Output Power VS Fuse Ratings

[3stagevtec 2]

The amp in question is a Linear Power 4.1HVS

taken from another forum..

Its the same way a linear power 4.1hvs can do 1250 wrms, on a 60A fuse and a 8002 does 800 on the same 60 A fuse, and a 502 does 600wrms.

Why? because the rail voltage on a 4.1 hvs is 160 volts.

Wanna see ohms law in action?

P=v^2/r

(160 x 160)/8 = 3200 watts of power available to run the outputs.

(8 ohms was used because linear power amps make rated power at 8 ohms stereo)

Here is a quote from Ray at Tips, the new home of Linear Power

The 2502IQ/2.2HV runs at nearly 90 volts internally, the 5002/5002IQ/502HV runs at 120 volts, the 8002SW runs at 140 volts and the 4.1HV runs at nearly 160 volts. This is why there are high voltage warnings on the biggest of these amps, if you have the bottom off the amp or touch the speaker terminals (in jsut the right way) with the amp at full power you can have a nasty shock if not electricuted.

The original engineer set up a test one time with an 8002SW at a show. US Amp was there showing at the time how they could arc cut an aluminum can with the output of their amps.

Linear's engineer had a 8002SW with a electrical outlet mounted on the end of the amp. The amp was playing the subs in the demo vehicle and he plugged a vacuum cleaner into the outlet and started vacuuming the carpet in the booth. THe US AMP guy just shut his demo down in he next booth and went to lunch. I have even tapped off the internal power rails to run play stations in SUV and vans for customers that needed houshold type AC voltage.

in the highlighted section above, i know there is a flaw in the maths.. can anyone please point it out for me??

[3stagevtec 2]

http://www.linearpower.com/manuals/41hvs.pdf

SPECIFICATIONS

RATED POWER @ 8 OHMS 75 WATTS

Min. RMS Continuous (8 Ohms mono) 1250 WATTS x 1

FUSE RATING 60 Amp

CURRENT DRAW (amps)**

8 OHMS - 90Amps

4 OHMS - 120Amps

**Peak current draw can be much higher than the average current draw as stated above.

If the fuse rating for the amp is 60A, then on a 14.4V system, it should produce 864W. Then when efficiency is factored in (say 70%), that will drop to a usable 600Watts of actual output..

but according to the manufacturer, you can get up to 1250W from it at 8ohms..

[johnecon2001 82]

And that's hard to believe why? Quite a few amplifiers are known to put out more wattage at higher impedances

[nem 2,019]

To understand that old school power, you need to have one. Very powerful set up properly!!

[Adrian_D 520]

The amp in question is a Linear Power 4.1HVS

taken from another forum..

Its the same way a linear power 4.1hvs can do 1250 wrms, on a 60A fuse and a 8002 does 800 on the same 60 A fuse, and a 502 does 600wrms.

Why? because the rail voltage on a 4.1 hvs is 160 volts.

Wanna see ohms law in action?

P=v^2/r

(160 x 160)/8 = 3200 watts of power available to run the outputs.

(8 ohms was used because linear power amps make rated power at 8 ohms stereo)

in the highlighted section above, i know there is a flaw in the maths.. can anyone please point it out for me??

To produce x watts you need to 'consume' y amount of watts. Doesn't matter if it's at 5 ohms, 50 ohms or 0.5 ohms. And doesn't matter if the rail voltage is 10v or 200v.

I don't know who the guy who posted the voltage rail argument is, his reasoning behind the fuse vs power rating is stupid.

And one more thing about the voltage rail vs power output. The voltage rail will drop under load because of the current demand. Measure the voltage at the outputs when it is wired at 8 ohms and measure when it is wired well below 8 ohms. Heck, measure the voltage rail and see that it drops below the idle value.

Ray at Tips certainly doesn't bring the fues thing into discussion. He simply explains what you can do with high rail voltage. To produce high power at high impedance you need high voltage.

People have been obsessing over fuse ratings for too long. The manufacturer considered it's safe to use a fuse that is rated at a certain amperage. It is there just to protect the amplifier in case something goes wrong. Fuses don't instantly blow when there is a bit more current passing through them.

