250 watts.
The blue line on each graph is the performance with only the 15 hz subsonic filter, the red line is with the subsonic filter AND the 40 hz high pass filter. Both filters are BW 12 db/oct.
This is only one way to do this. If you wanted to use eq instead of the high pass filter that could work too, might even work better. As you can see, when using the 40 hz high pass filter you don't have enough amp power to get the driver to xmax so a bit of performance is left on the table.
As shown, this will give you a strong 30 hz as requested, and 27 hz is about 5 db down.
Of course this assumes that the filters in your amp will perform as advertised. On a cheap amp they might not do exactly what they are supposed to do.
If you want to try using your eq as a high pass filter instead of the amp's built in high pass filter I can work something out for that too. I would need to know a bit about the eq settings - frequencies and slopes available.
Just note that a response like this might sound a bit boomy in room, but I have a feeling that's what you are going for.
Put a port in the 250 liter box that is 180 sq cm and 20 cm long. That can be a slot port or round. If it's round you can use a 6 inch port or four 3 inch ports. That should be big enough to keep velocity at an acceptable level with the filters used here.
Use the amp's 15 hz subsonic filter AND the amp's high pass filter set at 40 hz. You don't need to use your eq to cut anything, these two filters will give the response and displacement shown with 250 watts.
The blue line on each graph is the performance with only the 15 hz subsonic filter, the red line is with the subsonic filter AND the 40 hz high pass filter. Both filters are BW 12 db/oct.
This is only one way to do this. If you wanted to use eq instead of the high pass filter that could work too, might even work better. As you can see, when using the 40 hz high pass filter you don't have enough amp power to get the driver to xmax so a bit of performance is left on the table.
As shown, this will give you a strong 30 hz as requested, and 27 hz is about 5 db down.
Of course this assumes that the filters in your amp will perform as advertised. On a cheap amp they might not do exactly what they are supposed to do.
If you want to try using your eq as a high pass filter instead of the amp's built in high pass filter I can work something out for that too. I would need to know a bit about the eq settings - frequencies and slopes available.
Just note that a response like this might sound a bit boomy in room, but I have a feeling that's what you are going for.
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