DIY Subwoofer Build

[robin3989]

Hello Friends,

I have plans to build a single or dual subwoofers, and interested in hearing your helpful insights. It will be a passive sealed unit, driven by an outboard amp. Initially, i will use a dsp to supply low frequencies to the sub, and will later work on building an active low pass filter.

My priority is to get even bass and not some room shaking bass. When I play them at low volume levels, I would like to see them going equally loud as the mains at low frequencies (25 -30 hz) without any distortion. I'm more inclined towards building a sealed enclosure as I will be using the sub in my stereo for music listening only. Based on some online design documents, I finalized my driver search with Eminence Lab12s. This driver is compatible with sealed enclosures and claimed to provide good spl without distortion. I would like to know what goes well in my room that measures around 23ft×12ft. Either dual 12 inch or a single 15 inch?

 

[hydrovac]

One member's DIY project for reference:

My First DIY Subwoofer using Eminence Lab 12

I got the idea of building a Subwoofer when I realised that the shipping cost for a HSU VTF MK3 subwoofer from the US would be as much as the cost of the subwoofer itself. I started doing some research a couple of months ago, and finished my first DIY Subwoofer build a couple of weeks ago...

www.hifivision.com

I am sure there are couple other threads also on this topic... try searching.

...

 

[robin3989]

One member's DIY project for reference:

My First DIY Subwoofer using Eminence Lab 12

I got the idea of building a Subwoofer when I realised that the shipping cost for a HSU VTF MK3 subwoofer from the US would be as much as the cost of the subwoofer itself. I started doing some research a couple of months ago, and finished my first DIY Subwoofer build a couple of weeks ago...

www.hifivision.com

I am sure there are couple other threads also on this topic... try searching.

...

Thanks @hydrovac. I sent the FM a PM, awaiting response

 

[musiz_craze]

Thanks @hydrovac. I sent the FM a PM, awaiting response

Have you completed, If yes. Please share us.

 

[robin3989]

I'm in a different path altogether, and dropped the idea of building seperate subwoofer for LF needs and integrating it with the mains.
So, now I'm inclined towards highly efficient 3way designs, that can be driven by my existing 20wpc amp.
Don't want to complicate things by introducing a 500w PA amp to drive the sub alone. I like the sound of the current 20wpc amp i'm using, so checking designs, specially 3way that has reasonable low end extension.
Let's see how my mind swings.

 

[oldmonk]

that will increase size of the speaker and demand more space of the room - do consider this.

a nice 8 inch sub will be good to hide away somewhere as well..

making a subwoofer is much easier IMO

 

[robin3989]

that will increase size of the speaker and demand more space of the room - do consider this.

a nice 8 inch sub will be good to hide away somewhere as well..

making a subwoofer is much easier IMO

Alright!
Space isn't an issue. I was actually planning for dual subs and dropped the idea altogether because they will need a separate amp / amps and I would have to run them using active crossovers.

I completely agree, designing a speaker isn't easy. But just trying to find the right design and follow end to end. TG's 3way and fusion designs are tempting, but some of the designs that I like, the crossover component values are hidden and would come with the kit from Jenzen.
And not interested in importing anything and spend for shipping / customs.

Impressed by Tarkus by PC. Taking time to prepare myself before starting anything.

 

[kapvin]

hello Robin,

both approaches are very valid solutions to your problem but each bring their own quirks.

if you get the right mix, a 3 way would be the more "hifi" solution as you can get cohesiveness and time alignment between drivers. Of course, with a 20w amp, you are effectively limited to 2-3w average (keeping 7-10dB of headroom for music) So your speakers will need to be quite efficient, I would look at a system efficiency of at least 92-95 db/w @ 1m and more efficient if you listen loud..

on the other hand if you are otherwise satisfied with the sound of your system and just seeking a bit more depth, a pair of subs would be a good answer. there are 2 ways you could execute this - method1 by filtering at the pre out level (splitting the bass signal to the sub ampand sending the filtered signal to your tube amp), the advantage of this is better power handling for speakers (as they are not handling the bass) less IMD and also les chance of interference between the bass of your mains and the subs. disadavantages is complexity. (you can look at PLLXOs - Passive line level crossovers to "block the bass to the mains). method 2 is simply tapping the pre out or the amp out signal and connecting it to the sub amp after adequate attenuation. advantage is simplicity, disadvantage is interference between the mains and sub. in either method you can use DSP to shape the sub sound.

any way you choose, its gonna be a lot of fun!

 

[keith_correa]

<snip>Impressed by Tarkus by PC. Taking time to prepare myself before starting anything.

Your 20 watter is going to maybe struggle with the Tarkus.

