first DIY, subwoofer. need advise with components.

doors666

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Hi Guys,

I am planning to make a sub. It will be my first attempt at DIY, rather semi DIY as I personally probably wont be doing much:lol:, just buy the driver and the plate amp and get the cabinet made by a carpenter.

A friend of mine will get the plate amp and the woofer from the US. My budget is around 700-800$ including shipping in US. I can get a lot of good subs like vtf3 etc in this budget, so I should be able to make a much better sub than that with this much of money.

The sub should be musical, but should also have good SPL for movies. Dual subs are ruled out, though I can have 2 drivers (e.g. shiva 12) in the same sub, does that need 2 channel amp, separate amp is ruled out, passive radiator should be ok. 110 volt amp is ruled out.

Listening area

The main listening area is 19.5 x 18.5 x 10.5
3787 cubic feet. The system is kept along the 18.5 ft wall. The listening positions is about 12 ft.

But the Dining and open kitchen is attached to it, and the total area is 31.5 ft x 18.5 x 10.5 = 6118 cubic feet

So I guess I should consider the room to be 6118 cubic feet for subwoofer purchase purpose, right? Let me know if a rough diagram of the room will help in suggesting a sub and I will post it.

Usage
50% music and 50% movies
I mainly listen to classic rock, blues, heavy metal, jazz, classical music etc. Watch all sorts of movies from classics to action, scifi etc.

Current setup
Yamaha RX-V663 AVR, marantz cd6000 OSE cd player, B&W 602 S2 for mains, LCR 600S3 center channel, B&W rock solid for surrounds, HTPC with M-Audio revolution 7.1 sound card.

I dont know much about DIY, so I will be needing a lot of help from you guys.

Size Max size allowed (read WAF)
W 22, D 25, H = 30
As bigger subs are better, I would like to go for the max size possible.

I would prefer a 15 or 18 driver due to the large room size. How good is a 12 with a PR. Is it better than a 15/18. How about a dual 12.

Since the room is huge, I guess I will have to go for a ported design. I want the sub to be down firing as it will be relatively kid proof. I dont know much about the designing the cabinet, so I will need help from you guys in that too, but first I need to identify the woofer and amp that I want.

I saw the following good ones on the web, please feel free to suggest out of this list if you have a good one in mind.

Drivers

Maelstrom-x
18
395$

ED 19Ov.2
245$
18"

16Ov.2 Subwoofer
$225.00
15

Peerless 830500 XLS 12"
150$

Rythmik 15, dont know the price, but its within my budget.

Shiva x-12 with passive radiator
235$

BNS 18N850 18" 1200 W 6.6Kg 97 dB 1W/1M 20-200 4" 38mm Neodymium $350.00

15N840 15" 1200 W 5.8Kg 98 dB 1W/1M 22-300 4" 38mm Neodymium $295.00

I also saw the aurasound and morel drivers going above 400$ for 12. Are these subs that good.

SS RL-p18
420$

SS RL-p15
335$

CSS SDX-15
270$

Eclipse SW8200 Subwoofers 12"
220$

Amps

Is a 500w bash amp enough for my needs. What do I gain by going to a higher wattage amps, I dont usually play at very high volumes.

Model : LT/1300
450$
Number of Channels : 1
Power Rating : 1300W RMS @ 4?
Height : 12.000" - Width : 12.000" - Depth : 5.500"
I heard this one had current inrush problems, and needs a 20A socket, would rather not get this.

Model : LT.500
300$
Number of Channels : 1
Power Rating : 500W RMS @ 4?
Height : 10.625" - Width : 9.875" - Depth : 5.5"

rythmik amps will get if I get a rythmik driver.

Bash 500W Digital Subwoofer Amplifier
228.58
50 to 150 Hz low-pass crossover, 0 degree or 180 degree phase, line level inputs, speaker level inputs, line outputs, master on/off switch, auto on
500 watts RMS @ .5%THD into 4 ohm
Signal to noise ratio 105 dB A-weighted, Dimensions: 12" W x 8" H x 3-1/2" D

CSS bash 500
230$

CSS hpsa1000
450$

OAUDIO 500W bash amplifier
220v 249$


Questions:

