HU Voltages

[Sguirrelfeather]

My amps have a max input voltage of 8 volts. I have a 4 volt HU. No worries about getting them to match up. However, what I have come to realize is that with my current sub setup (I have the sub amp dialed down to 1400W) I have to put the gain around 75% just to get the max RMS wattage. When I upgrade and can utilize the remaining wattage available in the amp, I won't be able to get full output. So, I would have to get an 8V HU to take full advantage, right? Or am I not thinking this through?

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[nismotwin 10+ year member]

Nope your not thinking it through. Your not gonna find an 8 volt HU. A line driver won't help you either. Not really something to worry about unless you have low preamp voltage.

 

[nismotwin 10+ year member]

Low preamp voltage can cause you to clip your amp trying to get output. However uping the preamp voltage does not translate to more wattage from the amp. However it can improve SQ.

 

[Sguirrelfeather]

So, I've got an amp rated at 2600W into 1 Ohm. I'm currently running it at 1 Ohm, with gain set at ~75%. At that 75%, I'm getting 1400W. When I max out the gain, I'm not getting 2600W. This is set at 0db with HU set to 80% max volume, no clipping. So then if more pre-amp voltage isn't the answer, what is? My end goal is to upgrade the speakers so they can handle the amp's max wattage, but if I can't get the amp to put out, what's the point? Oh, and it's not a bad amp. It's an FSD FZ2600, which has dyno'd out well above rated. Oh yeah, yes, I have upgraded electrical. 00 battery cables, 00 cables to the amp, dedicated ground going back to battery, dual batteries, 250amp alternator, big 3, etc etc.

 

[Boomin_tahoe 5,000+ posts]

What amp is it? Sounds like your expecting too much from it. And while I'm at it, 75% of the gain turned up is too much. I see what your doing tho...trying to get that amp to play it's rated power in that ohm load. A lot of car audio brands overrate their amps wattage and either come up short or just isn't enough when bench tested.

Also, what sub(s) are you running? Brand, quantity, impedance rating, etc.

 

[Sguirrelfeather]

Amp is an FSD FZ2600. It's rated at 2600 at 1 ohm, but dynoed well over that. I'm running it on two Soundqubed HDS208 wired for 1 ohm. When I say 75%, it's not like I just turned it there and said ok. I used a DMM (no access to an o-scope) and set the voltage to reach 37.42, which correlates to 1400W at 1 ohm. This just happens to be about 75% of the max gain.

Voltage at the amp, with truck running and amp off, is about 14.3. When amp is hitting hard, it's about 13.7.....it's a long run of wire. Probably 25ft or so, because it's a Ford Excursion.

Because my HU only has four RCS-outs, I did have to split the cable off. I don't have a processor or any kind of crossover before the amps. I've read this should not make a difference, but I'm wondering if it would be possible if the HU isn't quite putting out what it's supposed to.

 

[Boomin_tahoe 5,000+ posts]

I don't cvare what anybody says. Having a gain turned up that much isn't good.

You might as well turn it 25% more and go fullballs to the wall.