Need advice on SUBWOOFER design..

[Deleted member 45006]

I was searching for a matching subwoofer for my old Infinity Reference 2000.3's powered from a HK reciever. So far, the bass from these bookshelves sounds good in my listening room.But still I dont have a subwoofer for movies.. I tried with 3 different subwoofer designs for my room,:sealed box with a Dainty woofer(I bought their most expensive 8 inch,still they r crap),ported one,and a downfiring one..(local made-powered from a transistor amp,rated 100w rms).. The downfiring sounded little better than the others.. Basically results were not impressive though they all sounded stable,loud.. but they all sounded like they dont go below,60hz.. Just for a curiosity,I opened one of an old bookshelf's and connected it to the subamp,and they sounded like they go really down(though it distorted when I turned up the volume to my normal listening levels,which is quite loud)... Now someone,please advise, about going for an open back design,Where can I get some good bass drivers in chennai? The bass doesnt have to go too loud,but my interest is how low it can go.. Happy to use two 8inch's or a 10 inch due to my room constraints ..

 

[doors666]

there's a peerless driver available from jeetubhai. search these forums. Apart from that, there are pretty much no known good diy options available here, unless you are willing to import. see if any of the car audio subs available will do a good job for home audio, there will be very few if any.

 

[Deleted member 45006]

I tried JBL's bass tube in my room,from my so-called transistor amp,but again,the the impedance match is a bit of trouble,most car woofers are 4ohms, but home amps, most of them have 6 ohms, to 8 ohms.. so, there wont be a linearity in sub to other components volume level,when I tie these up.. Thanks for ur suggestion, a small question, if I tie up two car subs,serially,will it solve my impedance probs,my amp is 8 ohm..

 

[ShaQ.Blogs]

i can share a infinity ported sub design which is specifially for movies. Tried and tested design by quite a few, easy to build.
But it is a 12 inch, you are loking for 8 / 10 inch....and it is car sub

 

[Deleted member 45006]

Thanks ShaQ.Blogs 12'' sounds okay.i recently changed the position of my tv to a bigger room,so things will be fine.but i dont have an idea abt the driver i should choose..

 

[trittya]

I was searching for a matching subwoofer for my old Infinity Reference 2000.3's powered from a HK reciever. So far, the bass from these bookshelves sounds good in my listening room.But still I dont have a subwoofer for movies.. I tried with 3 different subwoofer designs for my room,:sealed box with a Dainty woofer(I bought their most expensive 8 inch,still they r crap),ported one,and a downfiring one..(local made-powered from a transistor amp,rated 100w rms).. The downfiring sounded little better than the others.. Basically results were not impressive though they all sounded stable,loud.. but they all sounded like they dont go below,60hz.. Just for a curiosity,I opened one of an old bookshelf's and connected it to the subamp,and they sounded like they go really down(though it distorted when I turned up the volume to my normal listening levels,which is quite loud)... Now someone,please advise, about going for an open back design,Where can I get some good bass drivers in chennai? The bass doesnt have to go too loud,but my interest is how low it can go.. Happy to use two 8inch's or a 10 inch due to my room constraints ..

Dear Alby Tommy,
Welcome aboard to HFV, mate.

Subwoofer design and implementation/integration is more complicated that it seems. A SUBWOOFER consumes more power than any other kind of driver and is very unforgiving towards poor box design and/or construction.

Therefore, you must seek help from an experienced DIY-er if you want to build. Since you haven't mentioned either your room size or budget allocation, I will try to chip in on the (presumed) dual premise(s) that the room is a 15' x 12' (middle-path-to-room-size) and that we don't have money to throw around.

My suggestions :-
*Avoid an open baffle design since you will miss that chest-thumping bass for transient effects in movies.
*If you go in for a ported design, make sure the port(s) are not in the rear unless you have the luxury of at least 2' space at the rear.

*Avoid a sealed design, which though cleaner, tighter and more accurate (therefore, arguably more apt for music) than an equivalent ported design but it will need a lot more power (and possibly equalisation) to go "as low" as aported or TL design. Ditto for open baffle/dipole designs.

*Do consider going in for 3-4 smaller 8" sealed subs around the room instead of one 12 incher. Many believe it gives better overall bass effect but you will need a lot of amplification. Why I suggest sealed subs in case of a multiple sub setup wheras not so a single sub setup is because:-
a) Multiple ported subs are more likely to be more resonant and boomy at LFs/ELFs due to multiple port-noise/turbulence and/or standing waves.
b) 3-4 identical sealed down-firing subwoofers in one room should just suffice for LFs/ELFs, though you will still need a lot of amplification but you may not need active "bass boost", also known as equalisation.
c) Its really quite subjective, I mean you can do with lesser amplification with a ported/TL design, whereas it will be at a loss of accuracy not to mention, at an increase in undesirable "boominess".