1. Sealed vs ported. Probably ported.
2. What driver config. Single 15, 18, cheap dual 15, dual 12, 12 with PR.
3. Amp wattage? Is 500w enough
4. BASH amp vs non bash amp. Pros and cons.
5. whats the best utilization of money, split between amp and driver.
6. What else can I get from US that will help. Flared port? Wires, feet. What size flared port.
7. what else do I need apart from driver, cabinet and amp.
8. what price is 1 MDF in India. If its too expensive, what are the alternatives. Can real wood like sheesham be used for this. What about plywood, do u get 1. Which is better. Prices?
9. Can I use wheels for feet. The sub will be down firing.
10. Does the driver comes with the nuts bolts etc for mounting.
11. why most of the people try to avoid nails and use only glue. What about nails along with glue. What bout nuts instead of nails.
12. what specs do I need to look in a driver and the amp.
13. any good looking designs for the cab you have. i shoud be able to use it as a side table.
14. the t/s parameters, can some one tell me which ones should be lower/higher the better.
 
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GeorgeO

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AES Speakers( owned by John Janowitz) is an excellent source-their drivers incorporate a lot of the old Lambda Acoustics technology, they have a forum, and they also sell passive radiators.They will help in modeling the enclosure.
Check their site out-a little expensive, but very. I use dual PRs with a 12 inch driver, in an 84 litre enclosure.

Kevin Kaskins of diycable is another good person to deal with-Shiva and Maelstorm drivers and PRs. His forum is on Audio Circle. Read up posts about subs on both the forums and ask questions on them, and then decide what you think is best.
 

GeorgeO

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1. Consider PR-its a good option.

2. Dual with PR-these things are not light-bringing multiple driver will be VERY heavy-my Lambda driver weighs about 10+ kgs unpacked.

3. I think 250 watts is fine , a litle more is good, but no need for overkill.Check out apexjr.com for sub plate amps.

4. In my case 60-65% for driver PR+ 35-40% for amp-though my dual PR % are obviously slightly different.
5. Nothing if youre getting the driver ,PR and amp-use a local terminal.

6.Nothing else.

7. 18mm MDF is about 32-33 per sfit, 25 mm should probably be around 40-but I suggest you consider two layers of 18 mm instead of a single layer of 25mm. You can cover it with 4mm decorative plywood, do not use real timber for the raw casing-it has diferen and not suitable properties. MDF is easily available and will work fine.

8. Driver will not come with mounting bolts.

9.Avoid down firing, the surround will sag over time because most drivers are not designed for down firing-there are some that are designed for down firing( the Shiva used to be one of them , but you need to check before buying). If you have two PRs on opposite sides and the driver front firing the fourth ( rear) side can be against a wall. Just get a circular metal speaker grill and cover the driver for protection.

10. Yes you can use it is a side table that will thump a bit when in use!


George

Sealed vs ported. Probably ported.
2. What driver config. Single 15, 18, cheap dual 15, dual 12, 12 with PR.
3. Amp wattage? Is 500w enough
4. BASH amp vs non bash amp. Pros and cons.
5. whats the best utilization of money, split between amp and driver.
6. What else can I get from US that will help. Flared port? Wires, feet. What size flared port.
7. what else do I need apart from driver, cabinet and amp.
8. what price is 1 MDF in India. If its too expensive, what are the alternatives. Can real wood like sheesham be used for this. What about plywood, do u get 1. Which is better. Prices?
9. Can I use wheels for feet. The sub will be down firing.
10. Does the driver comes with the nuts bolts etc for mounting.
11. why most of the people try to avoid nails and use only glue. What about nails along with glue. What bout nuts instead of nails.
12. what specs do I need to look in a driver and the amp.
13. any good looking designs for the cab you have. i shoud be able to use it as a side table.
14. the t/s parameters, can some one tell me which ones should be lower/higher the better.
 

anm

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thanks guys for starting this thread.
I think subwoofers are highly overpriced in India. Making subs is easier than any other component AFAIK - so why not start making very good subs with just 20-30k budget - instead of buying them for 1L+

regards
 

aks07

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Oaudio Bash 500 watts is an excellent amp. In terms of bells and whistles it comes loaded with controls so that you can set it up exactly the way you want it. I am using one to power a Lambda Acoustic 12 driver in a sealed box. Both the amp and driver are made in North America and lugged all the way to desh kind courtesy GeorgeO. Depending on how you set up the BASH amp, it can be very musical yet powerful enough to rattle window panes 3 floors up.

As you describe your listening environment, 500W should be sufficient. Sealed or Ported, Downfiring or frontfiring will be (ideally) decided by the driver parameters. So would be the size of the enclosure. This is a delicate part and WAF may have some influence. I had to compromise a little on this.

