Backyard sound experiments

dragonfly Jafe · Post by **dragonfly Jafe** » Tue Oct 03, 2006 11:22 am

I just finished a quicky backyard sound test. I setup one JBL-15 eon loudspeaker on it's stand, appx. 6 feet off the ground. A CD player and pre-amp were connected to the speaker's input. A tape measure was used to measure distances directly in front of this one speaker, and to the side at a 90 degree angle opposite my RV (forming a wall to me backyard).

Playing music w/ significant bass content (widespread panic: Ball) the volume was turned up until 90dB peaks were measured at 25' (a-weighting, fast response). The meter was held in front of my body at head height, appx. in-line with the speaker output.

I would judge this volume level as "loud" (certainly louder than I could continue here in town at night for long without the police showing up), and sufficient for the average sound camp. People would have difficulty talking without cupping the person's ear they were trying to talk to, or shouting. It was not "chest thumping" loud, however, so dedicated sound camps would most likely desire to go higher than this if able. It did completely fill my backyard with sound. The music was clearly audible at the street, appx. 125' away on the other side of my house.

The sound level measured at the speaker was 108dB at 3 feet (1 meter). This is consistant with expected sound drop-off due to distance (I think I made an error in my post above stating 120dB would be required, relying too much on tables). Most speaker systems would be able to easily reach this level if powered by a 300w amp (assuming minimum of 88dB@1M efficiency), with "commercial" systems capable of playing at least 6-12dB higher at max. volume. using the same amp.

As a quicky test, I also made a measurement 25' away at a 90 degree angle on the other side of the RV; it was only a 70dB peak. This would suggest that solid barriers such as RV's have a significant effect on reducing noise (probably a "duh!" to most people). The volume was audibly "less loud" - conversation would be difficult, but possible. Even a small gap allowed the sound to peak again (between RV and shed, for instance, appx. a 3 foot gap).

While my speaker could go louder (pre-amp volume appx. 1/2 way up), I chose at this time not to do so, in order to prevent angering any neghbors that might be nearby.

In my opinion, the 90dB at 25' standard is a good one, but unlikely to completely satisfy picky neighbors (certainly not ones without earplugs). Wearing earplugs should reduce this level to appx 70dB 25' in front, or 50dB 25 feet to the side opposite a strong wall such as an RV). If one was to try sleeping 25 feet inside your camp, with earplugs, and the speakers were located opposite a strong wall, the level would be appx. 44dB, which in my experience is adequate for sleep to occur (ymmv).

Conclusions;

-bring earplugs for sleep (always a good idea within BRC)
-try to sleep as far inside your camp as possible, and opposite strong walls if a sound camp is next door.
-setup you speakers pointing away from neighbors at least 25' inside your camp, and ideally use strong walls between you and your neighbors.
-most sound systems will require volume control (ie- not cranked up all the way) to meet this standard.

BoxaRox · Post by **BoxaRox** » Tue Oct 03, 2006 2:45 pm

Your Eon's are not gifted with tremendously bass response. I believe they don't have much below 100 hz (perhaps even as high as 150) and certainly not at that volume.

This is where the "A" and "C" weightings can start making things murky. If you add some subs to fill in that bottom octave, you would find the chest thumping loudness would be there.

I believe that under the "A" scale, you'd have to turn your volume down a bit once the subs were added. On the "C" scale, subs are essentially "free."

One other thing to keep in mind is what I'll call the "party factor" -- what seems self-conscioiusly loud in an empty space becomes much more modest when you add a couple dozen/hundred people.

dragonfly Jafe · Post by **dragonfly Jafe** » Tue Oct 03, 2006 3:14 pm

...I believe you have "mixed up" a-weighting and c-weighting....

http://en.wikipedia.org/wiki/A-weighting

as I understand it,

A-weighting the sound measurement focuses on the "human perception range", and attempts to adjust the measurement to match more closely what humans perceive. Therefore A-weighting is more useful when dealing with human issues.

C-weighting looks at more of the sound scale, without such drastic adjustments (especially in the bass frequencies). Therefore c-weighting is more of an "absolute" method, but may over emphasize some frequencies (like bass) with respect to humans.

Do you agree with "fast" response for measurements (peaks), or should "slow" response be used (more of an average result, as opposed to looking at the peaks)

And I agree with the bass remark re:JBL15eons - they claim a response down to 50hz, but that is probably a -10dB mark. If cranked up, however, they will cause your chest to thump (of course, your ears are close to bleeding by then!) Perhaps next I will repeat the experiment and take a frequency response measurement to qualify how much bass is present...

Which leads to a question I have had for a while, is the 300w "rule" all the amps added up, or just one channel? I would assume all the amps added up, but there might be other opinions.