Personally, I'd go in for a sealed design with loads of amp power and/or some equalisation. But then, I am more interested in music than movies, even if its only subs that we are talking about. Accuracy is of more consequence than is that one note boom that refuses to decay soon due to additional standing waves from the ports.

*If on a tight budget, Do consider an audition of subwoofers at the likes of Craftel aka Audiocraft owned by Mr Mark Murugesan at Harris Street. Good VFM and plenty of thump, more suited for movies than music, IMO.

AND LAST BUT FAR FROM LEAST . . . .

* If you want to
feel your sub more than you want to hear it
(and want to save money and space as well)
and provided that
you have at least approx 3'(L) x 2 '(W) x 6" (H) space (for 4x6" drivers, more for 4x8")
under the couch/sofa/diwaan,
then, IMO,
this is the one of the best designs that one can go in for.
(provided, of course, taht you are as VFM-minded as I am)

Its quite an easy build too, though, I daresay that you will have to choose a 6" or 8" driver quite judiciously for a similar design inspired by this one here.

The Boogieman - Speaker Building Project at Parts Express

A good 500/750 W (750 in case of 8 inchers) subwoofer plate amp to drive these should be easy to source from Ritchie Street.
A word or two about alternate drivers here, don't go in for drivers with TS parameters that are grossly at variance with the Tang-Band driver(s) in the original design. You will surely need larger than normal Xmax(linear excursion) and lesser than normal Fs(resonating frequency) for starters.

Here's the picture and spec sheet for the 'original' driver

http://www.parts-express.com/pdf/264-832s.pdf


Here are a few 'randomly offhand' examples of alternate Peerless India drivers that I have picked (in no preferential order) by studying the FR graphs, text, pictures and available TS parameters, in a hurry. Peerless because you may be able source these easily from Jeetubhai (or his son) of Varsha Electronics, Mumbai.

Pity that peerless don't give out the Xmax figures and I don't know how to calculate those. Also, one would have to ascertain whether or NOT the driver under consideration is suitable for a down firing application (most of them are).

Nevertheless, in spite of being technically challenged, I can safely assert that these three drivers are the only ones on that site that are 'more-or-less' suited for the kind of "Boogieman-inspired" subwoofer application under mention. Larger ones may be more acoustically suited but then, anything over 8" size will make you lose that stealth-factor, that lends itself to an under-the-couch placement.
I request to be corrected by more knowledgeable FMs, if wrong, being the noob that I am. . . .


Driver 1
Products - PeerlessAudio.com

Driver 2
Products - PeerlessAudio.com

Driver 3
Products - PeerlessAudio.com

@Alby Tommy
Considering the inadequacies of these drivers in comparison to the Tang-band one, perhaps this may actually necessitate use of an 8" driver instead of a 6"/6.5" due to their apparently limited Xmax.

More on hearing from you. Please feel free to shoot your further queries in this regard.

If I can't answer any of them, I am sure someone more technically sound than I am, will do so. This wonderful forum is known for that.

HTH
Regards

 

[trittya]

a small question, if I tie up two car subs,serially,will it solve my impedance probs,my amp is 8 ohm..

You can do that but you will have to do so in series so that the net impedance becomes 8 ohms. If you connect two 4 ohm drivers in parallel, the amp would face a twice tougher 2 ohm impedance load.

Good low bass is all about moving a whole lot of air in the appropriate manner. To do that you need two things - one, a lot of amp power with adequate headroom and two, a lot of cone surface area aka Sd.

Please note that the Sd of four 6 inchers would roughly be equal to the Sd of a single 12 incher.

 

[Deleted member 45006]

Thanks trittya alot Do u have any suggestion on some subwoofer amp kit, around 2K? or that budget is too low??

 

[Masterjedi]

Forget about 6" & 8" micro subs, You will never get SUBWOOFER Bass unless you use a minimum 10" Driver .Get a Pioneer Car Subwoofer 12" TS-WX303 MRP. 6,990 (with an enclosure) or 12" TS-W304R MRP. 4,490 (available for around 3k ) & put it in a enclosure (solid 12mm MDF) for around 1k.
I am running Pioneer dual 12 inchers with a 150 watt Bridged Mono Amps which i have made myself with Active xovers @150Hz, it can do 120Db without even trying .

