Setting gains: Different voltage with diff hz test tones?

[Lurius 10+ year member]

Well I am once again, setting my gains(changed some stuff on the amp) and I first set the gains with a 50hz test tone.. but I was curious and tested it with a 35hz test tone and it is saying 55v instead of the 41v-42v I was getting with the 50hz tone.

Is this safe? Is this normal? What causes this?

Thanks again guys lol, sorry about so many questions, I just dont wanna fry my equipment!

-Lurius

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[helotaxi 5,000+ posts]

Where is your low pass crossover set? What about any bass boost? Having either of these turned on can affect the settings.

 

[ghart999 10+ year member]

I have always had this issue. No matter what test tone I use, a differnet one gives me different voltage.

 

[Lurius 10+ year member]

Where is your low pass crossover set? What about any bass boost? Having either of these turned on can affect the settings.

I actually just went outside a while ago and changed it up again.. I turned off the bass boost on the headunit(which works at 40hz), then changed the settings on the amp to 35hz and +12db. I re-tested the gain and its right at 42v now@ 35hz and lower at 50hz.. which following that same pattern as before, im willing to bet that @ 30hz it will be higher voltage than when on a 35hz test tone.. This making sense? Im no pro lol.

Thanks,

Lurius

PS: Im not tuning it for competition or anything, would just like the get the most power out of the subs. If I can ever get a good box design for under the rear seats then i may go to some better subs with higher output, but for now im stuck with .7 cubes and 5.57 depth =(

 

[helotaxi 5,000+ posts]

The next thinkg to ask is do you have a "true RMS" multimeter. A lot of DMMs for RMS just take an average based on a set sampling frequency. A true RMS actually calculates the RMS which is different from an average. With a lower freq, the average value will show as a higher voltage than the RMS.

 

[Lurius 10+ year member]

I have no idea =(.. How would I find this out?

-Lurius

 

[helotaxi 5,000+ posts]

The manual for it would tell you. It's a selling feature for DMMs.

 

[PhatTonyDeMarco 5,000+ posts]

Turn the bass boost off, you said you set it to +12dB, which it should not be...

 

[Lurius 10+ year member]

I was told before that if you wanted to use bass boost to set it accordingly before setting gains?

-Lurius

 

[Fast1one 10+ year member]

Dont use bass boost at all....

 

[helotaxi 5,000+ posts]

I missed that your bass boost was on. That is the cause of the different voltages.

 

[Lurius 10+ year member]

I put bass boost on +0db on both the amp and the head unit. I really only needed it so I could listen to some music without the bass booming too loud, but I just realized the bass boost on the HU has a - setting as well lol, so I can just turn it down there when I have to.

Thanks guys, it seems to be holding out good now, did a 20hz-100hz sweep test tone and the voltage did fluxuate still on different hz, but never got above 42v, so im happy and satisfied it wont F anything up!

-Lurius