Got Head?........Room

Kloppsta · Post by **Kloppsta** » Thu Apr 14, 2005 11:33 am

"Headroom"
A term often used when talking about an amp's channels, more often than not, in relation to the "clean" channel.
Also closley associated/debated with the given amps output rating.

A common argument -

"More Watt's = more headroom"
Less chance of the tubes breaking up when playing hard or with high output pickups. True/False?

I say...ok....how does a 50W compare to a 100W amp as far as "headroom" goes? Is there REALLY much in it? I mean c'mon! Does it really make a hell of alot of difference? As I understand it, watts don't measure volume but rather decibles do. Tube amps are not as loud as solid state amps because tube amps generally have a wider dynamic range over transistors which makes them louder.

anyway...50W vs. 100W

Headroom, Volume, Pros, Cons etc.
The way I look at it is, if you are going to play a venue that requires more volume / throw than a 50W tube amp can produce...you are either A. Well known and Rich enough to buy a bigger rig, or B. Its all going to be mic'd up anyway, so what difference does it make!!

Post by Bg » Thu Apr 14, 2005 11:47 am

Not a great deal of difference between 50w and 100w or 30w and 50w for that matter. DB is volume, and a good way to get more volume is by better quality/more speakers. As you say 50watt is sufficient for anywhere including stadiums

The Beatles used to use AC30's in stadiums!

Ok I have a 250watt bass head, but thats different. Its my wall of sound

and I want a nice clean bass sound. I have a 2x10 and a 1x12 but only one of the 10" speakers is connected as the other is fucked. It gives out plenty... One of our guitarists gigs with an old 70's yamaha SS amp. I think its a 60 watter and he's still too loud.

ant · Post by **ant** » Thu Apr 14, 2005 11:57 am

You get 3dB more headroom providing your preamp isn't distorting - as simple as that.. Or the same effect switching between G12H-30's and greenbacks. Tube amps are louder when distorted because when you first hit a note it actually exceeds its rated output(up to 5x in some cases!!!) for a millisecond, so it seems louder.

Less chance of the tubes breaking up when playing hard or with high output pickups. True/False? Depends if your pickups are overdriving the preamp, if you are overdriving the preamp the extra 50 watts/3db won't make any difference to headroom.

I would say if you need to do pristine clean, 50 watts is plenty for all situations, many good songs *don't* have a pristine clean sound as tubes sound better when being pushed a bit, it just adds to the harmonics & sustain, giving a much richer sound than a solidstate(no distortion) clean, for example "Under the bridge" by RHCP , and tonnes of older stuff

Check out the marshall 18 watt review on their website and the magazine reviewing it says 18 watts is plenty!!
If everything is being miced up, the ideal wattage would be where you can have your amp on full without killing the audience would it not? If you are being miced 50 watts is overkill

DC4 · Post by **DC4** » Thu Apr 14, 2005 1:26 pm

Bluesgeek got it right. (of course

) The effect of doubling the watts (all other things being equal) would a just discernable increase in the sound volume. It would need about 4 times the wattage to make a significant volume increase. Decibels is a logarithmic scale of measure...
Speaker efficiency plays the major part... in years gone past, picture theatres used 30 Watt valve amps, and hugely efficient speakers, and they sounded really loud.

Rog · Post by **Rog** » Thu Apr 14, 2005 1:39 pm

I believe the ratio is: 10 times more power equates to a doubling in volume.

Therefore, given the same input signal and the same speakers/cab etc in the same location (you get the picture) you'd need a 500W amp to be twice as loud as a 50W amp.

TMG 03 · Post by **TMG 03** » Thu Apr 14, 2005 1:52 pm

I only ever ran my twin at 25watts. It was still heard over a 250 bass amp.

Kloppsta · Post by **Kloppsta** » Thu Apr 14, 2005 1:59 pm

with all that said, then why is that major, minor & botique amp builders feel the need to offer power ratings of anything and everything up to 200W??? It seems the most common now days for a tube head is 100 - 120W. Why?? If it really isn't needed?

Also....going into Bass amps...why is it that the majority of bass amps range from 250W - 1200W?!?!!
Our bassist had a 200W bass head which was clipping and just couldn't be heard when playing live. He had to upgrade to an 800W to be heard.

ash · Post by **ash** » Thu Apr 14, 2005 2:16 pm

That logarithmic scale as mentioned so far is for any given frequency. The other dimension is also highly non linear, so 10W of power at 50Hz doesn't sound anything like the volume of 10W of 2kHz sound. Whats more the relationship changes with distance, so if you're outside and 200m away its all different again.

Huge bass amps are required because at those low frequencies it takes alot more power (Watts) to get the same volume (dB). And also the headroom factor comes into it as bass sounds mostly need to be clean.

Rog · Post by **Rog** » Thu Apr 14, 2005 2:16 pm

> Our bassist had a 200W bass head which was clipping and just couldn't be heard when playing live. He had to upgrade to an 800W to be heard.

Because he's playing too fecking LOUDLY!!

If he needs 800W to be heard - so are THE REST OF YOU!!

Sorry had to shout, 'cos if you're playing that loud you will be fecking deaf before long!

Post by Bg » Thu Apr 14, 2005 2:18 pm

TMG 03 wrote:I only ever ran my twin at 25watts. It was still heard over a 250 bass amp.

your amp never got any louder though, just more distorted :p

Kloppsta · Post by **Kloppsta** » Thu Apr 14, 2005 2:18 pm

We play Rock & F'n Roll man.....we aint gonna play soft.

Rog · Post by **Rog** » Thu Apr 14, 2005 2:22 pm

FWIW, I played for three years with a 75W bass amp. I now us a 200W bass amp. I play at the same volume. The only difference is I used to have to go to 5/10 on the 75W amp, where I only use 2/10 on the 200W. In between them I had a 550W amp which I never got over 1/10, so figured it was a waste of space and flicked it off.

The reason I changed is that I don't like my volume being past 5/10 on any amp.

I play in a 6 piece band playing loud classic rock and blues. Its all about balance, not volume wars...

Post by Bg » Thu Apr 14, 2005 2:25 pm

yep, my amp has never been past 5, no need with a Bass - it looks like a POS but it has tons of good clean sound

If I turned it up to 6 it would blow that pussy twin away

jimi · Post by **jimi** » Thu Apr 14, 2005 3:03 pm

If I turned it up to 6 it would blow that pussy twin away

I think it'd blow your speakers 1st.

^.~

Bluesbird · Post by **Bluesbird** » Thu Apr 14, 2005 3:23 pm

I've used my 20W Victoria at a jam with 10+ guitarists, drums, and bass, and had no trouble at all with volume. It is my opinion that this is what low-wattage amps are best for - at those volumes, you are right on the edge of overdrive. By manipulating the guitar volume, you can go from sparkling clean to smooth, natural overdrive.

What amuses me is these metal bands that play nothing but distorted, and yet go for the most powerful amps and as many speakers as they can lay their hands on, and then find they have to use a multitude of pedals to get distortion.

I'd understand using that much power if it was Jazz or something, where the clean headroom is needed, such as the JC120.