Hi all DIY gurus

Audiolab 7000A Integrated Amplifier
cmsajith
where are you based

im looking to build a DIY sub too
though my requirement is more for music

if you are in mumbai please do remeber to ping me when youre building

my budget is much lower though, about 250$ for the plate amp and a sub driver
my room is about 180-200sq ft

any advice on what i can consider?
cmsajith,cranky?
 
Cranky

I do feel that you're a "power monger":ohyeah:

I have two plate amps one is 175w and the other 250w.I hardly "crank'(pun intended) them up to about 10% of volume levels most of the time, sometimes les. Both my drivers are 12 inch, and at higher levels it does get a bit too much. So I feel -again, my personal view-in 95% of the usage, anything around 150-200 watts is more than adequate. If the room is huge, maybe more power is needed-but for a home environment, this is more than enough.

Now we all know about the fondness that Americans have for big cars, big servings of food, big amps!

George
 
 
@Magma,
I think its not a wise thing to import from US if you are looking for a 8"/10" sub unless you have somebody to bring it by hand, because the shipping cost will become a major part in the 250$ (as per your budget).

Reference HF 10" costs 125.79$ + shipping + other charges will takeup a major portion of your budget based on the 20North calculation, (((125.79 + (15% * 125.79))*50Rs) + (wt. in pounds * 281)) + 600 (surcharge)

The other 2 subs which you mentioned cannot be used as a sub, their XMax is very less, ~6-7mm.

Instead what i suggest is that try getting Eminence Lab12 (somebody got it for around 8.5K shipped from Cinetek Chennai) and try to get a plate amp locally, since you are in Bombay, try Palesha (heard that he makes good plate amps, not sure about his subs). Lab12 is specifically made for suspended Horn based designs, however they are better for ported designs also. Try to tune around 30Hz and it will go deep a little further with the room gain. No need to worry about the amp, try to get the max within your budget even though it will not squeeze the max from the sub. Later when budget permits, you can upgrade. Another option is to get a good locally made single channel poweramp (200w - 250w is more than enough for your room size) or a kit and buy a good active crossover with highpass \ rumble and lowpass filters.

@Cranky
I think a 240w amp (continuous) more than enough to get the max out of Dayton 15 sub in a ported enclosure. A 500w amp will damage this sub tuned to ~20Hz. Otherwise I need to tune it around >30Hz which will void the purpose of going for DIY, a commercial sub from Polk DSW PRO 600 will do the same. Moreover I was looking for a 300-350w plate amp, but it will cost 3/4th of another SA240 amp which I bought. Another option was to get a good power amp (Tapco J800), but that requires a good equalizer to tune the sub to ~20Hz which again costs 3-4K. J800 costs only 3K more, but another 3-4K I need to spend extra. More over I cannot feed the sub in bridged mode (800w), it will fry the sub. Moreover the power consumption is very high. The only difference I could find is in the SPL graph, which gives some db more with more wattage. When I plotted the 240w amp it gives me ~104db at ~18Hz with a very controlled cone excursion graph, which is more than enough to shake the walls. Even there are some mods recommended by Parts Express to change the rumble filter from 18Hz. I would recommended a 500w amp with a sub with XMax around 20mm minimum. (Dayton MKIII, not better for Music), Reference HF is better for both movies and music, however it requires a slightly bigger box than others.

Regarding 20North, the duty free shipping has the following charges:
- Surcharge : Rs600/gift
- Requires a PayPal a/c. Since I had it already, it didnt take much time, else you can create a new one using your Credit card, PayPal will charge 2$ on your card for activating your a/c but will be transferred to your PayPal a/c.
- PayPal will charge 2.5% on the $ conversion rate (came to 50.02..inclusive) for currency conversion.
- Gifts will come directly to the address provided for shipping, unlike the normal category.
 
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What I feel is instead of going for a single sub with huge power, its always better with a second sub tuned to the remaining frequency range (One from 18 or less to 40 and another from 40 to 80+). Drivers may be 12" / 15".

Correct me if I am wrong:)

GeorgeO said:
Cranky

I do feel that you're a "power monger":ohyeah:

I have two plate amps one is 175w and the other 250w.I hardly "crank'(pun intended) them up to about 10% of volume levels most of the time, sometimes les. Both my drivers are 12 inch, and at higher levels it does get a bit too much. So I feel -again, my personal view-in 95% of the usage, anything around 150-200 watts is more than adequate. If the room is huge, maybe more power is needed-but for a home environment, this is more than enough.

