Talking headroom

[Fun_Bucket]

I don't think this topic has been covered before, so i thought i would bring it up, not only for my benfit, but also for any one new, as it may give them a better understanding into how certain things work.

Ok, so i'm aware of the basic principles when it comes to the term "headroom" when reffering to amplifiers. I understand that having extra power readily available, can reduce, or even eliminate, any clipping, or distortion, being sent to the speakers.

What i'd like to know though, is what do you people consider to be a good amount of headroom, when selecting a suitbale amplifier?

 

[Tasmaniak]

headroom is a very broad term my man. It does not actually have a specified meaning. Reality is, headroom more often then not refers to input power and not output power. I think what you might be referring to is tolerance.

Running a 300wrms speaker with a 400wrms amplifier and turning the gain down does not mean you have a 100wrms "headroom"

Knowing that your input voltage is going to be around about 2Vrms and perhaps a 4V peak and then setting your gains to presume it will be hit with a 4Vrms input....thats headroom. So while the inputs are averaging around 2V and sometimes spiking to 4V.....because your gains are set low (4V predicted) then that means when it does spike up high, the pre-amp in the amplifier is not going to clip, therefore it's not going to send a clipped signal to the main amplifier...which in turn, should NOT send a clipped signal to the driver.

Headroom in essence is setting your input gains to give you room to move... because your music is unpredictable...sometimes it can be really soft and then BAM a big old bass note hits...what do you do? Do you dive for the volume control? If so...your system little to nil headroom. If you sit back in awe at cool that felt and how good it sounded...you have headroom.

I like lots of room to throw my head around.

 

[theSeekerr]

6dB above "maximum-average" listening level, minimum. 12dB would be better. Of course, that's 4x the amplifier power and 8x the amplifier power respectively.

What do I mean by "maximum-average"? I mean the average SPL when you're listening to music as loud as you ever intend to. Be realistic, very few people actually want 120dB in their car.

That said, you first need to consider how much power you're actually using anyway - the average listener rarely uses more than about 5W, and indeed many headunits aren't good for much more than about 10-15W RMS per channel. The important figure to consider here is sensitivity of the speakers - I won't re-explain that here, since I'm pretty sure HoldenCommodoreVP understands that, but if anyone is interested, I'll drag up some links.

But yeah. Point is, "8x" sounds like it's going to require an awfully large amp, but for most listeners who aren't into huge SPL, 150W per channel will provide >15dB of headroom.

(EDIT: Tasmaniak is pretty much correct, but I chose to answer the question I thought you were asking, rather than get caught up in the terminology.)

(2nd EDIT:

Actually, I feel like I should expand on that - Tasmaniak is right that clipping happens far more often in the input stage than the output stage, but the above discussion on ensuring you have sufficient output power is also important.

IMPORTANT NOTE: both kinds of clipping look the same to your speakers, ie. very very bad)