OND's other projects

[Ond]

Kodi & Volumio media servers

Last two days have been like an early Spring after a forever Winter. I have this queue of non-arcade projects I've been looking forward to getting back to. This thread is for those, and for anyone who feels like following along.

First one up will be this new media server I wanted to build. I've made a few home cooked Kodi servers in the past. You can buy cheap media boxes here and there, Fire TV Sticks, Android  stuff etc. I like to design and build my own because I can add features to suit my other gear plus make something I like the look of. I got this idea to use modular 3D printed parts along with other materials. Oh yeah, my original plan was to use a Kodi server for streaming, video and music. Then I discovered Volumio and decided to build two matching units, one for video (Kodi player) and the other for music (Volumio player). It's a lot easier to switch a dial between source inputs on my AV amp than it is to fiddle around in Kodi to switch audio settings between digital and analog, but more on that later...

The heart of this is a Raspberry Pi 5. Able to run 4K video at 60fps and paired with a M.2 ssd drive instead of an SD Card. Faster and good for much read/write the NVME SSD seems a good choice.

To start with, some way to connect one of these drives is needed.

It has a fragile ribbon cable connection onto the Pi so needs to be well supported. The media servers are based on 300x300mm sheet aluminum and 3D printed parts. All components can be screwed down onto the base panel.

The Pi 5 will be mildly overclocked to crank the best (reasonable) performance out of the CPU/GPU. That will mean some heat has to be managed with cooling. At the same time I want the enclosure to be as slim as possible.

My plan is take air from underneath using a very quiet 80mm fan and then pass the airflow over the Pi and out the back of the unit.

A 3D printed sort of manifold can do this.
 

Fitted like this:

The 3D printed parts are made up of corner pieces and edge lengths that slot together. Ultimately these will be painted in the same colors as the plastic.

Each edge has screw fittings for the base plate.

The rear panel has cutouts for connector fittings.

Next, fitting the extra hardware for audio management.

[Zebidee]

Enjoying your projects as always. Love the creative 3D printing. Pieces that go together like lego.

Lots of extra room inside - planning on adding anything?

[jeremymtc]

This is very cool!

I'm pretty uninformed when it comes to modern 3d design and printing. Does the modeling software you use have a library of primitives for things like port openings or mating/mounting flanges, or must that all be designed by hand each time?

[Ond]

Enjoying your projects as always. Love the creative 3D printing. Pieces that go together like lego.

Lots of extra room inside - planning on adding anything?

Thanks for the interest Zeb, there's a few other things I need to fit into the 300x300 space including power supply, digital audio extractor, dc to dc regulator and maybe one or two other bits I've forgotten for the moment. Then there's cables and wiring of course. I'll try and cover all that in pictures and words in a way that makes sense. These media servers tie back to a NAS. At the moment that's just via Wi-Fi, my longer term plan is to hard wire the network connections for better data speeds. In raw plastic and metal the look of these is just so-so IMO. The final product nicely finished should look pro.  I'd rather you guys take the journey with me than just posting them all done?

This is very cool!

I'm pretty uninformed when it comes to modern 3d design and printing. Does the modeling software you use have a library of primitives for things like port openings or mating/mounting flanges, or must that all be designed by hand each time?

Thanks jeremymtc! That's OK, I've been learning to design for 3D printing in only the last few months. I've had a lot of experience using 3D design software over the years but zero experience on the printing side. Until recently I didn't know there was any difference in 3D file formats for fabrication using printers or CNC etc, but there is. There is a lot of ready made objects you can access when you're designing. For instance, electronic parts suppliers often include 3D files for stock they sell (available for free download). You can view these in free CAD programs or SketchUp etc. For my part, in this project, everything is scratch drawn and designed. I'm forever measuring things with calipers and then doing test prints to make sure port openings etc fit. I often don't sleep too well these days. Instead of counting imaginary farm animals I work through design ideas in my head until I pass out  Those interlocking parts are an example of that.

This thread will document not just these first few projects but quite a few others as well. No sense in creating new posts in the Everything Else sub forum. Just join me here from time to time to see what's new. I'll happily juggle my arcade projects with these.

Other things on the horizon:

•   Cooking with OND 
•   PCB design (+getting them manufactured) for fun and maybe profit.
•   Building the ULTIMATE high fidelity loudspeakers, not my design BTW.
•   Turntables and vinyl records (I've never owned a record player - until recently, and I've got less than half a dozen records).

For some of these projects I'm a newb learning. I'll be asking you guys for advice here and there.

[jeremymtc]

Thanks jeremymtc! That's OK, I've been learning to design for 3D printing in only the last few months. I've had a lot of experience using 3D design software over the years but zero experience on the printing side. Until recently I didn't know there was any difference in 3D file formats for fabrication using printers or CNC etc, but there is. There is a lot of ready made objects you can access when you're designing. For instance, electronic parts suppliers often include 3D files for stock they sell (available for free download). You can view these in free CAD programs or SketchUp etc. For my part, in this project, everything is scratch drawn and designed. I'm forever measuring things with calipers and then doing test prints to make sure port openings etc fit. I often don't sleep too well these days. Instead of counting imaginary farm animals I work through design ideas in my head until I pass out  Those interlocking parts are an example of that.