Using fuses to determine the power output of an amplifier is like shooting in the dark, blindfolded and with 2 crippled hands holding the gun. I don't have any fuses on my Z1. Does that mean it will produce 0 watts ? Or unlimited power ?

[KU40 173]

Adrian has it. Output voltage has nothing to do with input power. His example doesn't even make sense, because he says 160 volts, but that already IS on the output side. So that 3200 output watts, given a 14 volt system and 100% efficiency, would consume 228.5 amps. Give that equation a spin.

Also asAdrian said, fuses don't blow instantly. Many take a few seconds of constant current at least, depending on how much the current exceeds the fuse rating. Music, however, is dynamic. Oftentimes the bursts that require more power only last for half a second at most. Therefore, the amp could draw 100 amps through that 60 amp fuse for .5 second and not blow.

[Jay-C76 333]

Easy way to cal. the amp load of said amp,

RMS watts / input voltage...

Adrian and KU40 raise some very good points.

The fuse has very little to do with the actual output power

of any amp.

It's there simply to protect from surges, accidental grouning,

and anything else that can go wrong.

I've seen a few in my day actually start to have a faint glow

when things were under major stress.

[3stagevtec 2]

I don't know who the guy who posted the voltage rail argument is, his reasoning behind the fuse vs power rating is stupid.

And one more thing about the voltage rail vs power output. The voltage rail will drop under load because of the current demand. Measure the voltage at the outputs when it is wired at 8 ohms and measure when it is wired well below 8 ohms. Heck, measure the voltage rail and see that it drops below the idle value.

This is what i was actually trying to figure out.. i'm not that versed on amplifier design..

where exactly is the rail (voltage) inside an amp? and does the speaker see the rail voltage or a fraction of it?

Using fuses to determine the power output of an amplifier is like shooting in the dark, blindfolded and with 2 crippled hands holding the gun. I don't have any fuses on my Z1. Does that mean it will produce 0 watts ? Or unlimited power ?

new amp under question..

http://www.americanbassusa.com/front/showc....aspx?fileid=99

American Bass VFL150.1

Specs

3300Wrms

200A Fuse Rating

using the 200A fuse rating..

Power = Voltage x Current

= 14.4 * 200

=2880Watts

factor in an 80% efficiency rating and the actual output looks more like 2300W..

so am i wrong here, or is it possible for the amp to do it's 3300Wrms rating on a 200A fuse..

-----------------------------------

AB VFL150.1

amp guts states

UsaCi ratings at 14.4V:

522.6 watts at 4 ohms

1562.8 watts at 1 ohm

Same board as:

. Emphaser EA1600

. Hifonics Brutus BX2200D

. SPL dynamics EXT-2000d

. Starsound SSA-D6000

. u-Dimension 2k1d

http://ampguts.realmofexcursion.com/American_Bass_VFL_150.1/

Hifonics Brutus BX2200D

Class D Mono amplifier

1 x 550W @ 4 Ohms

1 x 1100w @ 2 Ohms

1 x 2200w @ 1 Ohm

http://ampguts.realmofexcursion.com/Hifonics_Brutus_BX2200D/

SPL dynamics EXT-2000d

1 x 700W @ 4 Ohm ( 13.8V )

1 x 1200W @ 2 Ohm ( 13.8V )

1 x 2000W @ 1 Ohm ( 13.8V )

1 x 3000W @ 1 Ohm ( 16.5V

http://ampguts.realmofexcursion.com/SPL_Dynamics_EXT-2000D/

Emphaser EA1600

1 x 720 Watt RMS @ 4 ohms

1 x 1300 Watt RMS @ 2 ohms

1 x 2000 Watt RMS @ 1 ohm

http://ampguts.realmofexcursion.com/Emphaser_EA1600/

Starsound SSA-D6000

1 x 720W @ 4 ohm

1 x 1200W @ 2 ohm

1 x 2000W @ 1 ohm

http://ampguts.realmofexcursion.com/Starsound_SSA-D6000/

u-Dimension 2k1d

700 Watts RMS at 4 Ohms

1300 Watts RMS at 2 Ohms

2000 Watts RMS at 1 Ohm

http://ampguts.realmofexcursion.com/uDimension_ProX_2K_1D/

[Adrian_D 520]

I don't know who the guy who posted the voltage rail argument is, his reasoning behind the fuse vs power rating is stupid.