 

[trittya]

Thanks trittya alot Do u have any suggestion on some subwoofer amp kit, around 2K? or that budget is too low??

You are most welcome, mate. Its a pleasure . . .

Offhand, 2k does seem inadequate for a good subwoofer amp kit. Varsha Electronics sells a considerable plate amp called 'Forte' at about 5k or thereabouts. If you go in for a single medium (10"/12") driver, I recommend not going in for anything lesser.

There IS a thread here on a build with this amp and peerless driver, both procured from Varsha Electronics.
http://www.hifivision.com/diy/27432-group-diy-sub-build-peerless-driver-forte-200-watts-amp.html

Forget about 6" & 8" micro subs, You will never get SUBWOOFER Bass unless you use a minimum 10" Driver .Get a Pioneer Car Subwoofer 12" TS-WX303 MRP. 6,990 (with an enclosure) or 12" TS-W304R MRP. 4,490 (available for around 3k ) & put it in a enclosure (solid 12mm MDF) for around 1k.
I am running Pioneer dual 12 inchers with a 150 watt Bridged Mono Amps which i have made myself with Active xovers @150Hz, it can do 120Db without even trying .

Hmmmmmmm . . . .
Yes, thats yet another way of looking at it. However, do keep in mind that you must go in for this ONLY if NEAR-Field THUMP is what you need MOST. Personally, its something that I wouldn't go in for, especially for home use, but then thats just me.
Also, do note that the cheaper of those Pioneer Car Subwoofer drivers is still a mite expensive than the Peerless 12" driver mentioned in the aforesaid thread.

Nevertheless, I am by no means suggesting that YOU negate consideration of this. Perhaps, FM Masterjedi might even accede to helping you with the amplifier build.

Should you decide to go in for this, I have a couple of suggestions to make:-
1) Go in for at least 3/4" ply(preferably marine/boiling-waterproof grade) instead of 1/2" MDF. The extra thickness will make the enclosure walls less prone to flexing due to enhanced rigidity. Not only will it sound better, it will be comparatively more durable in the long run. Even if you go in for MDF(not a bad option, but no particle-board please) use 3/4" instead of 1/2".

2) Brace the enclosure adequately with well-seasoned hardwood regardless of whether you use ply or MDF.

Also, do try to avoid going in for a ready-made car sub enclosure for home use.

All the very best.
Cheerio

 

[Masterjedi]

I am not sure what " Near-Field Thump " is ,(never heard it ) but this solution will cost about 4 k , this sub in a sealed enclosure will give you Bass all the way down to around 35-40 Hz (100-120 db easy). Mind you this is earth shaking Bass in a room of around 300-400 sqfeet ,


if you want 25mm MDF then it's around 2.5 k , if you use good box building techniques then internal bracing is the way to go, but remember we are looking for an inexpensive Box here

A good birch ply would be the next option and offers the same tonal characteristics as MDF, however it's hardwood so it would hold screws better and you won't have to worry about anchors.Also, using a sealant, such as silicone, to seal any gaps or holes will help limit air flow and resonance.
It can be done, it just depends on cost and time. Plywood is easy to slap together, but it sounds like you want something to show off. Box joints or dove-tailed ends really pop! Solid woods work well too. Let me know if you need any more tips.

 

[trittya]

I am not sure what " Near-Field Thump " is ,(never heard it ) but this solution will cost about 4 k , this sub in a sealed enclosure will give you Bass all the way down to around 35-40 Hz (100-120 db easy). Mind you this is earth shaking Bass in a room of around 300-400 sqfeet ,

Hello, Masterjedi
Near-field thump is what is more felt than heard. No wonder you didn't hear it..
Jokes apart, there is apparently nothing wrong in all that you have said. I agree but then, I wouldn't go in for these drivers in a ported enclosure as shown on the Pioneer website. Some say that EBP doesn't matter overmuch but I am slightly old-school here (though there are many an exception, I concede).

Also, unlike you, I am actually tech-challenged but I would definitely love to hear these in a sealed enclosure though. The EBP for the WX303 works out to 50.85 while its 38.6 for the W304, thereby suggesting sealed enclosures for both.

if you want 25mm MDF then it's around 2.5 k , if you use good box building techniques then internal bracing is the way to go, but remember we are looking for an inexpensive Box here

I feel 3/4" is good enough via media/medium, provided, like you said, the bracing is done well. 1" appears to be slightly overboard, IMO.

