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Author Topic: 15in vs 12in  (Read 11748 times)

Phillip McVea

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15in vs 12in
« on: April 14, 2014, 01:55:46 pm »

summarized/bolded for the impatient people.
I was recently browsing selections for pole-mount/"point-source" loudspeakers, coaxial loudspeakers, "fixed curvature line array" loudspeakers, variable curvature line array loudspeakers, and also home audio loudspeakers.

Long story short i noticed that alot of manufacturers usually include the following variants in their speaker lines: 2-way 1/1.75in high & 12in low, 2-way w/ 1/1.75in high & 15in low, and 3-way w/ 1/1.75in high, 6.5in mid & 15in low.
These are all speakers that are made (primarily) for live sound reinforcement. By that i mean they're made to be loud as opposed to accurate. Most have peak amplifier power ratings of 1000-2000 watts (w/ mains input @ 120v). about 4/5 of the speakers i looked at had the amplifier built in to the actual cabinet housing.

While i understand many of the company's decisions to produce a 3-way model for better dispersion control (and the other benefits of a 3-way design), but i'm very weary of the 2-way models that use 15" drivers, often the same ones they put in the 3-way models. It concerns me because within a 2-way speaker, the woofer must account for some of the mid range frequencies, the same frequencies that would otherwise be created by a smaller 6.5in driver that could better reproduce the wavelengths of mid-range frequencies. I like the idea of using a 12in driver (at the largest) in a 2-way speaker because, while it is smaller, it could better create the entire sound range that doesn't end up sounding worse.

For example, i've noticed that in a 2-way system with a 15in LF driver, whenever someone with deeper voice speaks at the higher point of their voice, it sounds like there's something that's "holding" the sound back, almost like a muddy sound. As if someone taped a few layers of thin fabric over my ears when they speak like that. But as they progress into the deeper octaves of their voice, it sounds deeper and more direct i guess you could say.
it's kind of difficult to describe the difference without something happening right in front of me, but the point is if they were to repeat the same thing in a 3-way system with a 6.5in MF & 15in LF driver, their voice sounds CONSISTENTLY more "direct", clearer, even throughout the lower sounds. I find that even the mid range has more "punch" to it, like on kick-drums, you can feel the beginning of the note have more impact & spread from the speaker. And in bass music, those long notes that dip into the sub-bass region then fade up into a higher and higher sound. You can really feel the notes "carry through" and have a fuller sound, even as they carry over from sub-bass speakers to the full-range speakers.

While i'm far from an expert in sound reinforcement (and writing obviously), my personal theory is that this is because of the amount of air the driver is moving, and in relation to how fast/how often & loud it's trying to make it. Meaning 15in drivers are best for creating bass frequencies and ONLY bass frequencies, because the size of the wavelength is appropriate to the thing that's trying to create it. Just like 21in drivers are best for creating sub-bass frequencies and ONLY sub-bass frequencies. And just like 6.5in drivers are best for creating mid-range frequencies. Obviously the EXACT definitions of high/mid/bass range are all subjective to the actual speaker and various other factors (too many to list out).

BUT the point remains, what is the best balance of both loud AND clear, a 2-way system with 12in driver or a 2-way system with a 15in driver?
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TJ (Tom) Cornish

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Re: 15in vs 12in
« Reply #1 on: April 14, 2014, 02:01:18 pm »


BUT the point remains, what is the best balance of both loud AND clear, a 2-way system with 12in driver or a 2-way system with a 15in driver?
That's a big, fat "it depends".  "Loud", "Clear", and the speaker's ability to be clear at any particular loudness are more cost and design dependent, rather than specific driver configuration.

A 3-way system is not necessarily better than a 2-way system - with a simple speaker with drivers lined up (not all firing in a horn), there are time alignment issues and crossover issues that are worse with more crossover points.
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Taylor Hall

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Re: 15in vs 12in
« Reply #2 on: April 14, 2014, 02:03:58 pm »

TJ said it more eloquently that I could. Lots of variables to take into account, and not just driver/enclosure design, but also the venue.
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Re: 15in vs 12in
« Reply #3 on: April 14, 2014, 02:07:56 pm »

summarized/bolded for the impatient people.
I was recently browsing selections for pole-mount/"point-source" loudspeakers, coaxial loudspeakers, "fixed curvature line array" loudspeakers, variable curvature line array loudspeakers, and also home audio loudspeakers.

