# How Much Power?



## Stevens R. Miller (Feb 27, 2017)

I suspect this is asked (and answered) a lot, but most of the online guidance I've found has been (understandably) a bit vague. I'm hoping, though, that maybe someone has had experience in nearly the same setting as the one in which I'm seeking guidance.

After our last community theater musical wrapped, I made it clear to my colleagues that I have had my lifetime desire to work with badly maintained, curiously wired, largely undocumented dusty humming audio equipment of nostalgic vintage completely satisfied by our latest experience. Accordingly, I am pushing for us to get our own powered speakers, so we can stop using the in-house stuff in the middle schools we use as venues. The response has been cautiously supportive. But the threshold question, of course, is how much will this cost? That, naturally, depends on what we need.

Our typical venue is a middle school auditorium, with a seating area of about 4,000 square feet (roughly 80 feet wide by 50 feet deep), that seats about 480 people. They usually have a single center cluster of three speakers mounted on the ceiling, just above and in front of the proscenium arch. As far as I can tell, it is driven by a QSC CX1102 amplifier. I do not know the impedance of the speakers. If they are 8-ohm, QSC says both channels driven gets you 700 watts (I am not entirely sure, but I _think_ both channels are used in a bridged configuration). If they are 4-ohm, QSC says that gets you 1,100 watts. The masters on the amplifier are down about one-third from their least-attenuation position, and I know we could be driving the amp with higher line levels than we send it, so we have a lot of overhead that, I am guessing, we mostly never use.

So here's my question: if we're going to use a pair of self-powered speakers on stands, instead of the single center cluster on the ceiling, in a 4,000-square-foot, 480-seat middle school auditorium, how much power should each speaker provide?


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## jkowtko (Feb 27, 2017)

Stevens R. Miller said:


> ... I have had my lifetime desire to work with badly maintained, curiously wired, largely undocumented dusty humming audio equipment of nostalgic vintage completely satisfied by our latest experience.



Everyone always has at least one interesting thing on their bucket list ... 


Stevens R. Miller said:


> So here's my question: if we're going to use a pair of self-powered speakers on stands, instead of the single center cluster on the ceiling, in a 4,000-square-foot, 480-seat middle school auditorium, how much power should each speaker provide?



I run the semesterly instrumental music concert at the local middle school. Similarly sized auditorium with pull-out bleachers along one side wall where the ~500 parents sit.

For this I use two Mackie SRM450s on tripod stands at the corner edges of the "orchestra" area on the gym floor -- about 75-80 feet apart, 10 feet from the base of the bleachers -- and one Anchor AN-1000x speaker on a small stand in front of the conductor's riser as the center fill.

The center fill makes a BIG difference in sound ... it fills the entire space evenly. The center runs off an Aux so is a mono mix of LR.

The above setup has way more than enough horsepower to blast the parents in the auditorium. I run the speaker volume knob at ~10 o-clock (12 o'clock is the halfway point). The Anchor runs at 12 o'clock (halfway point). I've also used the exact same setup for a school assembly the following morning (spirit week) with rowdy screaming kids in the audience instead of relatively polite and quiet parents, and again had no problem pushing the band and the emcee up over the crowd noise.

If you don't have access to the SRM450, then QSC K-12 should be equivalent in volume, maybe with slightly cleaner sound. I wouldn't suggest anything less powerful.

And make sure you have that center fill.


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## Stevens R. Miller (Feb 27, 2017)

jkowtko said:


> I use two Mackie SRM450s on tripod stands at the corner edges of the "orchestra" area on the gym floor


Wow! Those are a thousand watts _each_, right? That does seem a bit potent.


> and one Anchor AN-1000x speaker on a small stand in front of the conductor's riser as the center fill.


I may be misreading their Web site, so let me know if I'm right or wrong: that one is only 50 watts(?). Is that enough to get the fill you're creating?


> The center fill makes a BIG difference in sound ... it fills the entire space evenly.


That's a very helpful point, thanks.

Sounds like you're in a bigger space than I'm using, but otherwise dealing with similar issues.

Thanks for the reply!


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## Stevens R. Miller (Feb 27, 2017)

Ah, wait... I didn't do my Googling. The SRM450 is available in different _versions_. The v3 is a kilowatt, but the v1 is 400 watts. I'm betting you're using the 400-watt model, correct?


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## jkowtko (Feb 27, 2017)

Yes the 400 watt model ... I may have the V1 ... mine are over ten years old.

The AN-1000x packs a punch. Not great music quality but gets fairly loud. As a fill it does what it needs to. if you want to put a larger speaker in there you could, but larger speakers will also start to physically block the view. The AN-1000X lays horizontally with side mount points so it can be tilted up.

My entire sound system for this concert including two SRM450s, two AN-1000x (another one for choir monitor), 4 wireless receivers and sound board, all run off of a single standard (15a?) 110v outlet from the wall ... nothing special. I've been doing this for several years now with the same speakers.

Also, I will caution you against getting the smaller speakers (SRM350 or QSC K-10) ... IMHO they pale in comparison in power and sound quality.


