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Subwoofer Driver Selection for DIY - Home Use

Wharfedale Linton Heritage Speakers

gp_freak

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Hello members, it's been a long time! I always wanted to build a sub to compliment my Puny Home theatre setup, but never found the time. Now with this work from Home scenario and me moving back to my hometown to my ancestral home, have a bit of time, space for DIYing, and also space for the additional Sub-woofer itself. After a lot of online searches, the only good branded drivers which are easily available without breaking the banks are the Car audio Subs and the PA subs. Any sub-woofer without the T/S parameters was rejected outright.

I am pretty sure many would look out for Good Sub drivers, but most good ones are available at most approx twice the price of what they cost abroad.

Some sub-woofers shortlisted based on the ease of availability and Price

  • Fredo 12 DVC ~ INR 3200 ( guess Delhi factory walks in to get them cheap )
  • JBL 1300 ~ INR 3800
  • KENWOOD W12PS ~ INR 3500
  • JBL 1500 ~ INR 4500
  • Infinity Prime 1270 ~ INR 4500 to 5000
  • Rockford – Prime 12 ~ INR 5000 to 5500
  • Infinity Kappa 12 1200 ~ INR 9000
  • Rockford Punch P1s4 15 ~ INR 15000 list price.
Some other Subwoofers considered were the PA Audio Subs with Roll surrounds instead of rubber ones.

They were from MCM audio 12 and 15 inches and Sweton 15 and 18 Inch – Only they had T/S parameters. Didn’t want to buy some fancy-looking subwoofers and then shoot in the dark. Of course, I could measure the T/S parameters myself with DIY, but why take that route with so much ambiguity? What if the parameters don’t provide me a response which I was looking for? So dropped them.

Contacted Xpider Audio because they had long-throw SPL Subs, wanted to check how they will turn out. Pity, they don’t have T/S parameters. I wonder why such manufacturers ( assemblers ) of subwoofers don’t spend some 10 K on proper Measuring tools say the DATS or create their own measurement Jig.

Guess the Indian market consumers are still not mature enough to be treated with proper specifications! Our Market is happy enough with hearing 1500 Watts Peak value. Only now people have started to talks about RMS. Guess it will take ages to start using the proper parameters and build a sub according to customer taste and need.

What I am chasing after is some Low-Frequency Extension for Movies with a very flat response. However, not sure how the room response will add to the output. So it's all theory now with all these sub-models thrown into WinISD to see what subs will be most suitable. The volume for a single sub can go up to 250 Litre Max Ported.

My Aim in making this post is just to show, hey a normal 3.5K sub can be models in theory to provide a similar response of a sub more expensive than it.
 

gp_freak

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  • JBL 1300 – VB 200 Litres, FB 21 Hz , Power – 110 Watts
  • KENWOOD W12PS – Just 7 mm X max, so rejected it after my initial try
  • JBL 1500 – VB 90, FB 27, Power 110 Watts
  • Infinity Prime 1270 – VB 200, FB 23 @ 190 Watts
  • Rockford – Prime 12 - VB 250 FB 23 @ 55 Watts
  • Infinity Kappa 12 1200 - VB 145, FB 21 @ 210 Watts
  • Rockford Punch P1s4 15 - VB 360, FB 20 @ 100 Watts
The Box volume and tuning frequency and Signal input is given and you can see the response graph in the attached file. While the Subs are rated to handle more power, when the subs are tuned as above, they reach their X max. For ex. Kappa Rated to 500 Rms reaches its X max at less than half its RMS. Also in the graph you will find it very difficult to differentiate JBL 1300 and Kappa 12. They are nearly the same and overlapping each other. INR 3800 vs INR 9000. How ever, Kappa does that in 145 litre Box and JBL does that in a 200 Litre Box. Also JBL 1300 does the near same SPL at half the watts of Kappa. No disrespect to Kappa, they are my loved ones, how ever, when taking an objective look, unless space is a premium, inst JBL 1300 the better choice ? 52.5 Cm cube = 145 litre and 58.5 cms cube = 200 litres . Just increasing the length of the cube by 6 cms gives additional 55 litres of internal space.
 