Thanks for the info! It will be neat to follow along on this. I totally get you on the constant background thought process when you're immersed in designing and building stuff, but there's nothing like it when a new solution presents itself and proves out. I think that feeling is almost more rewarding than the actual completion and use of whatever it is that's being built 

Other things on the horizon:

•   Cooking with OND 

I'm here for the Ond's buttered toast recipe and build log!

[Ond]

... there's nothing like it when a new solution presents itself and proves out. I think that feeling is almost more rewarding than the actual completion and use of whatever it is that's being built 

I agree! But I've also got to be a bit wary of that feeling, I'm a notorious non-finisher. 

Good progress on the Kodi media server today. I'm using two power supplies in this. One is the dedicated Raspberry Pi 5 PS and the other is just a 12v generic DC PS. Both have been removed from their original plastic cases. The generic PS provides power to the fan and, via a DC to DC converter, 5V power to an HDMI audio extractor. I'm fixing these parts into this 3D printed enclosure to isolate the mains AC voltages from anything metal. I'm not grounding the AC supply so these AC voltage parts need to go back into insulating plastic.

Here's the HDMI audio extractor module. It takes its input from one of the HDMI ports on the Raspberry Pi and provides optical digital audio to a (pre HDMI) Denon AV Amplifier I want to use.

Here's the complete set of parts, wiring and cables packed into the enclosure:

3D design and printing lets me make accurate port fittings and component joinery. I used to hand cut ports and panels in previous enclosures but no more!

The aluminum top panel will be primed and painted black. All black panels will be in matching matt black finish.

Before I get to the surface finishing I'm going to run it for a few hours to make sure the Pi CPU/GPU stay cool enough and Kodi runs properly.
The front panel will get some LED light fittings and a custom on/off button.

[Ond]

I'm happy with the bench test of the Kodi Server, overclocked at 2.7Ghz CPU and 900Mhz GPU. Average temperature after running video for around 30 mins is about 33 degrees Celsius (91 degrees Fahrenheit) which is fine.

I'm putting some extra write up effort into the front panel/button setup, with lots of little parts making up the result.

The parts coming straight off the printer are rough with filament layering showing. That's ok as parts on display will be surface finished and painted later on.
Here's most of the parts that make up the front panel:

I'm using a momentary push button as the base for the larger custom button. When I'm designing parts I use digital calipers to try and stay accurate.

That way the printed parts should fit snugly together. Sometimes I have to adjust and re-print a few times to get it right.

The button sits in this housing in which the larger button fits also.

To give  the panel an interesting 'glow behind' look I've designed these cutouts with the addition of some matching raised shapes. Here I'm fitting them in place.

Again, the parts look a bit rough close up, but its a good indicator of things to come.

The rear view of the panel shows how a translucent part can be fitted. In fact there will be two translucent layers here. One in red acrylic plastic and the other in so called clear PLA. If you look closely on the left of the panel you an see the hex nut fitting has broken. These are too thin and will need to be strengthened. That's fine, I'm learning as I go. I'll make some changes to the edge panel design to include stronger screw fittings and provision for two layers of backlight plastic. If I was hand making parts, doing things over would take forever. Adjusting and printing again takes minutes.

I'm going to backlight this panel with red even illumination, should look nice!

[PL1]

If you look closely on the left of the panel you an see the hex nut fitting has broken. These are too thin and will need to be strengthened. That's fine, I'm learning as I go. I'll make some changes to the edge panel design to include stronger screw fittings and provision for two layers of backlight plastic. If I was hand making parts, doing things over would take forever. Adjusting and printing again takes minutes.

Beefing up the hex nut fitting is a good start.

Changing print orientation may also help.

I assume you printed that part oriented face-down, right?
- If you look at the hex nut fitting in "layers" view, you'll see that the individual layers at the middle of the nut are very narrow so the part will break very easily when torque is applied to the nut. (left)
- In this orientation, that torque is like a martial artist breaking a board with the grain -- it's very easy to do.

If you print the same design in the upright orientation, the print path for the layers of the hex nut fitting will solidly trace around the nut so the part might deform a bit, but it won't break anywhere near as easily. (right)
- In this orientation, the same torque is like a not-so-smart martial artist trying to break a board against the grain.
- The only downside to this orientation is if your printer can't handle the overhangs with the angled cutouts.  The inner ones should be fine, but the outer ones might be too extreme.

Worst case, you might need to adjust the cutouts or make some other design choice like the nut clip braces mentioned here.


Scott

[Ond]

Beefing up the hex nut fitting is a good start.

Changing print orientation may also help.

I assume you printed that part oriented face-down, right?
- If you look at the hex nut fitting in "layers" view, you'll see that the individual layers at the middle of the nut are very narrow so the part will break very easily when torque is applied to the nut. (left)
- In this orientation, that torque is like a martial artist breaking a board with the grain -- it's very easy to do.