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## Chris15 (Feb 27, 2017)

Don't forget that 400W vs 1000W is only 4dB...


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## FMEng (Feb 28, 2017)

It's time to break some myths again...

The size of the amp has little to do with how loud the speaker is under normal operating conditions. All it means is how much power can be delivered to the speaker, if called upon by the input signal, without clipping distortion. You'd be surprised how many speakers are doing their job every day being driven by an average of a few tens of watts from a 1000 Watt amplifier. Having extra headroom is never a bad thing. Plus, there is always a certain amount of spec-manship with speakers. 1000 Watts sells better than 700, though you'd be hard pressed to hear the difference.

Another myth is that the setting of the volume control on the amplifier has anything to do with how much power is going to the speaker. All the volume control does is adjust how much input signal is required to drive the amp to a given amount of output. You can drive the amp to full output with the control set at 9 O'clock or 5 O'clock.

Mackie SRM450s, were excellent for their day, but subsequent generations of that product don't compare that favorably to the plethora of self powered speakers available today. They are fine for a tight budget, though. If the budget allows, consider Yamaha DXR/DSR series, QSC K/KW series, or EV EKX series, among many others. I would look for something with a 12" or 15" woofer.


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## RonHebbard (Feb 28, 2017)

FMEng said:


> It's time to break some myths again...
> 
> The size of the amp has little to do with how loud the speaker is under normal operating conditions. All it means is how much power can be delivered to the speaker, if called upon by the input signal, without clipping distortion. You'd be surprised how many speakers are doing their job every day being driven by an average of a few tens of watts from a 1000 Watt amplifier. Having extra headroom is never a bad thing. Plus, there is always a certain amount of spec-manship with speakers. 1000 Watts sells better than 700, though you'd be hard pressed to hear the difference.
> 
> ...


Hello @FMEng, possibly you'll write a few words about sensitivity and efficiency, 1 Watt/1 Meter. 
Toodleoo!
Ron Hebbard


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## jkowtko (Feb 28, 2017)

Chris15 said:


> Don't forget that 400W vs 1000W is only 4dB...



I agree the volume level difference is probably not that noticeable ... maybe the more relevant point of this is that two of these speakers plus other sound equipment for the gig would collectively be rated to run under one 15 amp circuit.

I also won't dispute the speaker quality issues with the newer versions of the Mackie. I would just say it's safer to audition them yourself before buying ... or buy from a place you can return them to if not satisfied when you first use them.


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## BillESC (Feb 28, 2017)

I'd suggest looking at the speaker offerings from Electro Voice.

The ZLX, EKX and ETX lines merit consideration and can adjust to any budget.


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## Stevens R. Miller (Feb 28, 2017)

Okay, looks like a general consensus is forming around two 400-watt speakers, with jkowtko making a good case for a low-power center-fill speaker. We are on the typically tight budget for a community theater company, but I certainly don't want to "save" money by wasting it on bad equipment.

At the low end of the price spectrum, I see a lot of products offered by Gemini. Example: Gemini AS-08P, 8-inch woofer, 500W, $99.95. That's an awfully attractive price for that many watts, but I'm naturally dubious when, for comparison, the Electro-Voice ZLX-15P, 15-inch woofer, 1000W, is $449.00. Twice the power and twice (or, four times, if you consider area instead of diameter) the speaker cone, but also about four times the price. Now, we can allocate more than $100 for each of two powered speakers, but $450 is out our range. I'd hazard to say that we'd like to keep it under $250, more like $200, if possible.

Any particular recommendations for a 400W device for $200?


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## TJCornish (Feb 28, 2017)

Stevens R. Miller said:


> Wow! Those are a thousand watts _each_, right? That does seem a bit potent.
> 
> 
> I may be misreading their Web site, so let me know if I'm right or wrong: that one is only 50 watts(?). Is that enough to get the fill you're creating?
> ...


As others are alluding to, you don't hear watts, you hear sound pressure level - SPL. The efficiency of various speakers can vary a lot - some take a lot of watts to make a certain amount of SPL; others that are more efficient can do the job with fewer watts. All of that is irrelevant, though, and most newer-generation products tend to have large amplifiers because it can now be done cheaply, whereas 10 or 15 years ago, high power amps were more expensive.

What kind of material are you working with? An 80' x 50' room isn't all that big, so I agree with the others that any reasonable model of modern powered speakers will likely be just fine unless you're looking for concert volume.

The JBL SRX800p, Yamaha DSR112, and EV ETX all sound really excellent and have much of the tuning work done at the factory, so you will get good sound by plugging them in and turning them on. The lesser offerings - JBL PRX, Yamaha DXR, and the lower-end EV series will work too, trading off performance for cost savings.

In my opinion, QSC is a bit behind at the moment with their powered speaker offerings.

I agree with FMEng that you probably want 12" woofers, as smaller speakers will have lower output and/or less bass ability. Often (again in my opinion) the extra weight and size of a 15" speaker doesn't really buy you very much. Any of the above speakers will do 95dB+ at 50'.