 

[robin3989]

hello Robin,

both approaches are very valid solutions to your problem but each bring their own quirks.

if you get the right mix, a 3 way would be the more "hifi" solution as you can get cohesiveness and time alignment between drivers. Of course, with a 20w amp, you are effectively limited to 2-3w average (keeping 7-10dB of headroom for music) So your speakers will need to be quite efficient, I would look at a system efficiency of at least 92-95 db/w @ 1m and more efficient if you listen loud..

on the other hand if you are otherwise satisfied with the sound of your system and just seeking a bit more depth, a pair of subs would be a good answer. there are 2 ways you could execute this - method1 by filtering at the pre out level (splitting the bass signal to the sub ampand sending the filtered signal to your tube amp), the advantage of this is better power handling for speakers (as they are not handling the bass) less IMD and also les chance of interference between the bass of your mains and the subs. disadavantages is complexity. (you can look at PLLXOs - Passive line level crossovers to "block the bass to the mains). method 2 is simply tapping the pre out or the amp out signal and connecting it to the sub amp after adequate attenuation. advantage is simplicity, disadvantage is interference between the mains and sub. in either method you can use DSP to shape the sub sound.

any way you choose, its gonna be a lot of fun!

Hello Kapil,

You have mentioned some important points on taking different routes to achieve the sound I'm interested in. I have decided to stick to 3way only after exploring the advantages and disadvantages going to a DSP based crossover. Main thing is the number of components involved to achieve the even dB response across all the frequencies. I'm sure that's going to be fun and a great learning. But I'm sure want to stick to the current 20wpc amp.

Yes, the amp does demand sensitive high impedance speakers, and I believe anything above 88dB for 1watt@1meter and 8ohm nominal (doesn't dip less than 6ohms) should work.

I would like suggestions on well documented efficient designs. Something like 12" + 6"/5" + 1" or 10" + 5" + 1". And this 20wpc amp is a SS (Musical Fidelity A1) and not a tube amp, so hoping to see some decent number of 3way design availability.

Your 20 watter is going to maybe struggle with the Tarkus.

I don't know the overall sensitivity, but the impedance curve by the designer shows few dips till 5ohms. The drivers overall have healthy sensitivity.
A1 is rated 20watts, but subjective listening defies that. I can't claim anything without measurements, but they are currently paired with castle stand mounts, and they get extremely loud, I never had to crank up the volume post 9'o clock.

 

[keith_correa]

I don't know the overall sensitivity, <snip>

~86 dB

 

[kapvin]

Hello Kapil,

You have mentioned some important points on taking different routes to achieve the sound I'm interested in. I have decided to stick to 3way only after exploring the advantages and disadvantages going to a DSP based crossover. Main thing is the number of components involved to achieve the even dB response across all the frequencies. I'm sure that's going to be fun and a great learning. But I'm sure want to stick to the current 20wpc amp.

Yes, the amp does demand sensitive high impedance speakers, and I believe anything above 88dB for 1watt@1meter and 8ohm nominal (doesn't dip less than 6ohms) should work.

I would like suggestions on well documented efficient designs. Something like 12" + 6"/5" + 1" or 10" + 5" + 1". And this 20wpc amp is a SS (Musical Fidelity A1) and not a tube amp, so hoping to see some decent number of 3way design availability.


I don't know the overall sensitivity, but the impedance curve by the designer shows few dips till 5ohms. The drivers overall have healthy sensitivity.
A1 is rated 20watts, but subjective listening defies that. I can't claim anything without measurements, but they are currently paired with castle stand mounts, and they get extremely loud, I never had to crank up the volume post 9'o clock.

If thats your choice, then I think a 12" is the right way. I would look at a pro audio woofer from eminence or faital (both have dealers in India). I would also look at a 5" mid . why not 6" inches? - because it places more constraints on your tweeter choices, since you have to cross it over lower to prevent beaming in the upper mids. you would have a wide variety of tweeter choices then.

a pro audio woofer is about 94-95db/w ( the 12" wide banders are more efficient but they just don't perform in the bass region) so after baffle step compensation it would come to 89-92db depending on how much BSC you choose to apply. this will give a wide choice of matching tweeters and mids.

In my mind this is the ideal woofer

KappaLITE 3012LF 12

Recommended for pro audio and bass in vented enclosures.

www.eminence.com

faitalpro also has similar woofers.

I have the 4ohm version of this for a DIY build that I am planning. its a lovely woofer.

Most DIY builds with "Hifi woofers" tend to have 4ohm woofers, precisely to overcome the dimnished efficiency due to baffle step compensation requirement ( you get 3db free efficiency by using a 4ohm speaker with a capable amp)


If you want to go the hifi woofer route; i would suggest a dual woofer configuration per channel with dual 6.5" or 7". you could do a 2.5way like this and reach about 87-88db/w

 

[robin3989]

If thats your choice, then I think a 12" is the right way. I would look at a pro audio woofer from eminence or faital (both have dealers in India). I would also look at a 5" mid . why not 6" inches? - because it places more constraints on your tweeter choices, since you have to cross it over lower to prevent beaming in the upper mids. you would have a wide variety of tweeter choices then.

a pro audio woofer is about 94-95db/w ( the 12" wide banders are more efficient but they just don't perform in the bass region) so after baffle step compensation it would come to 89-92db depending on how much BSC you choose to apply. this will give a wide choice of matching tweeters and mids.

