One of the 4way crossovers that came to market after I had embarked on the current course was the MiniDSP, I will probably make one of these up just for a comparable option. There is a diyaudio thread here:
miniDSP - diyAudio
The foam in my OB spheroid wave guides came from Earl Geddes.
There is a lot of information on the JBL PT waveguide since Zilch worked out a very good passive crossover to go with it on the Selenium D210TI.
col.
miniDSP - diyAudio
The foam in my OB spheroid wave guides came from Earl Geddes.
There is a lot of information on the JBL PT waveguide since Zilch worked out a very good passive crossover to go with it on the Selenium D210TI.
col.
I have a similar interest in making mid-highs for my DJ rig with exactly the same type components except I want to use a separate 15" midbass box and a quad 8" mmtmm box ( for when the 15" MB isn't necessary) with a 4" vc 2" throat horn(cuz I don't play alot of music that features 3" by 1/8" wind chimes)
I also use dual 18's as base(bass) stacks and my rig needs to be under 8'tall as well
I hope you get many excellent responses as this thread can help both of us!!!
I also use dual 18's as base(bass
) stacks and my rig needs to be under 8'tall as wellI hope you get many excellent responses as this thread can help both of us!!!
That line array v-dosc box has the 7" drivers x'd so low due to the dual cone coupling(1/2 wavelength ) spacing( cone c-c), also the reason that they use two comp drivers to be able to handle that 1100-1300hz x-over region. I have similar boxes in use (sans 15"ers) that sound really nice and are only 18" wide, though they are deep
Interesting, I would say that small driver have wider dispersion than large 12" and 15" which need to be crossed over lower due to this (and cone break-up). Crossover in the 1...2 kHz range has its own problems, especially a lot of compression drivers seem to sound very harsh and aggressive in that range when pushed (on the other hand, that is what many rock and punk bands want). I very much share the view of Tony Andrews (former designer for Turbosound, now the founder and head of Funktion-One), that is, mid frequencies should not be divided between two totally different drivers and line array is not a panacea for every problem encountered in pro audio.
with a 4" vc 2" throat horn(cuz I don't play alot of music that features 3" by 1/8" wind chimes)
One day someone's going to throw some mini wind chimes into your trance/dance and you'll never know it happened.
I've never worked with a band that wanted the PA to sound harsh, though I suspect one or two wouldn't have cared that much. I prefer to overspec everything in the PA to make sure it all runs well within its comfort zone. Hence the impression I may be aiming for max SPL. Not entirely true.
That makes sense to me. I am a bit reluctant to apply too large of a driver to mids since it usually puts the vocal range smack in the middle of a large cone break-up mode region. It depends on how smooth the driver is in that region I suppose. The systems using dual 15" woofers crossed to 2" compression drivers seem absurd to me, yet they are quite common. In fact a friend just bought an EV Power-X PA system with exactly that configuration
, which re-ignited my interest in this subject...Todd
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I don't expect to get cone break-up from a 12" driver that has a usable frequency range up to 4khz when I'm crossing out of it at 2.5khz with a 24db slope.
I think many club PAs sound harsh usually as a result of poor EQ'ing and lack of room correction. Especially, with high frequency reflections from long throw horns. In Melbourne there are many clubs with Funktion-One systems in them and they sound terrible due to bad room tuning. Actually, as much as I love the sound of a Good Funktion-One system at an outdoor gig. I have never heard one sound good inside a club.
col.
The systems using dual 15" woofers crossed to 2" compression drivers seem absurd to me, yet they are quite common. In fact a friend just bought an EV Power-X PA system with exactly that configuration
..Todd
I guess it's that "look, it's BIG, it MUST be good!" attitude. Where I live there seems to be a strong opinion that if it doesn't have 15" mid/bass driver, it's not a proper PA speaker. I've even seen more than one PA speaker built by some local "experts" that pair 15" bass driver with 2 or 4 horizontally arranged bullet supertweeters, which is, of course, totally inappropriate. The result - no real bass but overblown and boomy mid-bass, muddy low-mid, harsh high-mid (if it's even there) and treble, totally unintelligible vocals.
I thought I should throw in some info about line arrays. The article goes through history of sound reproduction and how it came up to this point.