I also agree that the width of the room may be a challenge without a front fill speaker. I am partial to the Yamaha DXR-10, which is the best of the bunch of the 10" speakers and is a great value. If you want to stick with the same brand, a pair of Yamaha DSR-112 speakers for left/right and one DXR-10 as a center fill would be a great system. You could chain the center fill off either the left or right main and it would be close enough. You'll want to turn the level down lower than the left/right speakers; it's purpose is to fill in the hole from the main system.


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## TJCornish (Feb 28, 2017)

Stevens R. Miller said:


> Okay, looks like a general consensus is forming around two 400-watt speakers, with jkowtko making a good case for a low-power center-fill speaker. We are on the typically tight budget for a community theater company, but I certainly don't want to "save" money by wasting it on bad equipment.
> 
> At the low end of the price spectrum, I see a lot of products offered by Gemini. Example: Gemini AS-08P, 8-inch woofer, 500W, $99.95. That's an awfully attractive price for that many watts, but I'm naturally dubious when, for comparison, the Electro-Voice ZLX-15P, 15-inch woofer, 1000W, is $449.00. Twice the power and twice (or, four times, if you consider area instead of diameter) the speaker cone, but also about four times the price. Now, we can allocate more than $100 for each of two powered speakers, but $450 is out our range. I'd hazard to say that we'd like to keep it under $250, more like $200, if possible.
> 
> Any particular recommendations for a 400W device for $200?


I didn't carefully read over your budget numbers. 

Gemini, Nady, Fender, Alto, Samson, Phonic, et al are all garbage and your current feelings of frustration will continue into the future. For new gear, a pair of Yamaha DXR-12 would be the bottom of the range that would be worth your time new (IMO). If your absolute max budget is $200, you're in trouble, even for used equipment. I recently sold some 15-year old Mackie SRM-450 speakers for $300 each. There's not much even used for $100 each.

Once again - forget watts. It's as meaningless as comparing fuel pump pressure on cars. Think SPL!


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## Stevens R. Miller (Feb 28, 2017)

TJCornish said:


> As others are alluding to, you don't hear watts, you hear sound pressure level - SPL.



That makes sense, given what I'm learning about speakers. I was shocked to find out how inefficient they are. Apparently, it's common for 99% of the power sent to a speaker to be lost as heat, not converted to sound. I'd have lost a bet on that one.

Let's see if I'm doing my homework right: SPL is the logarithm of the ratio of pressure created by a sound source and the pressure created by a reference sound. The common reference sound for audio work is 20 micro-pascals, chosen because it is at roughly the lower limit of human hearing. Expressed as decibels, SPL is 20 log10(p/p0), where p0 is the reference sound. The Yamaha DXR-12 quotes a maximum SPL of 132 dB (about 157,000,000 times the reference pressure). Am I correct in assuming that SPL must be measured at some standardized distance from the speaker? If so, is it safe to assume that all vendors are quoting SPLs that are measured the same way, thus making them directly comparable?


> What kind of material are you working with? An 80' x 50' room isn't all that big, so I agree with the others that any reasonable model of modern powered speakers will likely be just fine unless you're looking for concert volume.



We do musicals with pre-recorded soundtracks. Examples are "My Fair Lady," "The Little Mermaid," and "Fiddler on the Roof." You know, the usual stuff . We need a fairly fulsome level of sound, but we're not doing head-bangin' heavy metal.


> I agree with FMEng that you probably want 12" woofers, as smaller speakers will have lower output and/or less bass ability. Often (again in my opinion) the extra weight and size of a 15" speaker doesn't really buy you very much. Any of the above speakers will do 95dB+ at 50'.



My Googling suggests that the standard distance for measuring SPL is one meter. 50' is about 15.24 meters, and pressure should drop by in the inverse square law, so 132 dB at one meter would be about 116.6 at 50'. If I want 95dB, then, that DXR-12 would appear to be good enough (although their spec is 132 dB is maximum peak, not RMS; is maximum peak what I should be looking at?).


> I also agree that the width of the room may be a challenge without a front fill speaker.



Agreed, I think this is a very appealing layout and I have recommended it to my colleagues.

I learn so much at this site, but it's like drinking from a fire house. Add to that the fact that I'm advising other people on how to spend their money and it's a bit intimidating. I sure do appreciate all the guidance I get here.


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## RonHebbard (Feb 28, 2017)

TJCornish said:


> As others are alluding to, you don't hear watts, you hear sound pressure level - SPL. The efficiency of various speakers can vary a lot - some take a lot of watts to make a certain amount of SPL; others that are more efficient can do the job with fewer watts. All of that is irrelevant, though, and most newer-generation products tend to have large amplifiers because it can now be done cheaply, whereas 10 or 15 years ago, high power amps were more expensive.
> 
> What kind of material are you working with? An 80' x 50' room isn't all that big, so I agree with the others that any reasonable model of modern powered speakers will likely be just fine unless you're looking for concert volume.
> 
> ...


Efficiency is NEVER irrelevant. 
Toodleoo!
Ron Hebbard.


