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Old 12th May 2004, 03:11 PM   #1
Solinar is offline Solinar  United States
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Default Building a high output speaker

Hi all. I recently stumbled across these forums, and have a few questions.

First off, a little background.

Recently, a friend of mine decided he wanted to upgrade his home audio system. He is looking for a system to play metal and zydeco type music (hevy with bass) at high volume levels where sound quality is not as important as volume. He would like the system to be semi-portable, in that it can be moved outside his house to play for block parties and such. His first course of action was to head to a local retailer who wanted to sell him some PA equipment for around $1800 (2X$500 speakers and an $800 500watt/ch amp).

Upon hearing this, my first thought was, we could probably come up with something better for less money if we were willing to invest some sweat and time.

In the past I have built a few car and home audio subwoofers. My most recent project (that I'm just getting started on) is an infinite baffle sub for my Home Theater set up. That experience and a couple of electrical engineering basic circuits classes in college I took, and I think I am willing to give builing a 2-3 way loudspeaker with custom X-over circuits a shot, with the help of some design software like that at partsexpress.

My initial thoughts were something like a tempest for lows + a mid and tweeter in each speaker. Looking at amps, a crown XLS-602 appears to be a good choice pushing 600 watts per channel at 4 ohms for 440$.

Questions

1) If I am looking to push 500-600 watts per speaker, I know many high excursion 15" subs (adire, resonant engineering, dayton, etc) will take that kind of power no problem, but what midrange and tweeters will be able to handle that same feed. I know that the mids and highs get significantly less power from that feed as the lows do, but will a typical 25 watt capable tweeter be out of its class paired with a high excursion 15" sub for lows when being pushed by a 600 watt/channel amp?

2) Is a low, mid, and tweeter the way to go, or should I look into a horn (never used one before and not real familiar with the pros/cons of horns).

3) For the price range in question, is the crown amp a good buy or am I missing some better line/brand of amps that would be better suited?

Thanks for reading and any responses!
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Old 12th May 2004, 05:03 PM   #2
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I think a good PA sound reinforcement 15" woofer (not a sub) with a compression driver and horn is the tried and true method. A sub will deliver lower bass but will suck up lots of power. If he is looking for an efficient system, then get a low excursion woofer that cuts off at 35 - 45Hz.

Something like this:
WPU 1507 QCF

Or many of the others at part express.

The tweeter and horn combo has too many options to cover in one post. I use the same woofer with a Selenium D205Ti mounted to an Altec 511B horn. This combo is not for everyone but it sure works for me

The amp should exceed the woofers capability. Although this sounds funny, it's true because you can't really listen to them at full volume anyways (too loud), and the woofers will tell you to turn it down before they actually blow.

The commercial PA systems don't seem to have the guts they used to. Maybe those $1000 units are OK but it will be cheaper and more enjoyable to DIY.

Others can answer your questions about amplifier brands. My stuff is old.

Cal
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Old 12th May 2004, 05:36 PM   #3
haldor is offline haldor  United States
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Click the image to open in full size. Click the image to open in full size.

The Yorkville NX550P is a very hi-fi sounding PA speaker. I have used these for floor wedges and also as the as the mains speakers for smaller gigs. I've heard a pair of these used in a Home Theater setting and they sounded very nice. They include both pole mount sockets and are designed to be suspended. The are also very light weight (47 lb) for a powered speaker with their output (124 dB at 1 meter).

The NX550P has a 12" woofer with a neodymium magnet and a 1" compression horn. This speaker is biamped (built in active crossover and amps, 450W for the woofer, 100W for the horn). It also has a small mixer (mic and line inputs) built in so you can plug your CD/DVD player directly into it, no need for any external amps or other gear.

These sell for around $650 each.

Yorkville NX550P

Phil
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Old 12th May 2004, 05:47 PM   #4
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Default UNITY HORN

Surf for information on DIY UNITY HORNS. This design provides very high efficiency for mid-tweet plus good coherence. For bass, if you do not want to build a horn loaded design, you can pump high power into a well designed ported 15".

Also look at the Yorkville UNITY U15

http://www.yorkville.com/products.asp?type=29&cat=38
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Old 12th May 2004, 08:36 PM   #5
DunkH is offline DunkH  United Kingdom
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You could have a look at www.Dancetech.com click on the pa-gear link under the E of dancetech.

Theres a few designs for cabinets. Might not be portable enough though?

Most of the nice systems I've heard have used fairly large 2 or 3ft square midrange horns driven by what looks like 8 to 10" speakers. There are quite a few designs dotted about if you look on Google.
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Old 13th May 2004, 06:29 AM   #6
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Default Posible alternatice: 4X10" + horn

Hello Solinar,

Interesting project you have in mind.

Okay, one of the situations you run into with 15" woofers is the inevitable bass extension/efficiency tradeoff. The higher efficiency woofers have poor bass extension unless you put them in a huge horn cabinet, and then you have to go with a 3-way system. And an 18" woofer won't go high enough for you to get away with a 2-way system.

