I've had these 12" pieces of 8" PVC pipe hanging around forever. I've also had some 1" MDF hanging around collecting dust. I decided to make them into speakers as a proof of concept kinda thing. I would like to use them at the theater for things. If I do it right enough, they can be over-the-audience mains. If they don't have enough punch, they can be monitors for musicians or placed around the set for FX. If they suck at that, they could be program monitors for dressing rooms or something. If they fail entirely, I can always stab a BT plate amp on them and turn them into a portable speaker.
Pics in a little bit
Basic specs: 0.281 cu ft, 1" MDF baffle and back, 8" sched 40 PVC pipe. EDIT: I learned yesterday it's actually Sched 80 pipe.
My first thought was to buy some C-note components and add an amp. The C-notes hit above their weight class, but they're not overkill. I absolutely adore them in my 12 x 16 living room, but I don't think they would impress in a 50 x 60' theater, even if I did build 8 of them. I'm also having trouble finding compression/horn combinations that would fit along with a 5" woofer on an 8" round baffle.
So help me spend money. What would you do with 0.281 cu ft of super-beef enclosure?
No idea if these are any good, but look for coaxial speakers, something like these.
Parts-Express.com: 121 Results for coaxial speakers
Parts-Express.com: B&C 6FHX51 6.5" Professional Coaxial Speaker 70 x 70 8 Ohm
Frequency Response 85 to 18,000Hz
Sealed Volume 0.16ft³
Sealed F3 193.9Hz
Vented Volume 0.18ft³
Vented F3 84.5Hz
Need an 8" subwoofer
I've got a 18" dia. x 24" piece of pvc pipe wanting some subwoofer sitting in my back yard. 
I think it would be cool to just put woofers on those then mount some 2 - 4" pvc on one side with a midrange and tweeter in it. Maybe?
I always wanted to build two satellite speakers out of fiberglass reinforced 12" Earth globes with a set of these 6.5" woofers, with these ribbon tweeters, and these 4500Hz crossovers.
Parts-Express.com: Dayton Audio DS175-8 6-1/2" Designer Series Woofer Speaker
Parts-Express.com: Dayton Audio AMT Mini-8 Air Motion Transformer Tweeter 8 Ohm
Parts-Express.com: Dayton Audio XO2W-4.5K 2-Way Speaker Crossover 4,500 Hz
It wouldn't take much to mount the woofer and tweeter in a coaxial alignment.
If I'm going with my first wish, they'll be an array of mains for the theater, which means tweeters are pretty much out of the question. I'll need control over the dispersion. Will Supertweets/bullets get me there? I can't imagine finding a compression/horn that will fit beside a 5" or 6.5" woofer on an 8" face.
If I can't achieve the goal of being mains for the theater, I can do whatever I want. I'd really like to see if I can go for the gold.
The current setup at the theater is terrible. Big cabinets way up at the ceiling with horns that are way too wide dispersion. I was hoping to make 8 of these puppies and hang them much closer to ears in the theater, but controlling the dispersion will be key.
VolvoHeretic said:
I've got a 18" dia. x 24" piece of pvc pipe wanting some subwoofer sitting in my back yard.
That's 3.5 cu ft of glory waiting to happen right there.
VolvoHeretic said:
It wouldn't take much to mount the woofer and tweeter in a coaxial alignment.
I don't know enough about speaker design to know how that would work. I was under the impression that placement and being co-planar with the drivers was a key part of the frequency response and "stage".
dculberson said:
I think it would be cool to just put woofers on those then mount some 2 - 4" pvc on one side with a midrange and tweeter in it. Maybe?
That was one of my first thoughts, but it doesn't take much woofer to effectively use 0.28 cuft. 5" or 6.5" will likely be about the limit. I might find a 7" that would like 0.28 as a sealed enclosure, though.
fostex full range drivers? maybe build a small tube based amp to drive them?
ClearWaterMS said:
fostex full range drivers? maybe build a small tube based amp to drive them?
a simple ported enclosure based on on the size of your tubes can help determine what size driver will sound best:
https://www.fostexinternational.com/docs/speaker_components/recommended_enclosures.shtml
they won't go super deep (maybe not even 80Hz at -3db /wo room correction) but it's a simple build and would be kinda fun weekend project.
Curtis73 (Forum Supporter) said:
VolvoHeretic said:
It wouldn't take much to mount the woofer and tweeter in a coaxial alignment.
I don't know enough about speaker design to know how that would work. I was under the impression that placement and being co-planar with the drivers was a key part of the frequency response and "stage".
What I understand is that either the diaphragms need to be in the same plane or the front mounting surface (outside of the cones). Then there is something about the electrical phasing of the speakers.
Curtis73 (Forum Supporter) said:
The current setup at the theater is terrible. Big cabinets way up at the ceiling with horns that are way too wide dispersion. I was hoping to make 8 of these puppies and hang them much closer to ears in the theater, but controlling the dispersion will be key.
Have a picture of the theater? Are you running everything in mono?
VolvoHeretic said:
Curtis73 (Forum Supporter) said:
The current setup at the theater is terrible. Big cabinets way up at the ceiling with horns that are way too wide dispersion. I was hoping to make 8 of these puppies and hang them much closer to ears in the theater, but controlling the dispersion will be key.
Have a picture of the theater? Are you running everything in mono?
Depends on the show, but 80% of the time mono.
I have a Sketchup of the theater. Let me grab some screencaps.
So these are old, but they're all I have at home. Much of the shelving around the perimeter is now gone, and the seating risers were for a specific show, but the room is accurate. Grid is at 15' above the deck. Peak of the barrel roof is 27', so I would say the current speakers are 22-ish feet off the deck.