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## TJCornish (Feb 28, 2017)

Stevens R. Miller said:


> That makes sense, given what I'm learning about speakers. I was shocked to find out how inefficient they are. Apparently, it's common for 99% of the power sent to a speaker to be lost as heat, not converted to sound. I'd have lost a bet on that one.
> 
> Let's see if I'm doing my homework right: SPL is the logarithm of the ratio of pressure created by a sound source and the pressure created by a reference sound. The common reference sound for audio work is 20 micro-pascals, chosen because it is at roughly the lower limit of human hearing. Expressed as decibels, SPL is 20 log10(p/p0), where p0 is the reference sound. The Yamaha DXR-12 quotes a maximum SPL of 132 dB (about 157,000,000 times the reference pressure). Am I correct in assuming that SPL must be measured at some standardized distance from the speaker? If so, is it safe to assume that all vendors are quoting SPLs that are measured the same way, thus making them directly comparable?
> 
> ...


There are places to get off into the weeds - "peak" SPL, "Program" SPL, "Continuous" SPL, and various weightings - A, C, fast, slow, unweighted, etc. Loudspeaker manufacturers generally reference their specs to 1 meter and for every doubling of distance you subtract 6dB. That much is standard; how the vendor arrives at the initial number is murkier - is it peak SPL? (probably) Is it a level the speaker can reproduce indefinitely without damage? (Maybe) Does it sound good at that level? (Probably not).

Based on owning and having heard many of the current crop of speakers, all of them that are of reasonable quality - >$500 will likely do what you need. I came up with 95dB program SPL as a safe number that pretty much every speaker I mentioned above will be able to do and not sound like garbage doing it. 95dB is fairly loud and I think will meet your needs.


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## TJCornish (Feb 28, 2017)

RonHebbard said:


> Efficiency is NEVER irrelevant.
> Toodleoo!
> Ron Hebbard.


!? Can you elaborate with regards to this context?


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## EdSavoie (Feb 28, 2017)

RonHebbard said:


> Efficiency is NEVER irrelevant.
> Toodleoo!
> Ron Hebbard.



It is when you're not paying the bill 

(I'm kidding, I'm kidding)


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## RonHebbard (Feb 28, 2017)

TJCornish said:


> !? Can you elaborate with regards to this context?


I just find too many people get hung up on how many watts they're buying, or how many watts a device can sustain without releasing its magic smoke with little to no regard to efficiency. Those people are the music stores rightful prey.
Toodleoo!
Ron Hebbard.


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## Stevens R. Miller (Feb 28, 2017)

TJCornish said:


> I came up with 95dB program SPL as a safe number that pretty much every speaker I mentioned above will be able to do and not sound like garbage doing it. 95dB is fairly loud and I think will meet your needs.



We'd have two speakers, and most of our audience is within 10 meters. Losing 6dB at every doubling of the one-meter reference distance means we're losing about 24dB (at 8 meters, but let's keep the math simple and, hey, this is just an estimate). According to this Web page from Crown, you get back about 6dB by being in an enclosed space, so I'm going to guess I'm down about 18dB, which takes to me to 77dB where most of the audience is. Crown seems to think I need at least 90dB for our kind of musicals (I'm putting us in the high end of the "jazz" range), so does that mean I need speakers with about 108 SPL? They (Crown) seem to think I ought to be doing my math only with respect to the nearest speaker and, I guess, ignore the contribution made by the other one of the pair, but I have to doubt that when I'm in an enclosed space (particularly one with cinder-block walls).


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## FMEng (Feb 28, 2017)

I agree with TJ. Don't waste your money on <$400 speakers, otherwise you will be disappointed with the results. The SRM450 is what I'd go for on a tight budget. They will do the job.

Don't get lost in the weeds with the inverse square law. In indoor spaces, beyond a certain distance, the SPL does not reduce at the rate prescribed by the inverse square law.


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## JD (Feb 28, 2017)

Very little talk about how flat the speakers are and how much distortion may occur due to undersized HF throat sizes. There are big reasons to stay with established brands as compared to the cheap products that are out there. Electronics will clip when over-driven, but are usual pretty clean below that level. Not so with speakers. We talk about electrical watts, but not about acoustic watts. For example, in a compression driver, distortion occurs when you exceed 0.1 acoustic watts per square inch of throat area at it's tightest point. Luckily, 0.1 acoustic watts is pretty darn loud! However, when choosing a speaker system, you want to obtain one that has reasonable horn throat dimensions, which is usually found on you better systems, but not on the cheap music-store stuff. Remember, speaker distortion levels can be way above 20% even while within the power range of the speaker.
In other words, DON'T cheap-out on the speakers.

Article on "sound power - acoustic watts
https://en.wikipedia.org/wiki/Sound_power


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## jkowtko (Feb 28, 2017)

Sound characteristics also change with volume ... underpowered speakers will sound like they are "screaming" when you turn them up enough ... not pleasant. I prefer the "broadway" approach of bringing in a grossly overpowered PA system and running it at relatively low volume to produce the most accurate and full sound possible. You can never have too much speaker power ... you can only use too much speaker power.

