Input sensitivity / output voltage

[95Prober 10+ year member]

Hi.

I know that when determining the output voltage you use RMS x OHMS then the SQ.ROOT to get volts. However, do you just simply take the RMS rating that the company gives? I mean, what if the amp is underrated and puts out more RMS watts then is listed on the specifications?? In that case, it would change the total result

Does it matter that much?

Just curious Thanks!

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[thch 10+ year member]

this is one criticism of using a DMM to set gains. the manufacturer may misrate the amp either high or low. further, amps with unregulated power supplies have different power output capabilities as the battery voltage changes. This means that you will likely be off by a bit as well due to your charging system not being the same as the amp was rated with.

because minor clipping is largely harmless, especially for large woofers playing music for 5 minutes at a time, you don't need to worry too much. Further, you are measuring voltage to find power, so even if the amp is clipping slightly, its not putting more power to the speaker then rated, just more distortion.

since hearing is logrithmically based -- eg, sounds must have a huge amount of extra power to sound just a bit louder, this does not overly affect most setups.

the dmm still doesn't tell you if the setup sounds good. you still need to have some way to adjust volumes of each speaker stage individually to ensure the system blends together.

 

[95Prober 10+ year member]

this is one criticism of using a DMM to set gains. the manufacturer may misrate the amp either high or low. further, amps with unregulated power supplies have different power output capabilities as the battery voltage changes. This means that you will likely be off by a bit as well due to your charging system not being the same as the amp was rated with.
because minor clipping is largely harmless, especially for large woofers playing music for 5 minutes at a time, you don't need to worry too much. Further, you are measuring voltage to find power, so even if the amp is clipping slightly, its not putting more power to the speaker then rated, just more distortion.

since hearing is logrithmically based -- eg, sounds must have a huge amount of extra power to sound just a bit louder, this does not overly affect most setups.

the dmm still doesn't tell you if the setup sounds good. you still need to have some way to adjust volumes of each speaker stage individually to ensure the system blends together.

Well, my amps have Zenon boards in them, and from my knowledge, most if not all Zenons are underrated to a degree. So, if the amp is underrated by 200-300 watts, would that amount be a big difference regarding output voltage? the difference is around 6 volts.

Ill be running the class-d amp at 2 ohms and is factory rated at 1100x1 @ 2ohms but the spec sheet I got from them says 1405x1 @ 2ohms (not sure if its the official birthsheet though or not)

 

[n2audio 5,000+ posts]

Further, you are measuring voltage to find power, so even if the amp is clipping slightly, its not putting more power to the speaker then rated, just more distortion.

What?

I thought one of the definitions of clipping is that it produces more power than an unclipped signal at the same voltage.

 

[squeak9798 5,000+ posts]

What?I thought one of the definitions of clipping is that it produces more power than an unclipped signal at the same voltage.

Depends on what voltage we are talking about //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

For a sine wave, RMS voltage = Peak voltage * .707

For a square wave ("fully clipped"), RMS voltage = Peak voltage

If we are comparing RMS voltage, then the two will be of equal power. If we are comparing peak voltage, then the clipped wave will have more power.

 

[thch 10+ year member]

What?I thought one of the definitions of clipping is that it produces more power than an unclipped signal at the same voltage.

well it does, but there are two cases.

normally clipping is from people being greedy. eg, the amp's PSU provides 50V. the user puts in a strong signal and cranks the gain. in order to fufill this need, the amp would need to put out 2500V. this can't actually happen, so the amp outputs 50V. and the high gain assures that the amps output will stay at 50V (or -50V) for the majority of the wave. this cleary gives more power then a sine wave with a peak of 50V.

the second case is the amp giving up. eg, if in the same case the user set the gains to get 50V peaks (unclipped signal output), then later the battery sags to 10V from 12V and the PSU only provides 40V. now the amp is clipping, but never putting out more power then it would have if the users original, sane setting, were used.

and yes, for a given peak voltage, the clipped signal is higher power then the sine wave.

 

[95Prober 10+ year member]

Well, my amps have Zenon boards in them, and from my knowledge, most if not all Zenons are underrated to a degree. So, if the amp is underrated by 200-300 watts, would that amount be a big difference regarding output voltage? the difference is around 6 volts.
Ill be running the class-d amp at 2 ohms and is factory rated at 1100x1 @ 2ohms but the spec sheet I got from them says 1405x1 @ 2ohms (not sure if its the official birthsheet though or not)

so what do you think in my case assuming the amp is underrated by 200 - 300 watts ? do I use the spec sheet numbers (1405) or advertised rating (1100) when calculating?

 

[helotaxi 5,000+ posts]

200-300 watts isn't goin to provide a clearly audible difference in output so go with the more conservative number and leave your amp some leeway before clipping.

 

[dman4486 5,000+ posts]

birthsheets FTW....

200-300 watts isn't goin to provide a clearly audible difference in output so go with the more conservative number and leave your amp some leeway before clipping.

I went from rated 460wrms to birth sheet 1251wrms(~37vac) and got a huge difference

 

[helotaxi 5,000+ posts]

460 at what impedance? 4 ohms? Looking at the model number of your amp it's rated for 1250 watts.

 

[dman4486 5,000+ posts]

460 at what impedance? 4 ohms? Looking at the model number of your amp it's rated for 1250 watts.

460 total rms on a 2 channel kenwood 230 per rsd

 

[helotaxi 5,000+ posts]

So basically your post had no bearing on the topic at hand and you were just whoring it up as usual, copy.

 

[dman4486 5,000+ posts]

So basically your post had no bearing on the topic at hand and you were just whoring it up as usual, copy.

no...you said 300 watts wouldn't make an audible difference...I went from 230 per sub to 625 per sub and it made a huge difference

get off my nuts

 

[squeak9798 5,000+ posts]

no...you said 300 watts wouldn't make an audible difference...I went from 230 per sub to 625 per sub and it made a huge difference

His post was in regards to the difference between 1400w & 1100w, where 300w isn't going to make much (if any) of an audible difference.

It wasn't a general comment that 200-300w is never going to make an audible difference, as you apparently interpreted it.

 

[btdickey99 5,000+ posts]

no...you said 300 watts wouldn't make an audible difference...I went from 230 per sub to 625 per sub and it made a huge difference
get off my nuts

yea but you were also doubling your power...which does make an audible difference