Panoramic shot during the renovation in 2020 so you can at least see the grid for comparison.
And a little more clarity. The red circle shows the current crappy cluster of four cabinets. The green circles are where I want to put these smaller speakers. I was going to build 8 of them, but likely only ever need 6 or so at a time. The other two could be pit monitors, dressing room monitors, or lobby feed.
Or, here is a bit more beating of a dead horse...
Red is where the current cluster is. They hang on swivels above the grid. Green is where I would consider hanging the smaller speakers which would be about 8-10' closer to the audience ears
In reply to Curtis73 (Forum Supporter) :
I am no sound engineer, but I would try dropping your PA speakers down as low as you can get them. Is the stage on the back wall?
Edit: never mind I see your new diagram. I would still drop your existing speakers. I think that you are going to get some really weird sound imaging things going on with some speakers closer to the audience than others. Something about comb filtering. Audio University Online.com: Comb Filtering Explained: What Does a Comb Filter Sound Like?
So, what I'm seeing are 4 speakers trying to perform as a point source of sound which eliminates the comb filtering as much as possible and is placed in front of the performers so that their microphones don't pick up a direct blast from the speakers. Both good. You can't really drop them down as that will interfere with the stage lighting. I assume someone set up the sound system that new what they where doing?
VolvoHeretic said:
So, what I'm seeing are 4 speakers trying to perform as a point source of sound which eliminates the comb filtering as much as possible and is placed in front of the performers so that their microphones don't pick up a direct blast from the speakers. Both good. You can't really drop them down as that will interfere with the stage lighting. I assume someone set up the sound system that new what they where doing?
Well, I set it up, but I wouldn't say I know what I'm doing. I know the physics of sound, but most of my experience is in car audio.
Those four in the red circle are pretty close to the middle of the room. That's what we're using now. You're right, they can't come down any or they'll interfere with lighting.
Pros of the current setup
- It fires over the actors' mics directly to the audience which creates a ton of headroom before feedback
- They're on swivels so regardless of how I configure seating, I can point them to audience
Cons of the current setup
- Incredibly limiting because the horns are very wide, like 90 x 90 degree, which is too wide for some seating layouts and not wide enough for others. I'm either overlapping horns bigtime, or barely covering the audience if it's in the round.
- Two crap woofers and one partially blown compression driver means that they suck. That's not a placement problem, just a general con
The last show, I had one bank of seating, so I needed about 100 degrees of coverage. The show before that, I had seating in the round and needed 360 degrees of coverage. If I do a proscenium show, I only need about 60 degrees of coverage.
My thought with 6-8 cabinets with (let's say) 60-degree horns or supertweets, I can get the coverage I need by using any combination. Point two of them at a one-bank audience, use all 6 for in the round, have a couple spares for pit monitors or directional FX. I thought it would take some more careful aiming to prevent combing that way, but at least I would have a more versatile setup.
Am I crazy?
I'm not knowledgeable enough to advise you on your goals, I would say build a pair and see how they sound. I'm thinking you are going to need a lot of 6" speakers to fill that large of a room full of people. I'm also guessing that you are only trying to amplify human speech and singing so mostly all midrange. I would think that 8" woofers would work out better for you.
What size/brand speakers are you using now?
Yamaha 12". Great mid/high, but nothing below about 200hz really comes out of them. They're really better suited as front fills or monitors, but it's what I had. I have a Yorkville powered sub that I can crossover nicely to round it out. I also have in my arsenal some Peavey SP-3G monsters that I sometimes use for a proscenium show that rocks, like Tommy or Next To Normal or Hair.
Here's my thought on going smaller. The c-notes I have at home are a 5"/tweeter combo. For home theater, they actually make really decent lows. -3db point is 50hz. The downside to that is when you get really loud, the coil excursion is the limiting factor and you really have to crossover at more like 150hz. For that reason I paired them with an 8" sub and now I can drive the whole thing as loud as I want without any weirdness. I was thinking if I were to take that kind of design, but instead of a 5"/tweeter at 50Wrms, if I did a beefier 6.5"/Supertweet at 100Wrms, I think I could make some little screamers. A C-note on steroids, so to speak. That should cover voices and music down to mid-bass and let the sub crossover for real bass.
I have a friend who works for a local production audio place and he is getting me a quote for new/used cabinets, but he keeps coming back to the same conundrum... choosing cabinets with horns that can service anywhere from 60 degrees up to 360 degrees.
I also have a really killer pair of Community cabinets with 15s, but the cones are super tight, like 20 degrees. Kinda useless in a black box, so they might get liquidated/traded to fund whatever plan I can come up with.
Circling back to this. I have spent the better part of the week trying to find some combination of woofer and bullet tweeter that will A) fit on the 8" face of this baffle, B) will compliment each other's crossover desires, and C) matches the volume of what I have. I can cut the enclosures shorter and use a 5" woofer to get them to fit (thereby likely lowering SPL and cutting low range extension) or I can try hopelessly to keep the search for a 6.5" or 8" coax that will do the trick, but the only ones I'm finding are a bit cost-prohibitive. I found a great 6.5" for $178 each, but it's not like I'm going to spring $360 to build a proof of concept pair.
I think I've decided to go with an 8" sub that might get tucked in the corner of the van for myself. Problem is, I'm leaning toward a ported isobaric setup which is way beyond the "online box calculator"
Recommendations for a book? I've heard about Loudspeaker Cookbook. Is that the be-all end-all? I understand physics and the concepts behind audio, but I think I need a deeper dive
