Headroom- the exact definition

[JohnnyGuitar]

From what I've been reading lately I've encounterd different definitions of Headroom... anyone could clarfy the issue to me? what is headroom? why do we want more/less of it? how do we get more or less from it?

I'm confused...

 

[TwilightOdyssey]

Re: Headroom- the exact definition

Headroom is related to dynamics.

Are you talking about headroom in recorded material, or in guitar amps and PA systems?!

 

[JohnnyGuitar]

Re: Headroom- the exact definition

Guitar amps.

 

[frankfalbo]

Re: Headroom- the exact definition

It's easier if you define the headroom parameter. "Clean headroom" refers to how much louder you could go before the sound starts to break up, distort, or compress audibly. It's like if the sound can get louder and still sound the same, it means you have more clean headroom. So a POWER tube might have more clean headroom if when you put it in your amp, the amp can get louder and stay cleaner. But a PREAMP tube with more clean headroom might spice up your overdrive tone, IF that preamp tube cascades into a second preamp tube. Because if a preamp tube has more clean headroom, that means it gets louder before compressing and distorting. Technically that should make you have less distortion, but it might drive your driver tube harder, and your power tubes, thus creating more saturation depending on where that tube is in the chain.

In guitar amps clean headroom is a win or lose for some people. I like a little vintage Fender Champ because it has no clean headroom. You crank it up and wail away. But I like my '68 Showman amp BECAUSE it has tons of clean headroom. The power tubes are the highest clean headroom I ever found, and I love it because the Showman is the "power amp" to my rack. So the sounds I make with the rack tube preamps need to come out the Fender Showman without distortion, but with that fat warm bubbly tube amp sound.

 

[TwilightOdyssey]

Re: Headroom- the exact definition

Excellent definition, frankalbo!

 

[bungalowbill]

Re: Headroom- the exact definition

I believe it is how much physical volume you can get before "breakup".

 

[V!N]

Re: Headroom- the exact definition

Lets look at it as if an amp in fact is a room. You can walk around and jump up and down without problems. The jumping is the volume you put out and the higher (louder) you get, the closer you get to the ceiling to the point you can't jump any higher (you can't have a clean sound anymore).
That's clean headroom, but there's also a distorted headroom.

You can still jump and get more distortion and volume for boosts for your solos. This is with an amp with a regular master volume though. If you have one with a PPIMV (Post Phase Inverter Master Volume), you're already bumping your head against the ceiling. When you hit the boost, you can't go up in volume anymore. You'll just hit the ceiling harder (the sounds just gets more mushed out without getting louder)

Having the phase inverter as a phase inverter instead of a distortion deveice, you have room to jump higher when you need, without having to worry about hitting your head.

 

[JohnnyGuitar]

Re: Headroom- the exact definition

So let's see if I got it right... clean headroom is how much volume you can add until the amp distorts and distorted head room is how much volume you can add until your amp just distorts instead of get louder...

Or if you look at it just as headroom- how high can you turn the volume up until your tone breaks up to distortion and becomes less articulate...

Right?

 

[V!N]

Re: Headroom- the exact definition

Well, if you think distorted sounds are less articulate ..

I say you got it right in the first paragraph, but I highly suggest you find a room with a low ceiling and jump around in it for a while if you still have doubts.

 

[baritone]

Re: Headroom- the exact definition

A simplified example is the difference between an amp's output and a cab's handling. Most amps are rated in terms of RMS wattage, which is usually related to maximum level of clean output. The peak output is frequently substantially higher. When selecting a speaker cab, you want to be higher than the amp's RMS output to acount for the possible peak/distorted/ square-wave output. This acommodation is called headroom. My amp head is about 35 watts RMS, but it peaks/squares at 40-45 watts. So when selecting a cab, it is reasonable to have a cab that handles at least 50 watts. If it was less than 40, I would not have enough heardroom, and would be at risk for speaker damage. With my 35w RMS amp head, I use 2 different cabs at different times. My 2x12 handles up to 75 watts, so it gives sufficient headroom, and it gets utilized at an approximately optimal level of performance. My 4x10 cab handles up to 300 watts, so it gives massive headroom. I would be comfortable plugging a head up to 150w into that cab and still have enough headroom.

 

[D-EJ915]

Re: Headroom- the exact definition

watts are for suckers


measure the output voltage when the amp's cranked, the higher the voltage the higher the 'headroom' and 'volume' it has.

 

[baritone]

Re: Headroom- the exact definition

It works..

 

[Scott_F]

Re: Headroom- the exact definition

The most exact definition I know of is the space between the top of your head and the roof of your car. Too little is annoying, too much is a waste.

Now think of that roof of your car as being the point where your amp goes into distortion. The "distance" is now measured in perceived volume. The more perceived volume before the amp breaks up is the clean headroom.

 

[Rich_S]

Re: Headroom- the exact definition

I want to congratulate the members of this forum for not allowing (causing) this thread to take the nasty turn that its title suggested it might. Kudos on your self-restraint, purity of thought, and single-minded focus on important technical aspects of guitar playing.

 

[baritone]

Re: Headroom- the exact definition

Yeah, I actually have excessive headroom with my 4x10 cab, but if I get a more powerful amp in the future, I have just the cab for it.

 

[JohnnyGuitar]

Re: Headroom- the exact definition

Yeah, I actually have excessive headroom with my 4x10 cab, but if I get a more powerful amp in the future, I have just the cab for it.

So when you want to get more headroom a bigger cabinet is a factor?
It's logical... you don't need to raise your volume as high to get loud...

 

[baritone]

Re: Headroom- the exact definition

It's not necessarily the physical size. It depends more on the dynamics of the individual speakers. Some 12" speakers handle up to 30 watts each, while some 12" speakers handle up to 150 watts each. It also depends how the speakers are wired together. My 4x10 has 4 10" speakers which handle 75 watts each, for a total handling of 300 watts. Speakers or cabs with no headroom are at risk for being blown by the amp's power, speakers with a little headroom are expected to run at a near optimal performance with a little risk of being overworked but potentially better sound, and speakers/cabs with lots of headroom are totally safe but the full potential of the speakers may not be heard.

But for more headroom, functionally larger speaker or cabinet is appropriate, meaning it could be the same size, but it handle more.

 

[JohnnyGuitar]

Re: Headroom- the exact definition

speakers/cabs with lots of headroom are totally safe but the full potential of the speakers may not be heard.

And how would it effect the tone? how does a speaker which has its full porential used sound when compared with one who isn't?

 

[The Golden Boy]

Re: Headroom- the exact definition

I never really thought of having differing versions of "headroom" but I do it all the time.

1. The amount of space from clean to break up.

2. The amount of space from clean to saturation.

3. The amount of space from break up to saturation.

4. The amount of room until there is no more the amp can give.


In my bass playing train of thought- it's the amount of room you have between clean and the amp clipping, not the speakers- the amp.

 

[baritone]

Re: Headroom- the exact definition

I think it is a subtle difference unless you are an experienced player. Speakers like the Celestion Blues are popular because they give a small amount of headroom, so their sound breaks up a little when pushed; I feel this realm of speaker breakup is a delicate one and is best explored by an experienced player. With my 300 watt cab, it may not be getting proper abuse from my 35 watt head, but it sounds out perfectly, and it still shakes the whole house when I play.

With regards to amp volume > speaker breakup vs. clean output > square wave, the terminology overlaps a little, but the concept is about the same.