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Thread: Amp gain and DSP Volume

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    Noob Julian's Avatar
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    Amp gain and DSP Volume

    I could use some newb help with my volume. I set my amp gains using a multimeter and my 100W per channel amps are really loud. I put the HU volume at 25% (sub off) and hit 85 db which is my normal cruising volume to prevent hearing loss. I go louder here and there but stick mostly at 80-85db.

    I have a DSP408. I can lower the master vol slider in the dsp. Or reduce the amp gain. What would you all suggest to tame the volume to make for an easy tune and good SQ (noise floor)? I felt like my amps were choked a bit when I had the gain down. They seemed to open up. My midbass is on a class D. Mids and tweets a Morel AB.

    Thank you

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    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
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    Re: Amp gain and DSP Volume

    Do you like the way it sounds right now?
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Updated Justin tuning sheet (Justin and Erica tuning companion for SMAART and REW)
    Do it for them.

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    Noob Julian's Avatar
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    Re: Amp gain and DSP Volume

    It sounds more dynamic and noise floor is improved. Think I should leave it? I am on 7 out of 30 and it is at 85db. If I go to 10 it is pushing 95db. Pretty drastic. But it sounds good.

    I am still tuning. Been busy with work but should have time now.

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    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
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    Re: Amp gain and DSP Volume

    If it sounds good, then what problem are you trying to solve?

    I'm also curious, how are you measuring 85dB and 95dB?
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Updated Justin tuning sheet (Justin and Erica tuning companion for SMAART and REW)
    Do it for them.

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    Noob Julian's Avatar
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    Re: Amp gain and DSP Volume

    I measured it using the Umik and db meter in REW. Is that way off? It seemed to give rational values based on my perception of volume.

    Im more worried about what I dont know or might be doing wrong. It seems wrong to have the vol so sensitive? I am used to a more gradual change. If its fine, great, I will leave it.

    I still need to sort the tune. But wanted to revisit my gains first.

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    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
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    Re: Amp gain and DSP Volume

    Nothing wrong with umik and rew, I was only curious.

    If you'd like to make the rest of your volume knob usable, you can decrease the gain in the system somewhere. Like you mentioned, this can be done in a few places like the DSP or the input gain knobs of the amplifier and so on. You'll likely have a lower noise floor if you decrease the input gains on the amplifiers and keep the output signal on the DSP as high as you can. I encourage you to give it a try both ways since it's fairly easy to change the gain on the DSP or on the amplifier.

    If you routinely listen to "quiet" music such as classical or recordings made many years ago, you might need the additional hotness in your volume knob to make the quieter songs loud enough. Also, after you're done tuning most people will have lowered the overall output of the system by using more eq cuts that boosts. So, just keep these in mind as you decrease the overall gain in the system. There are few things more frustrating than spending all weekend getting a tune just right then having to change the amplifier gains to make it louder, but disrupting the balance between woofers and tweeters or fronts vs sub when you do.
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Updated Justin tuning sheet (Justin and Erica tuning companion for SMAART and REW)
    Do it for them.

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    Noob Julian's Avatar
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    Re: Amp gain and DSP Volume

    Thanks Justin. Being forced to change gains after the tune is not something I had considered. You def saved me a lot of time. I will try it both ways and post my findings for those who are curious.

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    Re: Amp gain and DSP Volume

    Amp gains should be as low as can be to attain the volume you require with no clipping in the signal chain

    if you are listening at 25% of radio volume then your gain structure is very wrong, ideally you want the radio to be as ‘turned up’ as possible while still keeping a clean signal and not clipping the dsp input

    it makes my brain hurt when people use 4v preout hu and only use the first half of the volume steps, that completely defeats the point of 4v preouts, the hu will only make 4v when the volume is almost maxed out in a lot of cases, and below 3/4 volume you won’t get above 1v most likely out of a 4v headunit just because the volume is logarithmic as that’s how we hear and need power/voltage delivered

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    Noob Jdunk54nl's Avatar
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    Re: Amp gain and DSP Volume

    Quote Originally Posted by dumdum View Post
    Amp gains should be as low as can be to attain the volume you require with no clipping in the signal chain

    if you are listening at 25% of radio volume then your gain structure is very wrong, ideally you want the radio to be as ‘turned up’ as possible while still keeping a clean signal and not clipping the dsp input

    it makes my brain hurt when people use 4v preout hu and only use the first half of the volume steps, that completely defeats the point of 4v preouts, the hu will only make 4v when the volume is almost maxed out in a lot of cases, and below 3/4 volume you won’t get above 1v most likely out of a 4v headunit just because the volume is logarithmic as that’s how we hear and need power/voltage delivered
    I would tend to agree, I would like more volume control than 7-10 out of 30. I would like to at least be around 20ish just for my own piece of mind. It really doesn't make much of a difference if you are not experiencing noise, but my ocd won't let me only use 7 out of 30 volume, I couldn't personally live with that. I am usually around 50% for most listening, but occasionally go up to 75%. Justin and I have had some conversations about this and how people must max out the volume knob! Even if the radio is SUPER LOUD at level 2 out 30, people will think it is too quiet or something is wrong if they can't use the majority of volume knob range.

    You also do need some gain overlap (meaning some volume left on the volume knob) for different songs with different recording levels. If you max out on music recorded recently, you are going to be fine, older music will generally be too quiet.

    This is a good site that Erin Hardison suggested with dynamic range of songs:
    https://dr.loudness-war.info/
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    Noob Stycker's Avatar
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    Re: Amp gain and DSP Volume

    The best analogy I heard for this is to think of the volume knob as a accelerator pedal. You would not want the car engine at full rev when the pedal is only depressed 10% and vice-versa.

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