volts?

[bureau13 10+ year member]

All things being equal, the higher voltage pre-outs are advantageous, as has been pointed out. However I see an awful lot of people taking this one spec and putting way too much emphasis on it. Even if you're just looking at sound quality and ignoring the UI, features, etc...you can not look at a pair of head units and deduce that the one with 5V pre-outs has better sound quality than the one with 2V pre-outs. There are many, many factors that go into this, and many of those have a lot more to do with good sound quality than the pre-out voltage level. You gotta listen...

jds

 

[HCCA 10+ year member]

True enough, but...115 S/N ratio, and dynamic range of 110, is almost useless if you have distorted output at full volume, and noise that is amplified at the amp because you have to crank the amp gains. It's like putting tires from a Pinto on a Lambo. All the performance from the Lambo won't be realized until you use tires that are up the task. UI, but no real performance? It's like a eally beautiful, ergonomic car....that has no engine. Beautiful to look at...but that's about it.

Now, if the industry were to go to optical outputs, only...hmmm! //content.invisioncic.com/y282845/emoticons/santa.gif.e1ec9cf2e0a0dd232ad35aa594a126d0.gif

 

[bureau13 10+ year member]

True, but 2V pre-outs does not necessarily mean you have distortion...and if you're spending a lot of time with the volume at full you need bigger amps! ALL amps are going to distort more cranked all the way up.

jds

True enough, but...115 S/N ratio, and dynamic range of 110, is almost useless if you have distorted output at full volume, and noise that is amplified at the amp because you have to crank the amp gains. It's like putting tires from a Pinto on a Lambo. All the performance from the Lambo won't be realized until you use tires that are up the task. UI, but no real performance? It's like a eally beautiful, ergonomic car....that has no engine. Beautiful to look at...but that's about it.
Now, if the industry were to go to optical outputs, only...hmmm! //content.invisioncic.com/y282845/emoticons/santa.gif.e1ec9cf2e0a0dd232ad35aa594a126d0.gif

 

[JimJ 5,000+ posts]

True enough, but...115 S/N ratio, and dynamic range of 110, is almost useless if you have distorted output at full volume, and noise that is amplified at the amp because you have to crank the amp gains. It's like putting tires from a Pinto on a Lambo. All the performance from the Lambo won't be realized until you use tires that are up the task. UI, but no real performance? It's like a eally beautiful, ergonomic car....that has no engine. Beautiful to look at...but that's about it.
Now, if the industry were to go to optical outputs, only...hmmm! //content.invisioncic.com/y282845/emoticons/santa.gif.e1ec9cf2e0a0dd232ad35aa594a126d0.gif

If there's no noise in the environment, then it doesn't matter where the gains are, or how much preout voltage there is.

If there's no noise in the setup, 2V is plenty.

 

[HCCA 10+ year member]

If there's no noise in the environment, then it doesn't matter where the gains are, or how much preout voltage there is.
If there's no noise in the setup, 2V is plenty.

Sorry, but I call B.S.!! What do you mean, "If there is no noise in the environment"? When you clip a clean signal...there's your noise! I will absolutely guarantee that ANY head unit that derives a 2v signal from the 12Vs in your charging system, and does not use a switching power supply to step up the voltage for a 4-8v output WILL clip. There is just no arguing that point, IT IS A FACT. PERIOD! Pick any head unit you want. I don't care what the brand name is. If it has a 2V output, it will clip the signal at full volume (from the output of the head unit). Doesn't matter what gain matching you do from there. You can match your gains til the cows come home. They can be matched, but the signal is already clipped!!!!

As I posted previously, there might be little to no noise picked up in the signal transmission lines between components. However, there are many vehicles that DO! In those cases, the noise picked up along the way WILL BE amplified along with the musical information. You turn the gains up to amplify the signal...you amplify the noise at the same time. It can't be avoided. So YOUR system is clean...contratulations. Some people a blessed....others aren't so lucky. BUT, it is a fact that the car audio environment is a noisy one. I don't think anyone will argue that. As such, most people will use ALL means at their disposal to fight noise. Some might not need anything. Hey...great! Some might need all the help they can get to combat noise.

