Can I “tone back” an amp?

[Josh1134]

I have 2 Skar IX-10”s wired to 2 ohms. The combined rms rating is 400 watts (200 per sub). My amp is rated at 800 watts @ 2 ohms. If I just make sure I’m not clipping/distorting, is it okay to run this set up? It is not currently distorting but I’m worried I may hurt the drivers by doing this. Any advice would be appreciated

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[ThxOne Premium Member]

Check this out...

They will handle 400w rms... on a sinewave, not music. They will be getting less power on music.
So, do this. Get a -10db 40hz test tone ready. Set your EQ flat, Sub crossover all the way up, no loudness, no bass boost, bass knob if you have one maxed all the way up. Disconnect your sub wires from the amplifier. Hook up a DMM's leads to the positive and negative speaker outs on the sub amp and set the DMM to A/C Volts. Turn your head units volume up to its max undistorted volume and play that 40hz test tone. Start turning your gain up until the DMM says 34.64 or rounded to 35v. 34.64v at 2 ohms should be near 600w. Now hook everything back the way it is supposed to be... set the crossover to like 80hz, turn down the bass knob, hook your sub back up, turn the head unit down.... Play some music and enjoy. You will now be closer to 400w RMS on music. Use a -10db 40hz test tone.

 

[n2audio 5,000+ posts]

Get a -10db 40hz test tone ready. Set your EQ flat, Sub crossover all the way up, no loudness, no bass boost, bass knob if you have one maxed all the way up. …..
Use a -10db 40hz test tone.

Using an attenuated tone for gain adjustment on an overpowered speaker is the opposite of what you want to do. C'mon.

It's actually not that big of a deal Josh. Just min your gains and adjust them by ear to a reasonable level. Obviously you want to err on the conservative side. Be particularly careful when you're listening at high volume.

If you want to verify by DMM use a 0dB tone. Instead of tuning the gain to 40v (Sqrt(2*800)), you'd just tune it to 28v (sqrt(2*400). That would ensure the amp's output would never exceed 400w. There would be no harm in setting it for 31-32.

 

[ThxOne Premium Member]

He isn't going to hit 400w on music and with box rise and the -10DB tone will give him a little more room if he needs it without frying anything.

 

[fithwheel]

I’m an old ear adjuster f all that test tone sh:t.
Ok for a noobs I guess

 

[ThxOne Premium Member]

When set with the -10db tone, the subs peak can now be eq'd down and evened out but when needed the bass knob can be used to boost the sub. When using the 0db tone there is no room to boost anything and you are stuck at that output.

Also, 600w divided between the subs gives them 300w apiece on a tone. On music they MAY be getting 225-250w apiece. -10db tone setting allows for that little extra... which may let the subs see 275+ apiece briefly during different musical passages which will not blow them.

 

[n2audio 5,000+ posts]

He isn't going to hit 400w on music and with box rise and the -10DB tone will give him a little more room if he needs it without frying anything.

You're telling him how to set an aggressive gain -- as though he has subs with double the power rating. Your answer to "how do I dial my amp back a bit for relatively low power subs?", is - just do it like normal, but give it a little extra.

Got it

 

[n2audio 5,000+ posts]

I’m an old ear adjuster f all that test tone sh:t.
Ok for a knob I guess

That's a lot better idea than using a -10 tone. Way better.

 

[ThxOne Premium Member]

No, if he sets his gain on that amp for a 2ohm load to 400w with a 0db tone... when is he going to get 200w per sub with music? You and I both know he wont see 200w per sub. They will be underpowered on music with no room to boost them without really distorting them with stuff like a bass boost on the amp or loudness in the head unit.

My suggestion will get him much closer to 200w per sub with room to boost the signal with different, quieter music.

 

[fithwheel]

A little experience along with some common sense is all it takes to adjust gains by ear.

 

[ThxOne Premium Member]

Some ears may not be able to hear what needs to be heard to adjust gains by ear. Just sayin'

 

[n2audio 5,000+ posts]

No, if he sets his gain on that amp for a 2ohm load to 400w with a 0db tone... when is he going to get 200w per sub with music? You and I both know he wont see 200w per sub. They will be underpowered on music with no room to boost them without really distorting them with stuff like a bass boost on the amp or loudness in the head unit.

My suggestion will get him much closer to 200w per sub with room to boost the signal with different, quieter music.

Your suggestion is likely to have him at ~250/sub, frequently, at moderate volume levels.

Just out of curiousity, if -10 is your conservative recommendation, what do you do when your amp and sub(s) are of equal power production/handling?

 

[ThxOne Premium Member]

Your suggestion is likely to have him at ~250/sub, frequently, at moderate volume levels.

Just out of curiousity, if -10 is your conservative recommendation, what do you do when your amp and sub(s) are of equal power production/handling?

What, like say if my sub(s) handle 1000w rms @ 1ohm and my amplifier puts out 1000w rms @ 1ohm?

Simple - I will use a -10db tone and set that amplifiers gain to 31.62v for that 1 ohm load. Or I will find an amp that puts out 1500 - 2000w rms at 1 ohm so I have a cleaner signal when I still set it to 31.62v with the -10db tone if that 1000w is the power I am looking for.

Edit: I would probably still set that original amp for like 34.64v Because we aren't listening to tones, we are listening to music.

 

[Josh1134]

Thanks for all the advice guys. I really appreciate it. Also I don’t know if it matters but the subs are in a sealed box. The reason I have this larger amp is because my old amp (380 @ 2 ohms) was overheating after an hour of moderate music.

 

[ThxOne Premium Member]

Just for the record and for the OP, I am practicing what I am preaching. I am running a single 10" sub that is rated for 500w rms at 2 ohms. I used a -10db 40hz tone and set the amplifiers gain to 35v on the nose. Right at 615w. I can crank the bass knob on ANY song and it does not flop, distort, or complain in any way. My sub bass eq is flat, no loudness, no bass boost. Just the bass knob and it sounds great.