small room vs large room acoustics

[IceBurghDJ]

I can only test my gear in my studio , a 2 car garage sized finished room.

Always get killer bass - but the waves don't have far to propagate.

so I'm comparing 2 12" ev subs with one 18" ev sub...1400w vs 1800w...and trying to determine if the 2 12" are 'enough'.
Using two yamaha DXR 12" tops.

Sure,they don't quite have the output of the single 18"...but they do sound 'lower' than the tops alone...now is that because they're on the floor and not 5' in the air?

Just for kicks I ran all three subs...nice. Now all I've ever read is to never every mix subs...of different size/brand, etc.

OK...so in my small space it sounds good...

Feb 20 I have a middle school dance and i'm tempted to take all 3 and play in a big room and see what it sounds like.

thoughts? Advice?

 

[rickryan.com]

I can only test my gear in my studio , a 2 car garage sized finished room.

Always get killer bass - but the waves don't have far to propagate.

so I'm comparing 2 12" ev subs with one 18" ev sub...1400w vs 1800w...and trying to determine if the 2 12" are 'enough'.
Using two yamaha DXR 12" tops.

Sure,they don't quite have the output of the single 18"...but they do sound 'lower' than the tops alone...now is that because they're on the floor and not 5' in the air?

Just for kicks I ran all three subs...nice. Now all I've ever read is to never every mix subs...of different size/brand, etc.

OK...so in my small space it sounds good...

Feb 20 I have a middle school dance and i'm tempted to take all 3 and play in a big room and see what it sounds like.

thoughts? Advice?

Take all of the subs with you and configure it on the fly at the event. Maybe even set it up so you can switch on/off the subs and try them out in different configurations.

 

[IceBurghDJ]

That's what I was thinking of trying.

I've read that you can get freq cancellations by mixing diff speakers, or having non-identical speakers producing the same freq.

My tops have a HP filter and a contour switch. With the HP engaged and FOH (vs flat) for contour it sounds great - in my small space. Going from FOH to flat the highs become very harsh - I'm sure that's not too difficult to adjust..but if the switch adjusts it then that is the fix, right? LOL.

I'll have to fire up some pink noise and see what that gets me. Besides TMI and confused LOL

 

[steve149]

If you're doing a school dance in a gym .. honestly, you don't have enough gear. My suggestion would be to rent or borrow a pair of good 18" subs and use the EV tops. 12s won't do it .. even 2 (I have Yamaha DXS12s) and as you point out, you may have a lot of issues to deal with combining subs, so the easiest way is to just bring bigger ones.

 

[IceBurghDJ]

Did this same dance, same place, for HS kids last fall - this is for MS kids. It's a cafeteria not a gym..so lower ceiling and more tables ..longer not as wide.

the real purpose to setting up the gear was to hear the 12" subs with teh DXR12 tops. Never put those together. It's a bit easier to haul the two 12" subs than the one big 18".
Since they were setup I figured why not run them all?

I'd love to move them outside and test..but it's snowing, nealry 2" today, and it's in the teens...

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[NickC]

For a dance like that, the more low end the better. Using the different subs will likely cause some comb filtering, and maybe some power alleys, so make sure and walk the floor all over when testing.

On second thought, those kids will just find the sweet spot and hang out in it!

 

[soundinmotiondj]

I can only test my gear in my studio , a 2 car garage sized finished room.

Always get killer bass - but the waves don't have far to propagate.

Acoustics is acoustics. That said, the complexity of the interaction of room modes in "small" (anything under about 60ft square) rooms will drive a normal person to drink. The boundary reinforcement in a 2 car garage size space will add 6-12 dB to the perceived output....for some listening positions.

so I'm comparing 2 12" ev subs with one 18" ev sub...1400w vs 1800w...and trying to determine if the 2 12" are 'enough'.
Using two yamaha DXR 12" tops.

Sound levels are not measured in watts. Sound levels are measured in Decibels. In general, anything over about 500w is only making heat, and is not making dB.

All things being equal, the 18" woofer will have about 12% more surface area than the two 12" woofers. Knowing nothing else, I would plan to take only the single 18 to this event.

thoughts? Advice?

Put the sub in the middle of the wall, facing the wall. Put the two tops 1-2ft over the heads of the people in the room, separated by 25-30ft. Run a mono signal to the tops.

Mixing both subs is a recipe for frustration. But, if you insist....put the 18" in the middle of a long wall. Put one 12" in each corner along that same wall. Split the wall into 1/3rds with the tops. That will give you the best chance of avoiding cancellations and integration issues with the subs.

 

[rickryan.com]

Sound levels are not measured in watts. Sound levels are measured in Decibels. In general, anything over about 500w is only making heat, and is not making dB.

I don't doubt that you know your stuff, but I just have a hard time wrapping my head around this statement. I've used 500w subs, and I use my 1500 watt Yorkie subs. There's a huge freakin difference in the db being produced, at least to my ears. I keep meaning to experiment with the wall-facing idea mentioned, but always seem to forget it.

