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| Re: Horn loaded Corona Build [message #93737 is a reply to message #92021] |
Wed, 12 May 2021 08:48   |
dawiipgh
Messages: 12
Registered: May 2020
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Chancellor |
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Hey guys!
It has been a long time but life kind of comes at you from all sides. When lockdown began around March 2020, I knew that I wanted to build a set of large efficient speakers. Four Pi speakers were well reviewed and recommended in a lot of the forums. So, I started poking around and eventually got the plans, crossover, and wave guide from Wayne. Compression drivers from Parts-Express and a set of preowned lightly used JBL2226 woofers from Ebay.
I was unloading several sheets of 3/4" Baltic Birch in May and it started raining so I started unloading faster. Instead of holding the sheets in front of me and walking down the grass hill to the basement entrance, I started walking backwards while sliding the wood on the grass. This shouldn't matter because I was going to true up the factory edge. Anyways, I tripped over my retaining wall and fell backwards with my hand outstretched. I ended up with a compound fracture on my radius at the wrist and a broken ulna at the elbow. So my wife 7.5 months pregnant gets me to the local hospital....
We arrive and my forearm looks like a sine curve and the bone is sticking out the bottom. The triage doctor takes a look at me and says, this might be above our paygrade here so let's get you downtown to where the real carpenters are. They set the bone that night and, in the morning, I have surgery and get external fixators put in.
This recovery with the external fixators goes on for about 6 weeks, then they remove them and open up my wrist again and screw in some plates and put me in a cast. Summer is gone and we have our second kid!
Cast comes off and I start physical therapy. I can't lift more than 3-5 pounds with very little grip strength so running a circular saw or a plunge router are last on my list of priorities. I have a buddy come over to help me manage the uncut sheets of wood and we get some rough circular saw cuts done and I decide to invest into a clamping straight edge.
So, I'm feeling better around February March 2021 (about a year from when this all started) and I start making my cuts in the back yard with full snow gear on. I learned a ton about wood working and clamping glued joints and the unruliness of routers.
After the boxes were built, I settled in on the front baffle and went with the recessed woofer and horn. Then I start on the cutouts for the port. It is an uphill battle, but at every point I'm learning more from the forums here and woodworking You Tube videos.
After the baffle is glued in, I complete an electrical hook up and it is so fascinating how much the enclosure shapes the tone and response of the woofer. I opted for a recessed baffle in order to incorporate a fabric grill in the future. I saw a great inspiration from vintage KLH, Klipsch, etc. and from a forum user here: Jensen. I opted for General Finishes Java Gel Stain and I am experimenting with mixing my own shellac and doing a final top coat with Deft spray Lacquer.
I wanted to push to get this done for my Birthday in April. We now have functional and stained speakers. A few punch list items include installing the fiberglass insulation, installing the gaskets around the horn and woofer (shower pan liner), final shellac / sanding / lacquer finishing, and a stand or feet with a 5-10 degree incline. Future projects include two flanking subwoofers. I currently hooked up a 10" subwoofer with a passive radiator which really changes the depth and heft of the sound. I can only imagine what 2 ported 12's or 2 sealed 15's will sound like! The current subwoofer is an Aperion Audio Bravus 10D. It rolls off around 40 Hz but still provides quite the depth of sound.
I am currently driving the speakers with a PS Audio Sprout 100 and even at 50 watts @ 8 ohms (100 watts @ 4 ohm), this system provides concert level SPLs with enough chest slam to have your HOA contact you.
So now we are a family of four who really enjoy Living Room dance parties. I even got on Ebay to pick up a fog machine, DJ Chauvet Kinta FX and a Scorpion dual laser aerial lights. Quarantine really came at us, but I think we are doing just fine.
Thanks to all the forum members and Wayne for all of the guidance and brainpower in this forum.
-David
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| Re: Horn loaded Corona Build [message #95997 is a reply to message #91874] |
Fri, 16 September 2022 10:13 |
dawiipgh
Messages: 12
Registered: May 2020
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Chancellor |
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Hey guys! I just wanted to weigh in on how impressed and happy I am with the 4 Pi speakers. I started with them in a small room of an open plan house. Wow. Even with a 50 WPC PS Audio Sprout amplifier, these pressurize the room. At reasonable listening volumes, everything is balanced and really feels like a live performance. I enjoy concerts (small venues and bars as well as large pavilions and arenas). During quarantine, that was missing.
I have since moved them down to the basement and they really shine in a larger room. It was interesting, since the drivers were so large, you could actually hear separation of the highs mids and low (port) because the speakers were too near field in my upstairs room. In the basement, you can experience the constant directivity. It's like you can walk around and the sweet spot is very large compared to typical dome tweeters.
4 pi's are really well balanced and the mid range is extremely lifelike. What it doesn't have is a strong low end <40 Hz. You will hear rock music bass guitar and full range of drums, low strings, and piano, but where it lacks is explosions in movies and synth bass / drum machines in EDM, House, Rap, etc. I actually messed around playing test tones (you can find them on spotify) to see where the speakers rolled off. I'm sure a calibrated mic will be in my future soon.
I had an Aperion Audio 10" subwoofer with 2 passive radiators and a 500 watt amp. It held up pretty well. But from what I've read hear and other forums / books / articles that multiple subs are the way to go. Walking around the room, you can hear noticeable volume differences in the bass response.
So since I have a 15" midwoofer, I can't reasonably be OK with a single 10" sub. so I'm back to the shop to build two 15" ported subwoofers.
It's roughly based on the 4 pi design but uses the Dayton Audio 15" subwoofer RSS390HO-4 instead of the Lab12c. Dimensions are 20" x 20" x 20" but instead of a single 4" port, I am considering two 3" flared ports from precision port 17" long each. I played around with WinISD looking at several drivers, and tons of box volumes, port arrangements and even passive radiator designs. This hit the sweet spot compromise of low end extension, port velocity, excursion, SPL and box size.
The amplifier that I bought used is a Crown Amplifier XTI 2002 to power both subs.
Admittedly, I currently do have the 4Pis hooked up to the crown and holy bananas, it's powerful. You can't beat the efficiency of these drivers. When these hit down around 50Hz it can literally pull the air out of your lungs.
So long story short, I'm really happy with my build and thanks to all in the forum for the support.
David
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