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Quest to build a best possible sub in a budget.

Naveenbnc

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Hey guys....

I want to keep this thread for all my future Subwoofer builds. The ultimate goal is to build a sub with the following features.

1. Obviously, should sound great (in a general sense)
2. Should be as compact as possible.
3. Should be built without spending huge money.

Some of you might know that I built the following subs till date.

1. 12" ported sub
2. 15" dipole sub
3. 10" ported
4. 10" sealed

The first one was built last year, and was designed by our FM ANIKET. Its working great for the price and very happy with it.

15" dipole: I couldn't make it a success yet. I suspect either the driver could be faulty or the placement could be wrong. The box is a bit bigger to do the subwoofer crawl easily. Need to work on it further. Our FM Yogibear is helping me with this.

10" ported & sealed are built with the same driver. Theoritically, this driver is more suitable for ported box, as per it's TS parameters. Same reflected in the performance as well.

Since im already using 12" sub, the 10" didn't surprise me much.

However, none of my builds till date could compete with "so called" highend branded subs, but they are great @ the price.

So I have to raise the bar keep building better sub. As a one time investment, I can buy a good branded sub, and enjoy. But I want to enjoy diy.

I may try to improve my existing designs, try a few more new drivers, try few more different designs etc. And most importantly, il keep learning. So this could be a long-term activity, il keep posting my trails.

Seniors can teach me with their suggestions, and others can also learn.

Regards,
Naveen
 
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tuff

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I think amplification is key to get the woofer to be controlled with authority, once you have the box and driver figured out. Also if possible, try using passive radiator and see how it performs.
Have absolutely no idea how to build one .Servo subwoofers are also more desired in some circles. Maybe also try to build an active crossover. Again, no idea how to build one.
 

Naveenbnc

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The next few ideas I'm considering are as follows. Some may or may not work, but just for the fun of trying it....il surely try these.....

1. 2drivers+2PR in a compact box. Our FM @diyaudio gave this suggestion, and he may help me in design too...
2. Our friend @Aniket suggested some drivers with good specs and higher power. Need to use one of them and build a sub.
3. TL design
4. Any kind of improvements to my existing subs.
5. Try different design like bandpass, push-pull etc etc...

Il take enough time, and keep trying these options.....lets see how it goes.....

There are many advanced r&d technics etc that companies may do....

For example....
http://www.sunfire.com/science-sunfire/high-back-emf

These kind of stuff may not be possible for a casual Diy person like me.... But within our scope, i want to build a best sub possible.

Few characteristics of good subwoofer ..

https://www.svsound.com/blogs/svs/the-5-performance-attributes-of-a-world-class-subwoofer

A few points on big drivers ...

https://www.svsound.com/blogs/svs/strengths-and-pitfalls-of-big-subwoofer-drivers

I think building a good sub can be achieved, but keeping it compact (just a little bigger than the driver itself) can be quite challenging !!
 
Last edited:

diyaudio

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Hey guys....
1. Obviously, should sound great (in a general sense)
2. Should be as compact as possible.
3. Should be built without spending huge money.
These are conflicting requirements since a sub is governed Hoffman's Iron law.

Commercial subwoofers are not a good comparison because of hype and marketing.

The sunfire is an exception. The subwoofer alignments that we normally use are arrived at by modelling (using T/S parameters) and they operate the driver at a relatively small efficiency. The back emf is negligible and does not figure out in simulations.

Sunfire does the opposite, it takes a very high BL driver, one with huge magnet/motor system which generates high back EMF. The back EMF is higher than the typical amps that we use. They use high voltage amps to operate the driver. This gives tremendous efficiency gains and amp size is reduced and current is reduced. http://www.xlrtechs.com/dbkeele.com/PDF/Keele (2003-10 AES Preprint) - Nom vs True Eff High BL.pdf. The smaller the box, the stronger the stiffness of air mass. The harder it is to make the driver work in it. Now if the motor is very strong, it has tremendous ability to compress the high stiffness of the small air volume of the small box. All good so far.

However as box volume becomes small, the driver becomes non linear, so its corrected by servo motion control. The creator, Bob Carver is a true genius.

For a DIYer, it too complicated. A specialised driver, A specialised amp. A specialised servo.

A 4th order bandpass suppresses distortion products and can rival many higher end systems or even exceed them if designed well.
 

Naveenbnc

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These are conflicting requirements since a sub is governed Hoffman's Iron law.
:D:D:D:p yes it conflicts the Hoffman's Iron law... As a compromise, whatever best I can achieve..... Il try...

Commercial subwoofers are not a good comparison because of hype and marketing.

The sunfire is an exception. The subwoofer alignments that we normally use are arrived at by modelling (using T/S parameters) and they operate the driver at a relatively small efficiency. The back emf is negligible and does not figure out in simulations.