 

[soundinmotiondj]

I don't doubt that you know your stuff, but I just have a hard time wrapping my head around this statement. I've used 500w subs, and I use my 1500 watt Yorkie subs. There's a huge freakin difference in the db being produced, at least to my ears. I keep meaning to experiment with the wall-facing idea mentioned, but always seem to forget it.

There are many things in play. The efficiency and tuning of the cabinet are HUGE in terms of the resulting output. The "power hungry" subs myth takes a bit of time to work through. Unless you measure the output of the amp with a test tone, volt meter, and set a hard limiter...you are guessing about how much power is being applied.

Look up "Power Compression" for more. Here are a few links to get you started.

This notes that power compression is a 3-6dB lowering of ouptut. 3dB is "2x" the applied power in watts. So a 1500w speaker with 6dB of power compression is only making use of 375w (1/4 of the applied power) to make SPL, the rest is just making the coil hotter.

General Audio FAQ

Gain compression - Wikipedia, the free encyclopedia

Power Handling Vs. Efficiency

 

[Handinon]

I've used 500w subs, and I use my 1500 watt Yorkie subs. There's a huge freakin difference in the db being produced, at least to my ears.

The discrepancies you're alluding to are the result of fantasy specifications sneaking into almost every manufacture's literature. I'm assuming the Yorkville subs you're referring to are LS-801p's. They are rated 2500 watts "Peak", 1500 watts "Program Power".

Rod Elliott's excellent article referenced above (Power Handling Vs. Efficiency) uses RMS or "Continuous Power", a much more accurate rating for a power amplifier. You can approximate that for the LS-801p by dividing it's "Program Power" rating in half, yielding 750 watts. Use that number when reading said article and you will see it makes a lot more sense.

The LS-801p also has a huge 70hz peak in it's frequency response, which also makes it seem louder.

I'm not singling out Yorkville here - almost all present day manufacturers do this.

 

[rickryan.com]

The discrepancies you're alluding to are the result of fantasy specifications sneaking into almost every manufacture's literature. I'm assuming the Yorkville subs you're referring to are LS-801p's. They are rated 2500 watts "Peak", 1500 watts "Program Power".

Rod Elliott's excellent article referenced above (Power Handling Vs. Efficiency) uses RMS or "Continuous Power", a much more accurate rating for a power amplifier. You can approximate that for the LS-801p by dividing it's "Program Power" rating in half, yielding 750 watts. Use that number when reading said article and you will see it makes a lot more sense.

I'm not singling out Yorkville here - almost all present day manufacturers do this.

Yes, my current subs are Yorkie ls801ps. My previous were passive, JBL M-Pro cabinets and I was pushing them with 800 into each cabinet. In the past 5 years I've also had an EV, 750-watt 15" active, and dual Peavey single-18" radiators (500 watts into each). The level of sound pressure I get out of these yorkies is nothing short of amazing in comparison to the others. I do hate having to wheel in 150lbs (per cabinet) but boy, is it ever a big hammer when you want to drop one on a crowd, not to mention it's entirely pleasing to the ears at lower volumes.

 

[MIXMASTERMACHOM]

Steve nailed it along with Rick. There's another thread that ask how do you separate yourself from your competition? By using the right tools for the job. What you have is OK. Not that great for a middle school dance IMO. Also you said you wished you could set it up outside. That's not a good thing. To wide open a space. You want the sound to be super impressive. Something that will have the students and staff take notice. Something that they aren't use to seeing or feeling. I second the 801p's. Even though it's in a cafeteria and not a gym you still need the sound to be over the top. You want to do this so they will definitely want you to come back to do another dance for the school in the future.

Myself I also have a pair of Earthquakes as well. The older model ones. Not the newer junk that they make today. If you can't afford to rent the gear you need then I don't know what to tell you. 12" tops for a school dance certainly won't cut it.

 

[IceBurghDJ]

yes, spl is 'the' measurement - but so many factors go into what matches well - and while there is 'science' behind much of it there is also are. All 18" subs are not teh same anymore than all 1000w speakers are the same.

Do watts matter? I've never been a big proponent of watts but more watts equates to more HP - good for acceleration if not top speed. And it seems class d amps are much more 'watt heavy' than the older 'real' amps.

As to outside vs inside...as mentioned the room acoustics/size affect the sound level- i don't play in 20x25 spaces but it's not easy to access a large ballroom for testing, so outside eliminates the effect of the walls/ceiling/boundary effects.

 

[steve149]

As surmised, everything just depends .. cabinet type, driver construction, magnet, porting, crossover, amp power, impulse response ...

SO .. mixing brands/sizes/styles is tough (phase, driver alignment, peaks, freq range) and the best cure is to use the same type of sub if possible .. same with tops (although if you have tops that are not overlapping you have a little leeway and can use "similar" setups).