BoxaRox · Post by **BoxaRox** » Tue Oct 03, 2006 4:36 pm

I was just testing you! You passed!

<blush>

Upon checking, my meter has C weighting on the left of the selecter switch, A on the right. I think in alphabetical order, I guess. <duh> hazards of working from memory.

Do you agree with "fast" response for measurements (peaks), or should "slow" response be used (more of an average result, as opposed to looking at the peaks)

Um, depends. <??>

the "fast" will produce higher readings (resulting in more conservative sound levels). I think the slow scale may be a little easier for the average Joe to track -- a skew very dynamic material less. (the standard boom boom that people grumble about is so highly compressed that the slow/fast readings will be very similar.

as far as the 300 watt thing, my vote goes to dropping that spec altogether. Because I believe that sounds systems that aren't overworked *sound* better, I'll vote for 300 watts per band (IE: stereo bi-amp would be 4 300w channels. This puts the responsibility on the operator, rather than the physical limitations of the system to keep volume in line, but it sounds better. ;)

unjonharley · Post by **unjonharley** » Thu Oct 05, 2006 7:46 pm

Mozy bonz · Post by **Mozy bonz** » Thu Oct 05, 2006 7:57 pm

BoxaRox wrote:I was just testing you! You passed!

<blush>

Upon checking, my meter has C weighting on the left of the selecter switch, A on the right. I think in alphabetical order, I guess. <duh> hazards of working from memory.

Do you agree with "fast" response for measurements (peaks), or should "slow" response be used (more of an average result, as opposed to looking at the peaks)
Um, depends. <??>

the "fast" will produce higher readings (resulting in more conservative sound levels). I think the slow scale may be a little easier for the average Joe to track -- a skew very dynamic material less. (the standard boom boom that people grumble about is so highly compressed that the slow/fast readings will be very similar.

as far as the 300 watt thing, my vote goes to dropping that spec altogether. Because I believe that sounds systems that aren't overworked *sound* better, I'll vote for 300 watts per band (IE: stereo bi-amp would be 4 300w channels. This puts the responsibility on the operator, rather than the physical limitations of the system to keep volume in line, but it sounds better.

A great sound engineer is like gold dust. Who combines the irreplaceable skills of taste, precision, technical expertise, patience and a great attitude with top of the range gear and a complete understanding of how to use it effectively

Mozy bonz · Post by **Mozy bonz** » Thu Oct 05, 2006 8:21 pm

sound engineer "I can't fix it it's on stage." You can’t let a DJ/live musician control the PA sound system that can’t hear what it sounds like in front of the stage. So they turn it up more because it sounds great on stage. That is why sound hurts sometime it can make you sick. Noshes vomit and no not the music the sound waves passing though your body. Some people like this wave and will stand holding on to an 8-foot stack. We had to tell new security in front of stage to not stand in front of the stack. Many a night with bad sound engineers people went home with bad headaches.

Jewel*** · Post by Jewel*** » Sat Oct 07, 2006 7:11 pm

i love watching the sound engineer at concerts. i'd like that job. but i always really wanted to do the lighting. Laser lighting. oh well, it was always just a dream.

Mozy bonz · Post by **Mozy bonz** » Sat Oct 07, 2006 7:48 pm

Jewel*** wrote:i love watching the sound engineer at concerts. i'd like that job. but i always really wanted to do the lighting. Laser lighting. oh well, it was always just a dream.

That's funnt right behind the sound board
is where I sit if I am not working a show.

That is where the best sound at a big show is also.
And both jobs can be allot of fun.

Jew Boy · Post by **Jew Boy** » Sat Oct 07, 2006 9:49 pm

Um, excuse me, but can you please turn that shit down? We're trying to sleep over here.

Jewel*** · Post by Jewel*** » Sat Oct 07, 2006 9:50 pm

hey, let me tag around with you sometime..........

Mozy bonz · Post by **Mozy bonz** » Sat Oct 07, 2006 9:56 pm

Jewel*** wrote:hey, let me tag around with you sometime..........

Me or sleepy guy?

Jewel*** · Post by Jewel*** » Sat Oct 07, 2006 10:15 pm

Mozy bonz wrote:
Jewel*** wrote:hey, let me tag around with you sometime..........
Me or sleepy guy?

Mozy, really, of course you

Mozy bonz · Post by **Mozy bonz** » Sat Oct 07, 2006 10:33 pm

Jewel*** wrote:
Mozy bonz wrote:
Jewel*** wrote:hey, let me tag around with you sometime..........
Me or sleepy guy?
Mozy, really, of course you

Thanks it would be great to take you to a real show with a real theater. Sorry but I watch very little of the show. The last show I just went to have fun was the Rolling Stones in Oakland I think it was the Babylon tour. Spent most of the show at the soundboard I could not see the stage. In luck for me the guy I was with was using his pass to take me all over the show. Spent some time back stage. Man I love the production of a big show.

