TL;DR:
I have some big empty 6cu ft. enclosures.
I want to bring them to life in some capacity. Ideally to experience the "aliveness" of efficient drivers in big reflex enclosures.
I'm not after perfection. Here to have fun and learn something through experimentation and this community.
I'd like to keep it under $1k USD.
Long version:
I fell into some speaker cabinets that likely started their life as DIY Altec A7 enclosures and more recently were refurbished as a 515B / 802D combo by the person that gave them to me.
Here's a photo of the before and after. Note that I only have the cabinets. No drivers, horns, xo's etc.
I took some measurements and made a drawing to calculate net volume:
External dims are 36x24x15"
Gross internal volume 6.21 ft³ / net (without driver displacement) ~6 ft³
So now the question is, what can I do with these?
My only real requirements:
$1k USD budget
Limit woodworking to small mods – baffle changes, bracing, etc.
I want to build something high efficiency to pair with my Amp Camp Amp or Fisher 400, but I also have some 100W Class D amps available if I go the DSP route.
I'm fine with soldering but have no experience designing crossovers.
The more subjective stuff:
I'm "horn curious" – I love the way they look and I'm wondering if there's econowave projects that might be a good reference here (though I haven't seen any 6 ft³ builds yet..).
One thought is that enclosing the horn in the cabinet will eat up some volume and get me closer to some of the 5 ft³ e-wave projects (or the 4pi, etc.)
I'm open to DSP – and I'm thinking that could be a good way to learn about crossover design and room dynamics.
I'm assuming I will need to cut a new baffle – both for speakers size and for port tuning.
From a budget standpoint, these Lii Audio 15" coaxials are attractive – even includes a crossover.. but the T/S params are confusingly lost in translation.
What would you suggest?
I have some big empty 6cu ft. enclosures.
I want to bring them to life in some capacity. Ideally to experience the "aliveness" of efficient drivers in big reflex enclosures.
I'm not after perfection. Here to have fun and learn something through experimentation and this community.
I'd like to keep it under $1k USD.
Long version:
I fell into some speaker cabinets that likely started their life as DIY Altec A7 enclosures and more recently were refurbished as a 515B / 802D combo by the person that gave them to me.
Here's a photo of the before and after. Note that I only have the cabinets. No drivers, horns, xo's etc.
I took some measurements and made a drawing to calculate net volume:
External dims are 36x24x15"
Gross internal volume 6.21 ft³ / net (without driver displacement) ~6 ft³
So now the question is, what can I do with these?
My only real requirements:
$1k USD budget
Limit woodworking to small mods – baffle changes, bracing, etc.
I want to build something high efficiency to pair with my Amp Camp Amp or Fisher 400, but I also have some 100W Class D amps available if I go the DSP route.
I'm fine with soldering but have no experience designing crossovers.
The more subjective stuff:
I'm "horn curious" – I love the way they look and I'm wondering if there's econowave projects that might be a good reference here (though I haven't seen any 6 ft³ builds yet..).
One thought is that enclosing the horn in the cabinet will eat up some volume and get me closer to some of the 5 ft³ e-wave projects (or the 4pi, etc.)
I'm open to DSP – and I'm thinking that could be a good way to learn about crossover design and room dynamics.
I'm assuming I will need to cut a new baffle – both for speakers size and for port tuning.
From a budget standpoint, these Lii Audio 15" coaxials are attractive – even includes a crossover.. but the T/S params are confusingly lost in translation.
What would you suggest?
170 litres… A whole lot more bracing.
This one is 135 litres with sufficient bracing.
dave
f you want the kind of box that tries to squeeze out more bass than the driver can really support.
My optimum HPD385 design is 55 litres.
dave
Ah--standard geezer cab for recovering horn-heads that have downsized 🙂 Lovely cabs. There's always the turnkey 4pi kit at Wayne's that should sate the ewave jones w/o much thinking. Make a baffle, assemble, and go. Omegas would be ~1.5dB below the 515's responses and reach a touch lower, depending. Lotta options--just depends how involved you want to be in development. If you want the full ewave design-your-own & measure-your-own, check the pro vendor sites for designs, too.
Do you think the 12" driver in the 4pi will start to cause comb filter issues on such a wide baffle?
Look here
https://www.eighteensound.it/en/resources/suggested-designs/
Also B&C spots some designs.
I was watching the news... what about a coaxial!?
https://www.bcspeakers.com/en/products/coaxial/12/8/12CLX64
https://www.eighteensound.it/en/resources/suggested-designs/
Also B&C spots some designs.