If you print the same design in the upright orientation, the print path for the layers of the hex nut fitting will solidly trace around the nut so the part might deform a bit, but it won't break anywhere near as easily. (right)
- In this orientation, the same torque is like a not-so-smart martial artist trying to break a board against the grain.
- The only downside to this orientation is if your printer can't handle the overhangs with the angled cutouts.  The inner ones should be fine, but the outer ones might be too extreme.

Worst case, you might need to adjust the cutouts or make some other design choice like the nut clip braces mentioned here.


Scott

When you're looking at putting any parts that come out of a 3D printer under stress this is good advice. Layer orientation does make a difference. In truth, my hex nut holder design was rushed and a bit lazy. I have beefed up the fitting Scott. Apart from trying to think in terms of the limitations of a filament printer, I'm also trying to take advantage of printing face down on a smooth plate. Smooth flat surfaces mean less effort and better results in the final product finish. In this case making fittings thicker and stronger should be fine. Take a look at the design image below. You can see the original hex nut support on the left is pathetically thin. Not much torque on the nut needed to break that!

The revised panels are already printed. I have to work a few days and then it's back to the fun!  The Volumio server will be very similar in looks to the Kodi Server. They can both be stacked one on the other and look cool. Whilst off-the-shelf media servers running Kodi are quite cheap to buy, a branded Volumio Primo is not cheap at around $899 US.

https://shop.volumio.com/product/primo/

 Building my own will be way cheaper, look better IMO, and have a similar high quality DAC on board with added volume control as well.

[PL1]

Apart from trying to think in terms of the limitations of a filament printer, I'm also trying to take advantage of printing face down on a smooth plate. Smooth flat surfaces mean less effort and better results in the final product finish. In this case making fittings thicker and stronger should be fine.

Looks great.   

The only thing that might not work as well as you'd like with that design is if you're using it to attach both the top and bottom panels, you might accidently push the nut out of the holder while loosening or tightening the screw.

One way around that is to use heat-set threaded inserts -- if you try them you'll love them.



If you want to stick to commonly-available hardware, consider captive hex nuts.

A great design option for captive hex nuts is to make a slot as thick as the nut and as wide as flat-to-flat on the nut like the one shown on this wheel.
- The nut drops into the slot then a machine/set screw goes through the side of the hub, through the nut, and tightens against the axle.
- An optional printed plug, retention fingers, tape over the slot, or a drop of hot glue in the slot will keep the nut from sliding sideways out of the slot if you tilt the case during assembly/disassembly.

https://www.thingiverse.com/thing:21486




Scott

[RandyT]

When you're looking at putting any parts that come out of a 3D printer under stress this is good advice. Layer orientation does make a difference. In truth, my hex nut holder design was rushed and a bit lazy. I have beefed up the fitting Scott. Apart from trying to think in terms of the limitations of a filament printer, I'm also trying to take advantage of printing face down on a smooth plate. Smooth flat surfaces mean less effort and better results in the final product finish. In this case making fittings thicker and stronger should be fine. Take a look at the design image below. You can see the original hex nut support on the left is pathetically thin. Not much torque on the nut needed to break that!

As I am sure you know, there are many things which affect strength and suitability of a printed part.  While orientation can play a role in layer adhesion, it's probably not the largest factor.  Infill, wall thickness and just plain using the correct polymer to achieve the "toughness" required, all come into play.  While changing orientation can provide a certain amount of benefit, it can also increase material usage, time for printing and post processing, as well as overall part aesthetics.  All of these need to be weighed against each other to find the correct approach.  Ultimately, much can be achieved with regard to strength simply through appropriate part design, regardless of the other factors, and this is usually the most effective, as stresses are rarely unidirectional.  I.e. a weak part for a given material will be weak regardless of the manner in which it is produced.

I am also a proponent of threaded inserts for parts which will be assembled and disassembled repeatedly, even though there have been some tests which show that directly threading into the polymers with fasteners is nearly as strong (and much simpler/ less-costly), provided the part is designed properly, and the fastener is correct for the job and is not over-tightened.  But again, "horses for courses", as they may not always be the proper choice.

If you do use heat set inserts, the best way to use them is to size the holes such that a bit of the molten material is extruded upward when the insert is set slightly below the surface, and a cool, flat object is used to flatten that material to be flush to the surface of the part, thus encapsulating it within.  This is most important where "pull-out" is of concern, but needs to be done well when parts are expected to be tightly mated to those surfaces, otherwise just the action of tightening the fastener could advance the insert from it's position and weaken the hold.  In that case, you might want to leave them slightly proud with the heated tool, and then use a cool, flat surface to press them flush.  This really helps to make them as perfect as possible.

BTW, your parts look great.  Happy to see that printer you chose is working out well for you

[Ond]

I knew about threaded inserts for wood but not heat set ones for plastic. There you go, I'm always learning. There will be a project in which I use them for sure  @ Randy & Scott.

I'm nearing completion of the Kodi media server so here's a few pics before final assembly. The 3D printed parts have all been smoothed, primed and painted.  They look less like typical filament printed parts now. They're a bit slicker, more solid in color, and smoother.

I changed the design of the power button a little so that when pressed, the Kodi logo will glow from a backlight LED along with the cutouts either side of the button. Better than just a solid plastic button IMO.