A good birch ply would be the next option and offers the same tonal characteristics as MDF, however it's hardwood so it would hold screws better and you won't have to worry about anchors.Also, using a sealant, such as silicone, to seal any gaps or holes will help limit air flow and resonance.

Thanks for the pointers. I feel its not very apt to talk of 'tonal characteristics' when we are talking of LF and more so with ELF. Tonality to me implies auditory perception of variations in pitch ie tones and chords organized in relation to one/more tone(s) of which there is indeed little in LFs/ELFS.

Therefore, my suggestion for enclosure material has more to do with long term durability than tonal superiority. People have made excellent subwoofers from 8mm thick cardboard tube. The seemingly meagre thickness does suffice there due to the the cylindrical shape which usually precludes bracing unless we are talking 18 inches and above.

Quite OTOH, subs have also been done in ceramic/concrete sewer pipes too but these are so heavy to move around. Personally, if I knew I did not have to shift house every couple of years, I would go in for a cylindrical woofer made out of ceramic sewer pipe. I had done a subwoofer in a tandoor (the base was damped with two circular rubberised cork sheets with a good old coconut-fiber mat sandwiched amidst with silicon caulk again) too, believe me, it was fantastic but when the time came for me to move, I gifted the El Cheapo no-name 12" driver and then had some great yummy Tandoori chicken and Naans in that very tandoor after putting it in a 200 ltr oil barrel (with some sand, ground glass and glasswool plus lipaai-putaai[claywork] done by the potter). Yes, I had used generous amounts of Silicone Caulk to mate the driver to the upper rim, just as an experiment, it worked. Caulk is wonderful material for a DIY-er, no doubt.

Its all very subjective, actually, about the enclosure material too. One school of thought opines that Birch ply sounds better while another goes with the notion that it only makes the enclosure more durable especially so for the way pro-audio gear is handled on the road. I would ideally speaking, rather go with Baltic Birch ply myself (just the peace-of-mind/smugness factor) but given the fact that it is so dear, I would really speaking, rather go in for marine grade ply/HDF(in drier climes) for subwoofers. I have seen some MDF disintegrating (slowly though) due to the extra humid sub-continental climatic conditions and I do believe that Chennai does figure at the top as far as humidity goes.

It can be done, it just depends on cost and time. Plywood is easy to slap together, but it sounds like you want something to show off. Box joints or dove-tailed ends really pop! Solid woods work well too.

I agree, other than the showing-off bit. In either case, one would go in for a finish. Also, I don't think there is anything to show-off about a plywood enclosure, much less the sound signature of the same.

As regards structural integrity alone, I too tend to rate marine ply higher than MDF. I would not go in for all-wood enclosures especially for subwoofers because one, wood tends to expand/contract inconsistently/unpredictably with time and seasonal changes and two, because even if one were to get appropriately seasoned suitable wood, its mighty tough to get planks in the desired sizes/width.

I once had half a mind to do a speaker enclosure in bamboo ply but the thickness, as well as the sheet sizes available were limited. The thickness can be catered for by sandwiching 1/2" granite between two sheets of bamboo ply but the sheet size problem remained unmitigated. Please note, I am talking of a 2-way bookshelf speaker here and by no means of a subwoofer.

Speaking of tonality, maybe one day You and/or I will try a T-line in an enclosure made of pine-wood ply, wherein, the T-line itself would take care of most of the additional bracing need methinxand hopes. do correct me anywher that you feel i am wrong.

Let me know if you need any more tips.

Thanks a lot for your tips, mate:clapping:. Its nice to see you sharing know-how on this wonderful forum. Looking forward to a lot more from you. Can you tell us a bit about the amps you made for that subwoofer? That would really be nice.

Warm Regards

 

[Masterjedi]

Hi Trittya,

Thankyou for all the kind words,
personally my choice for a Sub box is always 18 - 25 mm MDF, Sub boxes need to be heavy (to prevent walking ) & very very stiff, ply's always need bracing and lack inherent stiffness which is what is required, and this pertains to all kinds of PLY (becaue it is basically a manufactured wood panel made from thin sheets of wood veneer). Ply's are also susceptible to resonance which we want to avoid at all costs.

well about the Amps, instead of a Huge Subwoofer Mono amp , i take any good stereo amp (Philips Hi-Fi 50w + 50w, STK 50 +50) and bridge them to get around 100 watts output .(this is more than sufficient) you would be surprised to know how good and inexpensive these are .
You may add bigger heatsink's & cooling fans as per the build
Also it is important to use an active x-over , so i build 12db x overs with a cutoff around 150-200Hz.

