Headunit subwoofer level output VS amplifier gain

[Golitan11]

I have a Pioneer DEH-X7500S headunit (4V preouts), an Hifonics BRX1100.1D and a Sundown SA-12 D2. I was wondering what is better to set your gain right:

1. Turn the subwoofer level output up on the headunit (maximum for example, which is +6 in my case) to use the full potential of your 4V preouts and minimize the amplifier work (lower gain), and then adjust the gain from that to match the desired voltage with a DMM (28-30V in my case).

or

2. Keep the subwoofer level output on the headunit at 0 and turn up the gain on the amplifier (higher than option 1 for sure) to match the desired voltage with a DMM (28-30V in my case).

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[bbeljefe]

Set your gains with volume as high as possible before clipping and with subwoofer level at max. If you set the sub amp at a low output level from the head unit, you will send it into clipping when you turn it up.

That said, if you want to have a little headroom for media that's not recorded at full volume, bump the gain up slightly but don't use full volume when it's not needed. And for gods sake, don't let anyone else use your car if you do that. ;-)

Also, if you don't know where your head unit clips, set it at no more than 80% of full volume. On Pioneer units that have zero to 60 volumes and, iirc, they usually clip at around ~48. Maybe someone who has metered one will pop in and share some wisdom.

 

[Golitan11]

I just tried to get the voltage coming off the RCA's (subwoofer preamps) with my DMM at full volume (speakers off for sure) with a 50 hz test tone (no EQ or filter) and I got 1.8V each with the subwoofer output level set to +6 (maximum) and 1.2V each with the subwoofer output level set to 0. I am a bit confused with this since they are suppose to produce 4V. Why do I get those numbers? Is 1.8V too high? Thanks.

 

[maylar 10+ year member]

What was the source? The level you get depends on the level of the source. You will only get 4V with a 0dB recording. And 1.8v is fine.