A question - If you have your equalizer set one way, and then you turn every frequency up by one click, then should you have the exact same sound , only a little louder?

Also, what is the concept behind the "overdrive" on the volume control? For some reason, It makes me paranoid when I turn the unit into this zone. I assume something different happens when you get into the overdrive zone?



("Why not just make 10 louder?")
(These go up to 11.")

I assume something different happens when you get into the overdrive zone?

Correct. In the overdrive volume ranges you can get distortion and clipping, depending on your equalizer settings.

tanstaafl.

What happens there that makes the area past the "overdrive" point more prone to clipping or distortion?

Part of the reason that I am curious is because once in a while I crave a little more volume than the "0 db" level. I mean, I'm not overly worried as it still sounds fine to me, but I was wondering what exactly was happening when I ventured into the overdrive zone. If I knew then perhaps I would be able to shake the strange paranoia I get when I'm "in the red".

Set up the player to cap the volume at 0 if you're worried about getting into the distortion zone. That "overdrive" area is pretty much the same thing as turning your head unit beyond 3/4 range (which is generally close to where you get the loudest undistorted output).

Also, if you're linking a few devices that have volume/sensitivity/gain controls, just make sure your cumulative settings don't cause any distortion or clipping. I had some pretty crappy output on my first day because my Clarion HU (which I'm using as a preamp) was accidentally set to high sensetivity for its AUX inputs (where I have the empeg connected). I was overdriving my main speakers with the empeg volume locked to 0 and a number of songs sounded like crap.

I've got things set up now to get loud enough to cause severe ear pain yet with no distortion or clipping. I still have some sensitivity adjustments to make for my rear speakers and subwoofer to balance everything out a bit better.

Bruno

Oh, I'm not worried about it...I just was wondering if there was some kind of thing that took place when you went into overdrive, or if, like you said, it was just pretty much a marker to show the suggested limit.

I guess I don't really get the theory behind output voltage and amplifier gain levels...I just noticed that with my old sony head unit and the same amps as now, there was considerably more volume when the sound was 2/3 of the way up than now with the Empeg turned up to 0.

I don't have very powerful amps, but they did the job. Now they seem just a little weak. I have the gains turned all the way up. The sound is outstanding, breathtaking, no distortion or clipping whatsoever, just sometimes not quite loud enough.

The concept behind my asking was that I was wondering which would most effectively raise the volume level without distortion or clipping, cranking up every band on the EQ by one or two points, or venturing into the overdrive range. Of course I can just try both and use my ears to come to my own conclusion, but it's nice to know the facts and/or other people's opinions.

Go here: Basic Car Audio and read the relevant sections on amps and gain. Basically the gain is just a volume adjustment. Your Sony was louder because at the volume you're comparing, it was outputing a higher voltage than the empeg. If you have a sensitivity adjustment switch on your amp you can try putting it to its "high" setting if it's currently on "low"

When adjusting your gains and sensitivity, you're trying to set everything up to maximize (maximise your usage anyway) the output of your amplifier's power (not allowing it to clip) without causing distortion at the speakers by overdriving them. Turning up a gain does not increase the power of your amplifier, but it allows you to use more of its rated power than if you had it set too low.

Again, read the info at the site above. It's one of the best resources on the net for this type of info. Not the only place, but a very good place to start. Oh, there are also a number of ways people will suggest setting the gain of an amplifier. Some people use test tones and meters while others use only their ears and an initial head unit volume setting of around 3/4 (adjusting gain until speakers distort and then backing off a bit). Settings like EQ and Bass boosters will affect the point at which distortion happens of course.

Bruno

OK, thinking about this question, I realised I don't understand details myself:

So, suppose we have a WAV file with a loudest possible sample, 2^15. I understand that with volume 0dB and EQ flat, DSP will send exactly that, 2^15, to DAC. Am I right? Now, with volume set to some other value (let's suppose EQ is left flat, for simplicity), DSP will multiply sample with appropriate factor (factor of 2 for 10dB or something like that, right?) What I don't know is whether DAC has input range larger than 2^15, that is, is there a danger of 'digital clipping' if we go into overdrive? 'Analog' clipping in preamp is another question.

What you describe, as I understand it, is the exact problem in ``Overdrive''. The problem is that there is no value past the maximum value, and if you try to amplify that digitally, then you get some clipping.

Here's an example (Note that I've decided that the range of samples can run from 0-99, which easy to look at, and that each click on the volume knob increases sample amplitude by 1. Both of these are not accurate, but not too far off reality for demonstration purposes.):

Let's say you had a series of samples in a song that looked like this:

34 48 84 94 98 99 97 89 70 53

If your volume control is set at 0, then this is the exact set of samples that reach the DAC. If you increase the volume by 5, then you'd like to get the samples:

39 53 89 99 103 104 102 94 75 58

but the maximum sample amplitude (again, for the purposes for this explanation) is 99. So the samples that would actually get sent are:

39 53 89 99 99 99 99 94 75 58

So you lose data. Assuming that your system is set up to not blow speakers at normal levels, it's unlikely that going into this digital overdrive would blow them. It just won't sound as good. Then again, if you get severe clipping, it is possible to damage your speakers due to the odd signals that will end up getting sent to them. It seems to me that it would make more sense to increase the output of your amp slightly to make it so that you don't have to get into overdrive. But then again, someone with more analog electronics experience than me should probably correct these last few statements.

