No Ash - the old joke 'what's brown and sounds like a bell? yep dunnnnng!'
Getting back to 'headroom' folks, I'd allways thought of it as available volume/drive in the amp in excess of what you need to do the job but before the sound breaks up badly. Obviously it's usually linked to output wattage but having an amp that can handle severe overdrive/overlaod to almost violin tone standard would, in my book, be more headroom than an amp that simply broke up (harsh distortion).
An example of what I mena is in the old days (before mosfets etc) we used to talk about valve amps having more headroom that tranny ones because when fed by a fuzz box the valves would remain sweeter in sound than the tranny ones which became harsh and unpleasant.
Perhaps DC4 or Rog could explain in simpler terms what I'd understand as 'soft clipping' was wider on valve amps than 'hard clipping' but vice versa on tranny jobbies and the soft clipping mostly equated to the headroom - I'm not sure how to put this in simpler terms other than the above.
Thinking about it, the term 'headroom' seemed to have another meaning when talking about 'clean' amps such as Fender Twins - there the term seemed to mean the increase in volume and clarity staill available when you were already at playing levels although some slight distortion was evident.
In contrast amps with 'low headroom' went from nice to unpleasant very quickly on the volume knob i.e. from a clean sound to hard clipping in say one division.
That's my memory of the term anyway for what it is worth. I reckon modern boutique amp suppliers have greater efficiency in the speakers, better circuit design, better components etc and that is why, although they are lower rated, they are sufficient and still have good headroom.
Got Head?........Room
Moderators: Slowy, Capt. Black
-
B45-12
- Vintage Post Junkie
- Posts: 1585
- meble-kuchenne.warszawa.pl
- Joined: Thu Feb 05, 2004 1:56 am
The main difference between tubes and trannies is that the first usually sits at a very high voltage potential and in preamp terms is a voltage amplifier which means it can swing signal,if biased to do so,from the high voltage to the ground,or the cathode to be specific,so your talking a voltage swing on the plate of between 2 volts to about 200.Now this swing is dependant on whats hitting the control grid,or input,which given a guitar level is about 500mV and is swing accross a cathode set at about 1.5V above ground kinda means that you can put a very heavy voltage swing into the control grid before the plate starts running out of voltage,creating cutoff,no more voltage,and hitting the cathode and creating sag which is no more current.Now because this signal is in a tube its actually at a very high impedance which means its got lots of balls but hardly any blow,high voltage and low current and this means that by the time it hits the next stage,after going through a bunch of resistors and caps,to shape it somewhat,its lost most of its blow and is down to a small level again.Okay thats one valve stage.Lots of room to play at tone shaping and quite a bit of "headroom" to play with.
Then you've got the humble transistor and its voltage range is at most about 30 odd volts which doesn't seem so bad but the thing with transistors is that they ain't there as voltage amps but as current amps.They don't like seeing large voltage swings and get all hot and bothered when you ask them to do it.They start creating square waves and adding all sorts of yucky harmonics and basically sound like crap.They aren't designed to be pushed into voltage amps and really all they want to do is take that weeny voltage and add a bunch of push to it,theyre current amps and this is why they excell in tone shaping before we even hit the poweramp input...FX pedals.Oh and Bass amps.If a transistor is set up to have small voltages hit it and just does the job of amping current then it acts very linearly which means it doesn't add harmonics in the conversion.So back to tubes which aren't very linear in conversion which in the case of sound is actually a good thing especially in the sense that the harmonics created within tubes are the ones we actually find pleasing like octaves and fifths.Now as for clipping,soft and hard,its a matter of what is happening when signal hits the walls of available voltage and available current.Tubes kinda have built in inefficiencies where as you get closer to the walls they stop doing what they're kinda supposed to,built in braking as it were,they don't go full tilt into the wall but start working badly which means they round off the tops of the signal waves quite nicely or at least they have alot more potential to design this inefficiency into a sonic bonus for harmonic craving guitar players whereas the total efficient transistors,silicon anyways,just run smack into those walls and create the harmonic accidents that displease us and their running down a thin corridor in the first place so it careful driving or unpleasantness with no in between.But then you have Germanium transistors and they're cool because they are somewhat akin to tubes because they're basically inefficient.They have some brakes built in because they're leaky old things.You push germanium transitors and they don't wanna play,they stop doing what they're supposed to and what we actually want and enjoy which is slow down and just skim those walls...roundy tops for all.
