Ok you may have seen my other thread about stuffing my sub, and I have realised this won't make much difference to the depth of the bass.
As I said I would like my sub to delve a bit deeper considering how much excursion I get. Would adding a port ensure of this?
If so, whereabouts should I put it, what diameter should it be and what sort of tubing should I use, etc?
I don't have any specs for the driver, but here's a pic of the cabinet:
So what sort of port should I add?
Many thanks in advance.
As I said I would like my sub to delve a bit deeper considering how much excursion I get. Would adding a port ensure of this?
If so, whereabouts should I put it, what diameter should it be and what sort of tubing should I use, etc?
I don't have any specs for the driver, but here's a pic of the cabinet:
An externally hosted image should be here but it was not working when we last tested it.
So what sort of port should I add?
Many thanks in advance.
We are just shooting in the dark, here, Howard. So I will ask just a couple of questions.
I see you have a six sided cabinet-I remember it from a previous post. Didn't you put the carpeting on the outside? If so, nice job.
Isn't that a 10 inch speaker?
What is the outside height, and width?
What is the width of each panel?
From this, I hope to find the internal volume, (I am assuming ¾" material).
From that, I will give you a recommendation for a port. It will just be a guess, but if you want to experiment, here goes.
I see you have a six sided cabinet-I remember it from a previous post. Didn't you put the carpeting on the outside? If so, nice job.
Isn't that a 10 inch speaker?
What is the outside height, and width?
What is the width of each panel?
From this, I hope to find the internal volume, (I am assuming ¾" material).
From that, I will give you a recommendation for a port. It will just be a guess, but if you want to experiment, here goes.
Remind me, Howard. Do you say that you have excursion to spare or are you at the limit? If you've got spare then perhaps you could keep the sealed box and add a little equalization.Howard said:
Ok I'll answer both of your questions:
The excursion looks pretty "intense" and you can feel it quite a bit, but it's not as deep as the bass we get on our downstairs sub (with a port, part of a JBL ESC333 system). There certainly is a bass increase compared when just using my front speakers though, it's by no means a "weak" sub. It's just that I feel if I use any equalisation to increase the lower frequencies on this poor driver (I think it's a car sub) and it's just gonna distort. It does slightly at higher levels, so I'm hoping by adding a port I can reduce the sub's level thus allowing it to handle more power.
I use things like the StarWars EP2 DVD, and for example the huge explosion at the beginning sends my subwoofer crazy, I wouldn't like to say how much excursion I get, but at a guess about a couple of centimetres? It distorts a little bit if I turn the volume up on this part. By looking at this though I reckon it could "sound" deeper and not just look it!
It's a 12" driver, cabinet is 20MM MDF and it's not a carpeted cabinet, it's painted matt black 🙂
It's 42.5 CM tall and about 50 CM wide (from the two edges that are furthest apart, if you see what I mean
)
The width of each panel is 25.5 CM.
I have found this plastic tube (8 CM dia. 11CM length) that was part of this office chair but we forgot to use it and don't need it for anything else, this would make a quite good port "tube" if the dimensions are correct would it not?
Many thanks for your help guys,
Sorry if it seems like I'm waffling on!
Howard
(edit) P.S My dad and I are not affraid of changing the box in any way to acompany a port, etc, if it's gonna make it sound better, so don't worry about me wanting to "keep the sealed design".
The excursion looks pretty "intense" and you can feel it quite a bit, but it's not as deep as the bass we get on our downstairs sub (with a port, part of a JBL ESC333 system). There certainly is a bass increase compared when just using my front speakers though, it's by no means a "weak" sub. It's just that I feel if I use any equalisation to increase the lower frequencies on this poor driver (I think it's a car sub) and it's just gonna distort. It does slightly at higher levels, so I'm hoping by adding a port I can reduce the sub's level thus allowing it to handle more power.
I use things like the StarWars EP2 DVD, and for example the huge explosion at the beginning sends my subwoofer crazy, I wouldn't like to say how much excursion I get, but at a guess about a couple of centimetres? It distorts a little bit if I turn the volume up on this part. By looking at this though I reckon it could "sound" deeper and not just look it!
It's a 12" driver, cabinet is 20MM MDF and it's not a carpeted cabinet, it's painted matt black 🙂
It's 42.5 CM tall and about 50 CM wide (from the two edges that are furthest apart, if you see what I mean
)The width of each panel is 25.5 CM.
I have found this plastic tube (8 CM dia. 11CM length) that was part of this office chair but we forgot to use it and don't need it for anything else, this would make a quite good port "tube" if the dimensions are correct would it not?
Many thanks for your help guys,
Sorry if it seems like I'm waffling on!
Howard
(edit) P.S My dad and I are not affraid of changing the box in any way to acompany a port, etc, if it's gonna make it sound better, so don't worry about me wanting to "keep the sealed design".
You really will be stabbing in the dark by adding a port so blindly. That's not to say it won't work, but you may just ruin a very good looking enclosure. A couple of centimetes (20mm) in one direction is a lot already, although there is probably little accuracy in your perceived excursion.
