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Discussion Starter #1
Hello guys,

I am starting to finalize the install for my Chevy Bolt EV and I noticed a difference between the output voltage of the Helix MK2 DSP (8v output) and the input voltage of the Alpine PDX-V9 (4v).

When I was testing the gear, the gains for the amp were set as low as possible (counter clockwise) and feel that I still need to lower it more, especially for the 2 tweeter channels (3-way active system).

I have read that I could lower the output channels from the Helix DSP and I do see the options in the Helix software however it goes by dB (currently set to 0dB) and not by voltage. What would be the best way if possible or what dB should I channel outputs to configure the DSP so that it will output around 4v per channel instead of 8v so I could have more flexibility with the amp gains.

My understanding is the voltage does not double or get cut in half like wattage does by +/- 3dB.
 

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You wouldn't need to calculate anything. Just set the gains as you would normally (-10dB or such) so that you won't clip, and adjust the output levels for the rest of the amps so your'e at the correct leve.
 

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Yeah, you don't really need to calculate anything, but halving power will reduce voltage to 70.7%. So at full power you may have 20 volts, at half power that would drop by 29.3% to 14.14 volts
 

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Discussion Starter #4 (Edited)
You wouldn't need to calculate anything. Just set the gains as you would normally (-10dB or such) so that you won't clip, and adjust the output levels for the rest of the amps so your'e at the correct leve.
When you say set gains, do you mean the channel output from the Helix software to -10dB for each channel?
I cant adjust the gains on the amp anymore as it is as low it can go and is still too loud.

I am afraid that I am clipping or am very close to clipping the input stage of the amp.
 

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When you say set gains, do you mean the channel output from the Helix software to -10dB for each channel?
I cant adjust the gains on the amp anymore as it is as low it can go and is still too loud.

I am afraid that I am clipping or am very close to clipping the input stage of the amp.
Simply reduce the output voltage from the Helix. I haven't played with the software much, but I think there is a gain in there somewhere. Otherwise lowering each channel by 10dB should do it.
 

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You could measure the output voltage using test tones to figure out what dB setting will produce the voltage you're looking for
 

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As gijoe mentioned, lower the individual channel gains in the Helix software for the specific channels your concerned about. That will lower the output voltage from the DSP for those specific channels.
 

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Discussion Starter #8
It looks like I will probably start about -5.0dB or -6.0dB for each channel and see kind of results i get on the amp gains and work from there.
I just wanted to have some wiggle room on the amp gain knobs and that no clipping occurs on the input stage of the amp, especially at louder volumes.

Any negative side effects by doing this vs using a different amp that has 8v input?

I assume this could potentially (or increase the chances to) introduce noise in to the system, however I am thinking with this processor, it shouldn't really be an issue?

Thanks guys I appreciate all the help.
 

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If the amp gains are on minimum and you still think it is too loud for your tweeters in comparison to your mid bass, then leave amp gains at minimum and lower individual channel gain for the tweeter channels on the DSP.

Lower in dB until you acoustically reach your overall house target curve level for the tweeter frequency range.

Keep in mind that the ~8v output from the Helix DSP is not a constant 8v unless your playing a 0dB sine wave and the DSP is playing at nearly max volume.

Think of it more as it can peak up to 8v depending on your overall master volume level and the dynamic peaks in the music. Lowering the individual channel gains will bring down that 8v ceiling for those individual channels.
 

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Any negative side effects by doing this vs using a different amp that has 8v input?
No, this is literally the entire point of gain knobs. You do not need an amp that accepts higher voltage inputs, you just need to lower the output voltage from the DSP.
 
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