And one more thing about the voltage rail vs power output. The voltage rail will drop under load because of the current demand. Measure the voltage at the outputs when it is wired at 8 ohms and measure when it is wired well below 8 ohms. Heck, measure the voltage rail and see that it drops below the idle value.

This is what i was actually trying to figure out.. i'm not that versed on amplifier design..

where exactly is the rail (voltage) inside an amp? and does the speaker see the rail voltage or a fraction of it?

Using fuses to determine the power output of an amplifier is like shooting in the dark, blindfolded and with 2 crippled hands holding the gun. I don't have any fuses on my Z1. Does that mean it will produce 0 watts ? Or unlimited power ?

so am i wrong here, or is it possible for the amp to do it's 3300Wrms rating on a 200A fuse..

1. What are you exactly trying to figure out ?

The current I mentioned isn't the input current, it's the current that has to be produced at the output. For instance, to produce 3600w at 1 ohm you need 60v and 60A at the output. The power supply will have to 'produce' more current as the impedance decreases and the voltage rail drops because of this. This is why you get more heat when wiring lower.

The speaker will see a procentage of the rail voltage.

The rail voltage is the voltage output from the amp power supply and it 'feeds' the actual amplifier stage.

2. I already explained that judging power by the fuse rating will get you nowhere fast. You don't know the exact efficiency. You don't know how much over-current that fuse will take and for how long. Stop obsessing over the fuse rating. The only way you will know the output for sure is if you measure the amplifier with a clamp meter.

I hope I'll have some time this summer to clear up the fuse and show how much current a typical fuse can take before blowing. I measured close to 2000w with an 80A fuse on the input when testing out an amplifier and the input voltage was around 12v. You do the math.

[3stagevtec 2]

P=VI

2000W = 12(I)

I= 166A

factor in efficiency and the current will be even higher!

2000W off an 80A fuse.. very interesting..

i know an 80A will be able to take a certain level of current past its rating, but that's almost double it's rating! how long did you run the burp to measure that 2000W?

i'm not denying you, i'm just shocked..

The power supply will have to 'produce' more current as the impedance decreases and the voltage rail drops because of this. This is why you get more heat when wiring lower.

The rail voltage is the voltage output from the amp power supply and it 'feeds' the actual amplifier stage.

learn something new!

[3stagevtec 2]

Sundown 1500D

where is the rail inside an amp? assuming i'd like to measure the rail voltage with a DMM..

[Adrian_D 520]

P=VI

2000W = 12(I)

I= 166A

factor in efficiency and the current will be even higher!

2000W off an 80A fuse.. very interesting..

i know an 80A will be able to take a certain level of current past its rating, but that's almost double it's rating! how long did you run the burp to measure that 2000W?

i'm not denying you, i'm just shocked..

The power supply will have to 'produce' more current as the impedance decreases and the voltage rail drops because of this. This is why you get more heat when wiring lower.

The rail voltage is the voltage output from the amp power supply and it 'feeds' the actual amplifier stage.

learn something new!

I was shocked too, that's why I posted that find.

Sundown 1500D

where is the rail inside an amp? assuming i'd like to measure the rail voltage with a DMM..

You can measure the positive and negative swing between the amplifier ground (most likely the negative output terminal) and one of the pins of the rectifying diodes. Don't do it unless you are very sure you are measuring the correct points.

You could guesstimate the voltage rail by measuring the output voltage on a high load. I got 118V out of my z1 at 4 ohms nominal which is exactly the value of the voltage rails.

One more thing : the voltage rail is influenced by the input voltage. The higher the input voltage, the higher the voltage rail. That's why you get more power when wiring at 16v or even 18v.