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gp_freak

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So from the above graph i liked the Primus for more SPL , how ever, i was not sure whether i hit those volumes . So felt the JBL and Kappa to have the nice mix of low extension and the max internal volume i was ready to compromise on. It was kind of a no brainer to me to chose the JBL over Kappa due to the cost difference and spend the rest on Box build and tools. ( Still not sure whether i will build it my self or just get them build in a local shop. Unless i keep building for my self or friend, it made no sense to invest in tools. I would need a Circular saw, a Drill machine and router )

So which JBL ? 1300 or 1500 ? There is a good INR 500 Rs to INR 1000 cost difference between both, where 1300 cost lower. Both Subs in a 200 Litre Box tuned to 21 with a 4th order Butterworth highpass Filter @ 17 HZ applied is in the following Graph. Can you spot any difference ? Is there any difference at all between both ? I think there is ,most probably the JBL 1500 has a better power handling etc, but hey JBL 1300 has 300 RMS and 1500 had 325 RMS rating. How ever, the cheaper one does same SPl at 125 watts where as the expensive one needs 140 watts to achieve same SPL. The 1300 is approx 10% more efficient than 1500. . Ended up Ordering the JBL 1300 in Amazon.
 

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filmguy

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hi

where did you get the specs of all the drivers you've mentioned? esp the jbl's & fredo subs. i've emailed/contacted both but not got any reply about the parameters.

the fredo seller was very very rude & has mentioned different specs in different sections on amazon so i decided against it otherwise i would have liked to buy a "made in india" product. another similar option was some yokoma brand.

even i am considering the jbl 1300 & 1500. can you please post the product sheet once you get yours delivered.
 

sunilj

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Try the Tangband W8-740P in a tapped horn. I've built the TB1139 (6.5"). It can do 30hz comfortably and you can play with input coils (4.7uH ++) to flatten the output over a larger bandwidth.

The horn expansion can get tricky to build, so print a 1:1 and the carpenter used it as a template. Easy.

 

gp_freak

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hi

where did you get the specs of all the drivers you've mentioned? esp the jbl's & fredo subs. i've emailed/contacted both but not got any reply about the parameters.

the fredo seller was very very rude & has mentioned different specs in different sections on amazon so i decided against it otherwise i would have liked to buy a "made in india" product. another similar option was some yokoma brand.

even i am considering the jbl 1300 & 1500. can you please post the product sheet once you get yours delivered.
That is exactly the reason i dismissed Fredo , It did look good considering the fact that it was DVC, i may get one in the future and measure the values myself, but not right now. It took quiet some efforts to find the specs of JBL. The JBL india website is a joke and so is the Harman and Sahil international and so on. They are not what they used to be. I got them from youtube and by searching for JBL unboxing videos from India and took a screen grab when the guy was showing the manual for a couple of seconds. I have attached the details for you here. It was surprising to see the JBLs were quiet good.

@sunilj - Thank you very much. Sure , i wanted to build a quarter wave design , Folded Horn using Hornresp, but that is something which i have never used . So definitely, will be using the JBL parameters to model a Folded Horn or tapped horn or mass loaded or what ever this is to understand what they do differently. Will begin with something simple and focus on using the drivers which are easily available in India from any where. The drivers i have highlighted are easily available online/offline and wanted to take the non exotic route.

Tanband 8 inch driver cost around 7K in diyaudiocart, So will definitely consider it once i have built some understanding/knowledge. The areas where i will be definitely following others is electronics, crossovers and filters. For ex, i am looking for a passive high pass butterworth 4th order fiter for 17Hz to ensure the sub doesnt bottom out. I want a DIY route. No expensive DSPs or complex active cross overs. I dont see any such high pass boards in market because most of these subs are put in a smallish enclosure and tuned high to 40 Hz . My capability ends with identifying relays and Caps and nothing beyond.
 

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adas

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Hi , I would urge you not to tune these drivers so low , you will quickly run in problems of power handling and the subwoofers xmax capabilities. Try to tune them slightly higher than fs of the driver , you will encounter problems tuning this drivers higher as there will be a bump in frequency response.
To reach the f3 of 20hz you need approx 220L of enclosure volume ..and with a 4th order hpf at 17hz you can put in 140W before reaching xmax and your group delay is close to 80ms at 20hz...
 
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sunilj

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The JBL sensitivity is low at 86dB. What kind of VAS are you looking at?