But I fully share your opinion that for X amount of US$ is should be better than what is available at retail. This was a pre-requisite for me, and I believe to get equivalent performance (BASH + Lambda) on a retail product I would have had to spend at several times.
 

GeorgeO

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See this thread about driver position

Side Firing woofers


Also, doors666, pm me, I will be happy to show you my PRs, should you want to see what they look like. No one showed me these before I bought any of them :sad:

Starting next week, I will be mostly out of town for the next 10 weeks.
 

musicmypassion

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Typically sealed will have a lower F10 but a higher F3 and F6. The excursion is much better controlled in a sealed box, enhancing power handling. Sealed is also slightly less efficient. Ported is a little more resonant, but has a higher F3 and F, leading to impression of 'more' bass, subjectively speaking. The excursion below the port tuning is usually very large so for high displacement subs some amount of subsonic limiting is advised (<18Hz, 48dB/oct) when using very high power amplification. Listening tests would generally favour the ported designs though, and if the F3 is low enough (~22-25Hz) it is generally usable.

I'd like to make a sweeping generalisation and say I would instinctively prefer a sealed box for music (a moot point, as I don't use a sub for music at all, the Mini-Dancers have enough and more of what I need), and a ported one for HT and games. This would basically mean a smaller/lighter sub in a sealed box for a F6 of about 30Hz for music, and a larger driver would work better in a bigger enclosure (ported of course).

I was expecting the reply from you Cranky... :) thanks a lot for the detailed explanation...
 

doors666

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3. I think 250 watts is fine , a litle more is good, but no need for overkill.Check out apexjr.com for sub plate amps.

might not be enough, its quite a large area. Dont want to take a chance, if I make bad purchase decisions, WAF for DIY will go down big time. will stick to atleast 500w. do I need to get more, specially if I decide to go for a sealed one. Of course it depends upon the driver too.

7. 18mm MDF is about 32-33 per sfit, 25 mm should probably be around 40-but I suggest you consider two layers of 18 mm instead of a single layer of 25mm. You can cover it with 4mm decorative plywood, do not use real timber for the raw casing-it has diferen and not suitable properties. MDF is easily available and will work fine.

New development, now the max size allowed is 24x24x24. In that, using 1.5" thick wood probably will not be a good idea. For the baffle I will do that, specially if I get a heavy woofer. rest will be 1" mdf

9.Avoid down firing, the surround will sag over time because most drivers are not designed for down firing-there are some that are designed for down firing( the Shiva used to be one of them , but you need to check before buying). If you have two PRs on opposite sides and the driver front firing the fourth ( rear) side can be against a wall. Just get a circular metal speaker grill and cover the driver for protection.

ok. I guess down firing is ruled out unless i run into a good woofer for that.

I will also check out audio circle for more info.

Ideally I would like to go for a sealed one, but due to the large area, for movies, it might not be enough, hence ported. If there is a way to go with a sealed sub, and still get good effects for movies, I would prefer that. Can you guys suggest some options. I am ok with an 18" driver also if that helps, can buy a bigger amp if that helps. I want to select the driver that is suitable for the kind of sub I want, rather than build a sub according to the driver I get. If sealed doesnt work, would prefer ported but thats adding a lot of complications to my first diy:)
 

doors666

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Hi Guys,

I am trying to plot graphs in winISD to see how different drivers will eventually behave. I dont see any specifications any where for the room size, so how do i know if a given driver's FR is going to be enough for my room or not. For a 6200 cubic feet room, what kind of SPL is required for movies. I dont listen at ear bleeding levels, but sometimes its fun to go loud. So what should be my target?
 

doors666

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Hi Guys,

I am close to the business end of purchasing a driver and an amp. I am looking for a CSS SDX-15. I also considered the AE, but they take like 4 weeks to make and deliver and that wont work for me as my friend is there in US for just 2 weeks.

The issue I am facing with the plots is the Port velocity. Most of the times, the default graph has a very high port velocity. Either the port velocity goes off the charts, or the port size becomes unmanageable. I have also read conflicting statements reagrding the port velocity. Some people say that 17 m/s (5% sound speed) is max allowed port velocity, and some people say that for a dual 4" ports or single 6" ports, it does not matter. Which is true. Is there a guideline as to with which port, what is the max air velocity allowed.
Which option is better, dual 4" ports or single 6" port to avoid chuffing. What about a single 4"

I also compared the graphs of shiva 12" (with 500w amp) with sdx-15 (1000w amp) in about 6-6.5 cuft box and a 20hz highpass filter, I dont see much of a difference in both the graphs, the spl is just a little bit higher (around 2db) for the sdx, rest of the graphs look the same. Again the port velocity is about 25 m/s, while shiva is below 17m/s.
Is it really worth it to pay double price for such a small gain.