Eminience makes a very nice little 10" pro-sound woofer called the BP-102. It's only 91 dB efficient, but wire four of them in series-parallel and you get 97 dB efficiency, with better bass extension (in a suitable enclosure) than any high efficiency 15" woofers I know of. Total cone area is greater than that of an 18" woofer.

Now, the best thing about using four of these 10" woofers is you can use a good 90 by 40 degree horn, and by mounting two of these woofers below the horn and two above, side-by-side, you get excellent uniformity of the radiation patterns. Much better pattern control than you could possibly get with any single bass driver.

By the way, a horn-loaded compression driver is pretty much mandatory in sound reinforcement applications like this. I have had good results from Radian drivers, as a less expensive alternative to JBL. You can put together a very nice two-way system using a 1.4" Radian compression driver in a fairly large 40-by-90 horn crossed over to the four BP-102's between 1 and 1.5 kHz.

What size enclosure is your friend comfortable with? I can run some simulations and see if a quartet of BP-102's would indeed make sense.

Best of luck with your project!
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Old 13th May 2004, 02:08 PM   #7
Solinar is offline Solinar  United States
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Thanks all for the responses!

Hes a pretty big guy, and the speakers dont have to be easily portable, just able to be manhandled out to the front porch, etc, so a pretty big box would be acceptable.

4 10" drivers would be fine if the cost was not prohibitive, however what kind of bass would that provide? Looking at the volume of displacement, 4 of those appears to be around 1.7 liters, where as 1 tempest can move 2.5 liters, and some other 15s-18s can move as much as 7 liters. I thought volume displaced was the main indicator of total bass possible (with proper power driving the speaker).

I take it from the responses given here, horn tweeters are the better way to go for high volume applications? Are there other pros or cons to using them? Does the horn tend to disperse the sound for a wider field of listening, is that the point?

If I use a horn crossed over at 1 - 1.5 khz, will the 10's provide enough clean sound in the 100-1500 hz range to fill the mid range? Are mid-range horns available and do they serve a purpose?


"For bass, if you do not want to build a horn loaded design"

What is a horn loaded design in regards to bass?

"The higher efficiency woofers have poor bass extension unless you put them in a huge horn cabinet, and then you have to go with a 3-way system. "

What do you mean by a horn cabinet. Is it a cabinet that also has a horn mounted in it, or is it some kind of horn for the woofer itself?

Sorry to be such a horn newbie. Thanks again for the responses!
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Old 13th May 2004, 05:36 PM   #8
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Default Eminence front - it's a put-on??

You raise some good questions, Solinar. I'll take a shot at a few...

The ultra long-excursion subwoofer drivers you mention typically have efficiencies in the 87-89 dB range. They're great for giving you ultradeep bass in a home listening room, but are not optimized for sound reinforcement outdoors.

The application you describe for your zydeco friend is a bit different; rather than ultradeep extension, apparently the primary emphasis is on high output. The ultra long-excursion woofers will have a higher displacement-limited maximum SPL (applicable mainly below 40 Hz), whereas high efficiency pro-sound woofers will have a higher thermal-limited maximum SPL.

For example, the mighty Tumult woofer is about 87 dB efficient (calculated bass efficiency of 86.3 dB), and can handle 1600 watts. Well, that sure sounds impressive, but the array of four 10" Eminence woofers in series-parallel will play as loud with 160 watts as the Tumult will with 1600, and the Eminences will handle 800 watts total. Below ballpark 35 Hz the greater volume displacement of the Tumult will give it a higher maximum SPL, but above that point the Eminences will play louder. What the Tumult will do that the Eminence front cannot is give you flat output below 20 Hz probably as loud as you'd ever want in your living room.

Also, the Tumult and its kin are subwoofers - you'd need a midbass driver to fill in the gap before you could cross over to a compression driver.

The four Eminence drivers will work well in boxes between 6 and 12 cubic feet. You'd probably have a bit of a bump in the upper bass region, which isn't desirable for high-end audio but is for sound reinforcement, especially if you're going to use the speakers outdoors where there's no boundary reinforcement from nearby walls. It might be possible to use multiple ports and plug some of the ports for smoother response indoors, then unplug them for maximum bass SPL outdoors.

The 10" Eminence woofers aren't ruler-flat, but are better than most pro-sound 15" woofers in the midrange. The price is also pretty good at ballpark $60 each.

You also asked about horns. What horns do is narrow the driver's radiation into a particular angle, say 90 degrees wide by 40 degrees tall. This acoustically amplifies the sound, especially at the lower end of the driver's range. So most horns need some equalization built into the crossover, which is easily done. Now most of the time the woofer has a much wider pattern than the horn in the crossover region, and this discrepancy is undesirable. By using a 4-woofer array as I've described, two above the horn and two below, the woofers' pattern is narrowed considerably and matches up better with the pattern of the horn. JBL's top engineers, David Smith, D. B. Keele, and John Eargle, published a paper describing a studio monitor that matched up the radiation pattern of the woofer and horn back in the early '80's - here's a link:

http://www.pispeakers.com/AES_v31_n6_p408.pdf

Note that the symmetry and controlled directivity of the Eminence array is consistent with the recommendations of Dr. Earl Geddes for a high quality, high output home theater system.
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