Just from experience, 18s in a gym (or cafe) is probably the minimum for any serious dance.

 

[MIXMASTERMACHOM]

Another factor for me is doing a job that's impressive because I never know who is there and in the future either looking for a DJ or someone else that's looking for a DJ. I look at anybody at an event I'm doing as a potential client. Even someone that's 12 years old. They won't pay me but they can suggest that they check me out and see if I'm available to do an event.

 

[IceBurghDJ]

what's impressive?
If the last DJ they used brought no sub and 12" tops, one light then comparitively I'm gonna blow them away.

I got the call to come back because the kids danced. the last few dances NOBODY danced - and the people in charge told me "We put chairs down both sides because the kids don't dance" ...yes they will.... "they never dance at these school dances and I've been doing them for 3 years"...

they danced.

I need do no more than I did last time - and yes, i've done MS and similar age parties and they will dance next saturday. Probably not all night, but they'll dance. the more thump they more they'll dance - i've tested this a bit and believe it.

I was called a bit odd for spending $1500 on a sub for a $200 dance...now I'm being told I need a second one for a $300 dance!

You people make me laugh!

I'm gonna test/try the 12" subs with the 18" sub and see, um, hear what it sounds like. Only way for ME to know for sure.

 

[Handinon]

As surmised, everything just depends .. cabinet type, driver construction, magnet, porting, crossover, amp power, impulse response ...

As usual, Steve is correct, and given the choice, don't mix sizes and brands - but if you don't have a choice...

Sometimes, dumb luck beats science - if you're going to try mixing the subs, here's the best way to see if it's helping or hurting. The age group you are playing to is looking for bass in the 70-80hz range, so we will split the difference. Here's a link to mp3 test tones.

Stereo System Test & Analysis Tones by Nino B.

Scroll down left side and download the 75hz mp3 test tone. Get all your subs set up, I'd recommend clustering everything. Either have them next to the wall or at least 8' away from the wall. Que up the 75hz test tone in your laptops DJ program and loop on it so it plays continuous. Make sure the volume on your mixer or controller is low, turn on the 18" amp. SLOWLY turn up the volume to where you can start hearing it, we don't want to blow anything.

Walk around the room - your ears will quickly tell you where the bass peaks and nulls are. We are obviously looking for maximum bass on the dance floor (moving the subs only a few feet sometimes makes a big difference). Now turn on the two 12's and SLOWLY bring them up to about the same level as the 18", check out the dance floor again. Better? You just got lucky! Worse, you need to experiment further by separating the two 12's from the 18" (still leaving the two 12's clustered). You may not need much. Good luck.

Plan on setting up earlier if your only option is doing this the day of the dance.

 

[MIXMASTERMACHOM]

what's impressive?
If the last DJ they used brought no sub and 12" tops, one light then comparitively I'm gonna blow them away.

I got the call to come back because the kids danced. the last few dances NOBODY danced - and the people in charge told me "We put chairs down both sides because the kids don't dance" ...yes they will.... "they never dance at these school dances and I've been doing them for 3 years"...

they danced.

I need do no more than I did last time - and yes, i've done MS and similar age parties and they will dance next saturday. Probably not all night, but they'll dance. the more thump they more they'll dance - i've tested this a bit and believe it.

I was called a bit odd for spending $1500 on a sub for a $200 dance...now I'm being told I need a second one for a $300 dance!

You people make me laugh!

I'm gonna test/try the 12" subs with the 18" sub and see, um, hear what it sounds like. Only way for ME to know for sure.

You were asking us if what you have would be good enough to do this dance and we're telling you no. I'm talking about the gear you use to do this gig. I'm talking about it being what they may not be used to seeing a DJ using to do a school dance there before. Not making it just about the music. I say you want to impress them with both. In turn if you do a good enough of a job the students will tell the staff to get you to come back to another dance for the school.

 

[IceBurghDJ]

and you're wrong.
did a bigger dance in november with the same gear at the same location for the same administration folks. (hs then vs ms this time)
My personal experience counters your assumptions, sorry. I have enough gear. More is always better though.

The kids danced.

I got called back.

I'm getting paid more this time too.

Sounds like I know what I'm doing. I just want to improve more, try new things.

Since my experience runs counter to your advice, and I have a long history of questioning 'authority', often finding 'authority' to have been wrong, I'm gonna try/test see what mixing diff size subs truly actually in the real world sounds like. Maybe authority will be right...maybe not.

Testing in my studio today showed the 18" sub had a peak in output (db) at about 64hz, the 12" subs at 107hz, and combined the peak sat at 86hz. Assuming i can rely on a spectrum analyzer, but even if the absolute numbers can be questioned the relationship and delta are real.

 

[MIXMASTERMACHOM]

OK if it works for you. You didn't say this was a repeat client. That does make a difference. Tell us how it turns out.