Whatever you get, I would suggest not less than 12" woofers on the mains ... the large bass drivers will give you more bass, therefore fuller sound.

Try listening to the speakers at low, medium, and very loud volumes, close and far away from the speakers, to make sure you like the way they sound at each level and distance.

I wouldn't get hung up on the SPL ... just listen to the speakers, either in the store, or find sound people in your area, ask what they use, and drop by during their performances to listen to their equipment in action.

Fyi, 85db is my rule-of-thumb threshold for parent/family audiences. But that is at the sound table.


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## Stevens R. Miller (Feb 28, 2017)

Let me try to take what you guys are teaching me and see if I can apply it. Here are two speakers:

The Mackie Thump12 ($299.99)

and

The Behringer B212D ($249.99)

(I realize these are both well below the cut-off prices most of you are suggesting, but if the only actual options are $400+, I can tell you that we will simply go on using the schools' crappy, unreliable gear. My board of directors will not pay $800 for two speakers, end of story.)

Now, the Mackie is pitched as a 1000W speaker, while the Behringer is pitched as a 550W speaker. Until this thread, I would have naïvely assumed that meant the Mackie would be louder than the Behringer. However, in their specs, both are listed as "Maximum Peak SPL 125dB." The Mackie has a somewhat wider frequency range. Other than that, their specs look (to me) more or less comparable.

Based on those identical SPL numbers, would I be safe in assuming that these two speakers are going to put out about the same amount of sound as each other?


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## Stevens R. Miller (Feb 28, 2017)

jkowtko said:


> Fyi, 85db is my rule-of-thumb threshold for parent/family audiences. But that is at the sound table.



Here's where I get to show some of my inexperience: where, typically, does the sound table go? Middle of the house? If so, that 85dB is a very comforting number, much below the 95dB I had been working from.


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## TJCornish (Feb 28, 2017)

Stevens R. Miller said:


> My board of directors will not pay $800 for two speakers, end of story.


How about 1 reasonable speaker this year and 1 next year?

I have spent a lot of time in the volunteer trenches in my life and I continue to be amazed at how much effort, inconvenience, and often poor quality output is tolerated/expected to avoid a small financial expenditure. Each of us has to decide what our own thresholds are, but for me, there is only so far I will go investing my time and sanity dealing with/propping up a situation where apparently no one else values my efforts enough to make a small investment to fix them. I just left my church of 15 years over this issue.


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## TJCornish (Feb 28, 2017)

Stevens R. Miller said:


> Here's where I get to show some of my inexperience: where, typically, does the sound table go? Middle of the house? If so, that 85dB is a very comforting number, much below the 95dB I had been working from.


With sincere respect, you're still focusing on the wrong thing - a volume number. It doesn't matter if you get 85dBA slow at the back of the house, 95dBA slow midfield or anything else if it sounds terrible, and numbers are truly meaningless unless you have a meter to tell you what you subjectively desire at least initially until you get a feel for how loud 90dB sounds like. 

I have a friend that works in a situation with about 20 of the Mackie Thumps. He calls them Mackie "Thuds". They sound terrible and are not particularly resilient. I have not heard the Behringer, but can't believe they're any better.


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## Stevens R. Miller (Feb 28, 2017)

I feel I should add a bit more about our price point and needs, as I am extremely grateful for all the helpful advice and guidance I am getting here, and would not want anyone to think I am not taking his or her recommendations seriously.

We just wrapped a show ("The Little Mermaid") done in a very typical venue for us: a middle school auditorium. We did six shows and sold about 1,500 tickets. For the first weekend, the sound system hummed like a buzzsaw. I tried everything I knew to make it go away, but what I knew wasn't much. I actually run the lights for our shows. My partner, a local biology teacher, runs the sound. She is a terrific operator and can handle wireless mikes and her mixer effortlessly. But she is not an audio engineer. Neither am I, but I am an electronics hobbiest (amateur radio station WA4LDA), so the job of solving sound problems falls into my lap. We ran a long AC cord to the rack, to tie the mixer and amps chassis grounds as close together as we could, and that helped a fair bit. But when the hum persisted, I did some reading and bought an Ebtech Hum Eliminator (a pair of audio transformers with a bit of RC shaping adding). Worked like a charm! Hum just vanished and the audio quality was vastly improved. But, next up, the audio on one of our two channels out to the house (one being mikes-plus-music, the other being music-only, for the stage monitors) kept cutting out intermittently. We traced this to a problem in the school's rack mixer and solved it by moving to a different input channel. At another point, one of the monitors just died. We got it working again, but I really don't know how.