Next pics will be of the completed project. A few final things to do on this are cutting out the acrylic inserts which are fitted to the inside surface of the front panel for the red glow effect, wiring a fuse into the AC supply, final paint touch-up and assembly.

Since this thread will cover multiple projects I have coming up, I think I'll mark the start and end of each with a banner or something so it's easier to tell one project from another.

I'm working on three different speaker pair builds (along with other projects) at the moment. All are based on professionally designed high-end cabinets, crossovers and drivers. They are not my designs BTW.  I'm undecided on what to post of these. This isn't a DIY sound equipment forum, but I know there's at least a few members here that are into that. Hmm,  

[bobbyb13]

Very fun to stumble onto some Ond content!
Sure I'm late to this, but work is in the way of everything right now.

The elements to make things more than just utilitarian are the details I love the most.
Elegant embellishments on the form follows function paradigm are always so cool.

I at least will look forward to seeing some speaker unit production!

[Ond]

Very fun to stumble onto some Ond content!
Sure I'm late to this, but work is in the way of everything right now.

The elements to make things more than just utilitarian are the details I love the most.
Elegant embellishments on the form follows function paradigm are always so cool.

I at least will look forward to seeing some speaker unit production!

hey bobby, nice to see you are still at some projects and posting here  .  I have multiple projects all going at once right now, I thought since one of them is finished I'll update.

I've finished both Kodi and Volumio units.  Kodi for all things video and Volumio for all digital audio. They turned out alright I think. Some minor aesthetic changes along the way:

The Kodi box with improved (IMO) front panel. 

The Volumio box with it's own green theme.

The back panel showing connections.

side by side...

Just simple lighting on the Volumio unit.

Not that they will ever be stacked like this, but hey, just to see what they look like I plugged some fancy headphones into the DAC headphone jack.

Summary:  3D printing came in very useful for this project. It allowed me to make small functional and aesthetic changes and re-print parts as needed. At some point I may update the Raspberry Pi 4 in the Volumio box to a Pi 5, the Kodi box already has a Pi 5 in it. The main reason is that the Pi 5 has better on/off controls available than the Pi 4.  I may tweak LED lighting slightly in the Kodi unit to be dimmer and more even, but that can wait while I focus on other projects.

Next up loud speaker building! I'm building three pairs of different speaker designs simultaneously. 

[Ond]

Loud Speaker Design & Build

So why bother building my own speakers? The main reasons are that I can build great sounding speakers for way less than the cost of equivalent "off the shelf" models. Well designed speakers with quality components can get really pricey, crazy pricey in fact! The other thing is just the satisfaction of building something of quality myself.

I'm building three different loud speaker designs.  The renders are for reference. The big complicated angular ones on the right are for music. The less complex tall ones in the middle are for home cinema and the small ones are also for music. All of them are based on original pro-designs (not mine) including cabinets, crossovers and drivers, matched to a specific design and performance.  The only changes I've made are to two of the cabinet shapes, preserving the box internal volumes. 

The cutaway view below is of the Sasandu design from SB Acoustics.  Whilst there are cabinet kits you can buy for these, they are very expensive.  I took the open source plans for the cabinets and created CNC cutting files in Fusion. More on that later. They are a challenging design to say the least but feature design elements and drivers featured in high-end speakers.

Here is a concept render of the 'Artisan' based design finished in American Walnut veneer and gloss black.  I purchased plans for these quite a few years ago from a sound engineer in Sydney. They have relatively simple crossovers which I build myself. Most of the MDF panel work is cut on my own saw table. I've built quite a few of these in the past, some of which remained in a previous home as part of the sale agreement.

These days, I like to design PCBs in KiCad from the crossover schematics and get the PCB boards made. The crossover below is from the Artisan design. Of the three, it is the most simple. Just a two way x-over with minimal parts.

Here is the finished crossover ready to go.

The small 'Carrera' enclosures are the furthest along at the moment. I've taken the Carrera design specs by Paul Carmody and come up with boxes done completely out of 32mm 1.25 inch thick MDF. 

As I don't have a CNC I have to come up with ways to accurately cut speaker holes, rebates etc. I've put my 3D printer to good use for this and printed up cutting templates to use with a flush trim router bit. The system works pretty well and keeps the router work accurate.  I just have to be careful to keep the bit bearing spinning nicely or it can overheat the plastic template and then bad things happen! 

[bobbyb13]

Great finish!
I envy you gents with printing prowess.
Boy do I NOT need another hobby right now.

The music thing always gets me.
It has been a slog to rip all of my music down to flac files (J.S. Bach alone was... 142 CDs worth?!) and having a few daps loaded with stuff has been excellent.

The tease of a speaker build has the audiophile in me salivating.
I have no real playback gear to speak of.

Excellent to see a post from ya mate.
I'm looking forward to getting more fun happening myself this year.

Hope all is well with your summer!

[pbj]

Your Artisan speakers look very similar to my Klipsch floor standing speakers.  Mine have additional top firing speakers that are meant to simulate ceiling mounted surround sound.  I guess by bouncing sound off the 10-12 foot ceiling in a normal house. Anyway, I have them in my high ceiling living room and they do an excellent job of filling the room and second story walkway with sound.  They’re on a separate channel from my amplifier.  Something to consider adding… it feels very flat without them engaged.  I’ve read that no true audiophile likes Klipsch but they thump the garbage I listen to in a satisfactory way.

