DO amps pull more current if paused and played at full volume?

[vehementSPL 10+ year member]

Now before this gets moved it is here cause it is a general question. I have a friend that has heard for meca (cause they use certain fuse rules for classes in combination with cone area). If you "roll" into the volume on a test tone the fuse will hold up longer for a score. I figured the rolling into it heats up the fuse so thus would lower the time at which the fuse would handle a full power burp. I honestly don't know a great amount about amplifiers... Is it like an a/c compressor where it pulls more current at start up? honestly I highly doubt this... but again I do NOT know a lot about the internals nor works of an amplifier . The ONLY possible thing I can guess .... Is i know on average takes .approx 3 seconds for the termlab to register the full volume. And depending on what stalls the full reading maybe the time is bypassed by rolling up the volume (maybe part of the time is utilized by the lower volume roll up then only has to hold the full volume for a second or so to make the meter climb... only a guess. PLEASE audio experts help. There is somebody that does say if they pause and have it full volume and hit play it pops their fuse but if they roll into it.. it i fine for the run

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[Trixter 10+ year member]

well, if you think about it, it would make sense that it would draw more if you burp your amp as opposed to doing a sweep. think of the fuse as a gate or a dam. if pressue is put against it gradually, you could apply a said amount of pressure befor it would give. now say you hit it with the same max pressure in the last example, but this time it hits all at once. not sure if this is true, but it sound s good. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[vehementSPL 10+ year member]

well, if you think about it, it would make sense that it would draw more if you burp your amp as opposed to doing a sweep. think of the fuse as a gate or a dam. if pressue is put against it gradually, you could apply a said amount of pressure befor it would give. now say you hit it with the same max pressure in the last example, but this time it hits all at once. not sure if this is true, but it sound s good. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

That is kinda the theory I was going on lol. But this is an amplifier not water. I do know my old amps when I had them wired too low of an imp. if I pause/play on a tone it would clip it when subs were cold. but if rolled into it. it was fine.. Anybody have scientific knowledge on this. Perhaps audioholic? or immacomputer

 

[Immacomputer 10+ year member]

I'm not too sure if this is correct as I don't know enough about fuses but I think this may be what is happening:

Think of a fuse like a piece of meat. When the meat is frozen, it's very tough and won't stretch but it will break if the proper force is applied. If you warm up the meat gradually, you could apply the same force without breaking the meat. When solder is cold, it can snap easily but if it warms slowly, it can expand and it becomes more elastic which means it may be able to handle the expansion well if you roll into the volume instead of bursting it. This could be what is happening but I'm not too sure. It could very well be that the amp draws more current when burped at full volume but I don't know enough to say for sure. It seems more than possible though.

Oh, I mention solder because fuse material is similar to solder in the way it reacts to heat.

 

[vehementSPL 10+ year member]

Hmmm interesting.... Anybody else as well? we might try a few test with a clamp meter to see if there is a difference on current pull. And if there isn't I am going to assume it just starts reading on the meter a little sooner and doesn't have to hold the peak note as long. Not positive though. I would like to know for sure on if the amps draw more

 

[tommyk90 5,000+ posts]

Now before this gets moved it is here cause it is a general question. I have a friend that has heard for meca (cause they use certain fuse rules for classes in combination with cone area). If you "roll" into the volume on a test tone the fuse will hold up longer for a score. I figured the rolling into it heats up the fuse so thus would lower the time at which the fuse would handle a full power burp. I honestly don't know a great amount about amplifiers... Is it like an a/c compressor where it pulls more current at start up? honestly I highly doubt this... but again I do NOT know a lot about the internals nor works of an amplifier . The ONLY possible thing I can guess .... Is i know on average takes .approx 3 seconds for the termlab to register the full volume. And depending on what stalls the full reading maybe the time is bypassed by rolling up the volume (maybe part of the time is utilized by the lower volume roll up then only has to hold the full volume for a second or so to make the meter climb... only a guess. PLEASE audio experts help. There is somebody that does say if they pause and have it full volume and hit play it pops their fuse but if they roll into it.. it i fine for the run

In my vehicle, rolling into it DEFINITELY makes the fuse last longer. Plus it's not as hard on the sub either.

The aforementioned reasoning is logical as well. I'm assuming its not as much of a "shock" to the fuse.