The context within which we "cope" with these technical problems is a big part of what is driving me to get the company to buy its own gear. We have _extremely_ limited time in the school. For our six-show run, here's all the access we had:

Saturday, load-in from 0900 to 1500. Techies are running cable and hoping things work at all. At 1500, we are evicted.
Sunday, no access.
Monday-Thursday, tech week, 1730-2200. Techies are helping with rehearsal. If there is a break for notes or a "take five," techies try to solve problems like hum, unreliable connections, etc. At 2200, we are evicted (and must take anything we don't want the students to break with us).
Friday, first show, 1730-2300. Curtain is at 1930 which means this is the techies' only unbroken two-hour opportunity to fix problems.
Saturday, two shows, 1230-1630, 1830-2300. Again, they evict us at 1630 and 2300. Techies have almost no time to deal with problems.
Sunday-Thursday, no access.
Friday, third show, 1730-2300. Curtain is at 1930 which means the techies have only two hours to fix whatever the school screwed up during the previous four days.
Saturday, two shows, 1130-1630, 1830-2300. Again, they evict us at 1630. Techies have almost no time to deal with problems. Then we strike and it's over.

So here's my point: we already do our shows with lousy sound, and that's not yet a big issue. What is a big issue is that the equipment we are forced to deal with is both unreliable and not under our control. I would happily accept mediocre sound (since that's what we have now) if it meant I could take the school's equipment out of the loop entirely, and have all the time I need to fix problems before and between shows. My partner is of the same opinion. Just before Show Number Six, literally ten minutes before curtain, one of the school's channels died _again_. She was at her mixer with a hand-held radio, while I had another hand-held, squeezing myself between Prince Eric's ship and the audio rack, madly trying to find whatever bent wire, pulled plug, or bumped knob was about to cancel our final show for us. We found it and we fixed it, but it was, well... not much fun.

Someday, when I win the lottery, I will donate thousands of dollars' worth of high-end gear to this company. Until then, our problems are mostly about access to unreliable equipment of inferior quality. If we could solve the problems of access and reliability by owning our own equipment of inferior quality, that would be a major step up for all of us, one we would happily take, even if it meant putting off getting better quality sound for someday down the road.

So I just wanted everyone to know I am _not_ ignoring your advice about pricing. I'm just forced to stay focused on the problems at the top of our list.


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## Stevens R. Miller (Feb 28, 2017)

TJCornish said:


> How about 1 reasonable speaker this year and 1 next year?



I like your thinking, but these folks don't work that way. What I might be able to do is get two speakers this year, a new mixer next year, and some stage mikes the year after that. They like to see return on investment right away. One speaker alone would probably leave them thinking I had talked them into wasting money, and then they wouldn't buy much else on my advice after that.


> I have spent a lot of time in the volunteer trenches in my life and I continue to be amazed at how much effort, inconvenience, and often poor quality output is tolerated/expected to avoid a small financial expenditure. Each of us has to decide what our own thresholds are, but for me, there is only so far I will go investing my time and sanity dealing with/propping up a situation where apparently no one else values my efforts enough to make a small investment to fix them. I just left my church of 15 years over this issue.



I feel your pain. I went to a lot of trouble (with the help of another ControlBooth member) to set up and demonstrate a far cheaper, far superior lighting system for a local middle school. The PTA was impressed and donated the money to buy the new console. End result? The school system electricians took one look at it and said, "You're not allowed to use anything we didn't approve." The PTA literally had to take their donation back.

In this case, my angst is all due to lack of access, not lack of quality. The schools' audio systems already are forcing us to work with inferior sound. I just can't keep promising to make it even work at all, under the conditions the schools impose on us. As I said above, if I can spend $500 to replace inaccessible mediocre gear with accessible mediocre gear, that will be a major move up.


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## Morte615 (Feb 28, 2017)

Stevens R. Miller said:


> The context within which we "cope" with these technical problems is a big part of what is driving me to get the company to buy its own gear. We have _extremely_ limited time in the school. For our six-show run, here's all the access we had:
> 
> Saturday, load-in from 0900 to 1500. Techies are running cable and hoping things work at all. At 1500, we are evicted.
> Sunday, no access.
> ...



You might want to look into somewhere that gives you better access and control. Another theater in the area where you can work as needed during your time (not getting kicked out at an arbitrary time) and somewhere that you can secure when you are not present.
Lots of options, but don't know what is in the area. You may end up paying more (or at all) for the space but if you can either rent a system for shows, or get a space that has a system, then you may end up saving headaches to make the change in location worth it.

Also you may be able to talk to the location about loosening up some of the requirements. Not sure but I think you said it's a school so they are probably limited by things like school schedules and such and that's why you have such a hard time.

If you can get a group together renting a small store front somewhere and putting in a black box is not unduly expensive. But you need to keep a very close eye on expenses because it can get out of hand quickly.


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## Stevens R. Miller (Feb 28, 2017)

Morte615 said:


> You might want to look into somewhere that gives you better access and control. Another theater in the area where you can work as needed during your time (not getting kicked out at an arbitrary time) and somewhere that you can secure when you are not present.


Man, I would love that. The schools we use are within our budget, and there really aren't any other places in the county with DMX lighting that we can come close to paying for.


> If you can get a group together renting a small store front somewhere and putting in a black box is not unduly expensive. But you need to keep a very close eye on expenses because it can get out of hand quickly.


We talk about this from time to time, but mostly in a pipe-dreamy kind of way. I do keep my eyes open for possibilities, but you're right about costs.