Now we all know about the fondness that Americans have for big cars, big servings of food, big amps!

George
Click to expand...
 
cranky said:
a wall of subwoofers made of small (8-10") drivers is also a great way to create that pressure, as long as they are identical. I know someone who uses 16 small(8") subwoofers at all the nodal points in the room to create a bass wall.
Click to expand...

This is exactly what i was telling, using 10"/12" s, but not a bass wall:eek:. The freq cutoffs i told was just some rough figures to make my point.

By using a powerful amp, is there any significant improvement other than a slight increase in db?
 
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Crank, I couldnt find the attachments.

Fs of the sub is 18Hz.

PartsExpress had send me a pdf for the recommended vented design. It is recommending 8cuft and the box is tuned to 20.63Hz (Fb) and F3 at 16Hz.

Also i tried plotting the WinISD graph with 240w and attached the graph for 7cuft box tuned to 18Hz. SA240 has a rumble filter at 18Hz (4th order Butterworth) to protect the sub from over excursion. On closing the port (5inch), it gives a box tuned to ~28Hz with Qtc .607.

Graphs are attaching in the subsequent posts..

Comments welcome.
 
cranky said:
With that design, you're hitting 110dB SPL at listening position with 120 watts. Always halve the power output from your amp, to ensure you have headroom. 6dB is sufficient in most cases, though for subwoofers I'd like 10dB, just in case (listen to James Taylor's 'Gaia' to see what a bass transient can do to your system - it bottoms out every single woofer and subwoofer I've ever heard...

It looks OK. You will be able to work with that combination. Doubling the power adds another 3dB and I'd really like that additional grunt in my room, but you'll be fine too, as long as you don't go overboard on the levels and overload the amp. And the sub will not bottom out even with the 500 watt amp, the driver is at just about its limits with 400 watts, and will survive 800 watt peaks (two-way excursion).

Remember the recommended amps for this driver are all in the 400-1000 watt range, and if you don't need that much grunt you may as well drop down to the RS315HF and the SA240 (or BASH300, my preference). The SA240 is a great partner for the RS270HF/HO, and if that driver works in your room I would suggest partnering those two. There's not much point driving a Maruti 800 on Michelin Corsas, to take an extreme example, but you could if you wanted to :)

You won't lose whichever way you go, but I would save my cash and get a more 'appropriate' combination.

Post some pics whenever you're ready.
Click to expand...


I had opened another thread related to this and the moderator (Mike), he was not recommending 500w amp since it will bottom out very soon and was recommending amp around 300w for this sub. Only for MkIII, he was recommending 500w.
 
the port velocity is too high. If it exceeds 17m/s, you'll hear chuffing at those frequencies. You need to tame it.
 
Since I was closely watching the doors666 thread about the sub build,so i didnt try asking the same here.

I think its better start from the scratch.
My requirements :
- Sub should go lower (20Hz) authoritatively (chest hitting, deep, quality bass)
- Planning to use it for both Movies(60%) and Music(40%). So planning to do it as a ported and a sealed, by closing the port.
- Size will not be a big issue, but to some extend.

Could you please help me in building a box to get the max out of
- Dayton Reference HF 15" sub
- Dayton SA240 240w amp

I have attached the spec file.I am a novice in speaker building and whatever i have plotted is based on the recommendations from Hometheatershak members and its moderator.
 

Attachments

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Reasons:
- Had seen good reviews for this sub which performs well for movies as well as music eventhough it requires a slightly bigger enclosure than normal.
- 15" has better performance than a 12"
- Comes in my budget, only PartsExpress is having freeshipping (to get the best pricing through 20North) and this is one of the best they are offering.
- I couldnt find any other good 15" sub in the same price range.

Room Size : 16 x 12 (ft) Living room / Top floor corner Apartment / has a gap of 6ft between two apartments.
15" is a little bit overkill for this room. But i dont want to change the sub when I buy another house (ofcourse it will have a dedicated underground HT room). Dont know when, 50% done, purchased land sometime back:), waiting for other houses to comeup in the campus, havent thought of or decided any timeline, since the current apartment is less than 1 year old.
 
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