Setting gains.. Not the typical

[pimpnyou204 10+ year member]

Yes another one of those threads.. But mine I think is different..

Equipment-

Eclipse avn 726e

Rainbow slc set ran off amp crossovers

Greenlee dmm

Arc audio ks 300.4

Ok my headunit I've done a ton of research and everyone says it will not clip at full tilt at all unless u play with the treble and such. Reguardless I'm not pushing it to 5v. My speakers are 100 rms each. The amp is 90 rms at 4ohms and will not clip at all at 4v and supposedly won't slightly higher either. So obviously since my amp is the lowest at 4v that's the volume of my headunit I'm going to use.

Testing-

Ok so I play my 1k tone on repeat and turn the volume on the headunit up to 4v which is volume 77. Next I plug te RCA into my amp and with the amp gain at max (4v) I'm getting a reading of 40 voltage. Now going by the chart I should be sitting at 20 ac voltage for 100 watts at 4v. So I turn the volume down on the headunit and I'm at volume 72 which gives me the 20 ac volts from one channel on my amp. Now from the headunit at this volume I get 2.5v.

Since curiousity got me I wanted to see how much power it could put out at full power and I got 60 ac volts which is like 360 watts from one channel.. Seriously is that even possible from a small 4 channel?

Ok so basically saying why is my amp making rated power way below its needed voltage? And since it is what would u run the amp at? Greenlee I thought was a decent dmm could it be messed up? It ready my hu fine and the ohms of my speakers ok...

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[nismos14 5,000+ posts]

The gain at 4v, you mean it's at MIN right? If it's max, that's your problem. Max is probably 0.4V, not 4V.

 

[whitedragon551 5,000+ posts]

Why are you turning down the volume on the headunit to match voltage at the amp? You should be turning the headunit to the max volume you listen to at and use the equation to figure out where your voltage should be. Then use the gain knob on the amp to match.

 

[pimpnyou204 10+ year member]

The gain at 4v, you mean it's at MIN right? If it's max, that's your problem. Max is probably 0.4V, not 4V.

I beleive the higher number is max no? But either way it can go from .20v to 4v and since my hu can do 5v I'm honna do the 4v from my amp.

 

[pimpnyou204 10+ year member]

Why are you turning down the volume on the headunit to match voltage at the amp? You should be turning the headunit to the max volume you listen to at and use the equation to figure out where your voltage should be. Then use the gain knob on the amp to match.

I understand that and that's what I did.. But what I don't understand is why would my amp gains be set at 4v and my hu sends the signal thru at 2.5v and I'm already getting my max ac voltage from the amp..

If I did it your way and set it to volume 77 (4.5v) and my amp gain at 4v I'll have 40 ac volts coming out.. And 40 ac volts is 400 rms at 4 ohms per channel rms which is close to double my amps supposed rated power at that ohm...

 

[pimpnyou204 10+ year member]

Just to try and help

Headunit

AVN726E Online Manual / ECLIPSE

Amp

WoofersEtc.com - KS 300.4 - ARC Audio 4 Channel 700 Watt Amplifier

Dmm

http://www.amazon.com/gp/product/B000FCIOYW?ie=UTF8&force-full-site=1

 

[nismos14 5,000+ posts]

So you're saying that the gain knob is turned nearly all the way to the left, correct?

 

[pimpnyou204 10+ year member]

Yes it's turned so that in theory it would be the quietest (4v.)

 

[nismos14 5,000+ posts]

maybe the amp is underrated, or super duper efficient, or something was calculated wrong, or you're just overthinking it.

 

[bgowdy 5,000+ posts]

Why are you turning down the volume on the headunit to match voltage at the amp? You should be turning the headunit to the max volume you listen to at and use the equation to figure out where your voltage should be. Then use the gain knob on the amp to match.

whats the equation????

 

[pimpnyou204 10+ year member]

maybe the amp is underrated, or super duper efficient, or something was calculated wrong, or you're just overthinking it.

I actually called arc audio and asked.. They told me it is very under rated it can do 125 @ 4 ohms per channel and 200 @ 2 ohms on all channels unclipped.. He then explained it was bcuz of the 0db tone and said I should use a -6db tone bcuz music almost never goes above -6 yet alone 0.

 

[fish1234 10+ year member]

Yes it's turned so that in theory it would be the quietest (4v.)

I had a Arc Audio KS 900.6 amp and I had no gain at all, just a really efficient line of amps.

 

[pimpnyou204 10+ year member]

I had a Arc Audio KS 900.6 amp and I had no gain at all, just a really efficient line of amps.

Yes that is why I got it and after the phone call with arc audio I was told that he's never been able to put one into protect.. The only way he did it was the 800 watts unclipped he then taped the vents and threw a towel on top and played an hour.. That's dam good for this small amp. I've become a fan heh

 

[BnGRacing 10+ year member]

You can't set an Arc amp with a DMM. You'll be better off using your ears or paying a shop $50 to scope your car...

 

[keep_hope_alive Premium Member]

He then explained it was bcuz of the 0db tone and said I should use a -6db tone bcuz music almost never goes above -6 yet alone 0.

almost all modern music is fully pegged at 0dB for most of the song. it's called "equal-loudness mixing" and it plagues modern recordings. been this way for about 15 years now.

the other reason you got a sudden jump is because you were clipping. the HU may not clip at 14.4VDC supply but can clip at 12VDC supply. was the car running or off during your measurements. clipping increases the RMS value read by the DMM.

it's a moot point anyway - you won't listen to music at max volume and the speakers don't need that much power to satisfy you. you are just setting gains to ensure you don't clip, but now listen to the system and i doubt you'll ever go over VOL 60...

the point of the DMM setting routine is if you have an amp that is smaller than your expectations, and you want to ensure you don't clip when trying to get the most out of it. and yes, a scope is a better tool... or the DD-1.