 

[thylantyr 10+ year member]

One of the more interesting questions I've seen in a long time. I've done amps tests,

fixed amps, seen other people's amp tests, but I have never seen anyone do a test where

you drive the amp to full power on a burp, then plotted input current draw.

An amplifier has potential to draw alot of current upon turn on depending on the design

of the amplifier. A basic power supply design, when first turned on, can have very high inrush

currents that blow fuses. This is common knowledge in power supply design. Just by turning

the amplifier on [the power supply], you can cause high inrush. This is due to the transformer action from

off to on. A good power supply design will have some form of soft start circuit for the more

powerful amplifiers. For lower powered amplifiers, they may not even bother with implementing

a soft start because the inrush may be acceptable and not blow fuses.

There are high powered home audio amplifiers using conventional power supply design

that really needs the soft start circuit. In car audio though, it's an SMPS power supply,

it could be a simple and dumb SMPS design that can manifest this problem to some extent,

or it can use a smarter design where they ramp up the power supply upon start up, unbeknowst to the user.

I believe the common controller chip used in SMPS design already does this by default, the designer may

not have to do anything extra in the power supply design.

In that situation, there can be high inrush currents. But the question is, do you still

get high inrush currents after the amplifier has been turned on? Pause/unpause music

to burp at high SPL ?

Normally an amplifier has potential to score bigger numbers on burst tests. The shorter

the burp, the more power can be achieved up to the design limits of the amplifiers.

Continuous tones punish amplifiers vs. burst tones and those power numbers are the

lowest on continous tests. One reason why bursts offer more power is usually because the

amplifier rail voltage is at it's highest point under no load or very little load. Then under load,

when you unpause, the rail voltage can sag down. Lower rail voltage = less power. The burst

happens so quickly that the internal amplifier capacitors can hold the rail voltage high just

long enough to register the higher score, then the capacitors drain some to the sagging rail

voltage level.

But these are usually millisecond burst tests, lets say 25mS - 50mS tone bursts that can

cause higher power scores, but a continuous tone test can be alot less. But during this very

small time period, in theory, the amplifier wouldn't draw any extra current because the

amplifier didn't have any reason to because the capacitors took over briefly. In my weird

way of thinking, the amp may draw less than nominal. lol

But, the time period being discussed here is seconds, not milliseconds, so the story

will be different. Someone needs to test this as it is an interesting thing to check out.

 

[vehementSPL 10+ year member]

In my vehicle, rolling into it DEFINITELY makes the fuse last longer. Plus it's not as hard on the sub either.
The aforementioned reasoning is logical as well. I'm assuming its not as much of a "shock" to the fuse.

Well the question is how did you test them time wise? From the point you start rolling the volume up or once it hits full volume. The only way I am going to have to say to do a good test here. Is time it in seconds how long it takes for a burp pop. Then roll into it but DONT start timing till it hits full volume...

 

[tommyk90 5,000+ posts]

Well the question is how did you test them time wise? From the point you start rolling the volume up or once it hits full volume. The only way I am going to have to say to do a good test here. Is time it in seconds how long it takes for a burp pop. Then roll into it but DONT start timing till it hits full volume...

Problem is, not every burp is the same.

Take my runs at finals for instance.

Qualifying on saturday I didn't pop a fuse all day. Sunday I do the exact same thing volume wise and everything and I pop the fuse right after the first burp.

Fuses can be too inconsistent to get accurate readings from.

I can't burp my setup full tilt right off the bat. The sub doesn't like that too much. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I pretty much have to roll it up if i want to keep the coil in one piece.

 

[vehementSPL 10+ year member]

Problem is, not every burp is the same.
Take my runs at finals for instance.

Qualifying on saturday I didn't pop a fuse all day. Sunday I do the exact same thing volume wise and everything and I pop the fuse right after the first burp.

Fuses can be too inconsistent to get accurate readings from.

