I'm searching for an amp to power an idea bouncing around in my head. Given that budget is currently a concern, I'mm wondering how much power I really need (at least for starters). and price seems to go up exponentially with amp power (especially when there's a DSP involved).
My idea is just a decent sized TV stand with 2 15" drivers in there. The drivers are 4 ohms and most amps I've seen (rack/plate style) can only do 4 ohms at their highest rated configuration, so I'd have to rig the drivers in series rather than parallel. So that begs the question. Would 500w thrown at 2x 4 ohm drivers wired up in series for an 8 ohm load be louder than 500w running into just one 4 ohm driver?
The general rule of thumb I've gathered is the 4 -> 8 ohm would drop output by about 3dB. Adding another sub, would boost the output by around 3dB at the same amp power. If that's correct, it would be about the same volume in either configuration. Sound right, or not so much?
My idea is just a decent sized TV stand with 2 15" drivers in there. The drivers are 4 ohms and most amps I've seen (rack/plate style) can only do 4 ohms at their highest rated configuration, so I'd have to rig the drivers in series rather than parallel. So that begs the question. Would 500w thrown at 2x 4 ohm drivers wired up in series for an 8 ohm load be louder than 500w running into just one 4 ohm driver?
The general rule of thumb I've gathered is the 4 -> 8 ohm would drop output by about 3dB. Adding another sub, would boost the output by around 3dB at the same amp power. If that's correct, it would be about the same volume in either configuration. Sound right, or not so much?
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A decent sized TV stand with two 15" drivers will be able to get ridiculously, shockingly loud on a 150W plate amp.
2 drivers will always be louder than one. If you can fit them, always do two.
Don't confuse amplifier Watts with power. An amp that makes 100W into 8 and 200W into 4 is outputting the same amount of juice into the speaker. The units are changing so the numbers change, but it's passing the same current.
2 drivers will always be louder than one. If you can fit them, always do two.
Don't confuse amplifier Watts with power. An amp that makes 100W into 8 and 200W into 4 is outputting the same amount of juice into the speaker. The units are changing so the numbers change, but it's passing the same current.
Right, but at the same time, I don't want to damage them by under-powering them horribly. I'm thinking if I only stuff 500w into the pair, that'll keep excursion in check without under powering them too bad and will probably be louder than I ever need. Sims show, that 2 of these drivers running 1000w rms will play 120dB dead flat down to 20Hz (with a minor excursion dip) with an f10 at 13Hz. 500w sims 116Hz dead flat with no excursion issues. I'm thinking a "1,000w RMS @ 4 ohms" amp will actually produce roughly 600w when hooked up to an 8 ohm load.
Not at all. Ohm's aren't quite just divisible by 2 though. There are square roots and things involved in there somewhere, but I can't remember the exact formula at the moment. From my college band days, I remember 4 ohm heads (amps) could push roughly 2/3 (usually not quite) of their wattage into 8 ohms and it seems to be fairly similar in the diy audio arena too.
Not at all. Ohm's aren't quite just divisible by 2 though. There are square roots and things involved in there somewhere, but I can't remember the exact formula at the moment. From my college band days, I remember 4 ohm heads (amps) could push roughly 2/3 (usually not quite) of their wattage into 8 ohms and it seems to be fairly similar in the diy audio arena too.
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Your description seems incorrect. 😉
As an abstraction, amplifiers are roughly constant voltage devices, halving the impedance will double the current, thus doubling the power.
To the OP, this question gets asked so often it is almost sickening, have you tried the search function? How about google using the site:diyaudio.com modifier?
LMGTFY
LMGTFY
Sorry, the only way to damage a subwoofer is by overpowering it.
Yes quite, but I'm not sure how well the TV will do exposed to all that vibration.
I've built 15s into TV stands and it made even the best CDplayers skip, unless I rigged a suspension housing.
I would never dream of putting a turntable even close.
I would never dream of putting a turntable even close.
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