Full-range line array?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I posted this over at fullrangedriver.com also, but wanted to make sure I got everyone's opinion :)

I recently purchased 64 of the $0.69 cent Pioneer 4" speakers from Parts Express and 128 of the $0.48 Onkyo 3/4" tweeters to make a line array. After TONS of reading I guess I got into more than I can handle. The crossover designing in killing me and I got frustrated easily. I then ran across this project of a full-range speaker and got excited:

http://home.new.rr.com/zaph/audio/audio-speaker11.html

Sounds like the perfect driver for me! What I'm looking to do is to make a line array with 8+ of these drivers per side. I can do sealed or vented, whichever you guys feel will sound better. I'm leaning towards a sealed box because they're easier to work with, I think. Now, here's my second idea. Tell me if I'm stupid or not :D

I'm thinking of making a "sub box" on the bottom of the speakers in their own enclosed box, totally separate from the full-range section. Possibly put something like 2-4 6.5" drivers, or 2 8" drivers, or a single 10"..who knows..I would like this sub box to take care of the low end the full range Tang can not. Probably go up to where the Tang stops at 125-150hz. I do not want this sub box to take care of the extremely low stuff. I have an SVS sub that can hit 20hz no problem. I can have the SVS take care of 20hz to 50, 60, or 70, not sure yet, and have the sub box take care of the rest up til 125-150. I was thinking of powering BOTH tower subs off a subwoofer plate amp, like the ones they sell at Parts Express. I can put the plate amp into a custom box that sits on my A/V rack. Run the speaker wires from the plate amp to each sub box and use the crossover on the plate amp to control where I cut the bass off at. Most of the plate amps from Parts Express let you adjust from 40hz-160hz so I can use a Radio Shack SPL meter to help set it.

Is this a stupid idea or do you think this will work? Like I said I'm new to DiY speakers and thought this would be a cool project to do. Are there better full-range drivers in the same price range as these, maybe even a 4" so the need of a powered mini sub can be eliminated? ANY information is greatly appreciated. I've read this forum and you guys know some amazing stuff! I'm all ears, even to extreme amounts of criticism!

Thanks!
 
More than you can handle? The toughest part is drilling the holes. Forget the crossover at this point as that can easily (although not cheaply) be changed later. As for technical difficulty, there isn't any. It's mostly tedium stripping wires and soldering connections.

If it's your first project, do it in steps. The basic project is a line array, so build a couple of speakers with an array of eight or sixteen of the 4" Pioneers and dozen of those Onkyo's. Get them as close as possible (center/center distance) in just a simple open baffle. KISS principle. Wire 'em up series & parallel so you get between 4 and 8 ohms nominal and have a listen to just the Pioneers. Nothin' else. Just the 4" speakers. They cover 200 to 15K. Remarkably, that's about what your ears will hear anyway.

Listen for a couple days.

Now wire up the tweets and high pass them with some caps. See what they sound like at a high pass of 4, 5 or 6000 Hz.

Put the sounds together and listen for a few more days.

Find one of those powered subs with a plate and throw that in the mix... let it run out to 180 or where ever it gives up. Listen to some stuff and then decide what you like and don't like.

Start making holes!
 
Oh chipco, I know about the holes, trust me :D

I already have an OB with 16 of the Pioneers and 18 of the Onkyos installed (did 16/18 so they're both 8 ohms...I put the Onkyos centered for now. Got sick of drilling LoL). I just haven't had time yet to wire them up and have a listen. That part should only take me 1-2 hours so I'll probably have that done tomorrow. I did do a "prototype" before with 12 4" and 16 of the tweeters. The sound was HUGE and remarkable. I couldn't believe it. It was nowhere near a great sounding speaker in my books(response-wise), but the sound was just HUGE and with little power.

These full-rangers seem like an ideal way to go. The 4" sound decent full-range but I'm looking for something more accurate that won't cause myself a headache trying to make a crossover for.

Thanks!
 
Have you checked out this thread?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=28755
The Isa gets loud and has a huge soundstage, reasonably efficient too. I'm contemplating reworking the crossover (does this ever end?) to see if I can tighten up the imaging. The one thing that is very nice is the bipole ML-TQWT cab which the 5" woofers occupy. Beautiful bass response from this unit.
 
Tim - any comb filtering/imaging problems with the Isa? I'm curious as to how you guys avoid it in the full-range arrays.

Yes, I am having some issues. If you keep your head perfectly still the sound is superb, if you turn or move your head you can hear a drop in HF. I use the speakers in my 5.1 HT so I don't notice very much but I'm not ready to give up. Going to keep fiddling with it.
 