I was watching the news... what about a coaxial!?
https://www.bcspeakers.com/en/products/coaxial/12/8/12CLX64
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I'm starting to see a fork in the road:
1 – take the econowave route and look at many of the proven combos. Jerry rig the net volume by adding bracing and other displacement strategies (e.g. closing off the horn in its own chamber) to suit "proven" designs from Zilch et.al which tend to be in the 5 cu. ft. range.
My understanding is that this route will require I get into DSP and some trial and error experimentation – the enclosure I have is likely to different from existing ewave designs to just blindly assume those respective crossovers will work.
I've somehow convinced myself that the DSP-measure-adjust route is going to be easier than designing or modding a passive xo. Happy to be convinced otherwise!
2 – keep searching for a suitable "drop in" driver. The way I see it, options are:
a. full range 12" or 15"
b. coaxial with an existing passive xo – something along the lines of lii audio's offerings or finding a pair of 604b's for $500 and tracking down a Werner Jagusch xo for about the same.
c. three way options.. Cornscala type B is nearly same dims as my cabinet. Maybe there's a budget version – huge rabbit hole here!
Random question – what would be the issue with just removing the back panel of the enclosures and treating it like an open baffle? Is that foolish?
1 – take the econowave route and look at many of the proven combos. Jerry rig the net volume by adding bracing and other displacement strategies (e.g. closing off the horn in its own chamber) to suit "proven" designs from Zilch et.al which tend to be in the 5 cu. ft. range.
My understanding is that this route will require I get into DSP and some trial and error experimentation – the enclosure I have is likely to different from existing ewave designs to just blindly assume those respective crossovers will work.
I've somehow convinced myself that the DSP-measure-adjust route is going to be easier than designing or modding a passive xo. Happy to be convinced otherwise!
2 – keep searching for a suitable "drop in" driver. The way I see it, options are:
a. full range 12" or 15"
b. coaxial with an existing passive xo – something along the lines of lii audio's offerings or finding a pair of 604b's for $500 and tracking down a Werner Jagusch xo for about the same.
c. three way options.. Cornscala type B is nearly same dims as my cabinet. Maybe there's a budget version – huge rabbit hole here!
Random question – what would be the issue with just removing the back panel of the enclosures and treating it like an open baffle? Is that foolish?
Uncertain if you meant diffraction from all the ledges or resultant of narrowing of lobes from increased CTC driver spacing w/ outboard horn (or both or ???) BUT...there are good and bad things about reusing cabs--those points would be the latter 🙂 If you choose coax or not, you can always tilt your baffle say 10 deg, too. FWIW, 4pi is 15" and you could just post on Wayne's board if you wanted to talk to him about it all, too. Notions of wide and narrow perhaps depend on when one was born. Do some quick sims to convince yourself -- 6 ft3 isn't that far out of line unless you plan on running high power. If this is for home use/levels and you want closer to bass range (than just midbass), 6 ft3 is right in there, allowing for some bracing, etc. Everything in 2-ways is a tradeoff that hurts. Tilting the baffle back say 10 deg would eat a little, too, for not too much woodworking complexity. The flip side of the rabbit hole is wide-open choice (and the gift of forcing you to really think about what's important to you).
I'm so new to all of this! Honestly I don't know. I'm inferring that there are undesirable effects based on wide baffles, mostly based on the fact that I see that most large-ish modern two way design seem to attempt to minimize this "negative space".
Interesting! Never considered this.. Aesthetically I'm certainly in the wrong generation – but it does seem to be swinging back the other direction with Ojas etc.
Just keep it fun and don't overspend if you are uncertain. Do what's comfortable. Know that it is audio and that it's easy to find people in 100% advocacy or 100% opposition to whatever the subject (eg baffle width) is. Check with people who already have things you're considering. If you find yourself compromising too much to reuse your cabinets, remember that it's just a little more work to turn the cab 180 degrees and make a new front 🙂 I offer you my favorite quote from @tmuikku: "On the other hand big speakers are so much fun small problems don't mean nothing. "
Given the cavity resonce you would probably do better with a Boffle:
http://p10hifi.net/tlinespeakers/forum/boffle-RadioElectronics.pdf
http://p10hifi.net/tlinespeakers/forum/Boffle-patent.pdf
dave
Eminence Kappapro-15A has Vas of 5.92 cuft. Vented reflex boxes of about Vas let one go down to near Fs, which 47 hz. Hit the eminence website, click on the cabinet diagram for this woofer, you'll see suggestions with dimensions and max power to not damage the suspension or coil. Vent diimensions also. Different height, width, depth will cause internal reflections of your boxes to be different frequencies than the eminence design.