Long story short i noticed that alot of manufacturers usually include the following variants in their speaker lines: 2-way 1/1.75in high & 12in low, 2-way w/ 1/1.75in high & 15in low, and 3-way w/ 1/1.75in high, 6.5in mid & 15in low.
These are all speakers that are made (primarily) for live sound reinforcement. By that i mean they're made to be loud as opposed to accurate. Most have peak amplifier power ratings of 1000-2000 watts (w/ mains input @ 120v). about 4/5 of the speakers i looked at had the amplifier built in to the actual cabinet housing.

While i understand many of the company's decisions to produce a 3-way model for better dispersion control (and the other benefits of a 3-way design), but i'm very weary of the 2-way models that use 15" drivers, often the same ones they put in the 3-way models. It concerns me because within a 2-way speaker, the woofer must account for some of the mid range frequencies, the same frequencies that would otherwise be created by a smaller 6.5in driver that could better reproduce the wavelengths of mid-range frequencies. I like the idea of using a 12in driver (at the largest) in a 2-way speaker because, while it is smaller, it could better create the entire sound range that doesn't end up sounding worse.

For example, i've noticed that in a 2-way system with a 15in LF driver, whenever someone with deeper voice speaks at the higher point of their voice, it sounds like there's something that's "holding" the sound back, almost like a muddy sound. As if someone taped a few layers of thin fabric over my ears when they speak like that. But as they progress into the deeper octaves of their voice, it sounds deeper and more direct i guess you could say.
it's kind of difficult to describe the difference without something happening right in front of me, but the point is if they were to repeat the same thing in a 3-way system with a 6.5in MF & 15in LF driver, their voice sounds CONSISTENTLY more "direct", clearer, even throughout the lower sounds. I find that even the mid range has more "punch" to it, like on kick-drums, you can feel the beginning of the note have more impact & spread from the speaker. And in bass music, those long notes that dip into the sub-bass region then fade up into a higher and higher sound. You can really feel the notes "carry through" and have a fuller sound, even as they carry over from sub-bass speakers to the full-range speakers.

While i'm far from an expert in sound reinforcement (and writing obviously), my personal theory is that this is because of the amount of air the driver is moving, and in relation to how fast/how often & loud it's trying to make it. Meaning 15in drivers are best for creating bass frequencies and ONLY bass frequencies, because the size of the wavelength is appropriate to the thing that's trying to create it. Just like 21in drivers are best for creating sub-bass frequencies and ONLY sub-bass frequencies. And just like 6.5in drivers are best for creating mid-range frequencies. Obviously the EXACT definitions of high/mid/bass range are all subjective to the actual speaker and various other factors (too many to list out).

BUT the point remains, what is the best balance of both loud AND clear, a 2-way system with 12in driver or a 2-way system with a 15in driver?

Interesting theories.  Why don't you test them out and publish the results.  I'm sure there would be some interest...
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Phillip McVea

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Re: 15in vs 12in
« Reply #4 on: April 14, 2014, 04:24:38 pm »

Interesting theories.  Why don't you test them out and publish the results.  I'm sure there would be some interest...

I'm sure i don't have all the skills/resources to make all the fancy graphs and charts i see on this website all the time. I just noticed an observation, and wanted to see how a wider audience would react to it. I was trying to make the post as subjective and about the speakers as possible, as it seems like all the other factors (processing gear, environment & scenario, content, wear & tear/fatigue, etc etc etc etc) are constantly changing.

When i actually heard what was described in the first post, the situation was just me & a few friends testing out speakers in his driveway. All the subwoofers were sitting on top of a metal frame table about 3.5-4ft high with a wood surface(just like a generic warehouse shelf idk how to describe it) The full-range speakers were all resting directly on top of their respective sub cabinet, if not then directly on the table.

For the most part we were just taking turns mixing on some "Traktor" things, it had 2 audio players on the sides and a 4 channel mixer in the middle. We were mostly playing trance, house, electro. Most of the songs were displaying 80-120bpm. We started playing more bass tracks after a while, dubstep, drum & bass and a few hip-hop sounds. Before we wrapped everything up we plugged in a laptop & played a few youtube videos to hear/test speech and content that isn't as "complex" as music. Strangely enough, it was at this point was when i noticed the differences.