Thanx
doors
 

doors666

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Don't aim for the flattest looking line, always look for the smoothest line to F3 (gradual roll-off). Very high port velocity is only encountered at maximum power and output, coupled with a tuning frequency that is too low and too close to the driver's Fs. Always tune the box a few Hz higher than the driver's Fs, as you will want the driver to handle some power below port tuning.

You can make your port sizes a bit more reasonable with square ports flared at both ends, or a few smaller ports. A single, smaller port will have shorter length but is more prone to chuffing, large ports tend to become longer and may exceed the box size. Downfiring ports can help you reduce the port size, but I don't know of a simulator that will help you calculate that. Generally the air volume below the sub, or a part of it, is added to the port to arrive at the total port volume and therefore the length of the port. Usually one can get away with a short and wide port when faced downward...

I tried to increase the tuning frequency, result was that the port length reduced and the air velocity went up big time.

I have attached the project files, if you could tweak it or make recommendations, that will be great.
 
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doors666

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The CSS gets my vote. With a 3.5 cuft box and a 4" x 17" round flared port, you're able to get much better power handling and cone control, plus a little more efficiency (1 or 2dB is not little, though).

The only issue is group delay (I guess due to the very high VAS and inductance), but you should use your bass management in the receiver to compensate. Likely at real-world levels (~100 watts) you will have no problem.

With which amp? 500w or 1000w. 1000w is about 200$ more expensive.
Is a bash amp a better choice or the class a/b amp.

I can go upto about 7.5-8 cuft outer box, so usable internal volume will be about 4-4.5 cuft. bigger the better right?
 

doors666

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No, bigger is not always better, cone excursion increases with the size of the enclosure, and ports tend to get longer, which increases the possibility of chuffing. You should look at the smallest enclosure that results in a tradeoff between power handling, low-end extension and mechanical limits (Xmax/wind speed).

A 1000W amp can be run at 500W all day. A Class A/B amp will typically dump about 200-250 watts of heat at that power level, and a Class D will dump 50, but for all intents and purposes they will perform identically.

A 500W amp will run at 250 without any problems. Choose your amp and driver basis the output levels you normally run at, add 6dB for peaks, and then 6 dB again for headroom. A SPL meter is indispensable for this, really.

8cuft box with 4 cuft internal? Where are you getting these numbers from? For a 1inch construction with braces, you will have to tack on about 15% volume to the internal volume, no more. Simply get the cube root of the volume in cubic inches, and add 2.5 inches each side (1 inch construction + 1.5 inch for braces and driver volume) to compute external dimensions.

i guess then it will be a bash amp. difficult to get 1000w class d plate amp though, havent seen any so far on the web.

I dont have a sub, so dont know what power levels I listen at:). i usually listen at -25 to -15 db on my avr. dont know how much that translates to. I usually dont listen at very loud levels. give me a rough idea, during action movies, say in some intense scenes, how much db does it usually goto at decent listening levels. a range or approximate value will also do as presently i have no idea.

i calculated it the other way, compute the external volume and subtract for all entities.

For a 2'x2'x2' box
Total 8 cuft.
1 wood
approx 3 feet apart from the box, so total size 24x24x27

Subtract

1. Port volume
e.g. For a 4 diameter, 18 long port volume pi x r x r x l
= 0.52 cuft
2. driver volume + amp volume = max 0.5 cuft
3. bracing volume = 0.5-.75 cuft
4. outer box wood volume =
if w, h, d is x, y, z (all are 24 in our case)
then wood volume (with 1 wood) = 2xy + 2 xz + 2 yz = 3456 cubic inches 2 cuft.
Total = about 3.5 cuft
Remaining is internal volume = 8-3.75 = 4.25 cuft. another .25-.5 cuft for polyfill is what I forgot, is that needed for ported designs?

Hmm. as per your calculations, I can get about 5.75 cuft out of a 8 cuft external box. I guess I will calculate the exact internal volume properly using correct numbers to figure this out.
 
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GeorgeO

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8cft is pretty big. One of my enclosures is about 18 inches cubed, and another one is a bit bigger. If you raise volumes levels too much it does get to drown out the other sound,a s well as overwhelm you.

George
 
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