Remember that by porting the enclosure you will get lower frequencies and the excursion will be less near the tuning frequency, but below that, the excursion will increase rapidly. And some subs just really won't perform as well in a ported enclosure. You could end up reducing the volume a lot to reduce distortion and physical damage, considering that the cone already moves that much.
I've not read your other post, but I'm sure they boys will have mentioned ways of obtaining the sub parameters, which will allow you to model your sub to high accuracy. Why is this not an option? You could see how much excursion you have, and how it will change above and below the tuning point, and it will tell you how much lower you can go with a port.
That's not a bad size. The larger the diameter, the better for reducing port whistling/noise, but the longer it will be as well.
I've caluclated your internal enclosure size to be 89.7 litres (you will need to negate the driver diaplacement and bracing from this figure, and eventually the port as well!) To give you an idea, I've removed 15% to account for these. So enclosure size is now 76.25l. If we pick a tuning frequency of 35Hz (this may be far from ideal) , for your 8cm port, your port length will be 9.99cm.
Again, with T/S params you will be able to see what kind of response and excursion you'll get.
Hi. Thanks for your help.
I cannot find any information on how to contact the manufacturer of this driver from anywhere, therefore do not have any TS parameters. Also I do not have the necessary equipment to obtain them. How would this be done?
I am trying not to "blindly" add the port, hence me asking here for advice, and any that helps and assists me in getting deeper frequencies is much appreciated! 🙂
Is there any way of measuring excursion? A ruler isn't much use, I'm just guessing what looks like a couple of CM! Lol.
I cannot find any information on how to contact the manufacturer of this driver from anywhere, therefore do not have any TS parameters. Also I do not have the necessary equipment to obtain them. How would this be done?
I am trying not to "blindly" add the port, hence me asking here for advice, and any that helps and assists me in getting deeper frequencies is much appreciated! 🙂
Is there any way of measuring excursion? A ruler isn't much use, I'm just guessing what looks like a couple of CM! Lol.
I would highly recommend going down the Speaker Workshop route. There is a learning curve involved, but it will prove worth it if you're in the DIY audio game. You should build a jig that will allow you to obtain all the measurements, and do other useful stuff. I can build you one if you're not up to it, just pop me an email.
And of course you're doing the right think by asking, but I think we're all in the dark without those crucial T/S parameters. It's a bit like speaker design of the cave man days.
There are ways of finding xmax, though I can't say of the top of my head. A google search should lead the way.
Vikash said:
What do you mean a jig? I don't really wanna go through too much "research" just to add a port to my subwoofer. This is gonna be probably the only DIY speaker project I do
🙂
Perhaps I can make a suggestion. As this is probably going to be your first and last speaker project, why not build yourself a better sub? Leave the one you've got as it is, look for the sub you want and build that. You could have a great sounding sub.Howard said:
Listen to commercial subs to find designs that you could copy or build a DIY sub from a kit. Even better, Auntie Google could provide as many designs and theories as you need, if you search them out. You'll also get help on this forum. Take advantage of Vikash's offer, it's generous.
I don't think that this route would be too difficult for you but more rewarding. Can you hear the sub you might end up with?
What do you want from your sub? Start there.
Eric Wallin's Jig v2 for use with Speaker Workshop.
If you decide to just go for it, you can try different port lengths that will result in different tuning frequencies until you hear something you're happy with. As the tuning frequency goes down, the port length increases. My suggestion in this scenario would be to start with a long port length to give you a low tuning frequency and do some *careful* listening tests. If you think it's being pushed too much then reduce the port length to increase the tuning frequency. The thing we can't help you with in such an experiment is knowing where the "pushing it too much" point is.
For a 76.25l enclosure, you could start at a reasonably low tuning frequency of 30Hz (considering a 12" sub) which would result in a port length of 15.72cm for your 8cm diameter pipe (this should be inner diameter). If you wanted to get silly (start at the lowest point possible), then you could tune to 20Hz (probably way below your driver fs, and thus illadvised) and the port would still fit within you enclosure dimensions: port length = 42.69cm.
Fair play. In that case your options are really to get someone else to measure the sub and give you the specs, hunt down the manufacturer, or just stab and live with the results.
If you decide to just go for it, you can try different port lengths that will result in different tuning frequencies until you hear something you're happy with. As the tuning frequency goes down, the port length increases. My suggestion in this scenario would be to start with a long port length to give you a low tuning frequency and do some *careful* listening tests. If you think it's being pushed too much then reduce the port length to increase the tuning frequency. The thing we can't help you with in such an experiment is knowing where the "pushing it too much" point is.
For a 76.25l enclosure, you could start at a reasonably low tuning frequency of 30Hz (considering a 12" sub) which would result in a port length of 15.72cm for your 8cm diameter pipe (this should be inner diameter). If you wanted to get silly (start at the lowest point possible), then you could tune to 20Hz (probably way below your driver fs, and thus illadvised) and the port would still fit within you enclosure dimensions: port length = 42.69cm.
I just had a play with it and the excursion isn't 2CM as I guessed, it's more like 1.
I don't really wanna build a whole new sub, just optimise this. It certainly doesn't sound bad, but could just delve a bit deeper.
