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Real wattage to subs, Impedance rise and frequency.


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  • 5 weeks later...
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Not to hijack the thread, but how is a clamp test performed? Stepping up to a lvl 4 dc 12, which is 1500rms, and im running a taramps smart 3 so I’d really like to tune it in to 1500~  The smart 3 is pretty efficient as I’ve read, so I dont think I’d have any problem reaching 1500+ So I’d like to know what I’m feeding the sub! Thanks 

‘16 ram. Net Audio. Taramps. JL. DS18.  Fox Acoustics. XS Power. 226.08” of DC Audio blue carbon fiber. 

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  • 1 month later...
On 8/9/2020 at 12:29 PM, JakeW said:

Not to hijack the thread, but how is a clamp test performed? Stepping up to a lvl 4 dc 12, which is 1500rms, and im running a taramps smart 3 so I’d really like to tune it in to 1500~  The smart 3 is pretty efficient as I’ve read, so I dont think I’d have any problem reaching 1500+ So I’d like to know what I’m feeding the sub! Thanks 

DMM - set to A/C voltage setting - the positive probe in (+)speaker terminal and negative probe in (-)speaker terminal

 

Amp Clamp - set to A/C amperage setting (peak hold if you have it) Put clamp on (+) speaker wire.

 

Play a frequency to see what max RMS Watts (actual max NOT boss ratings type deal here) you're amp is pushing on your system  - 40hz is typical 

 

If you want to do on music play whatever you want. 

 

VOLTAGE ÷ AMPERAGE = OHM LOAD (this is where you see your box rise)

 

VOLTAGE x AMPERAGE = RMS Wattage

 

Need a volt meter or another DMM if you want to know at what voltage. 

 

 

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On 7/8/2020 at 10:18 PM, Backwoods said:

I do understand my amp is rated for 1K at 14.4 volts, so at 13 volts I'll see less. And do understand impedence rise a bit... But don't really understand how wattage changes with different frequencies.

That's how a subwoofer plays different tones and different frequency. If it was a flat line of Watts you would have the same level of bass, that is what we call flat.

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  • 1 month later...
On 7/8/2020 at 11:37 PM, Backwoods said:

Yeah that 3K is probably delivering less than 1k to your sub according to all this. But if that sub is rated at 600rms then you are probably getting close to it's rated RMS finally, and with the old amp was probably only getting half, or less, of what it's rated at after losses and impedence rise.

 

 

Crazy stuff. More and more I'm wishing I went with a 3K amp for my 2 Sundown SA 12s instead of the 2K... But they were rated at 750 each... I figured 2K for a little head room... Now I'm thinking even the 2K won't push them to their full potential... Hell a conservatively set 5K even.

Love your build thread btw. Looks pretty bad ass.

 

I invested in an AMM-1 meter recently so I can start figuring all this out. My manufacturers rated power for my set up is 6k watts at 2 ohms (Subs are rated 3k rms each). I'm sitting at 2.8 ohms for my dyno power at 1828 watts (1/2 volume). If I had less impedence rise, maybe I get close to my rated power at half. 

 

if I understood more of this earlier I would have gone in a different direction.

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  • 2 months later...

I agree with the original statement, something about why the [big/pro manufacturers like SunDown, Deaf Bonce, Fi, PSI, Crossfire, DC, etc] don't use average clamp numbers as their rated power for pairing amps with subs. My Taramps Bass 8K 1-ohm @ 1-ohm clamps 4K, 50% of it's rated power. Typical is somewhere around 40% of rated power. However, I have my amp to output only 5K and yet clamps 4K (actually just shy of 4K, like 100 watts shy) I used -5dB tone of it's peak freq of 43 Hz. One D2 DVC sub 5K RMS. My amp is set to put out 100V which equals 5K at volume notch 3 (3 out of 8 notches because beyond 3 is slight clipping on my factory 8" t/s head unit). (currently is a Skar DNR 15" D2) My box is tuned to clearly play music freqs between 27Hz and 55Hz well. I'm about to sell this set-up because I bought a new set-up I'm prepping to install. 2 15" D2 Fi Neo 4.11 released Nov 2020, each powered by it's own Taramps Bass 8K at 0.7 ohm which equals 20,000 RMS watts. Therefore I'm aiming to clamp 6K each sub if I can design this box to be as efficient as the last one (current one which has 4 aero ports and large plexiglass window). If it matters, 390a JS alt, 4 runs of 2/0 SHCA OFC, 3 SMD fuse blocks all with 500 a fuses, XS Power D3400 which is being replaced with XS Power's newest Bluetooth Managed Lithium Direct Fit Titan8+ 6500, and I my current set-ups newest addition is the $1,300 Super Bank of caps: SB1500-75 also by XS Power. Also use LC7i by Audio Control and some other stuff like 4 small coaxial door speakers and a 400.4 amp to push them, 8" factory touchscreen in my Ford Edge. Lmk if anyone is interested in knowing the exact numbers I had in order to come up with what I clamped. If in doubt, ask. Don't assume.