From the mixer (had to use an RCA to XLR converter plug thing) the signal line went to a "active speaker management" box, I was told it's a dbx driverack model. From there was a ART CX310 crossover, outputting directly to 2(left & right) full range speakers & depending on the speaker we were using at that moment in time 1 or 2 subwoofers.
We played about 2-3 songs on each speaker (I remember a few of them if it matters), just moving the XLR & IEC cables from each different speaker we wanted to try. I believe all the speakers were on the -10db volume trim.

We used 4 sets of speakers (all kindly volunteered by different people):
Set 1: 2xYamaha DSR 215, 2xYamaha DSR 112, 2xYamaha DSR 118.
Set 2: 2xJBL EON 615 (no sub)
Set 3: 1xQSC KW153 & 1xQSC KW152
Set 4: 2xElectro Voice ELX112P, 1xElectro Voice ELX115P, 2xElectro Voice ELX118P

We also had 2 other speaker pairs without the built-in amplifier from Electro Voice and a company called Gemini. We couldn't use them because the external amplifier would turn on, generate this high pitched static noise for no longer than 5 seconds, make this weird chirping tune then immediately shut off. We never even got the the chance to input a signal to it before it gave out. It was the strangest thing.

I tried to describe the scenario as best as i can, however not a single piece of equipment belonged to me. Next time i'll just take a picture. That seems alot easier.
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TJ (Tom) Cornish

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Re: 15in vs 12in
« Reply #5 on: April 14, 2014, 05:25:17 pm »

We used 4 sets of speakers (all kindly volunteered by different people):
Set 1: 2xYamaha DSR 215, 2xYamaha DSR 112, 2xYamaha DSR 118.
Set 2: 2xJBL EON 615 (no sub)
Set 3: 1xQSC KW153 & 1xQSC KW152
Set 4: 2xElectro Voice ELX112P, 1xElectro Voice ELX115P, 2xElectro Voice ELX118P
You have a variety of mid-level gear here.  Kudos to you for setting it up, listening, and trying to learn stuff. 

Electronic music is not particularly revealing of fidelity for anything other than sub frequencies.  Acoustic music, vocals, and drums generally have a lot more detail where you can differentiate.

Active speakers generally have some amount of tuning built-in, so generally they sound fairly good with no additional processing.  That being said, speakers at this level can usually be improved and/or customized to the current situation by some external EQ done by a competent person. 

Your workflow doesn't go into great detail, but you say you used an ART CX310 crossover and a drive rack of some kind.  These tools are like sharp knives - in the hands of someone who knows what they are doing, they can help.  In the hands of someone inexperienced, they can cause damage.  For the average user, buying subs and tops from the same series is generally a good idea, and most systems like this are designed so that you plug the line into the sub, and then use a post-crossover output on the sub to feed the mid/high.  Doing this per the manufacturer's design will give good results.  Using an external crossover may be actually worse than using the internal crossover of the powered speaker, as there may be phase and EQ alignment issues that need to be compensated for.

Another potentially relevant thing is speakers that are designed for live sound may be tuned differently than "DJ" speakers.  Live sound speakers are generally flatter, which to someone who is used to smiley-face EQ, may sound dark.

All this is to say that your observations are very instructive and to keep at it, but make sure you understand all the variables before going too far out on a limb making a conclusion.
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Len Zenith Jr

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Re: 15in vs 12in
« Reply #6 on: April 14, 2014, 06:12:14 pm »

15" drivers start to beam around 1050hz, while 12" drivers a bit higher, around 1350hz, and your 6" driver around 2750hz. Depending on where the speakers cross over to the high frequency horn, this may have been the effect you are describing. Beaming is where the drivers start to become directional, so if you are standing for example 45 degrees off axis from the speaker, everything that the 15" driver reproduces above 1050hz would drop off in level, the more off axis, the greater the effect. I have a set of 2-way speakers at work where the crossover is at 2200hz and uses a 12" woofer; off axis, the hole between 1350hz-2200hz is very prominent. Even on axis, although the frequency response of the direct sound is flat, the reflections off the walls/ceiling, etc from the off axis of the speaker with the hole in the mids gets bounced back with that hole in the mids confusing our ears.