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## MikeJ (Feb 28, 2017)

Basically, most powered speakers will be loud enough for your needs. Some will sound better than others. The only way to find out is to listen to them. Both of those speakers you posted are probably available at Guitar center, so go give them a listen. Bring some music on your phone that is the style you will be using them for, then crank it up and go stand at the back of the room. Cheap speakers like that always lie about power output, and often don't sound great, but If it saves you a lot of time in troubleshooting and sounds at least as good as the house system, then it may be a very functional solution. 

Remember if you don't already have XLR cables and power cable extensions, and speaker stands(preferably tall ones) you will need to fit those into your budget as well.


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## Stevens R. Miller (Feb 28, 2017)

MikeJ said:


> Basically, most powered speakers will be loud enough for your needs. Some will sound better than others. The only way to find out is to listen to them. Both of those speakers you posted are probably available at Guitar center, so go give them a listen. Bring some music on your phone that is the style you will be using them for, then crank it up and go stand at the back of the room. Cheap speakers like that always lie about power output, and often don't sound great, but If it saves you a lot of time in troubleshooting and sounds at least as good as the house system, then it may be a very functional solution.


Good suggestion. I'll do it.


> Remember if you don't already have XLR cables and power cable extensions, and speaker stands(preferably tall ones) you will need to fit those into your budget as well.


Ah! I have included line items for enough XLR cable and stands, but didn't know about the power cords. Thanks.

Are there any sites that publish objective reviews of this kind of gear?


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## FMEng (Mar 1, 2017)

All you need are common extension cords. It doesn't take anything exotic.


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## Stevens R. Miller (Mar 1, 2017)

FMEng said:


> All you need are common extension cords. It doesn't take anything exotic.


Even so, I appreciate the reminder, as the folks who use the shopping list I'll put together will be technically ignorant artists, not engineers. They get nervous if anything, however small, is found to be missing later.


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## MikeJ (Mar 1, 2017)

I just like to be very detailed when I plan things. There have been plenty of times when I used to work in low-budget theaters, where something is overlooked and I ended up going to Home Depot and buying it out of pocket, or having to beg and borrow from other people.


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## TimMc (Mar 1, 2017)

Stevens R. Miller said:


> Let me try to take what you guys are teaching me and see if I can apply it. Here are two speakers:
> 
> The Mackie Thump12 ($299.99)
> 
> ...



The difference between the two speakers is this: the Mackie should be called "the THUD", for the sound it will make when you pitch it in the bin. The B-word speaker is slightly better and when you realize that you're still disappointed, you will still have $50 in your pocket.

The wrong product at the right price is still the wrong product. Buy once, cry once.

Watts measure an instantaneous amount of power being either consumed or generated. The relationship between the power consumed and the resultant acoustic output is not a linear constant; it varies for each and every different transducer or loudspeaker system. Also as a matter of "rating" loudspeakers the numeric figure given in Watts is often misleading; a "1000 Watt" rating is for how long? Can we apply that current all day, or for a few milliseconds before the voice coil fails? 1000 Watts of what? Pink noise with a 6dB crest factor, "programme" or a sine wave?

Likewise most peak output ratings should be viewed with skepticism. At what frequency and for how long? At what distortion level? You will find these are hard specifications to come be even if there IS a specification for them...

Thanks to marketing there is a huge amount of specifications that still do not allow meaningful, direct comparisons between products. As The Fire Sign Theatre once said "everything you know is wrong."  Okay, not quite, but the without knowing how a given published specification has been arrived at, there is a semi-deliberate obfuscation of physics.

So to conclude my little sermonette, Watts are for space heaters and light bulbs and figuring out your power bill. As something directly meaningful about loudspeaker output? Naw...


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## Stevens R. Miller (Mar 1, 2017)

TimMc said:


> The difference between the two speakers is this: the Mackie should be called "the THUD", for the sound it will make when you pitch it in the bin. The B-word speaker is slightly better and when you realize that you're still disappointed, you will still have $50 in your pocket.
> 
> The wrong product at the right price is still the wrong product. Buy once, cry once.
> 
> ...



So... since they quote the same maximum peak SPL, what can I conclude from that?


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## RonHebbard (Mar 1, 2017)

Stevens R. Miller said:


> So... since they quote the same maximum peak SPL, what can I conclude from that?


That both their marketing departments agree on this being a good number for marketing targets this month. (And not much more than that. The vast majority of loudspeaker specifications are bogus marketing hype and precious little more.)
*Edit:* Speakers are for listening to, demoing before purchasing, trying before you buy then buy once cry once, NOT for reading about.
Toodleoo!
Ron Hebbard.


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## MNicolai (Mar 1, 2017)

Stevens R. Miller said:


> So... since they quote the same maximum peak SPL, what can I conclude from that?



That below a certain price point, it's Whose Line Is It Anyway -- everything's made up and the points don't matter.