Well worth the read and might help understand some differences and goals this thread is about.
http://www.diyaudio.com/forums/multi-way/153474-large-format-concert-arrays.html#post1952625
Well worth the read and might help understand some differences and goals this thread is about.
http://www.diyaudio.com/forums/multi-way/153474-large-format-concert-arrays.html#post1952625
I just finished reading it. To me it looks like some marketing text to Nexo. All that bashing of conventional point source use for large systems. Don't get me wrong, I've heard good sounding line arrays (Martin Audio IIRC) and just plain awful point sources, but the fact is, if you know what you're doing and use the right tools, you can get excellent results with point sources for large systems. Line arrays generally have some serious compromises and so-called "compact line arrays" consisting of 2 to 8 small 2-way boxes with 6,5...8" midbasses won't work at all as a true line source, just more-or-less like conventional speaker boxes but with fancy rigging hardware. Sadly the industry is largely just fashion-driven.
col,
You cannot avoid them. Cone breakup modes exist in all code drivers and is a permanent physical property; the resonant patterns within the cone material. The larger the cone, the lower the frequency of those modes. For a 15" driver, you can expect them to start probably around 500-700 Hz. For 6" drivers, they will start nearer to 3-5k, requiring less EQ or simpler crossover designs below that region.
You can easily see them on a driver's frequency response chart. It's where the response starts to go crazy on the way up near where it rolls off at the upper limit. The less cone damping there is, the more pronounced they will be. Check out the graph of any aluminum cone driver, and compare it with say a paper or Nomex cone driver.
For home stereo speakers with a passive crossover you will permanently deal with them in the crossover design. Some excellent speakers have pronounced BUMs that must be dealt with. But for pro audio the crossovers are typically active 'textbook' crossovers, you pick the frequency, slope, knee and you're done. You must then EQ the PA to correct those aberrations. (Digital crossovers [can] provide that custom tuned approach that passive crossovers provide -- one of their big advantages IMO.)
A good strategy for PA use, IMO, is to avoid BUMs rather than deal with them. You can look for drivers whose breakup modes are not too pronounced, or just work with smaller drivers where the modes are higher than the passband (or combine both approaches).
..Todd
more background reading:
Rod Elliot's article is very pro-horns, but then it comes from someone who was doing pro sound in the 70's. Does lay down some good basic facts to keep in mind though.
PA Systems
Also, Rog Mogale's article about using front loaded reflex boxes for small venues:
Speakerplans.com
col.
Rod Elliot's article is very pro-horns, but then it comes from someone who was doing pro sound in the 70's. Does lay down some good basic facts to keep in mind though.
PA Systems
Also, Rog Mogale's article about using front loaded reflex boxes for small venues:
Speakerplans.com
col.
The articles are relevant background information for designing and setting up PA systems. Why would that not be relevant? The information helps to narrow down the decisions that need to be made before embarking on system building. I think both articles and the opinions they contain are a very good insight into PA design and they come from experienced, knowledgeable experts in this field.
col.
col,
This thread is about getting input and feedback about a very specific purpose and very specific type of PA system, as described in the first couple of messages, from what I hoped would be folks with plenty of experience (like mine) in that field who understood those particular challenges. So far there's been some good information/ideas. But if it degenerates into a general DJ type PA design thread, with PA 101 chatter, then I'll bail.
Having said that, I would love to know more about those JBL PT waveguides. I read some of those other threads that were referenced, but real information was scant. Did Earl actually end up measuring them? Did anyone else? Are they actually good or are they, as Geddes suspected, just marketing hyperbole from JBL? They don't look like a waveguide as Geddes' AES papers describe. I am skeptical, but would love to learn they are decent. The noise/signal ratio in those other forums was too high to suffer through long enough to find that information.
..Todd
This thread is about getting input and feedback about a very specific purpose and very specific type of PA system, as described in the first couple of messages, from what I hoped would be folks with plenty of experience (like mine) in that field who understood those particular challenges. So far there's been some good information/ideas. But if it degenerates into a general DJ type PA design thread, with PA 101 chatter, then I'll bail.
Having said that, I would love to know more about those JBL PT waveguides. I read some of those other threads that were referenced, but real information was scant. Did Earl actually end up measuring them? Did anyone else? Are they actually good or are they, as Geddes suspected, just marketing hyperbole from JBL? They don't look like a waveguide as Geddes' AES papers describe. I am skeptical, but would love to learn they are decent. The noise/signal ratio in those other forums was too high to suffer through long enough to find that information.
..Todd
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No worries. I don't think any of my posts have deviated from that purpose though.
The threads regarding the JBL PT waveguide (earl calls it a defraction horn) that are worth reading are here:
http://www.diyaudio.com/forums/multi-way/123426-horn-vs-waveguide.html
and here:
AK Design Collaborative - Econo-Waveguide Speaker - AudioKarma.org Home Audio Stereo Discussion Forums
col.
The BMS 2" 4950 driver in the brown bag system looks very interesting, being a coaxial compression driver 300 Hz to 22 kHz! (Not Cheap!)
The extended bandwith opens up a few more options.
Maybe 18" drivers on the bottom end crossing over to 12" drivers
(12" drivers seem to have the edge when it comes to comparing efficency)
Crossing over to the coaxial BMS at a low enough frequency to avoid any breakup - beaming on the 12"
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