Setting gain *yes I read the sticky*

[bubbagumper6 5,000+ posts]

h/u SUB setting? where are the subsonic/hpf set at? if they are filtering out some of the 50hz that can do it..
while using a load on the amp is ideal most don't have dummy loads like that.. I sure don't

EXACTLY. Ideally your gain should be set with an oscilloscope, but what we're providing is the cheapest most cost effective way to set your gains with a decent amount of accuracy. Most noobs on here don't even want to spend $5 on a DMM you think they're really going to run out and buy dummy loads JUST to set their gains? Get real bro.

 

[bruceg 10+ year member]

Head unit is a Lanzar SDN70U.

HPF is as far down as it goes and the switch is over to LPF.

Subsonic is all the way down. (I assumed it was supposed to be?)

I didn't mess with the HU's subwoofer level. In fact, I didn't even know that could be directly adjusted as I just have regular right channel/left channel RCA outputs going to the amp.

 

[KyleBechtold 5,000+ posts]

Head unit is a Lanzar SDN70U.HPF is as far down as it goes and the switch is over to LPF.

Subsonic is all the way down. (I assumed it was supposed to be?)

I didn't mess with the HU's subwoofer level. In fact, I didn't even know that could be directly adjusted as I just have regular right channel/left channel RCA outputs going to the amp.

Sorry I meant the LPF.. if it is all the way down that is why you can't get the voltage you need.. if this is a ported setup set that to about 80hz then you should be able to get the voltage

 

[bruceg 10+ year member]

Gotcha. Will turn it up to ~80 and see what I can do. It's at 30 right now.

Thanks!

 

[Mitch86 5,000+ posts]

EXACTLY. Ideally your gain should be set with an oscilloscope, but what we're providing is the cheapest most cost effective way to set your gains with a decent amount of accuracy. Most noobs on here don't even want to spend $5 on a DMM you think they're really going to run out and buy dummy loads JUST to set their gains? Get real bro.

Not to mention a True RMS meter which would cost more than some of these peoples entire set up. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[RSDXzec 10+ year member]

I do not have the sub connected when I am setting the gains.

 

[bruceg 10+ year member]

Sigh, you all say something different in regards to hooking up the sub or not hooking it up. lol

 

[RSDXzec 10+ year member]

Sigh, you all say something different in regards to hooking up the sub or not hooking it up. lol

here's what you do: set the gains without the sub, then connect the sub and measure the voltage. It should be lower, by setting the gains without the sub you are sure that you aren't pushing it past rms in any way. If you have the sub connected then you will definitely be closer to that limit. It all depends on how safe you want to be. I'd like my sub to last forever, so I set gains without the sub connected.

 

[bruceg 10+ year member]

This logic is sort of faulty tho.

You're setting off RMS, not what the sub can take MAX. You still have a big window there to play with before doing damage.

Right?

 

[RSDXzec 10+ year member]

This logic is sort of faulty tho.You're setting off RMS, not what the sub can take MAX. You still have a big window there to play with before doing damage.

Right?

no, not right, setting the gains to match the rms is what the sub can take constantly, I would only set the gains close to max if I was in competitions, where subs can burp at high power for a short period of time. If you want to set them to max then go ahead, let me know how long it takes for your subs to smoke up.

 

[bruceg 10+ year member]

Right that's what I was saying. Set the gains to RMS, NOT max.

 

[IonRL205 10+ year member]

You can connect them or just leave them off. Most people choose not to connect it so they don't have a 50 hz test tone blasting in their ears, but either way will work. I saw a video of somebody testing it and the voltage stayed the same, and I've tested this myself and it still reads the same.

 

[Flex68 10+ year member]

OP, setting your gains via the DMM and formula you used is easiest way, even if the least accurate.

To wit: You calculate for your amp's max output of 760WRMS, set your gains to make your amp output the 55.1V, and all is kosher, yes?

Not really!

This is based solely upon rated speaker impedance....but but what about box-rise?

Theoretically, say your enclosure presents an additional load of 0.85 ohms. Well, that would mean you need an additional 11.7V added to your earlier calculation of 55.1V.

BUT, since the load seen by the amp is reactive versus purely resistive, anyway....then there's temp variation, voltage drops across speaker wiring and terminal connections, and several other variables to be taken into account.

Anyone got a non-linear equations book handy.....? //content.invisioncic.com/y282845/emoticons/suicide.gif.a649d21efc0d1fd4890a6428166586c1.gif

Ah, well. Maybe you should just set it up for 55.1V without subs connected.

At least for now!

 

[bruceg 10+ year member]

So set for 55.1 with no subs since this will drop anyway after taking into account speaker wire, box resistance, etc?

 

[Flex68 10+ year member]

That's what I would do, guy....plenty of time later for "tweaking" if you want to use a clamp-on AC meter to test and make adjustments for box-rise, and etc, ad nauseum.

Assuming your speakers are able to handle the amp at max, then 55.1V should be a nice, safe initial setting to get you bumping