For DJ type sound reinforcement where you will always use subs, the 12" boxes typically have better off axis sound (where most of the audience is anyways). Not because a 15" with appropriate hf horn couldn't be designed, but because usually the 15" version was designed for more low frequency extension (not needed with subs) and the off axis hole in the mids is just a trade off as a larger 2" hf driver with a lower crossover point would drive costs up too much.
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Luke Geis

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Re: 15in vs 12in
« Reply #7 on: April 14, 2014, 06:21:21 pm »

In theory you are correct in your assumptions of how a particular speaker should be. However this isn't necessarily the truth in all cases. 15" speakers are more of an intermediate all around speaker usually placed in a cabinet that is tuned to get usable sonic range between 40hz ( and lower ) and up to the 20khz area. Your typical 12" is usually sitting around 50-60hz for it's lows. The 15" speaker will work ok without a sub and fill the room with an acceptable level of bass frequencies. The 12", perhaps not as much? So why do many 3 way systems employ a 15" speaker? To get the sonic range. It gets low enough to have sub and is detailed enough to have a higher level of clarity and precision.

This is not to say that a 15" speaker cannot be made to sound as good as a 12" in a similar application though. The 12" speaker should be able to acquire a higher level of detail, but isn't the holdfast rule, or truth. A 3 way system that utilizes a 12" speaker may be found to be wasting resources with no distinct increase in performance? In other words the sonic range and added cost may not justify the slightly better performance? Tough to say really. I don't design speakers, I simply test, work with and employ a lot of different brands and models and study the market for the best tools for the jobs I perform. I have found that just about any speaker can be made to sound ok and that the more work it takes to get a good sound, the less volume you typically will acquire. A good speaker sounds good with little effort and has usable level that exceeds the need. That is really the difference between a $300 dollar speaker and a $1000 dollar speaker in the same catagory. The higher dollar speaker will likely sound better and achieve higher volume levels with little effort.
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Phillip McVea

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Re: 15in vs 12in
« Reply #8 on: April 14, 2014, 07:00:27 pm »

You have a variety of mid-level gear here.  Kudos to you for setting it up, listening, and trying to learn stuff. 

Electronic music is not particularly revealing of fidelity for anything other than sub frequencies.  Acoustic music, vocals, and drums generally have a lot more detail where you can differentiate.

Active speakers generally have some amount of tuning built-in, so generally they sound fairly good with no additional processing.  That being said, speakers at this level can usually be improved and/or customized to the current situation by some external EQ done by a competent person. 

Your workflow doesn't go into great detail, but you say you used an ART CX310 crossover and a drive rack of some kind.  These tools are like sharp knives - in the hands of someone who knows what they are doing, they can help.  In the hands of someone inexperienced, they can cause damage.  For the average user, buying subs and tops from the same series is generally a good idea, and most systems like this are designed so that you plug the line into the sub, and then use a post-crossover output on the sub to feed the mid/high.  Doing this per the manufacturer's design will give good results.  Using an external crossover may be actually worse than using the internal crossover of the powered speaker, as there may be phase and EQ alignment issues that need to be compensated for.

Another potentially relevant thing is speakers that are designed for live sound may be tuned differently than "DJ" speakers.  Live sound speakers are generally flatter, which to someone who is used to smiley-face EQ, may sound dark.

All this is to say that your observations are very instructive and to keep at it, but make sure you understand all the variables before going too far out on a limb making a conclusion.

The idea we had behind using a crossover is so that the signal would reach every speaker when it's supposed to. We figured phasing issues would actually arise if we didn't use the crossover, due to the first speaker processing the sound, dividing it and then sending to another speaker entirely. So, what exactly are the indicators of phase misalignment? Obviously if there's a blatant delay between the two speakers, but if it's more subtle than that yet still enough to effect the performance, how do you know?