I can't burp my setup full tilt right off the bat. The sub doesn't like that too much. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I pretty much have to roll it up if i want to keep the coil in one piece.

yeah good point about the fuses. I guess resist. test fuses till ya find two similar. I know overall time rolling up last longer but that is cause the first few seconds isn't drawing current above the rating of the fuse.. Now the one way I can see this as I said before. I know I hear the lab takes up to around 3 seconds to read. so one way to do another test to see if maybe rolling it up starts the time of the lab to meter. Is with any fuse burp it and caculate how long it takes to get the full score. do a few test. then roll into a few times and once you hit max volume and start timing. who knows maybe a full burp takes close to 3 seconds. But if you roll into it you only have to hold max volume for 1 to 1.5 seconds. Which would be nice. It just may be a termlab trick and we think it is a fuse trick. NOW I do NOT know how or why the termlab takes a few seconds to fully take the reading. So this is just a "guess theory" off the top of my head. I would like to see some test though

 

[tommyk90 5,000+ posts]

yeah good point about the fuses. I guess resist. test fuses till ya find two similar. I know overall time rolling up last longer but that is cause the first few seconds isn't drawing current above the rating of the fuse.. Now the one way I can see this as I said before. I know I hear the lab takes up to around 3 seconds to read. so one way to do another test to see if maybe rolling it up starts the time of the lab to meter. Is with any fuse burp it and caculate how long it takes to get the full score. do a few test. then roll into a few times and once you hit max volume and start timing. who knows maybe a full burp takes close to 3 seconds. But if you roll into it you only have to hold max volume for 1 to 1.5 seconds. Which would be nice. It just may be a termlab trick and we think it is a fuse trick. NOW I do NOT know how or why the termlab takes a few seconds to fully take the reading. So this is just a "guess theory" off the top of my head. I would like to see some test though

Even if the fuses have the same resistance that doesn't mean they will last the same amount of time. Too many variables would have to be exactly the same for the test to be valid. Voltage before burp, voltage during burp, sub temperature, cabin temperature, etc.

I know in my setup, when I roll it up the "full" volume part does last longer than if I just straight burp it (this mostly happens by accident). But like I stated before, one time it will hold fine for 3+ burps, then the next time I'll blow the fuses instantly. It's a big guessing game sometimes.

 

[vehementSPL 10+ year member]

hmmm cool then. Yeah there are a few other factors

 

[vehementSPL 10+ year member]

One of the more interesting questions I've seen in a long time. I've done amps tests,fixed amps, seen other people's amp tests, but I have never seen anyone do a test where

you drive the amp to full power on a burp, then plotted input current draw.

An amplifier has potential to draw alot of current upon turn on depending on the design

of the amplifier. A basic power supply design, when first turned on, can have very high inrush

currents that blow fuses. This is common knowledge in power supply design. Just by turning

the amplifier on [the power supply], you can cause high inrush. This is due to the transformer action from

off to on. A good power supply design will have some form of soft start circuit for the more

powerful amplifiers. For lower powered amplifiers, they may not even bother with implementing

a soft start because the inrush may be acceptable and not blow fuses.

There are high powered home audio amplifiers using conventional power supply design

that really needs the soft start circuit. In car audio though, it's an SMPS power supply,

it could be a simple and dumb SMPS design that can manifest this problem to some extent,

or it can use a smarter design where they ramp up the power supply upon start up, unbeknowst to the user.

I believe the common controller chip used in SMPS design already does this by default, the designer may

not have to do anything extra in the power supply design.

In that situation, there can be high inrush currents. But the question is, do you still

get high inrush currents after the amplifier has been turned on? Pause/unpause music

to burp at high SPL ?

Normally an amplifier has potential to score bigger numbers on burst tests. The shorter

the burp, the more power can be achieved up to the design limits of the amplifiers.

Continuous tones punish amplifiers vs. burst tones and those power numbers are the

lowest on continous tests. One reason why bursts offer more power is usually because the

amplifier rail voltage is at it's highest point under no load or very little load. Then under load,

when you unpause, the rail voltage can sag down. Lower rail voltage = less power. The burst

happens so quickly that the internal amplifier capacitors can hold the rail voltage high just

long enough to register the higher score, then the capacitors drain some to the sagging rail

voltage level.

But these are usually millisecond burst tests, lets say 25mS - 50mS tone bursts that can

cause higher power scores, but a continuous tone test can be alot less. But during this very

small time period, in theory, the amplifier wouldn't draw any extra current because the

amplifier didn't have any reason to because the capacitors took over briefly. In my weird

way of thinking, the amp may draw less than nominal. lol

But, the time period being discussed here is seconds, not milliseconds, so the story

will be different. Someone needs to test this as it is an interesting thing to check out.

Yeah I would love to see some tests