I was planning to build an efficient sound system. Another user commented "Good subwoofers don't come cheap."
So, let's play.
I've trolled Ebay. So far I have . . .
TPA3116D2 Class D 2.1 amplifier board: $10.00
19v Laptop PSU (4.7amp) $6.00
12" Driver from Electrovoice Evolve 50 system: $8.00
I still need a box - circa 50 litres.
I hope to make this (reduced power) portable so I'll need a 12v rechargeable battery.
What else will I need?
So, let's play.
I've trolled Ebay. So far I have . . .
TPA3116D2 Class D 2.1 amplifier board: $10.00
19v Laptop PSU (4.7amp) $6.00
12" Driver from Electrovoice Evolve 50 system: $8.00
I still need a box - circa 50 litres.
I hope to make this (reduced power) portable so I'll need a 12v rechargeable battery.
What else will I need?
You missed the key word: "Good"
You can build a subwoofer very cheaply. You can't build a good subwoofer cheaply. Not if you're buying the parts at fair market value.
Also, that driver sells for ~$200 new give or take $20-30 depending on source. You're trying to claim the rule is invalid by cheating it through relying on good fortune. You can buy a brand new $25k ultra high end sub for $1 off of a friend. Doesn't mean you broke the rule of good subwoofers not coming cheaply.
You can build a subwoofer very cheaply. You can't build a good subwoofer cheaply. Not if you're buying the parts at fair market value.
Also, that driver sells for ~$200 new give or take $20-30 depending on source. You're trying to claim the rule is invalid by cheating it through relying on good fortune. You can buy a brand new $25k ultra high end sub for $1 off of a friend. Doesn't mean you broke the rule of good subwoofers not coming cheaply.
IIRC, that amplifier was disappointing (running into distortion) with 12V if used down to 30 Hz, used down to 40 Hz it fared better at normal listening levels inside. I would advice a higher voltage power source and/ or a larger cabinet volume to squeeze more out of the driver. Something along the lines of the MTH30, THAM12 or Cubo 12 Mod.
@Diogenes: I can't find the comment or commenters. Was the rule about market value established and published at the same time as the statement that good subwoofers don't come cheap? If afterwards, it feels like that person could have been more specific and is altering the de-facto statement to save face.
Good is subjective and thus personal or specific to purpose. I have 2 bicycles (I'm Dutch after all), as for market value, ones value is expressed in 2 digits, the other one is probably at 4. Both good (and better than the other) for their specific purposes, wouldn't want to switch them in that regard.
@Rademaker At over 50 litres I lose portability. I'm looking to compromise. A system offering full output when plugged into the mains but offering a couple of hours of reduced power from batteries.
I can't find the T/S parameters for the driver but in the (similar sized) original cabinet has an f3 of 43hz at the lower end so 30Hz outside, running on battery power was never an option.
Thanks for your interest.
I can't find the T/S parameters for the driver but in the (similar sized) original cabinet has an f3 of 43hz at the lower end so 30Hz outside, running on battery power was never an option.
Thanks for your interest.
I'd suggest an 18V rechargable battery instead of 12V. Just measure it and make sure it won't exceed the amp's maximum voltage input.
FWIW, I ended up buying a B-stock battery drill with 2x 5Ah LiPo batteries and a charger, for less than the price of 2x new batteries. The drill has a small scuff and the batteries look brand-new. Result!
To the question on-hand, I'd suggest measuring the driver's T/S parameters and then firing up Hornresp. It's common for PA companies to put large amounts of EQ boost in their speakers, so don't be surprised if your simulated LF response is lacking in comparison.
Chris
FWIW, I ended up buying a B-stock battery drill with 2x 5Ah LiPo batteries and a charger, for less than the price of 2x new batteries. The drill has a small scuff and the batteries look brand-new. Result!
To the question on-hand, I'd suggest measuring the driver's T/S parameters and then firing up Hornresp. It's common for PA companies to put large amounts of EQ boost in their speakers, so don't be surprised if your simulated LF response is lacking in comparison.
Chris
Thanks, Chris. The amp will do 28v with a bigger heat-sink.
The 18v battery is a worthy suggestion. Measuring the driver's T/S parameters is beyond my capabilities. I actually thinking I'm wasting a perfectly good driver (it's brand new). I can build something similar using for 6.5s
The 86 liter (gross) Evolve 50 sub is around -3dB at 50 Hz without the low frequency EQ boost modes engaged.
That said, the EV 12" is going to make more boom per watt than a 6.5".
It's a 100ohm resistor, couple of guitar cables cut in half, a USB interface and a bit of soldering. Are you sure?
Chris
Even if you're not tuning the enclosure to 30 Hz, if you're playing music with 30 Hz content you can still run into the same distortion, unless you use a high pass filter before the amplifier (an inline high pass filter or DSP would be a good addition to your system).
At 50 liter a simple reflex is likely your best option, tuned to 40 - 50 Hz.
Just a small note that if you build it to use 18/20v tool batteries and you don't want to risk damaging them, consider adding a low voltage cutoff board set to about 15v, unless you determine that the battery has one built in. (Dewalt for example puts it in the tool, not the battery, so without any added protection the amp will happily drain the battery down to 12v or lower, damaging it.)
I talked about some of the pros and cons here (second project down): https://www.diyaudio.com/community/...boxes-3x-complete-another-in-progress.388333/
I talked about some of the pros and cons here (second project down): https://www.diyaudio.com/community/...boxes-3x-complete-another-in-progress.388333/