I took Chipco's advice and wired the 4"ers up full-range and listened to them for about an hour. They are on an open baffle with 16 drivers and 18 tweeters (got sick of making holes). For the test I only wired up the middle 8 drivers for an 8 ohm load. At first I wasn't very impressed with the sound. The speaker was placed ~3 feet from the wall. I then decided to adjust the bass/treble knobs on my Harman Kardon AVR230. WoW! Sound MUCH BETTER! The 4" Pioneers sound SO much better with the bass turned all the way up. Before the adjustment they sounded very weak and hollow, but after boosting the bass (generically, I know) they really stood out. I even had to turn to treble way up to help them with their weaker high-end. Very impressive! Not near audiophile quality but a damn bargain at under $10 shipped.

I then wired up 9 tweeters to match the 8 ohm load and the high-end opened up. I did mess up a little with this prototype: I drilled out 1.5" holes for the tweeters without any kind of roundover. They are mounted behind the 3/4" MDF and not much of the sound is getting out. They're also mounted about 2.75" apart as I haven't taken off any of the excess plastic yet.

After this test with running the 4"ers full-range I am getting high expectations on better built full-range drivers. I can only imagine what a quality Tang will sound like. With just the 8 4" speakers I almost went deaf at a listening position of about 10 feet. For a stereo pair I'm not sure if I'll really need to make the full 16 driver towers. This would save me a lot of time as my woodworking skills aren't stellar and also up the WAF. :xeye:

One question...I'd like to keep running the 4" full-range as they sound much better to me this way then hooked up to a crossover. Should I cross the tweeters over around 3-3.5k like suggested with the C-C calculation, or could I let the tweeters cross over a lot higher, say in the 8-10k range? Or is this stupid? I just don't want the 3k-8k or 10k range (or higher or lower, whatever) to be playing excessively loud. OR would it be better to let the 4" speakers go until say 5k or so, and let the tweeters take over after that? Your call. I'm all ears!

THANKS! :D


EDIT:
I just tried the speakers again with the crossover hooked up (Infinity Kappa car crossover) but this time I turned the bass and the treble up (forgot to last time). Sounds STUNNING! Unreal! Turning the bass/treble back to flat makes these sound subpar, but once it's boosted up they are remarkable speakers. I usually prefer my bass/treble at 0 (flat) but not with these.
 
They are on an open baffle with 16 drivers and 18 tweeters (got sick of making holes).

That's the reason you need bass boost. I have 8 Pioneers in a TL and they run to 80 Hz room assisted.

The speaker was placed ~3 feet from the wall.

That's OK open baffle, but NG with a closed box, giving a null at about 100 Hz where you least can afford it.

Should I cross the tweeters over around 3-3.5k like suggested with the C-C calculation,

The C-C calc is not universally accepted as being accurate. It assumes that the driver is a true point source,whereas in reality a far larger portion of the radiating plane (cone) serves as the sound source. Real world measurements indicate and that you can go higher.

They are mounted behind the 3/4" MDF and not much of the sound is getting out. They're also mounted about 2.75" apart as I haven't taken off any of the excess plastic yet.

That's why the highs aren't there.

would it be better to let the 4" speakers go until say 5k or so, and let the tweeters take over after that?

The fours are OK to about 6Khz, but above that they have a nasty response peak on axis, while the off axis response falls off precipitiously. Therefore both response and imaging concerns dictate crossing over no higher than 6kHz. The falling off-axis response will be a problem with any full-rangers. Whizzers will help, but then the spacing becomes more problematic than with discrete tweeters. Don't knock the quailty of the Pioneers; their only deficiency is in power handling, and using eight or more of them takes care of that problem.
 
Thanks for the input!

This speaker was built just to let me see how a line-array sounds and if I want to pursue making a real pair of them. After my listening I DEFINATELY want to pursue this project.

As far as mounting the tweeters. Do you think I should use a router and recess the whole back of the MDF where the tweeters will mount say 1/4" or more, so the tweeter will be closer to the baffle? I can still roundover the tweeter hole but I'm not so sure having the tweeters 3/4" behind the baffle is a smart thing to do. What size tweeter hole should I use?

I'm still learning about crossovers and was wondering if I would benefit from stepping up to a 3rd order instead of a 2nd order like you did, Chipco? Or does this just add unneccessary cost and sound degredation? (I have no clue).

If you had this project to do over again, how would you make your speakers, learning from what you now know? Maybe this can help a speaker newbie like me out :angel:

Lastly, I messed up when I said I had 8w 9t. I really had 9w 8t to get the 8ohm load. If that matters or not.