Hunting down the manufacturer (SPLX) has proved incredibly difficult, I've tried looking all over the internet for hours, with no avail 🙁
I don't really wanna build a whole new sub, just optimise this. It certainly doesn't sound bad, but could just delve a bit deeper.
Hunting down the manufacturer (SPLX) has proved incredibly difficult, I've tried looking all over the internet for hours, with no avail 🙁
Motorworld sells SPLX subs, though not your particular one. They don't even come with the T/S specs in or on the box, and that really shows the budget market they're aimed at (not my words, but the guys over at Motorworld)
If you want to take it further than they mentioned the importers: Sakura. But for a £20 sub without any specs, Steve's suggestion comes to the front line, else just cut and stick a port in with your fingers crossed.
Oh, they also recommended a 1 - 1.25 cuft enclosure for the current 12" SPLX sub, although I don't know where they pulled this number out from. For comparisson, your internal volume is about 2.7 cuft = more bass, less transient response if the drivers are the same.
The potentially larger than recommended enclosure means there is less suspension provided by the enlcosure, and the net effect could be the high excursion your witnessing.
If you want to take it further than they mentioned the importers: Sakura. But for a £20 sub without any specs, Steve's suggestion comes to the front line, else just cut and stick a port in with your fingers crossed.
Oh, they also recommended a 1 - 1.25 cuft enclosure for the current 12" SPLX sub, although I don't know where they pulled this number out from. For comparisson, your internal volume is about 2.7 cuft = more bass, less transient response if the drivers are the same.
The potentially larger than recommended enclosure means there is less suspension provided by the enlcosure, and the net effect could be the high excursion your witnessing.
Vikash said:
No question that Howard is "taking a stab". However, a couple of things that tend to indicate it's a good gamble.
A) If he vents his sub with PVC pipe, the PVC can be bought, cheaply, with an end cap. So the modification is reversible. In fact, he could make a "convertible", depending on how he feels at the moment, There have been "convertible" speakers in the past-Marantz made one back in the seventies. Even if he likes it sealed better, he can always put the end cap back on and call it something.
B) He can always make port longer and stuff it. This can be a third option that has a good chance of working well if the port gives the response too much "boom".
C) Assuming that 1-1.25 Ft³ enclosure is sealed-and with no mention of tuning frequency or ports, it probably is-then that makes it all the more likely that in his size enclosure, the SPLX would work well in a ported configuration. This would assume that there is a relationship between the current SPLX and Howard's, but such a relationship is not unusual model to model. Many, many speakers have two recommended enclosures-a smaller one for sealed, a larger enclosure for ported. Never the reverse. Since Howard's enclosure is much larger than the recommended enclosure, (albeit recommended for the current model), this would fit that pattern.
Thanks, some good suggestions.
Any idea how I can contact this company, Sakura, to maybe get some specs?
So what rough size should I make the port? And what will the worst outcome be?
Any idea how I can contact this company, Sakura, to maybe get some specs?
So what rough size should I make the port? And what will the worst outcome be?
The worst outcome is that you will end up with some "boom" in the bass. And you can minimize that somewhat.
The best is that you can strengthen and extend your bass downward quite a bit.
I might warn you that the Thiele-Small parameters of some budget models, which this certainly is, are often off quite a bit. For better brands, the Thiele-Small parameters often are off, but balance each other and therefore work well when the speaker is placed in the box. For budget speakers-who knows?
The best is that you can strengthen and extend your bass downward quite a bit.
I might warn you that the Thiele-Small parameters of some budget models, which this certainly is, are often off quite a bit. For better brands, the Thiele-Small parameters often are off, but balance each other and therefore work well when the speaker is placed in the box. For budget speakers-who knows?
The driver in my sub isn't the same model as on the MotorWorld website. Although it's probably fairly budget, yes.
So what size would you recommend then for the port? Give me some measurements that could work best?
So what size would you recommend then for the port? Give me some measurements that could work best?
Vikash said:
Ok this 8CM pipe is only 11CM long 🙁
Is there a formula (for the 30 hz tuning freq you mentioned) to work out the required length from the diameter of the pipe? I ask this because I'm going to have a look round my garage for suitable piping.
Thanks.
OK I'm gonna buy some drainpipe or something that's about 8CM in diameter and cut it to 15.7 CM in length...How sure are you that this will make a fairly positive difference?
I used WinISD to caluclate the port length. All you have to do is enter your enclosure size, the desired tuning frequency, and the diameter of the pipe. It will spit out the port length required.
Try it out with your current pipe, and if you don't get what you're after and want to attempt tuning lower, then you can go and get a longer pipe (assuming a pipe of the same diameter can be easily found)
It will make a difference, but I can't say whether it will be positively so. By using a 11cm long pipe, you will be increasing your tuning frequency by 4Hz (to 34Hz). Not such a big difference and it's still a resonable tuning frequency for your 12".
Try it out with your current pipe, and if you don't get what you're after and want to attempt tuning lower, then you can go and get a longer pipe (assuming a pipe of the same diameter can be easily found)
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