I would typically build a 2 way with a CD+horn going down to 1000 hz. Kappapro-15A has a 4 db rise from 1000 to 2500 so I would build the crossover to suppress the woofer response some above 1000. Tuning the crossover, I use a graphic equalizer and 2 amps for prototyping, then when it sounds good I go for coils capacitors and resistors. if you love simulation, try vituixcad or somesuch, but the A7 sounded good enough originally that this should not be way off.
I'm using n314T-8 for my horn drivers, though you can find cheaper ones. I would stay with 1.4", most 1" CD struggle at 1000 hz. You don't need titanium diaphragm in a home, you could get away with plastic up to 100 W. I have found A22 Peavey on used horns as low as $120 the pair on ebay, bar bands tend to trash the woofer more than the tweeter. Or you could dive off into silk dome tweeters. Make sure you stay above Fs at the crossover frequency. You don't have to drill holes, you can set the tweeters on top on a wood flange. Tweeters don't need to be in the bass reflex box except it makes the wiring & crossover less messy.
I would typically build a 2 way with a CD+horn going down to 1000 hz. Kappapro-15A has a 4 db rise from 1000 to 2500 so I would build the crossover to suppress the woofer response some above 1000. Tuning the crossover, I use a graphic equalizer and 2 amps for prototyping, then when it sounds good I go for coils capacitors and resistors. if you love simulation, try vituixcad or somesuch, but the A7 sounded good enough originally that this should not be way off.
I'm using n314T-8 for my horn drivers, though you can find cheaper ones. I would stay with 1.4", most 1" CD struggle at 1000 hz. You don't need titanium diaphragm in a home, you could get away with plastic up to 100 W. I have found A22 Peavey on used horns as low as $120 the pair on ebay, bar bands tend to trash the woofer more than the tweeter. Or you could dive off into silk dome tweeters. Make sure you stay above Fs at the crossover frequency. You don't have to drill holes, you can set the tweeters on top on a wood flange. Tweeters don't need to be in the bass reflex box except it makes the wiring & crossover less messy.
I had that thought, too.
<Aside: Any chance you're sitting on a copy of that "New Notes in Radio" that he wrote, too? Been looking for that for a long while. I see one in a library in Scotland... 🙂 >
Those appear more like the 612 cabinets. A much different soul than the 825 cabinet from the A7.
Too bad you are so far away. Shipping makes what I have for you, priced out of the market.
Something I'm realizing:
The cabinet may be a fixed parameter for me, but net internal volume can swing pretty widely:
My thinking is that the 2 chamber strategy would be the best route to getting a "drop in" 4pi implementation going
any major pros/cons I should be aware of with either approach?
crude sketch to illustrate. Note that driver and horn are strictly for illustration – not based on any actuals. Also doesn't factor in ports.
The cabinet may be a fixed parameter for me, but net internal volume can swing pretty widely:
- bracing can eat up around .75 ft
- and/or subdividing the cabinet into separate woofer and horn chambers (sort of a Klipsch "hat" I suppose) can easily bring the woofer volume down to 4 cu ft.
My thinking is that the 2 chamber strategy would be the best route to getting a "drop in" 4pi implementation going
any major pros/cons I should be aware of with either approach?
crude sketch to illustrate. Note that driver and horn are strictly for illustration – not based on any actuals. Also doesn't factor in ports.
Some comments: All Waynes alignments are a bit overdamped on purpose and you can read about why at his site. Second, the 4pi doesn't go that low (measurements are over there), just look at those and do some sims before you aim for 3-4ft3 vs. what you seek for LF. If you use subs for HT etc--by all means--keep them smaller. If not, my 2c is to be sure to consider the data and 4pi owner feedback regarding extension before nailing down details. Many 4pi owners have them on short stands which are reclined a few degrees. Opinions will (always) differ on bracing, but it may be worth considering how much work you want to do (easier to blow holes in cad than in the garage, etc). The good bit about 2 chambers is that you don't have cabinet mud radiating out of your horn walls, too. The bad bit is that it places one wall closer to the driver (reflection) & reduces the space available for lining at that location. The Pi designs use cross braces with a hunk of fiberglass sitting on it, FWIW.
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Can you point me to a good beginners resource to bracing best practices or theory?
I don’t think you will find anything. There are a number of good threads here.
I have been sucking upo everything i could consume on the subject and built hundres of boxes thru which what i read, and the physics of the application to reach my methods.
B&W again may be a good source. There molded plywood boxes with extensive matrix bracing are quite advanced. Even if you don’t really like the complete loudspeaker.
dave
I have been sucking upo everything i could consume on the subject and built hundres of boxes thru which what i read, and the physics of the application to reach my methods.
B&W again may be a good source. There molded plywood boxes with extensive matrix bracing are quite advanced. Even if you don’t really like the complete loudspeaker.
dave