Oh, and should I do 4, 6 or 8 ohms? Sorry for all the questions!!!

THANKS GUYS!
 
but I'm not so sure having the tweeters 3/4" behind the baffle is a smart thing to do.

You really have to get the faceplates flush with the baffle or you'll have all sorts of diffraction problems in the high end.

3rd order instead of a 2nd order like you did, Chipco? Or does this just add unneccessary cost and sound degredation?

A 2nd order doesn't give adequate bandwidth isolation between the two lines and will lead to horizontal combing. The two lines have to be physically as close together as possible and a 3rd order crossover is the minimum.

should I do 4, 6 or 8 ohms

8 is always safe.
 
I will defer to BillF's experience because I'm new at all this. However, I will make the following statements:

1. On my first version I used the Onkyo's and drilled a 1 1/4" hole and rounded over the front of the hole with a 3/4" radius bit. The effect was like a little horn when I was finished. From the standpoint of physics, that didn't hurt it. Further, the appearance was improved over surface mounting the tweets. I used 24 of them.

2. On my second version, I used Dayton ribbons. One ribbon is placed at about 5' and the second at 3'. These correspond to on-axis heights of sitting and standing "ears". They are better if for only avoiding the forty eight holes.

3. V1 was wired at 8 ohms using straight series/parallel scheme. V2 used a staggered series/parallel scheme and came out to about 5 ohms on the woofer section. I think V2 sounds better.

4. As for the combing issue. I am sure I have heard it and seems more pronounced within the near field distance. Step back and it disappears. Does it bother me? No.

5. Bass. I added a sub box that I stole from my son. Good for classical but only adequate for rock. However, the most noticable effect of the line of 4" drivers is the "punch", like when a drum is struck. I guess this is not exactly bass but it hits you viscerally like bass.

6. Number of drivers. I think the Griffin paper is quite clear that if 8 are good, 16 are MUCH better to achieve the line array "effect". The graph does rise at an geometric level. In my particular circumstance, 2 to eighth power quantity drivers was too much freight cost and would not pass WAF standards.

7. Crossover frequency. This is the toughest question. There are two possibilities here. The first is to equip yourself with with a bandolier of caps and coils and have at it. I gave up that idea based on cost and I am presently preparing active filter MOX boards for biamping these arrays. IMHO, most of the listening is in the 200-5kHz range and I have avoided the cross in that area. The MOX will let me play for free.
 
2 questions...

Bill...you stated:
"You really have to get the faceplates flush with the baffle or you'll have all sorts of diffraction problems in the high end."

How can I accomplish this using the Onkyo $0.48 tweeters? I brought up the idea of plunging my router into the back of the baffle about 1/4" or more and routing out the whole tweeter section so the tweeter would only be 1/2" or less mounted to the back of the baffle. I would still like to use a roundover, like Chipco did, in order to eliminate the 90 degree cut and maybe apply somewhat of a "horn".

Chipco, you get question #2 =)

"3. V1 was wired at 8 ohms using straight series/parallel scheme. V2 used a staggered series/parallel scheme and came out to about 5 ohms on the woofer section. I think V2 sounds better."

I understand V1 as all of my plans have used a 4 or 8 ohm load on both w/t lines. When you say a staggered series/parallel do you mean something like:

8-8 = 16
8-8-8-8 = 32 }
8-8-8-8 = 32 } parallel these 2 to achieve a 16 ohm, then parallel these with the 8-8 to get an 8 ohm nominal? If not, then what do you mean? This is considered power tapering, right? Where you'd probably put the 8-8 in the center and the 32 ohm loads out the outsides?

Thanks!

-The newbie
 
I did purchase some 6.5" Vifa (Infinity) Buyouts from Parts Express to use in a line array. Problem is I don't have the $$$ right now to get tweeters that will do those drivers justice. With a 6.5", and even moreso with an 8", you'll have to cross the tweeter over much sooner (in most cases). I also think it's more difficult to achieve good midrange from a large woofer, like an 8" in your case. I'm even a little reluctant to try it in a line array.

I was thinking of making a set of bookshelfs first, before I jump into the line array project. Maybe a set of MTMs with (2) of the 6.5" Vifas and a nice tweeter. Do you guys think these drivers will work well in an MTM speaker?

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=299-493

If not, how could I use them? And is there something more desirable than an MTM?

Thanks! :)
 
My cab used the round Onkyo's, which I mounted in holes using silicone sealant. Flush mounting is the best method, but a radiused faux horn is the next best option.

The problem with large drivers isn't so much the C-C as it is dispersion, and with eights that pretty much forces you down to 2kHz, which is OK, you just won't get tweeters that go that low for $.32.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.