Another question about gains. I was looking at the manual to my Xtant 403 amp and it has input and output gain. The labels are kind of self-explanatory. But if I have my volume level set @ 10, will adjusting the input or output gain affect the power output of my amp? Or will it only affect the volume level?

 

Power output?..........no, that always remains constant. It will affect the output of the amp in relationship to the volume control of your deck.

 

Look at the gain control as the multiplication key on a calculator...every time you turn it up, you're saying "Multiply my input signal by a larger number". Eventually, though, the resulting signal becomes so large the display can't show you all of the digits...at that point you've maxed out the amplifier (calculator) and you need to turn the gain (multiplier) down.

 

Wont' input gain increase noise that's already in the signal? And how can you tell if the clipping is from the HU or the Amp?

The Crossover for my CDT-CL61 has a +3db, 0db, & -3db adjustment on the higher frequencies. But MacGyver said that "passive components (such as speakers) cannot have a signal boost". So how does the +3db setting affect SQ and Volume?

 

Oh Another Question.

I remember hearing that the average human vocal range is approx between 200~2500hz. Is that correct?

 

The generally accepted range starts at about 100 Hz for males and 200 Hz for females and goes up to around 3 kHz, but 200-2500 will work.


Increased input gain will increase the noise, but it increase it in proportion to the signal as a whole. If I double the signal volume, I also double the signal's noise component.

If you turn down the volume slightly on the head unit and the distortion decreases compared to the signal, it's the head unit clipping. If you turn the amp gain down and the distortion disappears, it's the amp clipping.

The 3 dB boost is created in the crossover, not the speaker. To be specific, the crossover in your amp is an active filter, so it can create a gain.

 

I was refering to the crossover for my component speakers - CDT-CL61. I thought speaker crossovers were mostly passive ones.

Based on this info, it's definitly my stock HU that's causing the clipping which prevents me from hitting higher volume levels. I guess a new HU is my next priority then.



Back to the pre-out voltage question. Everything else being equal, will a 4v preout on the HU enable higher volume level than a 2v preout? If so, by how many percentage?

 

You know what? Now that I think about it, it's not necessarily your HU causing the clipping. If you're at the edge of clipping in your amp, turning down the volume on the HU will lower the clipping in the amp, so my previous advice was bad. Let me think on it a bit more and I'll try and come up with a more foolproof method. I'm so tired now I'd be afraid of what I would advise you on...

Ugh, I've erased my answer to the preout question several times now as each explanation seemed to confusing...its so late at night and I'm so tired I'm afraid of how I might answer. Essentially, a 4V preout will not allow a louder volume than a 2V preout, it will only allow better noise reduction.

Amps are designed to amplify a signal's voltage level. Let's say to make an amp just start to distort, you have to turn the gain all of the way up for an input signal of 1V. Now let's make the input signal 2V...we have to turn the gain down by 50% to prevent hitting that same point of distortion. Now bump it up again to 4V...we have to further decrase the amp's gain another 50% to again avoid distortion. As you can see, the amp puts out what it can, regardless of the input signal. By changing the voltage of the input signal we need to decrease the amount the amplifier multiplies that input signal so we don't hit that maximum amplification point.

 

Assuming clipping caused by the HU is not a problem. Won't 4v preout enable higher volume levles? I mean if 100db requires 120w of power, with a 4v preout the amplifier has to amplify the signal by 30 times, vs a 2v preout where the amp has to amplify the signal by 60 times. I know the P=VI formula but never really understood it, so I know my logic here must be flawed. So please correct my thinking.

Thanks

 

Lets assume that most amps can reach their full rated output with 1V at the amps input. What a 4V preamp section on a deck does for you is allow you to drive the input of the amp with the amp gain DOWN..............so the amp can reproduce a cleaner signal without alot of the associated noise that would normally be present if the amps gain were at a higher level. An amp can only put out it's rated power ONLY, no matter if you are using a 1V preamp or an 8V preamp section on your deck..................the difference will be how clean the signal is at the amps output because of the lower gain setting on the amp. Another advantage of a high output preamp is the ability to drive the input(s) of multiple amps, whereas a 1 or 2V preamp would come up short on its ability to drive multiple amps to their full rated output. I hope this answers your questions..............and by the way, Xtant makes an EXCELLENT amp! ENJOY!............................................ .................................................. .................................................. ...........Bob