gain setting and imp rise

[orioles26 10+ year member]

When setting the gains on the amp wont the amp actually be seeing a higher impedence so the gains would be slightly lower then they should be. So would it be safe to set the gains slightly higher to compensate for imp rise?

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[theCybe 5,000+ posts]

Yes.

 

[jellyfish420 10+ year member]

Yes.

depends. even though you'd have a slightly higer imp rise. the signal will still clip at a certain point. the safest route to set an amp is w/ an o-scope.

and no the gains aren't slightly lower than they shoud be, your just getting a little less power than you would w/ a 4 ohm load (or what ever load). when ever you set your gains you set them knowing that a 400x1@4ohm amp does 400w@4ohm. so just be careful you don't clip it.....

 

[theCybe 5,000+ posts]

there are a zillion variables.

* Is the amp capable of more power than the sub's rated RMS?

Cranking the gains above whatever voltage produces the 400watts your sub is rated for with an amp that's rated for 350watts isn't a good scenario. Conversely, if you have 600wrms at your disposal, you're good to run an extra volt or two into your 400wrms rated sub.

* Are we already pushing it with a low input voltage?

If the amp's only finding a few millivolts input, it'll already be gained pretty high to achieve the desired output. That extra little bit may be enough to clip, especially if you're dealing with an input signal from the type of unit that's only capable of a few drops of preamp voltage.

* How's the source material?

That compressed amatuer rap remix MP3 in conjunction with your extra few output volts could be a disasterous combination. On the other hand, if you're playing the SQ CD, or any material that's mastered correctly (and the above possibilities are in the safe zone,) you'll be just fine.

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It's not a yes or no question, but I threw yes out there because audio dynamics are just as much an art as a science.

You won't blow anything up unless you're irresponsible about it.

Impedance rise isn't a constant, it varies with driver, enclosure, power, temperature, frequency, and any physical resistance / energy.

I wouldn't count on it to save your *** unless you've done the research and know for a fact that the x Hz burp you're playing yeilds y ohms of resistance.

 

[theCybe 5,000+ posts]

* Was that enough information, or was the "Yes." sufficient? //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[jellyfish420 10+ year member]

It's not a yes or no question, but I threw yes out there because audio dynamics are just as much an art as a science.

You won't blow anything up unless you're irresponsible about it.

Impedance rise isn't a constant, it varies with driver, enclosure, power, and tone.

i'm just assuming that he already has the gain up to deliver what the amp is rated for, regardless of sub. if you go to turn the gain up on a 400w amp thats already set for 400w, that in all actualality, only does 375w then your already clipping the amp, and by turning it more your just gonna clip the signal even more. and an underpowered clipped sub will blow faster than an overpowered clean sub (to an extent)

either way, like cybe said, just don't go stupid w/ it and you should be cool.

 

[thch 10+ year member]

what goal are you trying to acheive.

lack of distortion occurs when the amp can always provide adequete voltage and current to the speaker. lower impedances draw less current, but do not affect the voltage.

protection of the speaker occurs when the speaker cannot overheat or overexurt. this can happen regardless of the amp's clipping or not (based upon power output and speaker), though clipping is the best chance method to blow a speaker (maximal power output)...

i am still of the opinion that gains shoud be _set_ by ear, and _checked_ by dmm/oscope. with the exception of competitive SPL setups which can benefit from oscope/clamps.

 

[orioles26 10+ year member]

I have a power acolustik a3000db at 1 ohm on two 12" type rs. from listening to it i think they can handle more power thats why i was wondering if i could turn the gain up some.

 

[theCybe 5,000+ posts]

Which opens another can of worms: can your charging system support that much draw?

 

[jellyfish420 10+ year member]

Which opens another can of worms: can your charging system support that much draw?

which brings up the real problem. not impedance rise...but voltage drop:crap:

 

[thch 10+ year member]

yes. if you look at the curves, if gain is constant (set to "max") an impedance is increased, then the power decreases. if impedance is decreased, the currents become higher and this causes heat and other issues.

if one keeps a constant impedance and turns down gain, power decreases. if they turn up gain the output voltage limit is reached and distortion is added (as well as the associtate power)

because speakers are usually seen as being damaged by overpower or overexcursion, there is a good chance that they can be undamaged by an amplifier with overly high gains, except the high gains also cause distortion.