Sunfire does the opposite, it takes a very high BL driver, one with huge magnet/motor system which generates high back EMF. The back EMF is higher than the typical amps that we use. They use high voltage amps to operate the driver. This gives tremendous efficiency gains and amp size is reduced and current is reduced. http://www.xlrtechs.com/dbkeele.com/PDF/Keele (2003-10 AES Preprint) - Nom vs True Eff High BL.pdf. The smaller the box, the stronger the stiffness of air mass. The harder it is to make the driver work in it. Now if the motor is very strong, it has tremendous ability to compress the high stiffness of the small air volume of the small box. All good so far.

However as box volume becomes small, the driver becomes non linear, so its corrected by servo motion control. The creator, Bob Carver is a true genius.

For a DIYer, it too complicated. A specialised driver, A specialised amp. A specialised servo.
Thanks a lot for so many inputs Sir.... Very greatful to you...:):)

Commercial subwoofers are not a good comparison because of hype and marketing.
I did this mistake many times :D:D
Sometimes for lack of better comparison in my experience.

Secondly i auditioned a few branded subs in different places, and out of them, 2 to 3 models are hugely impressive, especially with their compact size. The latest one being 10" sealed Martin Logan at our fm @sasank place... damn!!! Its a tiny beast !!!

Out of the 3 Hoffman's limitations, I can sacrifice compact size easily though....
 

Dr.Lakshay

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Hi, I suppose you are enjoying your diys, but since you say that you want to build on a budget, have you considered that if the money you spent on so many drivers and so many boxes, if you just add it all spend that much money on a single driver and box you might end up with something that is good enough and might satisfy you? Make it as a one time process after due diligence and research with something that is tried and tested. It will save you some time and effort and may be some money too.
For example I see many great reviews on Dayton ultimax in Marty box and mini Marty box. That's what makes me want to try Dayton sub. Similarly there are good reviews on SI subwoofers. Just the caveat is that these drivers will have to be imported.
Ps- I don't mean to demotivate you from your experiments. It's great seeing you experiment and deep down many of us wish we could experience the same. But what I am saying is just wish vs practicality.
 

Naveenbnc

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have you considered that if the money you spent on so many drivers and so many boxes, if you just add it all spend that much money
Yes !!!! I considered this. I may end up spending more money by the time I succeed in this. Buying a couple of drivers, building and scrapping a few boxes is going to cost lot of time and efforts too !!!! But I'm ok just for the fun of it.....

Make it as a one time process after due diligence and research with something that is tried and tested
You are absolutely true. I agree with you fully...


Ps- I don't mean to demotivate you from your experiments.
That's not a problem at all.... :D:D
 

tuff

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I believe to fail the first few times is necessary. Failure is the best teacher. The trick is to keep going, when everything seems going wrong.
 

Naveenbnc

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A 4th order bandpass suppresses distortion products and can rival many higher end systems or even exceed them if designed well.
In that case i won't leave without trying this ...:):):D

money you spent on so many drivers and so many boxes
First il try to do whatever best I can with my existing drivers. 4th order band pass can be tried with my existing 12" driver. Similarly I will try passive radiator model with my existing two 10" drivers. I will see if PR itself can be made diy.

So the first few trails can be done without spending money on drivers. Ofcourse, plywood, Cnc cutting etc will cost some bucks.

Next stage will come where I may have to get a driver with better specs and higher power.

So I'm guessing.... I may try not to spend too much money as far as I can... Lets see. :D:D

hi all .... a query regarding the amplifier power for a particular driver ....
iwai power rating.JPG

From the above specs from a driver ....
Does it mean it needs an amp that can deliver continuous 200W power or 600W ?
What is the safe operating power without damaging the driver ?

If the driver can handle 600Watt continuous power, what is the necessity/significance to mention 200W in the specs ?
(I assume it can handle 1000W for a very short time .... )
 

diyaudio

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Keep some headroom and use the lower of the figures. Even that is a lot of power.
Instead of looking at raw figure, look at power needed at max excursion of driver.
 
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Naveenbnc

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those are the specs of my existing 12" driver.
The basic reason for asking that question is to know if my existing amp is sufficient to drive it at full potential or I need to upgrade my amp.

I connected that driver to a 250W stereo amp.
Only one channel is connected to the sub (may be it is giving half of that power 125W approx)

"Assuming" 125W is delivered to the driver..... even at 60 to 70% volume, the sub is reaching its maximum excursion.
I am just wondering how the driver would survive if 600W is really fed to it.
May be these specs are just like top speed of the car that we never really use.

As you said, if i have to look at the lowest of the specs as realistic.... that clears my doubt.
Thanks a lot !!!
 