 

[Ond]

Great finish!
I envy you gents with printing prowess.
Boy do I NOT need another hobby right now.

The music thing always gets me.
It has been a slog to rip all of my music down to flac files (J.S. Bach alone was... 142 CDs worth?!) and having a few daps loaded with stuff has been excellent.

The tease of a speaker build has the audiophile in me salivating.
I have no real playback gear to speak of.

Excellent to see a post from ya mate.
I'm looking forward to getting more fun happening myself this year.

Hope all is well with your summer!

Heh, even though I've been doing plenty of 3D printing I still don't really see it as a hobby. It certainly is a useful tool though. I got complacent with it recently, I left it printing something in the house while I worked in the garage... Finally I came inside to find most of the print bed and extruder completely covered in molten plastic. The hotend was destroyed. Plastic had forced itself into every nook and  cranny. I ordered another hotend on Amazon and two days later the printer was back up and running. Guess I'll invest in a camera so I don't have to sit with it all the time.

Great sounding speakers with a good amp (and sound source) are a real pleasure. I just hate the price of 'audiophile' gear so here I am slaving away over hot MDF 
My summer vacation is nearly over but I've got plenty done so it's all good. Your projects always fascinate me, hope you find the time bobby 

Your Artisan speakers look very similar to my Klipsch floor standing speakers.  Mine have additional top firing speakers that are meant to simulate ceiling mounted surround sound.  I guess by bouncing sound off the 10-12 foot ceiling in a normal house. Anyway, I have them in my high ceiling living room and they do an excellent job of filling the room and second story walkway with sound.  They’re on a separate channel from my amplifier.  Something to consider adding… it feels very flat without them engaged.  I’ve read that no true audiophile likes Klipsch but they thump the garbage I listen to in a satisfactory way.

 

Sounds like your place is well suited to those Klipsch speakers. I've never heard them but people generally say good things about them. There's always some expert ready to rubbish mid-range gear.  After never owning one my whole life I finally bought a turntable recently. To go with it I bought a Schitt Mani 2 phono pre-amp. Made right in Texas. YouTube reviews keen on it also had their fair share of those same guys commenting. I know it's really good value though. 

The Artisan plans call for hardwood bracing set into rebates.

Here's the rounded off bracing glued into the side panels:

Here are the partially completed crossovers for the Carrera speakers. Two way crossovers, but quite a bit more complex than the Artisan's. Also the 3D printed ports. I couldn't find ports of the dimensions specified in the design so, printed em.

The router cutting template is being used here to cut the port holes. Another will be used for the flange rebate.

Getting close to finishing basic cabinetry on two sets of speakers!  I enjoy the finishing (veneering and painting) much more.

[Ond]

Testing the fit of the Artisan panels:

Both Artisan enclosures glued up except for baffles. Most circular cuts were done with my router using a flush trim bit and the 3D printed cutting templates. I'm using threaded inserts for most screw fittings with either M4 or M5 Button head machine screws:

Here I've sealed the lower chamber of the Artisan enclosures with silicone. Crossovers screwed into place. The lower chamber will be filled with sand. You can just see the hole I've cut in the bottom to allow sand filling;

I'm starting to line the insides of these with foam. Once that's done I can glue the baffles into place:

Here I've just positioned the baffle in place and I'm making sure the drivers clear the port. Its a tight fit, the magnets on the back of each driver just clear the end of the port:

Here are the completed crossovers for the Carrera bookshelf speakers. These little bookshelf speakers are more costly to build than the tall floor standing Artisans.

Here are the Carrera enclosures with rebates finished and ports glued in place:

Soon I'll start looking at the third design, the most complex (and expensive!) the Sasandu speakers. I'll cover the 3D design prep I did in Fusion for CNC cutting the panels, and a first look at the 3 way Sasandu crossovers, built once again on my own PCBs...

[Xiaou2]

Ond, If I may make a Suggestion...

 Ive owned like 30 different pairs of speakers... as Im a sort of Speaker-Holic.   Ive picked most of them up from Thrift shops, for
dirt cheap prices.

 However... Through all of my purchases... I had only ever ran into ONE audiophile grade speaker (and they needed an extensive rebuild:  AR3-A).

 One day, I walking into my friends   Slot Car Track + Classic Arcade.   He had some disco playing... like Earth Wind and Fire.
The Clarity alone, was astounding.  However, what really blew my mind... was how "Holographic" the sound was... and just how
far and deep that Soundstage was.

 I was so blown away by the sound... that I spent the next 10 minutes, trying to find these speakers.   Realize, that my ears are still fantastic..
able to hear extremely high frequencies.  It would normally only take me a few seconds to locate a speaker.  But in this case... the sound was
so Holographic... that the speakers projected Origins, actually Vanished.

 Now... The dude is a bit of a Pack-Rat.  He has stacks of DVDs, Slot Car parts, Magazines, paperwork, and all sorts of other stuff, all
over the place.   So, visually... it wouldnt be easy to spot them.