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  • 4 months later...
On 7/9/2020 at 5:08 AM, Backwoods said:

I know there are older threads about this, but instead of resurrecting a really old thread i figured we could start a new one and discuss... 

 

So, i did a clamp test on my sfb1K today... It was eye opening and a good learning experience... My amp puts out the most wattage at 30hz, and only put out 602 watts.... At 40hz, even though that sounded noticeably louder to my ears, the amp was only putting out like 400 watts according to my calculations. Now i may not of done things perfectly, and the clamp i used was a real cheap one... But i was really surprised how much less i was getting under rated power, and how frequency also determined how much wattage the subs got.

 

A couple questions, how does frequency change the power actually sent to the subs? And how does box tuning affect this?

 

Setup. Sfb1K amp on 2 SA dual 4 ohm 12s wired to 1 ohm, My box is 3.7 cubes net ported and tuned to 32-34hz.

Electrical is all stock, and sat at 13.1-13.2 volts during the test. 

 

Hey :)

I hope I understood correctly your question (sorry I'm a French frog eater), but I'll try to answer what I understood from it with what I know:

 

- Subwoofer impedance will change depending on many factor (frequency played, box design, pressure inside the box or vehicle, without talking about temperature,....)

   So with that said, it's totally normal to have a variation of power depending on the frequency you play (amplifier outputs approximately the same voltage, but impedance changes, which induces that the current going into the sub changes (Current = Voltage /Impedance), then Power follow the lead (Power = Voltage x Current as we know).

 

- Now if we consider an amplifier wired to a resistive load, the output impedance won't change, and we consider that the input voltage stays the same.

If you try to run different frequencies into the amp, you may notice a slightly change in the power output, because as we know there are no "perfect" amplifier, the electronics perform differently with the frequency change.

Two things to notice here :

1. the variation in terms of power I mentionned is usually small (maybe a few %)

2. Usually (it's really depending on the amp) amplifiers will have a noticeable output power decrease at lower frequencies (korean boards are usually better at it than brasilian ones).

 

- How does the box tuning affect this ? Well, in short terms, the tuning frequency of a box is the point where usually you have the strongest pressure output and most of all it is the point where your subwoofer impedance rises the most.

BUT, as long as you have your box in a car, the car resonant frequency also affects the sub. Maybe your box is tuned to 32-34hz (you can verify by playing your box outside of the vehicle and see where the impedance is the highest), but your vehicle has his own resonant frequency (probably higher than your box), which could explain why @40hz you have less power (higher impedance rise due to the car).

 

I hope I'm clear and hope the community can confirm or contradict me if needed :)

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7 hours ago, Car Audio 83 said:

 

Hey :)

I hope I understood correctly your question (sorry I'm a French frog eater), but I'll try to answer what I understood from it with what I know:

 

- Subwoofer impedance will change depending on many factor (frequency played, box design, pressure inside the box or vehicle, without talking about temperature,....)

   So with that said, it's totally normal to have a variation of power depending on the frequency you play (amplifier outputs approximately the same voltage, but impedance changes, which induces that the current going into the sub changes (Current = Voltage /Impedance), then Power follow the lead (Power = Voltage x Current as we know).

 

- Now if we consider an amplifier wired to a resistive load, the output impedance won't change, and we consider that the input voltage stays the same.

If you try to run different frequencies into the amp, you may notice a slightly change in the power output, because as we know there are no "perfect" amplifier, the electronics perform differently with the frequency change.

Two things to notice here :

1. the variation in terms of power I mentionned is usually small (maybe a few %)

2. Usually (it's really depending on the amp) amplifiers will have a noticeable output power decrease at lower frequencies (korean boards are usually better at it than brasilian ones).

 

- How does the box tuning affect this ? Well, in short terms, the tuning frequency of a box is the point where usually you have the strongest pressure output and most of all it is the point where your subwoofer impedance rises the most.

BUT, as long as you have your box in a car, the car resonant frequency also affects the sub. Maybe your box is tuned to 32-34hz (you can verify by playing your box outside of the vehicle and see where the impedance is the highest), but your vehicle has his own resonant frequency (probably higher than your box), which could explain why @40hz you have less power (higher impedance rise due to the car).

 

I hope I'm clear and hope the community can confirm or contradict me if needed :)

 What do you mean French frog eater?

:stupid:“How can we help you?”
:guido:
“And don’t forget to tell them that 
the customer isn’t always right.”

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