Setting gains with DMM...Have a couple questions?

[SilverBullet6.0 10+ year member]

I installed my RF T500-1bd amp today. Im hooking it up to 2 Kicker CVR 10's. These amps have 2 sets of outputs wired parallel internally, even though its a mono amp. My amp make 750 watts at 1 ohm. I hooked each sub @ 2 ohms to each output for a 1ohm load on the amp. My head unit has a 3-band eq as well as a sub level control, 0-14. I set my gains with the sub level up but the eq flat. Its not near as loud as it should be. Since my amp has parallel outputs, if I hook the dmm to one output, do I set gains to half of the v=sqrt(watts x impediance), or just v=sqrt(watts x impediance)? Also, should I set the gains with the hu's sub level up or down?

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[gunz4me2 10+ year member]

What test tone did you use to set your gains with? 0 dB, -3 dB, or -6 dB? Also what was your desired objective for final power? 500 watts or 750 watts?

If you want 500 watts @ 1 ohm, you are going to need to read 22.36 volts AC on your DMM. If you want 750 watts RMS @ 1 ohm, you are going to need to read 27.39 volts AC on your DMM. Generally a 50 or 60 Hz test tone works the best since that is close to where household AC floats around. ETA: Many of the lower cost meters won't read AC outside of the 50 to 75 Hz range OR they get horribly innacurate outside of that range.

Lastly, setting your gains via DMM should only be used as a starting point. You need to learn to trust your ear! //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[microhaxo 10+ year member]

I know for a fact that on Alpine and Sony decks that if you increase the sub level past FLAT (sony) or default (Alpine) that you introduce distortion.

Best bet is to leave it flat and set gains that way. If you have to crank up the gain to reach those levels then you should consider a pre amp line driver.

 

[SilverBullet6.0 10+ year member]

Im goin for the full 750. I set my gains with a 45hz 0db test tone since the bass boost is centered at 45hz. I originall set it to 27.4ish, but turned it down due to thinking I should halve it due to 2 outputs. Ill go reset them with the sub level 0 and set them to 27.4ish

 

[SilverBullet6.0 10+ year member]

Ok, so I tried resertting the gains, but mow Im even more frustrated! With the eq flat and bass level 0, i set the gain to 27.4. This amp is capable of putting out 750rms at 1ohm. I have 4ohm dvc subs wired parallel for 2ohm and the subs together parallel for 1ohm. With the gain set this way, it is quieter than my old amp which ws a kicker zx250.2 puttin 125 watts to each sub. This RF amp should put 375 to each. When I turn the gain or bass boost up farther and listen for distortion, it does get louder. But, before it gets as loud as it should it starts cuttin out? All my wiring is hooked up correctly. If I set it where it sounds good on one song, it cuts out on the next song! Ive tried setting my crossover to differnt frequencies and turning the infrasonic filter on and off but i makes no difference. Its either quieter than my old amp, or it cuts out. My gain isnt even a 1/3 of the way turned up to keep it from cutting out. What could be wrong?

 

[SilverBullet6.0 10+ year member]

Btw, I have an Optima yellow top under the hood and a 145amp alternator. Power and ground wires are 4awg RF. The wiring came with a 100amp fuse. And, there are no visible fuses on the amp? Where are they?

 

[SilverBullet6.0 10+ year member]

I figured it out! It was so simple too! I was setting my gains with my key on, motor off. I tried it with the motor running today, and viola! No cut-out and alot louder! With my motor off, the voltage was dropping to about 10.7-8, with my motor running, it hovers around 13.8-9. The amp was just "shutting-off" due to voltage drop.

One more question though. I incorrectly stated my hu's adjustments in my first post. It does have a 3band EQ, but the sub level is adjustable from 0 (highest) to -14(lowest). So, should I set my gains with this on -14, or on 0? With it on 0, and setting my gain to 27.4Vac for the full 750watts at 1ohm, the amp is quieter than my old 250.2? With my volume at 35/40, which I can hear no audible distortion at, I can turn my gain up further without hearing distortion and it does get pretty loud. So I'm thinking maybe I should set my gain with a dmm and my sub level at -14?

 

[Chrispy 10+ year member]

I know for a fact that on Alpine and Sony decks that if you increase the sub level past FLAT (sony) or default (Alpine) that you introduce distortion.
Best bet is to leave it flat and set gains that way. If you have to crank up the gain to reach those levels then you should consider a pre amp line driver.

No need to even mention Sony, but I always thought is was ok and sometimes recomended with Alpine decks to set the gain with the Subwoofer setting at 15/15 or somewhat high. Bass should be at 0 though.

But to the OP, I dont know what kind of HU you have but I say go with what ever is louder as long as there is no clipping or distortion. But if you have a bass and a seperate sub level you might be safe leaving them both at 0. Either way set your gain after you set your sub level.

 

[gunz4me2 10+ year member]

When it comes to Alpine, 15 is the true "0" point and anything less than 15 is a cut to the subwoofer volume. Then again, I'll throw a disclaimer in there since I only own a pair if CDA-9885s and a CDA-9887. I'll probably buy another 9887 when the replacement model hits stores and they discontinue production.