Since you're linking to powered speakers, let's look at the QSC K-series, one of my favorite powered speaker lines on the market. Notice that they put the same 1000W amplifier in each and every speaker, even the sub. This is for economies of scale in manufacturing more than anything else. They can market their 8" cabinet as a 1000W speaker, but that's more of a reflection of the amplifier than it is the driver element. As stated before, even on passive speakers the wattage ratings are misleading because they don't take into account efficiency, but active speakers really make wattages completely meaningless.




In contrast, depending on how you choose to look at it, here's a 700W speaker that puts out 145dB.

So what, pray tell, does a better speaker get you?

A larger driver element with extended low-end response and better pattern control. It also gets you a couple extra dB of headroom, which most people will never notice with a meter. What they will notice with their ear is that with a smaller speaker, they cannot "feel" the sound like they would instinctively expect to and may perceive that as a quieter speaker, which then they drive into clipping and distortion trying to feel the low-end that that size of speaker cannot possibly produce.

When I recommend the K-series to someone, I usually go for the K10 or K12, not because of SPL, but because of pattern control. The K8 is better for a small, crowded room where the speakers are immediately in front of a crowd and taking advantage of the 105° conical pattern. Any larger rooms benefit more from a K12 because it keeps the sound on the audience and off of the walls and ceiling.

Shifting gears a little bit, let's talk about SPL over a distance.

An ideal line source attenuates at -3dB per doubling of distance from the speaker. If you are 60' away and hearing 100dB, then in an ideal laboratory environment, the speakers within an array couple together to produce a wavefront that at 120' would be apprx 97dB. At 240', 94dB.

An ideal point source attenuates at -6dB per doubling of distance. That means at 120', you would hear 94dB. At 240', 88dB.

Traffic is a good example of a line source. The reason highways are particularly obnoxious to residents nearby is because once you get enough cars on the road, the nature of the noise source behaves more like a line source and the noise carries farther. Not because it's all that much louder, but because the noise from each of the vehicles is coupling together as they scurry down the roadway. So at midnight or noon, traffic behaves more like a point source and attenuates to a much quieter level to the neighborhoods next to the highway. At rush hour though, it acts like a line source and in an ideal environment attenuates apprx half as much as at lunchtime. The noise carries _much_ farther and is much more of a nuisance.

What does this all mean?

SPL matters in larger environments much more than in smaller. The intensity of the noise source will vary significantly near the speaker, no matter what. In a small room, a difference of 3-6dB is generally insignificant, though it will be audible. However, as the noise propagates away from the speaker, that 3-6dB can have consequences for a larger group of people. If we have a point source and take the chunk of space between 60' and 120' and say it has mean SPL of 85dB, that's quite a bit of audience space that falls into a 6dB window, between 82-88dB. You may be incinerating the people sitting directly in front of the speaker, but at this 60-120' distance, you have what would be considered an acceptable amount of drop-off between the first row and the back.

On the other hand, if we stick that 6dB window at 85dB between 10' and 20' away from the speaker, well now it doesn't really matter what you do. Unless you're holding your performance in a shoe box, someone in the front row is either getting incinerated or someone in the back can't hear. This is because if we have 88dB at 10' with a point source, we have 82dB at 20', and 76dB at 40'. If the first row is at 10' and the last row is at 40', it will be perceived as literally half as loud in the back row as in the first row. (Human perception is 10dB = twice as loud)

Put all of this together, and if you're buying a system for a rock and roll show in a stadium, you want a line array so your sound makes it across the field, and the farther you get away from your stage, that extra 3 or 6dB between one speaker model and another begins to really, _really_ matter because at a distance it affects a much greater footprint of the field and of the bleachers.

This is the long way of saying that for a smaller environment, there any number of factors that take precedence over pure loudness. Distortion, pattern control, headroom before clipping, low-end response and whether you can feel the <80Hz content, how the speaker is aimed within the room, how much distance is between the speaker and the first row, how distance is between the first row and the last row, if the system is tuned and delayed properly or used with out-of-the-box settings, how good the speaker sounds in a blind demo compared to the runner up, and of course -- the quality of the signal chain and the microphones. A $1,000,000 PA still sounds like a bad car stereo if you put $35 generic headset mic's in front of it or if the faders on your mixer are all dusty and crackle whenever you move them.


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## JD (Mar 2, 2017)

I would add that the system also depends on if you are augmenting vocals only, or need full range for music reproduction. A 10 inch driver will be more responsive in the vocal frequencies (400Hz to 1kHz) as there is less cone mass. However, a 10 inch driver will produce a greater amount of intermodulation distortion if you are pumping it full range. IM distortion is created when the diaphragm moves to produce a lower frequency, imposing a Doppler effect on other frequencies the speaker may be reproducing. A smaller diaphragm will need to move a greater distance to produce a given low frequency then a larger one. This is also why you end up with 3 and 4 way systems. A good compromise might be to use the 10 inch drivers, but cut lows below 150Hz and add subs with larger drivers below 150Hz, IF you need full range for music.

I should also add that low frequencies are pretty omnidirectional so there is not the "sound image" problem with the location of subs that there is with your higher range speakers. This allows for odd placement of the subs with little to no ill effect.


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