On the other hand, are we talking about 60db of alt whine through the speakers at min volume? Or, are we talking about 10 db of hiss, on a quiet track at 3/4 volume. The difference is great, but the source might still be the same. Induced noise through the transmission lines! The higher the output voltage, the more noise can be rejected. It's like this... If you have .012v of noise picked up in your transmission lines, with an average signal voltage of 1 volt at normal listen levels...that's less than 10-1 signal to noise (picked up through the lines, not referenceing the inherent S/N ration of the head unit). Add to THAT, you have to turn up the amp gains!!!!

Conversely, if that noise is constant, you use a 5V unit. That same listening level would be closer to 2.5V, at normal listening level. The noise would still be .012V. That's almost 20-1 ratio of signal to noise. PLUS, now you can keep you amp gains all the way down, and not amplify the noise by turning up your gains.

And, further still...what has not been covered through all this...output impedance. That is the better focus of noise rejection. The old Pioneer m-88 had like...4 ohms output impedance. THAT'S what SHOULD be focused on more than anything. 0 ohms would be ideal. Obviously, 0 ohms would be effectively a dead short, and you can't generate a voltage across a dead short. 4 ohms would be great. 1000 ohms...not so great. 10,000 ohms...well...that's as good as an antenna to reach out and grab noise!!

However, a switching power supply to get a clean, UNCLIPPED signal is still better than a 2V, with 10% distortion at full volume...ANY DAY OF THE WEEK!!!

True, but 2V pre-outs does not necessarily mean you have distortion...and if you're spending a lot of time with the volume at full you need bigger amps! ALL amps are going to distort more cranked all the way up.

Read above.

 

[JimJ 5,000+ posts]

What do you mean, "If there is no noise in the environment"? When you clip a clean signal...there's your noise!

I meant inducted or radiated noise external to the interconnects/head unit, not a distorted signal. The argument about whether or not a head unit will clip at full volume is an academic one. I'll use whatever maximum unclipped level it has.

Nothing you said really contradicts the point.

 

[shaneb 10+ year member]

So this means that my 5v pre-out Eclipse CD4000 has a built in line driver of sorts? Interesting.

Also, is it likely that my eclipse does not reach its full output voltage until close to clipping or because it has this "switching" voltage driver it always has a 5v pre-out? This was aquestion I was wondering earlier when I decided I want to re-tune my gains to proper levels.

I searched the manual. Didn't see anything. Is it a rule of thumb that if you have a 4-5 pre-out voltage then it is always at that voltage despite volume level? Due to a built in switching unit?

 

[Gebrochen 10+ year member]

With that whole thing with pre-amp voltage, a lot of people are running line drivers myself being one and yeah no real diff in sound but you do get a little more out of the higher voltage, I'm running line drivers simpley to keep my gains down in hopes of getting longevity out of my amps. (there mounted on back of rear seat behind box not a ton of cool air especally on there sides like they are). Over kill maby but i don't care my car my crap.

Even with the gain set lower, you're still driving your amp just as hard (with gains set for the same output voltage). The gain is just there to adjust the input signal to the power stage of your amp. Higher pre-out voltages won't add more watts to your output unless there is a severe mismatch in your equipment.