 Eventually, I actually gave up... and asked him, What speakers were playing, and WHERE the heck they were?!

 He walks me to the front of the store, about 1ft away from the massive front store window.  There was a 1ft x 1ft tall bench, that
sat in front of the window... and on that bench, was a lot of various things, piled up.  Then he pointed to the speakers...

 These were quite small in size.. only slightly bigger than bookshelf speakers.  One was oriented vertically, with like 2ft worth of
magazines on top of it.   And the other was laying horizontally, with like two stacks of magazines on top of it.  It was also
partially behind a Sit-Down version of Atari's "Race Drivin" video game.

 Despite possibly the worst speaker placement possible... the sound was utterly Astounding.

 You got a near perfect stereo Image... almost anywhere you stood, within about a 15ft x 15ft  square area, of the Arcade...
without any notable "Drop Off" (where one speaker sounds quieter than the other).   And even when walking further into the
room... the sound was still good... its just that you actually noticed the Drop-Off in the volume levels of the "3D Image".


 Im not an easy man to please... as far as it comes to sound quality.   Not that much longer ago... I got into Audiophile grade
headphones... so I knew aproximately what audiophile sound was all about.  However... Id never experienced that level of
response, from the speakers that Id ran into.

 Anyway... I had to have them... and eventually picked up a pair, off of Craigslist, Re-Foamed, for only a mere $100.
It seems that these are special Gems, that the Audiophile's have not yet seemed to have discovered.

 The design is a 2-way.  An 8" Woofer, with a MASSIVE and heavy magnet.  And a special Inverted tweeter (cone instead of dome).
They are about 2ft tall, and 1ft deep.   They sound fantastic, no matter how or where you place them... but they sound best
when placed near a wall, and on the floor (greater bass response).

 This was also my first "Sealed" speaker.  As all of my other speakers, were Ported.  Let me tell you... Once you hear Bass from
a sealed speaker... you can NEVER go back to a ported speaker.   I also owned a pair of 90s era Techniques 12" 3-Way speakers...
which are Ported... and while those can play a little Louder... they cant even compare to the EPIs.  Not even close.  The bass on
the EPIs is deeper, thumpier, and is more "Musical"... where as the bass on the Techs.. is slow, muffled, and droning, in comparison.
The Techs bass sounds Artificial... where as the EPIs sound "REAL".   Its something I might never have known... until I heard it
for myself... and again... once you hear what bass is SUPPOSED to sound like... you cant go back to ported designs.

 I took apart both of these speakers, to compare the drivers... as I was Amazed that an 8" woofer, was destroying a 12" woofer.
The Techs used a very small sized magnet... where as the EPIs used massive and heavy woofers.  In fact... One EPI woofer...
probably weighed more than TWO of the Tech woofers combined.   That explained it.   The Tweeter itself, also had quite a honkin
sized magnet, for its size.


 I would eventually look up information about these speakers.   It turned out the the designer, used a special technique, that Ive
never heard about before.  He used heavier Gauge wire on the Voice Coil windings,  to automatically filter out the high-frequencies...
which eliminated the need for an additional Crossover Component.   The reason... was to eliminate any potential Micro-Distortions,
from additional Crossover components.   And let me tell you... that, in combination with these powerful drivers... proved to be true.

 In one of the songs I played on them... I believe something from Phil Collins... there is a part of the song where I could never
fully understand the lyrics that he was singing.  However, when playing this song though the EPIs... I could understand every single
WORD... without any strain at all.   Not only that... but there was more Separation (details) between the Backing instruments, and
the vocals.   It seems that all of my previous speakers... were suffering from Micro-Distortions.. causing the Instruments and Vocals,
to slightly Melt into each other... and slightly "Muddy" the details.   I always just assumed, it was a bad recording issue... never realizing
that the speaker were the real issue.

 Now... as far as LOOKS goes... they dont look like they would be anything special at all.  The box shape, is incredibly Basic.  But the
sound that the produce... Destroys speakers that cost several THOUSANDS of dollars.   In fact... I compared them against the local
high end stereo shops  Flagship $3000 speakers... and I almost laughed at the Salesman, when he asked me what I thought of them.
My little EPIs destroy them in every single Metric... by Lightyears in comparative differences.  Those speakers were Modern Towers,
that had several 6" woofers in them.. .and a few other drivers for the high end.   The sound of them were too Harsh/Hot (fatiguing)..
and they were missing a certain spectrum of Bass.   Even with their Over-Priced Subwoofer added into the mix... it didnt help the
sound at all.


 Anyway... "EPI"  eventually sold out to  "Genesis Physics".  Genesis used these same EPIC drivers, for MOST of their new
speaker lineup.  Though, some of their designs have different configurations... such as adding a Passive Radiator.

 There is a website, called  Humanspeakers   where you can find make and model information... as well as buy Kits, with all Brand New Drivers.
The guy that runs the site... used to work for EPI/Genesis... and as such, knows the proper ways to reproduce these drivers.  In fact, he claims
to have even Improved the drivers, even better than the original specs.

 You can buy a kit to build a replica of the  EPI 100  for less than $400.   This is a total Steal, compared to audiophile speakers, that cost thousands more
and dont give you even Half of the Experience.