We tired to keep the signal as untouched as possible until it got to the speakers. That's why is was elected to use only 2 pieces of equipment from the source to the speaker. Although, i'm not sure exactly how the "speaker management" thing was supposed to help. Or what exactly it's even supposed to manage.
We saved all of the bass music for later in the evening when we could use the Electro Voice & Yamaha systems so we could use the subwoofers. I was playing Rusko - Lion's Paw (http://www.youtube.com/watch?v=301LGWph_rw), I played it once with the processor in. Took the mixer's output & put it straight into the crossover. Sounded EXACTLY the same. The bass wobbles were still just as low, heavy & bouncy. The horns & high hats were just as high, loud and sharp as they were without the box. I didn't know it was going to be in the set-up and i had no clue why it was there either.

Also, one of the more... intense, discussions we had was sampling content. I tested the exact same, 2116kbps 85Mb .Wav file on all the QSC, Yamaha & Electro Voice speakers. Most of the people there agreed with me that if you use the same song across each speaker you should be able to hear the differences. And it's not like it's a lousy song, i'd consider it a high-quality recording, and i know i'm not the only one. I've heard the song countless times & am very familiar with it. Many people agreed that it reproduced sounds all over the entire audible frequency range, although the bass in the song is what stands out the most, if you focus on other details, you will notice them.
But strangely enough, some people argued that no matter what you play, the speaker will perform as good or as bad as it will regardless. Saying that picking a certain sampling source to compare everything to is pointless. It didn't really make any sense to me. Like if all speakers sound the same then i didn't understand why they were there in the first place???

Anyways, what's the golden standard on sampling content? Is there a certain criteria for finding the perfect universal piece that all systems can compare to? What about the equipment it's played from?

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Phillip McVea

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Re: 15in vs 12in
« Reply #9 on: April 14, 2014, 09:22:27 pm »


15" drivers start to beam around 1050hz, while 12" drivers a bit higher, around 1350hz, and your 6" driver around 2750hz. Depending on where the speakers cross over to the high frequency horn, this may have been the effect you are describing. Beaming is where the drivers start to become directional, so if you are standing for example 45 degrees off axis from the speaker, everything that the 15" driver reproduces above 1050hz would drop off in level, the more off axis, the greater the effect. I have a set of 2-way speakers at work where the crossover is at 2200hz and uses a 12" woofer; off axis, the hole between 1350hz-2200hz is very prominent. Even on axis, although the frequency response of the direct sound is flat, the reflections off the walls/ceiling, etc from the off axis of the speaker with the hole in the mids gets bounced back with that hole in the mids confusing our ears.

For DJ type sound reinforcement where you will always use subs, the 12" boxes typically have better off axis sound (where most of the audience is anyways). Not because a 15" with appropriate hf horn couldn't be designed, but because usually the 15" version was designed for more low frequency extension (not needed with subs) and the off axis hole in the mids is just a trade off as a larger 2" hf driver with a lower crossover point would drive costs up too much.

So what i take from this is that the problem isn't how the sound is made by the driver, but rather how it travels away from the driver? But is that problem solved by going from 15in to 12in (with a system that includes subwoofers), or just lessened?
 
You mentioned directivity, in most cases i was standing in the middle of 2 speakers making a mirror image from each other. We had "listening spots" - pieces of tape on the ground that represent 8ft, and 20ft from the speaker, with a center, left & right(each 6ft away from center) point for each distance mark. On the 15in 2-way speakers, it sounded pretty uniform at both distances & sides. it was only when you went to extremes (15-20ft to the left/right, 25+ft back from the center). However, I did notice that, from the 15in 2-way boxes that had no sub, what bass they did create traveled further, but only if you stayed in the center. Like when i was at 8ft, there was plenty of bass of course. If you go to the sides, it decreases a bit. I stood at 20ft center, and there was a reasonable amount given the circumstance. But it was only when i moved to the left or right that the bass lessened dramatically, at a much faster rate than at 8ft. The "muddy" sound only became more pronounced the further off center i got, like you said. At higher sounds, i moved the same distances to the left & right, and the sound didn't diminish such a substantial amount. At both 8ft and 20ft the loudness was still appropriate for the distance, regardless of how far off center you were.

From what i know, the volume was what most people would consider barley/moderately loud. Alot of people got around 80db, but this was also outdoors with the wind blowing, cars occasionally passing by, construction, etc. Plus, no one really went into this trying to get numbers out of it, just matching some speakers up to see which is best.


 
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Re: 15in vs 12in
« Reply #9 on: April 14, 2014, 09:22:27 pm »


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