 

[Gebrochen 10+ year member]

Sorry, but I call B.S.!! What do you mean, "If there is no noise in the environment"? When you clip a clean signal...there's your noise! I will absolutely guarantee that ANY head unit that derives a 2v signal from the 12Vs in your charging system, and does not use a switching power supply to step up the voltage for a 4-8v output WILL clip. There is just no arguing that point, IT IS A FACT. PERIOD! Pick any head unit you want. I don't care what the brand name is. If it has a 2V output, it will clip the signal at full volume (from the output of the head unit). Doesn't matter what gain matching you do from there. You can match your gains til the cows come home. They can be matched, but the signal is already clipped!!!!
As I posted previously, there might be little to no noise picked up in the signal transmission lines between components. However, there are many vehicles that DO! In those cases, the noise picked up along the way WILL BE amplified along with the musical information. You turn the gains up to amplify the signal...you amplify the noise at the same time. It can't be avoided. So YOUR system is clean...contratulations. Some people a blessed....others aren't so lucky. BUT, it is a fact that the car audio environment is a noisy one. I don't think anyone will argue that. As such, most people will use ALL means at their disposal to fight noise. Some might not need anything. Hey...great! Some might need all the help they can get to combat noise.

On the other hand, are we talking about 60db of alt whine through the speakers at min volume? Or, are we talking about 10 db of hiss, on a quiet track at 3/4 volume. The difference is great, but the source might still be the same. Induced noise through the transmission lines! The higher the output voltage, the more noise can be rejected. It's like this... If you have .012v of noise picked up in your transmission lines, with an average signal voltage of 1 volt at normal listen levels...that's less than 10-1 signal to noise (picked up through the lines, not referenceing the inherent S/N ration of the head unit). Add to THAT, you have to turn up the amp gains!!!!

Conversely, if that noise is constant, you use a 5V unit. That same listening level would be closer to 2.5V, at normal listening level. The noise would still be .012V. That's almost 20-1 ratio of signal to noise. PLUS, now you can keep you amp gains all the way down, and not amplify the noise by turning up your gains.

And, further still...what has not been covered through all this...output impedance. That is the better focus of noise rejection. The old Pioneer m-88 had like...4 ohms output impedance. THAT'S what SHOULD be focused on more than anything. 0 ohms would be ideal. Obviously, 0 ohms would be effectively a dead short, and you can't generate a voltage across a dead short. 4 ohms would be great. 1000 ohms...not so great. 10,000 ohms...well...that's as good as an antenna to reach out and grab noise!!

However, a switching power supply to get a clean, UNCLIPPED signal is still better than a 2V, with 10% distortion at full volume...ANY DAY OF THE WEEK!!!

Read above.

I disagree with your view of 2V. If the amp is designed or gains set for a 2V signal, you won't clip. You can even get a good signal off of 500mV if that's what the interface is designed for. You will only run into clipping if the amp needs higher than 2V signal for full power (this means you'll be turning your HU up way too far and will need a line driver to match the levels). You mention turning your HU up to full volume. You shouldn't ever have to do this.

Yes it is true that higher voltages can overcome environmental noise, but you can have audio levels of 2V or less with no clipping. So, yeah, I do agree there. I would definitely want a higher voltage from the HU in real life.

 

[HCCA 10+ year member]

I disagree with your view of 2V. If the amp is designed or gains set for a 2V signal, you won't clip. You can even get a good signal off of 500mV if that's what the interface is designed for. You will only run into clipping if the amp needs higher than 2V signal for full power.
Yes it is true that higher voltages can overcome environmental noise, but you can have audio levels of 2V or less with no clipping. So, yeah, I do agree there. I would definitely want a higher voltage from the HU in real life.

In the car audio realm..I wish that were true. But, the head units on the market today will clip the output signal before you reach full volume. No amount of gain adjustment will fix a signal that is already clipped. The gain downstream is not the reason it's clipping, and I challenge anyone to show me a standard, off the shelf HU, with a rated 2V output (or less) that does not clip the output signal near full volume.

I'll use whatever maximum unclipped level it has.
Nothing you said really contradicts the point.

So,...you're going to stop turning up your volume at the exact point where clipping begins? And...you've tuned your system this way?!?
Also, if you read what I posted earlier, again, umm...it DOES contradict the point.

Whatever...