Box Burner · Post by **Box Burner** » Sat Oct 07, 2006 11:20 pm

I like to have the full spectrum. I think that even though the human ear cannot hear it, it still affects the overall quality of the sound. Of course I could be wrong. But that is what I always thought. And yes a good sound engineer is priceless.

Mozy bonz · Post by **Mozy bonz** » Sun Oct 08, 2006 9:15 am

Sorry Jafe
back on topic A good book to read about sound "Psychology of Music"By Carl E Seashore

Standard study by founder of Seashore test. Relationship between physical phenomena of sounds and our perception of them. Music as a medium, physical acoustics, auditory apparatus, sound perception, host of other topics.... It has some Amplification of sound —Principles of measurement and guidance.

Jewel*** · Post by Jewel*** » Sun Oct 08, 2006 12:01 pm

Mozy bonz wrote:
Jewel*** wrote:
Mozy bonz wrote: Me or sleepy guy?
Mozy, really, of course you
Thanks it would be great to take you to a real show with a real theater. Sorry but I watch very little of the show. The last show I just went to have fun was the Rolling Stones in Oakland I think it was the Babylon tour. Spent most of the show at the soundboard I could not see the stage. In luck for me the guy I was with was using his pass to take me all over the show. Spent some time back stage. Man I love the production of a big show.

sounds like fun!!! just give me enough time to get my ass across the country.

Jew Boy · Post by **Jew Boy** » Sun Oct 08, 2006 3:02 pm

Hey I said, TURN IT DOWN!

Don't you people have any sense of decency?

Gizmo · Post by **Gizmo** » Sun Oct 08, 2006 3:58 pm

A great sound engineer is like gold dust. Who combines the irreplaceable skills of taste, precision, technical expertise, patience and a great attitude with top of the range gear and a complete understanding of how to use it effectively[/quote]

Everybody wants to be the lead singer or guitar player. Nobody ever said "fuck being Mick Jagger or Keith Richards, I want to run the SOUND BOARD!". Groupies for the sound guy? Stand in line behind the drummer.

It all starts with high school garage bands.
If you are a cousin of somebody in the band and you own a pick-up truck,
then you get to be the roadie/sound guy. No talent required.
Sad, but oh so true.....

Mozy bonz · Post by **Mozy bonz** » Sun Oct 08, 2006 4:20 pm

Gizmo wrote:A great sound engineer is like gold dust. Who combines the irreplaceable skills of taste, precision, technical expertise, patience and a great attitude with top of the range gear and a complete understanding of how to use it effectively

Everybody wants to be the lead singer or guitar player. Nobody ever said "fuck being Mick Jagger or Keith Richards, I want to run the SOUND BOARD!". Groupies for the sound guy? Stand in line behind the drummer.

It all starts with high school garage bands.
If you are a cousin of somebody in the band and you own a pick-up truck,
then you get to be the roadie/sound guy. No talent required.
Sad, but oh so true.....[/quote]

Very true very very true....can I be Mick?

Post by **AntiM** » Mon Oct 09, 2006 8:10 am

Snort. I've run a sound board at one time. I liked it. Of course, the band was small (Canned Heat) and the venue smaller (assorted clubs on Diego Garcia), so what do I know?

But then I was a cute young female and had no problem whatsoever getting gropies, band or no band.

Bin Noddin · Post by **Bin Noddin** » Mon Oct 09, 2006 10:15 am

AntiM wrote:(Canned Heat) ...(Diego Garcia)

So THAT's where they ended up.

Mozy bonz · Post by **Mozy bonz** » Mon Oct 09, 2006 10:22 am

AntiM can I be your gropie?

Canned Heat very impressive...the same that was at Wood Stock?

I worked with a sound guy that worked as a grip at wood stock. He was just a kid.
There is a picture of him on the album. He would only just say he was one of the kids on there. Someone said on top of a speaker stack I could never find out which one he was. And for the record the Executive Producer gets the best groupies and that is what I choose to be.

Post by **AntiM** » Mon Oct 09, 2006 3:31 pm

No, not that Canned Heat. I should be so lucky, eh? I think one of them discovered the "real" band shortly after I transfered and they switched over to Intense Heat band.

I sure could use a few gropies right now ....

gyre · Post by **gyre** » Mon Oct 09, 2006 3:54 pm

Richard Hite, Bear's brother played my house warming party a few years ago. I wish I had pictures. I told them to bring a couple of amps, but they set up the full show with lighting. They kept turning the amps up, but they were so harmonic, the neighbors only had praise.