 

[trittya]

Hi Trittya,

Thankyou for all the kind words,
personally my choice for a Sub box is always 18 - 25 mm MDF, Sub boxes need to be heavy (to prevent walking ) & very very stiff, ply's always need bracing and lack inherent stiffness which is what is required, and this pertains to all kinds of PLY (becaue it is basically a manufactured wood panel made from thin sheets of wood veneer). Ply's are also susceptible to resonance which we want to avoid at all costs.

Hmmmmmm . . .
I do get your drift, Master. I shall keep it in mind.
Actually, all my subs are/have been MDF/HDF
Perhaps my own reasons for this recent shift towards ply is because I have begun to mull over a design for a 21" sub using this driver

P.Audio SD21 21" woofer - The P.Audio SD21 is a 21" speaker for subwoofer speaker systems. P.Audio SD21 21" woofer here at US Speaker.

I have been 'gifted' this driver by a very dear friend ie FM Kanwar. He has already used it in a 21 inch T-Line implementation christened The "Avepa" built by Kanwar of Zypher Power Labs, Indore for FM Hifiashok.
Details here
http://www.hifivision.com/active-speakers/23553-avepa-zyphers-z-21-active-subwoofer.html

A few pics

First, a close-up of the driver

A close up of the Transmission Line Terminus at the rear

For size co-relation with the sofas beside

Avepa's rear

The Active Crossover

Would you still stick to MDF/HDF (given the fact that the sub is most likely to be mishandled during transit) for this monstrosity? I guess not, eh? Do let me know of this please. . .
You see, I am in a transferable job. Thats the reason I am not going in for the "Avepa" design, not only does it weigh about 90 odd kgs, but also that I will never have a room as large as Ashokji's till I get back to my farm, there are a few years left for that. Therefore, I intend to go in for a smaller down-firing, semi-sealed (Passive radiator)design that can be placed in the center of the room as a 2 ft high coffee coffee table with a 12" PR on each side, thus making the Sd aprox equal to that of the P-Audio SD-21. What say you?

I am going slightly OT here but then, with no intent to hijack the thread and in keeping with the thread title, the OP (and other FMs) are likely to benefit from this discussion, even if only from a theoretical standpoint. In case the OP, Alby Tommy has no objections, I shall continue here else one can always edit this post and commence a fresh thread. The OP and Moderators are requested to advise.

well about the Amps, instead of a Huge Subwoofer Mono amp , i take any good stereo amp (Philips Hi-Fi 50w + 50w, STK 50 +50) and bridge them to get around 100 watts output .(this is more than sufficient) you would be surprised to know how good and inexpensive these are .
You may add bigger heatsink's & cooling fans as per the build
Also it is important to use an active x-over , so i build 12db x overs with a cutoff around 150-200Hz.

Hmmmmmm . . . .
Tell me something, Master, are dual monoblock amps bridgeable too. I have a pair of Pulz RS-250s rated at 60wpc@ 8ohms. I guess NOT, huh?:sad::sad:

Here are the specs of the same. The right half of the image pertains to the combo's power section while the left one is about the pre-amp RS-100. Sorry about the poor quality but thats all I have from the web/otherwise.
http://imageshack.us/photo/my-images/843/pulzmanual.jpg

Pics of the Pulz pre-power-amps here
http://imageshack.us/photo/my-images/3/pulzfront.jpg
http://imageshack.us/photo/my-images/705/pulzrear.jpg
http://imageshack.us/photo/my-images/101/pulzcollage.jpg
(Sorry, these 4 pics above not getting embedded here)

Do you think these are bridgeable for subwoofer use?
I have another Australian AMAV 2.2P power amp (sold by Sonodyne in India) which is used in bridged mode to power this 10" bandpass subwoofer.
qbic
But nowhere do the tech specs or the manual indicate that it has dual power supplies. Is that why its bridgeable or is there more to it?
Here are the specs
Welcome To Sonodyne
and here's the pdf manual
http://www.australianmonitor.com.au...ance-Convection-Cooled/AV2-2P-2-4P-manual.pdf

More on hearing from you. Looking forward to the same.

Thanks a bunch
Cheerio

 

[kanwar]

Hmmmmmm . . . .
Tell me something, Master, are dual monoblock amps bridgeable too. I have a pair of Pulz RS-250s rated at 60wpc@ 8ohms. I guess NOT, huh?:sad::sad:

Bridging is possible.......