In my mind this is the ideal woofer

KappaLITE 3012LF 12

Recommended for pro audio and bass in vented enclosures.

www.eminence.com

faitalpro also has similar woofers.

I have the 4ohm version of this for a DIY build that I am planning. its a lovely woofer.

Most DIY builds with "Hifi woofers" tend to have 4ohm woofers, precisely to overcome the dimnished efficiency due to baffle step compensation requirement ( you get 3db free efficiency by using a 4ohm speaker with a capable amp)


If you want to go the hifi woofer route; i would suggest a dual woofer configuration per channel with dual 6.5" or 7". you could do a 2.5way like this and reach about 87-88db/w

Thanks for providing more info.

Are there 3way designs that use PA drivers to handle LF. I took a look at the Eminence, Faital Pro and 18sound, they maintain decent impedance across frequencies, and reasonably sensitive. But do they match up to the speed of hifi drivers?
Getting an efficient 12" hifi driver itself looks difficult and their sensitivity loses after putting them in a box is again unknown whereas PA drivers have promising figures.

I am okay to choose efficient drivers (LF + Mid + Tweeter), build seperate enclosures, consider physical time alignment and taper the front baffle as well based on the driver spec and measurements. But I'm sure I can't design the crossovers myself. So, looking to stick to a design, even if they use PA drivers.

 

[sandeepsasi]

Hi,

Did you look at these designs by Troel's Gravesen?

Faital 3-way classic with 12" bass driver: http://www.troelsgravesen.dk/Faital-3WC.htm and it's larger version: http://www.troelsgravesen.dk/Faital-3WC-15.htm

The 12" version is 93dB sensitive, can be driven by 20+ Watts and has F3 at ~30Hz, after considering room gain.

With regards,
Sandeep Sasi

 

[oldmonk]

The OP doesn't want to import etc...

 

[SIDEWINDER18X]

 

[robin3989]

Hi,

Did you look at these designs by Troel's Gravesen?

Faital 3-way classic with 12" bass driver: http://www.troelsgravesen.dk/Faital-3WC.htm and it's larger version: http://www.troelsgravesen.dk/Faital-3WC-15.htm

The 12" version is 93dB sensitive, can be driven by 20+ Watts and has F3 at ~30Hz, after considering room gain.

With regards,
Sandeep Sasi

Thanks, they are some nice designs. But I'm not at all interested in importing anything.

After several hours of reading, decided the 3way, because that's more suited. I am taking baby steps here as I'm totally inexperienced and have never built a crossover myself, so did not yet buy all the required drivers.

The first step here is to get PA woofers (over 95db spl) for LF duty (50hz - 300hz), put them in seperate enclosures, design a passive LPF and HPF, so i can integrate them with my existing bookshelf speakers.

I'm working out on a deal for the woofers, if things go smooth I will end up getting dual 15inch PA woofers which will kick start things. Will keep this thread posted.

 

[sandeepsasi]

Thanks, they are some nice designs. But I'm not at all interested in importing anything.

After several hours of reading, decided the 3way, because that's more suited. I am taking baby steps here as I'm totally inexperienced and have never built a crossover myself, so did not yet buy all the required drivers.

The first step here is to get PA woofers (over 95db spl) for LF duty (50hz - 300hz), put them in seperate enclosures, design a passive LPF and HPF, so i can integrate them with my existing bookshelf speakers.

I'm working out on a deal for the woofers, if things go smooth I will end up getting dual 15inch PA woofers which will kick start things. Will keep this thread posted.

Understood. These pages can still serve as a good reference and can save you some time while evaluating various drivers. Especially the 15" bass driver - Faital 15PR400, could meet your requirements. Apart from other designs from Mr. Gravesen, I have seen this driver being used in other designs as well, like the Calpamos 2-way: http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Calpamos.pdf

With regards,
Sandeep Sasi

 

[robin3989]

Understood. These pages can still serve as a good reference and can save you some time while evaluating various drivers. Especially the 15" bass driver - Faital 15PR400, could meet your requirements. Apart from other designs from Mr. Gravesen, I have seen this driver being used in other designs as well, like the Calpamos 2-way: http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Calpamos.pdf

With regards,
Sandeep Sasi

Thats true! TGs website is flooded with lots of information required not just for driver selection, but also enclosure and crossover build.
I was very much interested in Beyma SM115N, which is cost efficient and work well in vented enclosures and often used in 2 way systems too because of very good linearity all the way upto 1khz. Meanwhile, I just found a cheaper solution with dual 18sound 15 inchers as I'm planning to use these as LF drivers to handle everything below 400hz. If I get these, will keep this thread posted.

 

[oldmonk]

its important to opt for a holistic approach and not a piece meal one only due to cheaper prices or deals available...

especially if you dont have speaker designing or building skill previously

sites like - TG gives you a consolidated approach as per budget......and you can get the cabinetry done locally as per drawing...