With a 4th order xover you will have even more losses. The coil values will be hard to get air-gapped, which means iron-core.
 

gp_freak

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Hi , I would urge you not to tune these drivers so low , you will quickly run in problems of power handling and the subwoofers xmax capabilities. Try to tune them slightly higher than fs of the driver , you will encounter problems tuning this drivers higher as there will be a bump in frequency response.
To reach the f3 of 20hz you need approx 220L of enclosure volume ..and with a 4th order hpf at 17hz you can put in 140W before reaching xmax and your group delay is close to 80ms at 20hz...
  • JBL 1300 – VB 200 Litres, FB 21 Hz , Power – 110 Watts
Reached X max with above tune producing 108 dB SPL. I am not trying to hit anything above 105 dB and the goal is not SPl, but LFE. Also, i am not really worried about the high group delay around 20 Hz. I don't think any music goes so low and probably only movies will have those LFE track for special effects.

Btw, the Fs of the JBL is 28 Hz, so 29 Hz in 220 Litre box means the peak SPL of 112 dB at 30 Hz and F3 will be at 26.6 Hz and at 20Hz, just 96 db , which is 13 less than F3. Also the GD is 46ms at 30 Hz where as the model with B 200 Litres, FB 21 Hz has just 21.5. Only at 60 Hz does the model tuned to 28 Hz meets the model tuned to 21Hz. Less GD as we go higher is better and if its GD is chasing after, i just should go sealed. The lower the sub is tuned, we loose power handling, increased Box volumes and increased GD. You loose 3 to gain one !

How ever, if i want to play music, i just go ahead and seal the ports and voila, it now has a GD of 7 ms at 20 Hz and still it produces same SPL @ 20 Hz when compared to the 220 litre box tuned to 29 hz.

@adas - Please let me know if i am talking with my head inside the sand. Open for all comments and criticisms. Btw, i was about to ask your help in designing a circuit for 4th order Butterworth Highpass filter at 17 Hz to protect the sub. Are there any pre built boards in the market or can we build it easy in a Dot pcb easily ?

@sunilj , 17 Hz was chosen as HPF to ensure that the curve is steep and keep the sub safe. You can see attached response. Pl point out the area where you are referring the loss
 
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filmguy

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That is exactly the reason i dismissed Fredo , It did look good considering the fact that it was DVC, i may get one in the future and measure the values myself, but not right now. It took quiet some efforts to find the specs of JBL. The JBL india website is a joke and so is the Harman and Sahil international and so on. They are not what they used to be. I got them from youtube and by searching for JBL unboxing videos from India and took a screen grab when the guy was showing the manual for a couple of seconds. I have attached the details for you here. It was surprising to see the JBLs were quiet good.

thanks for the specs. unfortunate that customers in India have to jump through so many hoops for basic stuff.

bit suspicious of the JBL's stated specs though. a1300 & a1500 have almost same specs, what could be reason there's a difference of almost 1k? think this model is an India-only one as have not found it elsewhere. it seems jbl india have outsourced the car audio dept to an outside company autosonics so not sure how much we can trust them? were you able to find any info on procedure for returns if something were to go wrong in the warranty period?
 

gp_freak

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thanks for the specs. unfortunate that customers in India have to jump through so many hoops for basic stuff.

bit suspicious of the JBL's stated specs though. a1300 & a1500 have almost same specs, what could be reason there's a difference of almost 1k? think this model is an India-only one as have not found it elsewhere. it seems jbl india have outsourced the car audio dept to an outside company autosonics so not sure how much we can trust them? were you able to find any info on procedure for returns if something were to go wrong in the warranty period?
Probably Marketing ! Using all the same raw materials, jigs and dyes and just improving the power handling a tiny bit, and renaming to higher number and attracting the customer. These JBL are coming in from China it seems, even apple does not manufacture many of its own components. Btw, wrt to trust worthiness of the parameters, we need to measure to confirm.

@adas Please ignore this "How ever, if i want to play music, i just go ahead and seal the ports and voila, it now has a GD of 7 ms at 20 Hz and still it produces same SPL @ 20 Hz when compared to the 220 litre box tuned to 29 hz"

When sealed with VB 200 litres, GD drops to 34.xx ms, not 7 which is still substantially less when compared to ported. I had too many drivers opened in winisd and had misread Kappa sealed data. No wonder Kappa is tight and musical and fast ( calling names ) in a sealed Box.
 

gp_freak

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@gp_freak you must have a huge room , I had issues accomodating a 66L enclosure , can't even begin to imagine 220L ...
That's a 400 + Sq ft hall. If you add the dining , its around 550 + The Initial idea was to put two subs, but now starting with just one. Btw, with cubes, 66 L need a 40 Cm cube. 200 L needs a 58 Cm cube. Increasing the side length by two times increases the internal volume of the cube by 8 times. Was your enclosure a cube or a rectangular prism ? I haven't started the build. These are just some simulations to choose the driver. However, clearance received in home to put two 2×2×2 Feet boxes . For now one side will the Mini yamaha sub for serials and music. The bigger one for movies. If I want more, then a other one will be added.
 