Aniket

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Hello Naveen,

the amp puts out 250W per channel into a 4ohm load. this is continuous average power output of the amp(20-20000Hz) into a 4ohm resistive load. so actually this is a 500W stereo amp.

the power figures of the subwoofer are rated for pink noise signal having a crest factor of 6 dB, with active filtering @12dB/octave below 40 Hz and above 5 kHz.
200W is claimed as the nominal power this driver can withstand continuously within the passband.
600W is probably claimed as the continuous program power, it is defined as 3 dB greater than the nominal rating.(actually it is twice the nominal power)
1000W is probably claimed as the peak music power, in short bursts.
 

Naveenbnc

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Hello Naveen,

the amp puts out 250W per channel into a 4ohm load. this is continuous average power output of the amp(20-20000Hz) into a 4ohm resistive load. so actually this is a 500W stereo amp.

the power figures of the subwoofer are rated for pink noise signal having a crest factor of 6 dB, with active filtering @12dB/octave below 40 Hz and above 5 kHz.
200W is claimed as the nominal power this driver can withstand continuously within the passband.
600W is probably claimed as the continuous program power, it is defined as 3 dB greater than the nominal rating.(actually it is twice the nominal power)
1000W is probably claimed as the peak music power, in short bursts.
thanks a lot for all the inputs Aniket, now it makes sense .....
your amp is driving to full Xmax even with 60 to 70% volume !!!:D:D
And now I got clarity on how the driver specs are given .... thanks again !!!:)

hey guys ... just an update ...
this is my 4th attempt and I built a 4th order band pass.
please find the details and pics in post#11 from the below link
(testing yet to be done with different port sizes ... )

https://www.hifivision.com/threads/trying-to-simulate-4th-order-bandpass-some-help-needed-please.73594/#post-813994

Well this is just a quick and fun build. Theoretically this driver is suitable for ported, but i just tried a compact sealed box.
The volume is maintained to have 0.7 as the overall system Q. This is supposed to give better transient response.

First observation is that bass sounds less boomy, but loudness has dropped drastically compared to ported. (natural for sealed)
I have to crank up the amp more to get enough spl (loudness)
But the box is very compact and placement is very easy anywhere in the room ...

sealed12_1.JPG

some bracing to the rear panel.
sealed12_2.JPG
 

Naveenbnc

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well this is not an advancement, but i threw away all my earlier sub boxes and decided to make two identical ported subs.
Both boxes are exact same size, but one is tunded to 43Hz (F3) and the other is tuned to 30Hz (F3).
I created a mess in my room with couple of different boxes with different sizes. :D :D
My living space became cramped. So I had to get rid of all earlier boxes.

Now the height of these two new boxes are same as my AV rack.
So they will be placed on either side of AV rack (may not be ideal position) but the whole setup looks more pleasant now !!

After building these boxes, some of our seniors suggested to use German brich ply instead of MDF.
I should have thought about it little earlier :confused::confused: !!!

But that's fine.... its a journey. As of now a single sub is already rocking. :D:D
Second box is waiting for driver.

subs.JPG
 

Naveenbnc

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I tried my luck with RIPOLE sub. I used two 15" pro drivers with higher Qts.
I followed some online articles to estimate the area of front and rear chambers.
But somehow I did not succeed upto expectations. I am not sure if my calculation is wrong, or the high Qts driver is not suitable.

The bass is soft and room filling. (something like commercial subs in Bose packages) But it is neither loud nor punchy.
I tried both polarities of one driver.

ripole1.jpg


ripole2.jpg
 

tuff

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That is one mother load of a subwoofer. What's R Pole? Heard of dipole and bipole's . Gotta give it to you at trying various designs. Is the amplifier powerful enough to drive them together? Just wondering.
 

Naveenbnc

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Later I tried H frame Subs.
Thanks a lot to @yogibear for all his guidance on the enclosure size.
This is not ideal size basically, I built smaller boxes just to accommodate in my small room.
This is a temporary build with minimum glue and a few screws, just to test if it works.

The bass is quite different compared to my earlier experience with ported subs.
These H frames integrated well (compared to ported sub) with my Ahuja fronts. Im very happy for this !!!:D
But with speakers like Boston Acoustics A26 they will be a mismatch. (to the best of my guess work)

Bass is not like low end rumble, its more clean, realistic and effortless for music. (this depends on integration with fronts i guess)
Drum beats in rock, and dark country music are nice enjoyable.
Drum cover versions of many rock songs are really awesome !!
Drivers break-in didnt happey yet. I played them only for few hours.
So these are my initial comments as on date.

I built these H-frames for someone else.
So I don't think its correct to reveal the driver details. (hope you guys can understand:D)

H frame1.jpg

H frame2.jpg
 
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