 Now...  If you pick up a pair of USED  EPI's or Genesis speakers...

1)  Make sure the Drivers are Originals.  Original woofers have smaller diameter dust-caps, and are pretty easy to spot.

2)  Make sure the Inverted Tweeters, are the New-er Model.  The older inferior tweeters, have a Fiber-Board backing plate.  The
upgraded tweeters, have a Plastic Backing bezel.  Again, very easy to spot the difference.

3)  If you choose to buy one that has the Elder tweeter... it wont be anywhere near as impressive.  However, you can buy replacement
upgrades from the Humanspeakers site.

4)  I eventually picked up a different pair of Genesis speakers, that have Passive Radiators.  However, due to health and other issues...
Ive never had the chance to compare them to the  EPI 100 's.

 I did recall reading on a post.. that they preferred the sound of the smaller EPI 100.. over the larger EPIs... as the bass sounded
Better / Punchier.   Sorry.. I just cant confirm, at this moment in time.

5)  Depending on the Model... they can be quite Power Hungry to drive.  Mine are labeled as 4 ohms, 8 nominal  or something like that.
I dont quite understand the Nominal stuff.   My amp doesnt seem to have any issue powering them, in 4 or 8 ohm mode... but my amp
is kind of a Beast.   An older Pioneer model.. made in the 90s.  One of the first few amps to get 5.1 surround sound.  I bought it when I
was like 16... and Im now 51... and the thing is still working flawlessly, after Decades of daily +8h a day use.  They dont make amps
with such quality, at that fairly low cost, anymore.   Todays Pioneer amps probably wouldnt last 3 yrs worth of use... and probably have
an inferior output to boot.

6)  Because these are a Sealed Speaker... they can sound a little Anemic in bass levels, at LOWER volume levels.  However, once you
crank them to med / high volume levels.. its Pure BLISS... with some pretty Powerful Bass.   To solve the lower volume issue.. you can
use an EQ to boost the bass frequencies... and that will get those drivers thumpin pretty good, at lower volume levels.   Furthermore,
I also often use Software EQ... to push my speakers to their Maximum bass potentials... right at the edge of potentially blowing them.

One time, as a fun test... I placed these small EPIs on top of much larger sized ADVENT bullnose speakers.  I had my buddy sitting on
the couch, about 8 ft away... and I played some music... then asked him to point to the speaker that he Thought were playing.  He
actually pointed to the EPIs.  I got a good Chuckle out of it... then did an A to B comparison.   He was pretty amazed at how much bass
those little buggers were putting out.


 It appears that one of the main reason why so many speakers, are not Audiophile quality.. is due to using weaker magnetics.
If the music demands a certain acceleration speed.. and the drivers are slightly slower than what is demanded... it will cause a
micro-distortion.   Furthermore... when that fast moving driver is asked to STOP immediately, and Reverse at max accelration...
this can also cause delay issues... as the magnetics might not be powerful enough to stop the cone Instantly... due to Momentum,
and those weaker magnetics.   So, the cone will over-shoot the intended stopping point... and then also be further late, in its
reversed acceleration.   All of these lead to micro-distortions... and will result in a loss of details, and separation... as well as
a reduced or flattened 3D Image.

 Also, from my experience... any Horn based drivers... also seem to Flatten the intended projected 3D image... due to how the
soundwaves change when traveling through the horn shape.

 Now.. I have heard a few Ribbon Tweeters, as well as SuperTweeters.. and none of them came close to the EPI tweeters.
The supertweeters sound very Airy... but they are Noticeable (draw unnatural attention to themselves).   And a Dipole
Ribbon tweeter... while amazing in details... was creating these crazy echo effects, in a non-treated room (getting the same sounds
from various directions, at different time intervals).

 Ive also heard from many reviewers... that the Soundstage on Planer tweeters, is extremely Narrow.  If you even move a
mere Foot in any direction... you will notice a massive Drop-Off in the Volume differences, between the left and right channels.
Meaning... that you have to sit perfectly in center..  to get a decent listening experience.   Personally, I could never accept that.
I like the EPIs... where it doesnt matter if Im sitting, standing, or walking around the room... and am still getting a near
flawless stereo image.  Very few drivers can do that kind of thing.

 As far as Bass goes... the EPIs are not DJ/Club grade speakers.  They are not designed for very large parties, with loud room
noise.  They are plenty loud enough to get you kicked out of your Apartment... but they are not Club speakers, with bass that
would shake the neighbors garage doors.   They are specifically Audiophile grade speakers.. and will play any kind of music,
with the highest levels of Precision, and excellence.  Its a musical Nirvana... rather than pure brute power (and lack of quality).

 The only other speaker that blew me away in the Bass dept... was a Phillips mini system, that used special Passive Radiators
called  "Woox".   That system used special 6.5" woofers, that had extended travel.. to prevent over-excursion based distortions.
The woox passives, extremely amplified the bass potentials... making them sound like some decent powered subs were being
used.  But it was even better than that... because most modern subs often Muddy the music / bass.  Where as these didnt
muddy the sound, nor did they sound "Droning" (hearing the same artificial sounding bass note, repeated over and over again).
Even when maxing out the Amps volume levels... there was Zero distortions at all.

