reality check: 5 watt head in the rehearsal place

[JohnnyCrash]

Originally Posted by Joe-Bob

I'm not buying it for a minute. A 3dB increase is more than just barely noticeable. You're not comparing apples to apples. Volume is not percieved as watts, and frequencies are percieved and reproduced at different volumes as well.

Hey, I was just trying to break down the two poster's math.

I agree volume is not simply watts - there's more to it.

The thing with tube amps is: compression. What gets compressed (what frequencies?) by the amp as it gets more and more overdriven? What gets compressed (what frequencies?) by the speaker as it gets more and more break-up? Brighter amps may cut through the mix better, etc.

This does affect things... so some 5 watt amps can do better at the job on certain frequencies, some speakers better too... but in the end, as I mentioned - you won't have ACDC/The Cult sparkle and bottom end from a Champ's natural overdrive as compared to a 50w Marshall's overdrive. Mic it, add extension cabs, do whatever you can - the tone and volume aren't there for some uses.

As far as the math - I got that from a few other sources, and the two posters knew about this as well. muchxs can tell you as well from personal experience how sneaky a doubling of perceived volume can be.

I just go by wattages because that's what I'm used to. I build amps based on the horsepower (wattage) for certain uses. Some small for home use (1.5 watts is still a mite loud), some big for bottom end... other than wattage I consider the circuit (bright, middy, etc?) and the speaker... a V30 and Celestion Blue can be loud with any amp.

My 1.5 watt amp is friggen loud. My 5 watts, 10 watts, 15 watts, 30 watts, 40 watts, and 50 watts are all friggen loud. The difference between my Champs and my Marshalls in my room doesn't seem like much, but when I drag it to band rehearsal the 5 (and sometimes 10) watt amps get washed away (for my music).

[JCSouthpawtele]

Originally Posted by muchxs

I don't know what you're not buying.

My AudioPhool buddy uses a McIntosh 500 watt per channel amp into a pair of Altec Voice of Theaters for his home stereo. The meters on the Mac are graduated logarithmically so they read .5 watt, 5 watts, 50 watts, 500 watts in what look to be linear gradations but if you look closely they're log. The VOTs put out around 103db 1w/1m with a lot of it coming from the compression drivers. BTW the horns are damped, it's custom and it sounds a lot better than stock. So... crank it up to .5 watts with the meter just tickling the .5 watt level. Then crank it up to 5 watts. Twice as loud, right? Well, it sounds louder...

(Loud enough for me in fact. Those Altecs are loud. 1 watt to an Altec is loud. Don't take my word for it, ask the neighbors. The neighbors know what's "loud", too. They run jacked up mud trucks, they shoot guns, they have a little band and they gig every Saturday night.)

Same deal with the next step up to 50 watts, the meters don't lie. That works out of 50 watts with a ton of headroom, there's no discernable distortion. We didn't spark up our RTA, had we did it would read out sound pressure levels anywhere in the room. In theory that's 103db spl + 10db + 10db

Ok now your getting into some professional sound engineering talk.
Frequencies travel at diffent speed's and wavelength. so a lower frequency is not heard right at the speaker.(have you ever noticed how sub's shake your pantleg's at 20 feet back?)

here is a distance calulation...If I am mixing at Front of house 100 feet from my speaker and my DB meter is reading 100dB then the sound at the speaker is actually 112dB

SPL (Sound pressure level) calculator

Loudspeaker sensitivity (1W/1m) dB SPL
Amplifier power/speaker W Correction/1W dB
# of speakers (4)
in phase Correction/1 speaker dB
Distance to speaker (m=metres, ft=feet) m ft Correction/1 m dB

Theoretical (calculated) Total SPL dB SPL Total correction.

Here are some wavelength calculations from the speaker.
80Hz -14.06ft
125Hz -9.003ft
500Hz-2.25ft
1000Hz(1k)-1.125ft
400Hz(4k)-0.281ft


I can walk a room and know where the bad spots are. Bass trap areas and high's that bounce off windows,etc. I ran sound in a high school gym. and had to delay the entire PA to however many miliseconds (basically a millisecond for every foot so I think about 20ms) because of a slapback from the wall behind the band. the snare was echoing off the wall.. to get rid of(or hide) the slap. I delayed the system to"wait" till that sound was travelling outward.

[muchxs]

Originally Posted by JCSouthpawtele

Here are some wavelength calculations from the speaker.
80Hz -14.06ft
125Hz -9.003ft
500Hz-2.25ft
1000Hz(1k)-1.125ft
400Hz(4k)-0.281ft.

Yeah. So: 40Hz is 28 feet (using your numbers) so the bass sounds great somewhere out on the front lawn. That's the hassle with this guy's listening space, there's not enough room for a full cycle of the bass frequencies.

Originally Posted by JCSouthpawtele

I can walk a room and know where the bad spots are. Bass trap areas and high's that bounce off windows,etc. I ran sound in a high school gym. and had to delay the entire PA to however many miliseconds (basically a millisecond for every foot so I think about 20ms) because of a slapback from the wall behind the band. the snare was echoing off the wall.. to get rid of(or hide) the slap. I delayed the system to"wait" till that sound was travelling outward.

Which may entirely change with a room full of people.

[JCSouthpawtele]

Originally Posted by muchxs

Yeah. So: 40Hz is 28 feet (using your numbers) so the bass sounds great somewhere out on the front lawn. That's the hassle with this guy's listening space, there's not enough room for a full cycle of the bass frequencies.



Which may entirely change with a room full of people.

Yes, bodies absorb frequencies. things change throughout the night, Last night for example I had mics on the drum kit. Kick,Snare,H.hat,tom1,tom2,l&r overheads. the snare was too loud becausedthe room was empty to start. so I just line checked the snare mic and left it off with just a bit of overheads. by the second set the dance floor was filling so I put the snare mic in the mix. the guitars got louder so I dropped back my fader level on them to keep them from eating up the all important mids battle where vocal and guitar fight for clairity.
humidity and temp effect sound too.

[crawdad]

Theory aside, don't send a boy to do a man's job. If you are playing with a loud drummer and a bass player who's using his 400 watt rig, and you are trying to compete with a cranked FOH mix, your "loud" Champ amp is going to drown in the mix.

And if you want crystal cleans, think Twin Reverb or Super at the minimum.Playing an acoustic coffee shop, the Champ might be great, but not in a band that has a rhythm section with some muscle.

[JCSouthpawtele]

Ok..here is my real world results. I was contacted through my CL post to start or join a band. After meeting up with the singer I went to there rehearsal space in the other guitar players basement. All I took was my Strat,Blackheart Little giant Head and 1-12" cab..pedals were a Tube Screamer,Option 5 Destination overdrive and a Delay. I tilted tha cab back on a chair thinking I would not be able to hear myself over the drummer and the other guitarist Marshall MG100 valvestate and 4-12" cab..to my suprise the singer told me to turn down.
I don't think I will be joining them. I have been working around pro musicians as a sound engineer for 14 years and have played on stage at benefits and as a guest with these guys/gals several times through those years. I have put together one off bands for a few occasions but never been in a full time band of myself. After "Jamming" on 6 tunes that I learned correctly I pointed out mistake's. I came in prepared with sheets noted and chord charts. Also they said they tuned down a half step to Eb but when I tuned to my chromatic tuner they were still off, more like a whole step..
Needless to say I learned a few things tonight...
Never over think it or think you seen it all.