Then you've got the humble transistor and its voltage range is at most about 30 odd volts which doesn't seem so bad but the thing with transistors is that they ain't there as voltage amps but as current amps.They don't like seeing large voltage swings and get all hot and bothered when you ask them to do it.They start creating square waves and adding all sorts of yucky harmonics and basically sound like crap.They aren't designed to be pushed into voltage amps and really all they want to do is take that weeny voltage and add a bunch of push to it,theyre current amps and this is why they excell in tone shaping before we even hit the poweramp input...FX pedals.Oh and Bass amps.If a transistor is set up to have small voltages hit it and just does the job of amping current then it acts very linearly which means it doesn't add harmonics in the conversion.So back to tubes which aren't very linear in conversion which in the case of sound is actually a good thing especially in the sense that the harmonics created within tubes are the ones we actually find pleasing like octaves and fifths.Now as for clipping,soft and hard,its a matter of what is happening when signal hits the walls of available voltage and available current.Tubes kinda have built in inefficiencies where as you get closer to the walls they stop doing what they're kinda supposed to,built in braking as it were,they don't go full tilt into the wall but start working badly which means they round off the tops of the signal waves quite nicely or at least they have alot more potential to design this inefficiency into a sonic bonus for harmonic craving guitar players whereas the total efficient transistors,silicon anyways,just run smack into those walls and create the harmonic accidents that displease us and their running down a thin corridor in the first place so it careful driving or unpleasantness with no in between.But then you have Germanium transistors and they're cool because they are somewhat akin to tubes because they're basically inefficient.They have some brakes built in because they're leaky old things.You push germanium transitors and they don't wanna play,they stop doing what they're supposed to and what we actually want and enjoy which is slow down and just skim those walls...roundy tops for all.
Alnico at both ends and as little silicon in between as you can get away with.
If the brain is veiwed as a muscle then it may hurt when you push it but it will also get stronger because of that.
And I'm all for giving out hard won knowledge because the more people know the less likely brand fixed mojo myths are spread and the more likely it becomes that the real mojo factors become apparent.
But anyways,I'm glad you waded through it and hope it made some sense as it really is quite a leap from accepted description to actual reality of the mechanical things that are going on inside bottles and doped PN junctions.
I ain't really that up on this stuff,I can make them work for me,with some help with the more arcane aspects,but I ain't in the territory of impedance versus frequency and plotting elliptical resonses on characteristic charts but I do kinda get it and occasionally the middle ground I stand in between the Hoi polloi and the boffins....here he goes again...
The water analogy works to a certain degree until you try and compare viscosity to frequency and then theres really no point so after years of getting to grips with this stuff and being a frequent poster at places like Ampage and AX84 I've kinda figured out that the hit 'em hard ,hit 'em fast....but hang around and look after all the survivors actually works the best.
And if you think thats hard work you wanna try Mr Mark Hammer,the stompbox theoretical king.For that guy I used to have to copy his posts,print them out and give myself an hour or two with pencils and paper and reference books.Absolutely brilliant man and I love him.I'm even going to go visit him if I get to Canada,its where I was born,in the not to distant future.Oh,and you'll find him, as well as a few other modern sonic geniuses of the WWW,at Arons Stompbox Forum.
And thanks for being a benefactor of this site...I'm sure we all appreciate it as much as I do.
And I'm all for giving out hard won knowledge because the more people know the less likely brand fixed mojo myths are spread and the more likely it becomes that the real mojo factors become apparent.
But anyways,I'm glad you waded through it and hope it made some sense as it really is quite a leap from accepted description to actual reality of the mechanical things that are going on inside bottles and doped PN junctions.
I ain't really that up on this stuff,I can make them work for me,with some help with the more arcane aspects,but I ain't in the territory of impedance versus frequency and plotting elliptical resonses on characteristic charts but I do kinda get it and occasionally the middle ground I stand in between the Hoi polloi and the boffins....here he goes again...
The water analogy works to a certain degree until you try and compare viscosity to frequency and then theres really no point so after years of getting to grips with this stuff and being a frequent poster at places like Ampage and AX84 I've kinda figured out that the hit 'em hard ,hit 'em fast....but hang around and look after all the survivors actually works the best.
And if you think thats hard work you wanna try Mr Mark Hammer,the stompbox theoretical king.For that guy I used to have to copy his posts,print them out and give myself an hour or two with pencils and paper and reference books.Absolutely brilliant man and I love him.I'm even going to go visit him if I get to Canada,its where I was born,in the not to distant future.Oh,and you'll find him, as well as a few other modern sonic geniuses of the WWW,at Arons Stompbox Forum.
And thanks for being a benefactor of this site...I'm sure we all appreciate it as much as I do.
Alnico at both ends and as little silicon in between as you can get away with.
All these posts and nobody has addressed the original question.
What a bunch of thread hijackers!
Head room is a term referring to how loud the amp will go before break up begins. No wait, head room was the reason they invented tilt steering wheels. No, no, that's not it. Head room refers to the hotel suite occupied by the Black Crows. Nope. Still wrong. OK, here we go. Head room will cost you 50 bucks to get into. The tail room is a lot more.
What a bunch of thread hijackers!Head room is a term referring to how loud the amp will go before break up begins. No wait, head room was the reason they invented tilt steering wheels. No, no, that's not it. Head room refers to the hotel suite occupied by the Black Crows. Nope. Still wrong. OK, here we go. Head room will cost you 50 bucks to get into. The tail room is a lot more.
__________
When you have to choose between two evils, pick the one you never tried before.
When you have to choose between two evils, pick the one you never tried before.
You know I've often heard the 'valves create the great harmonics' statements but I often wonder - I'm beginning to think it's more a function of the hefty output xformer that normally goes with those amps because you can get some nasty sharp sounds/breakup from low wattage (say 5watt) valve amps with capacitative output (ie just an electolytic leading to a speaker from the output valve cathode).
You can't do THAT on stage!