adas

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@gp_freak there is a company called iwai they make drivers for Indian companies like sonodyne and also many of their drivers are exported . You can contact them they have a excellent 12inch & 10inch subwoofer in triple magnet configuration.
My subwoofers are rectangular
 

arunkvivek

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That's a 400 + Sq ft hall. If you add the dining , its around 550 + The Initial idea was to put two subs, but now starting with just one. Btw, with cubes, 66 L need a 40 Cm cube. 200 L needs a 58 Cm cube. Increasing the side length by two times increases the internal volume of the cube by 8 times. Was your enclosure a cube or a rectangular prism ? I haven't started the build. These are just some simulations to choose the driver. However, clearance received in home to put two 2×2×2 Feet boxes . For now one side will the Mini yamaha sub for serials and music. The bigger one for movies. If I want more, then a other one will be added.
That's a lot of space! If you can afford to put SW as center tables or room partitions, you should consider Open baffle SW (H-Frame or U-Frame). Super easy to make and great VFM performance. They can be super effective as you move them away from the walls. I have 2 H-frame SWs with each having a pair of 15 inch Driver (GRS). Brands like PRV are locally available. If you decide to tread this way, you should check out the Yogibear's posts.
 

gp_freak

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@gp_freak there is a company called iwai they make drivers for Indian companies like sonodyne and also many of their drivers are exported . You can contact them they have a excellent 12inch & 10inch subwoofer in triple magnet configuration.
My subwoofers are rectangular
Thanks for the info, made a quick model with the IWAI 12 inch with the data sheet provided in their page and it looks like a decent sub-woofer.
Has the same motor strength as JBL 1300 even though it has three magnets. I was a bit skeptical initially seeing it to have just 8 mm X max when the product was touted to be a Large X max sub-woofer. However, It provides a good flat response in just a 90 litre vented enclosure with ports tuned to 24.5 Hz. starts rolling off at 30 Hz with F3 @ aprox 24 Hz and -9 dB at 20 Hz.

I just remember reading in Brians Steele's post for Room gain. Quoting him here
"In most rooms, the room itself provides additional gain at frequencies below approximately 30 Hz. There's a slight risk of creating a boomy system if you create a design that on paper has a cutoff point much below 30 Hz. A commonly-recommended rule of thumb is to aim for a design with a response that is -3dB at 30 Hz and -9dB at 20 Hz, which should work well in most rooms."

The IWAI driver follows it to the word in principle when modeled . Link to T/s below.
http://testsite.iwai.co.in/product-detail/12-long-throw-subwoofer-4ω-200w/


@arunkvivek , i was in to your thread earlier when i was looking for sub builds in this forum. In my case, the subs needs to placed near the walls.
 

gp_freak

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@gp_freak the xmax should be around 12-15mm , I think there is a mistake in that data.

I would be very surprised if that X max is that high. Many indian subs have X max of 5 to 7 mm. By that standard, 8 mm in the spec page of IWAI may be right. Probably the X mech might be around 12- 15. Do you know how much does this sub driver cost ? Even with 8 mm excursion, it looks good.
 

adas

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It has triple magnet i.e total 60mm of magnet structure , so 12-15mm is not impossible it has voice coil winding length of 35mm and top plate thickness of 8mm so theroitical xmax of 13.5mm is very much possible. It cost around 5-6K I guess now
 

gp_freak

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It has triple magnet i.e total 60mm of magnet structure , so 12-15mm is not impossible it has voice coil winding length of 35mm and top plate thickness of 8mm so theroitical xmax of 13.5mm is very much possible. It cost around 5-6K I guess now
Quiet possible, i am just wondering how could the Iwai guys make such a blunder about an important large signal parameter in their site. I have mailed to them to check whether they have any subs in 15 or 18 Inch size and about the pricing of the 12 inch one. Fingers crossed !.

Edit: In theory, 32-8/2 = 12 which can be the X max. How ever, at X Max, the voice is to be @ 70% Bl ? Though this one has three magnets, its strength is equal to of a dual magnet JBL for comparison sake. So 70% of 12 mm equals 8.xx mm which is as per the X max figures given by the IWAI site. On contrary, i think IWAI could be very honest and accurate with their parameters too
 
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