Have a look at this. About everything you could hope for about input levels, noise, and amplifier settings.

I sure love those Audiocontrol guys. If anybody ever needs an outboard EQ or crossover, I highly recommend them.

In reply to:

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It seems to me that it would make more sense to increase the output of your amp slightly to make it so that you don't have to get into overdrive.

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Of course this is true, but if you already have your amps turned up to their maximum levels, then you don't really have anywhere to go other than overdrive, or possibly boosting the EQ levels.

At this point one might think that it was time for a bigger amp or more efficient speakers, but I feel that I should be able to get a little more volume out of the amps as my former head unit using the same amps delivered sound that was far louder than I would ever want.

This is only an issue for certian recordings, such as early Black Sabbath, some P.J. Harvey, things that seem quietier than most other recordings.

Perhaps the eaisest solution would be to edit these songs myself and crank them up a bit...?

Well, going into overdrive is better than playing with the EQ because the EQ probably isn't going to increase the volume equally over the entire frequency range, as I understand it, plus, it's still doing it all before DAC, so you'll have the exact same possible digital clipping issues. You might want to investigate why it's so quiet and fix that. I know I'm making an obvious suggestion, but there might be something you haven't considered. For example, I read that if you have multiple speakers attached to one output on an amp, you might end up reducing the volume depending on whether they were hooked up in series or in parallel. But now I'm just parroting. I'm in way over my head now. Then again, you might just have a weak amp know it. I know I do.

It's not a question of bigger amps. That won't help you unless the new amps have a wider range gain and/or sensitivity adjustment. You're already not using the full potential of your current amplifier. A bigger one would just leave you with more unused power.

You need to increase the voltage at the ampifier inputs. Either using an EQ or another preamp I suppose. But, you're sure that there aren't any other tweaks at the amp for sensitivity, right?

If you edit the songs, that could potentially be a lot of work. Plus if you play them later on different equipment you may find you don't like the way the sound when normalized/averaged or artificially ramped up. Your best bet (though not the cheapest in terms of $) might be to reconfigure the way you have things connected or get another amp that has a sensitivity switch. What about something simple like using the original Sony as a preamp for the empeg? It'll have to have AUX inputs or be adapted with an XA-107 or XA-300 module (I think at least one of those model nunmbers might be wrong (the letter part).. )

Bruno

I told you I didn't know what I was talking about.

I thought your info was good. In my last message when I mentioned an EQ, I should have specified an outboard analog EQ. I don't have much info on how the one on the empeg behaves.

Things like boosters on head units (bass boosters or otherwise) will also affect overall volume. Some are frequency specific (or a small range) and other things like channel level and input sensitivity are full-range.

Bruno

If you really want more volume, you could also get a pre-amplifer to increase overall volume levels into the existing amps. Likely, your Sony just had more output oomph than the Empeg (which seems surprising actually unless your amp uses speaker-level inputs).

Look at the Overdrive preamp at Audiocontrol for an example..(around $100).

No, I don't work for Audiocontrol. Just a happy customer.

According to the info, the empeg/rio puts out 4V. the only way the sony could sound louder was if it put out more than that .As long as the amp gains were not changed.The sony also may have sounded louder because it was already clipping at that level, compared to the undistorted output of the rio. Yes/No Mike

That's right. The empeg probably puts out a bit less than 4V at full volume. Some head units put out close to 9V. I have no idea what the Sony above is rated at, nor if it was using line-level or speaker-level connections to the amp (which I also don't have details on )

At home (where the empeg is rated at 1V), set to 0db, mine is not as loud as my Denon CD player connected to the same Denon amplifier.

In the car I have far more control and can make sure it's at a level very close to the CD player built into my Clarion HU.

Bruno

Some factory head units put out 12v, so they can be used to drive speakers directly if you don't pay for the 'upgraded' sound system which includes an outboard amp (with speaker-level inputs). Monsoon systems in VW's seem to use this trick.

Many home audio CD players, especially semi-high-end ones, put out 1.2v or 2v so they sound 'louder.' Many of those have spec sheets that say "1v output".

That way, if you compare two CD players to each other in-store, you'll prefer the one that sounds louder, because you'll think you didn't touch the volume control. Psychoacoustic marketing 101.

A little sleazy? Isn't all marketing sleazy?

When I bought my amp, the sales-guy put it on with some speakers that were close to but not exactly what I have in my truck. I knew that I would never be able to compare the amp's performance in the store, so I had to tell the guy that I wouldn't be able to hear the difference. The only similarity the speakers had were the brand, and in that environment, factory speakers would probably sound the same..