Gain setting with over/underrated amps

[thai_creeper 10+ year member]

How do gains get set correctly using the specs the company provides? what if the specs are underrated/overrated?

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[alpine3612 10+ year member]

Same way they get set with all amps... by ear

 

[vorgath 10+ year member]

Sounds like someone's trying an Audiobahn //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[thai_creeper 10+ year member]

lol I didn't mean by ear, I mean using a DMM with the gain setting tutorial sticky

 

[bjfish11 5,000+ posts]

o scope FTMFW

 

[mtdewelf 10+ year member]

you still would set it to what you expect outta amp, correct? the writing on amp,or paper makes no difference to your electrical system, if you wanna set a orion 1200d to 900@1ohm then use the sticky and figure what your DMM should read for that. This makes sense to me, could be off though

EDIT: re-read and thought maybe you are asking how to tell if underrated, if so you are gonna have to get her benchtested to be sure. Most amps should come with birthsheet too.

 

[Decipha 10+ year member]

don't set your godly 2000 watt legacy to 900 watts at any ohm load, you'd clip shit to death... sub death that is

 

[thai_creeper 10+ year member]

you still would set it to what you expect outta amp, correct? the writing on amp,or paper makes no difference to your electrical system, if you wanna set a orion 1200d to 900@1ohm then use the sticky and figure what your DMM should read for that. This makes sense to me, could be off thoughEDIT: re-read and thought maybe you are asking how to tell if underrated, if so you are gonna have to get her benchtested to be sure. Most amps should come with birthsheet too.

Yeah the first part is what I was asking about, because if an amp is underrated and you set it using the "false" claimed wattage(put into the equation) then wouldnt there be a risk of clipping? Also how accurate are birthsheets? I thought I read somewhere that nowadays birthsheets don't really mean much(probably for lower brand amps)

 

[mtdewelf 10+ year member]

the birthsheet should be what the amp did on a benchtest, they might of givin it more Volts then you will, so you might have to componsate for that. but i've only bought 3amps NEW and all came with one. what amp you using?

 

[thai_creeper 10+ year member]

right now I have a hifonics amp powering an L5, wondering about that when I upgrade amps(not sure what yet) but yeah for the most part it was more of a curiousity question

 

[mtdewelf 10+ year member]

easy fix then, don't buy a garbage amp.

 

[thai_creeper 10+ year member]

easy fix then, don't buy a garbage amp.

lol half the time i see people bashing hifonics, the other half the time people are defending them:crazy:

 

[alphakenny1 10+ year member]

o scope FTMFW

x2 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[thch 10+ year member]

To set the gains, you have to define the goals. there are 3 common goals:

1.) SPL -- get the most power without distortion and without damage to equipment.

2.) Street -- maximize the volume of the system, limiting distortion to an "acceptable" level and allowing for "adequate" tonal balence.

3.) SQ/HiFi -- minimize distortion and give good tonal balence while achiving a volume deemed "loud enough". SQ is a more subject goal where you might choose to add distortion or change the tonal balence because it just sounds better to you. but the goal isn't to get as loud as possible.

#2 is the most common goal. in all cases, damage to equipment is undesired.

only goal #1 can be acheived using a DMM or Oscope.

An Oscope or DMM is a tool and should be used in all 3 cases.

My General method for #2, #3.

1.) turn HU to 3/4 max volume. disconnect speakers. turn off effects.

2.) increase gains on all amps. use DMM to find an output voltage that is either the rated output of the amplifier, or the rated power of the speaker. MARK THIS GAIN. a cell phone camera or dot of ink/paint can be used. or a drawing.

3.) decrease all gains to minimum.

4.) reconnect a set of speakers to an amp. (apply filtering as normal)

5.) increase the gains until the speakers begin distorting or the value found in #2 is found, or the speaker becomes too loud. decrease gain slightly.

6.) disconnect the speaker. repeat #4,#5 for all amps

7.) reconnect all speakers. now all speakers are playing at the "loud" setting.

8.) leave the gain setting for at least 1 amplifier as it is. the speakers attached should be the least loud with the gain setting you found.

9.) lower the gain setting on the other amplifiers as needed to acheive an acceptable tonal balence.

10.) at this point you should have a fairly clean sounding system. it is now that you can optimize the system for your goals. if the subwoofers can handel the extra power, you can boost the gains on the subwoofers to give extra power (and minor clipping).

the DMM and Oscope are tools. if you set the gains using just these tools you will end up correcting yourself by adjusting the balence/fade/ect... on the HU to control the volume. at that point its only marginally better then cranking gains to maximum (and setting the volume to 5/30). *it is fine to set all gains using the DMM/OScope and then using the HU to control the actual volumes. i don't like this as much because if the battery gets disconnected, you usually lose your settings! so long as you realize that the DMM is just a tool you will be fine.

if you follow a method above, you should be able to achevie a goal of a system that is as loud as you want it (for SQ/HiFi) while limiting distortion to acceptable limits (HiFi/Street), and giving acceptable tonal balence (HiFi,SQ,Street).

edit --

if the amp was overrated, then you should have heard distortion and stopped increaseing the gains (inf steps 4,5). if the amp was underated you are still fine. Only for goal #1 is this an issue. for this goal, the amp should have its gain set using an Oscope or creatively with a DMM.

 

[thai_creeper 10+ year member]

wow thanks for takin the time to post all that, much appreciated. I like the idea of using the highest volume you would normally listen to though, just my opinion but thanks again for the response