 Those Phillips woox speakers competed similarly to the EPIs woofers... and in certain cases... produced a more enjoyable bass
experience.  HOWEVER... the phillips tweeters and mids... were a mess compared to the EPIs inverted tweeter.  The phillips
didnt produce much of a soundstage... and the drivers were often very "Hot".  With a little EQ, you could tame them a bit..
but they still were no match at all, for the EPIs single tweeter.

 Unfortunately, the Woox speakers suffered foam rot.  While I was able to refoam the woofers... the Woox passives also started
to rot... and there was no way to repair them.   I believe Phillips released all-plastic versions of the woox devices, which would
have lasted forever... but I had gotten the foam version.. and was pooched at that point.  Ended up leaving them behind, when
I had to move.

 One final note... is that a friend whom was moving... gave me a pair of large Advents.  I believe the Advents use a 9" woofer, with
as 12" basket... and a special modification to do this.  They produce an INSANE amount of bass.. far more than the EPIs.. BUT...
its actually way too much bass, for the music.  The bass sounds way too over-exaggerated for the music (something I thought Id
never say).   Ive thought about replacing the Caps to see if it might help things... but Im way too happy with the EPIs to care
about them.   That said... they do add some great sub-like effects, to Movies... such as the Train Rumble in the Polar Express.
The advents fried-Egg tweeter... has a good deal of details.. but it doesnt produce a 3D Image, like the EPIs.  Its both Flat..and
the tweeter sounds too "Colored".   Again, SOME of this might be down to Caps needing to be replaced.

[Xiaou2]

Obviously, one cant get an Accurate idea of Audiophile speakers, without having audiophile headphones / gear...
and depending on how good they recorded everything.

Here is an example of  Genesis Physics 2 speaker, which have the Passive Radiators:




Heres one playing the  EPI 100 's   in a large sized, untreated room  (slight echo)




Unfortunately, there isnt a lot of good recordings of the EPIs / Genesis Speakers
(But then again, it also keeps the used prices, affordable)

[Ond]

It's a good moment when you hear speakers that really surprise and please you AND are affordable. I've had a few of those moments too.  To experience music you've heard many times like you're hearing it for the first time is what its all about. So I've done a bit of a read-up and research of the Genesis Physics II speakers. By all accounts very well balanced design taking advantage of a passive radiator to extend the bass with a well detailed tweeter. Great for listening at moderate levels with a detailed and pleasing soundstage. I like the look of vintage 'boxy' speakers because it reminds me of times listening to vinyl as a teenager  .  Downside of these speakers is the drivers may need refurbishing and cabinets may need work or replacement.  Thanks for sharing details on these, I'd happily refurbish a pair back to mint if I found some!

The three pairs of speakers I'm building rate something like this:

Artisan floor standing - great for home cinema, ok for music listening. comparable retail around ~ $2 - $4K
Carrera bookshelf - superb compact speakers for music listening - comparable retail quality around ~ $5K
Sasandu floor standing - high end speakers, I will be using only for music but could be used for anything really, competitive with $16K+  models.

[Xiaou2]

Im glad you enjoyed my novel.  >_< 

 Not sure if you didnt catch this... but  Humanspeakers.com  sells kits to build replica EPI speakers,
for only $372 a pair.   Supposedly, his new drivers, use the same design technology, but with slightly improved capabilities.

(Ive never purchased from him, so I cant verify.  He used to work for EPI/Genesis, and his Site has very Detailed information
on all of their Models)

https://www.humanspeakers.com/diy/81.htm


 Mostly, I recommended these for the specific Purpose, of using their Drivers.   As Ive never heard tweeters that could
produce an Image like the EPIs.   So wide, deep, and Holographic.   The woofers are fantastic too... though, not quite
as special as the tweeters.

 Had I never suffered health issues... I might have liked to try to experiment with different configurations.  For example...

 One of the best Midrange drivers Ive ever heard... was a 3" Dome midrange.  Im usually a man that tons down midrange...
as Im very sensitive to that frequency range... and it can become too harsh and overbearing.  However, on this one speaker
pair... they sounded so damn luscious... that I had to purchase them.  Unfortunately, the rest of the drivers on those speakers
were fairly average trash (I couldnt tell you what the make/model is, as they are in storage).

 Anyway... Id considered trying to wire those Mids into the EPI drivers.  Creating a larger Box.  Adding in a Passive Radiator.
And maybe even wiring a 2nd woofer in, for even greater power output.

 EPI & Genesis have certain models that are like this.  Their Ultimate speaker, is the EPI 1000... which has Four Pairs of
drivers per 6ft tall Tower.  Im not entirely sure I agree with how they placed all of those drivers (one pair per side)... but
the guy whom runs the Humanspeakers site.. built a pair himself, and claims that if he ever sold them, he would just
immediately build another pair.


 Anyway... One thing that people seem to misunderstand... is that Driver technology has not really change much,
since the 70s.  There may be slightly improved materials, to make slightly lighter cones... but the differences are incredibly
minimal, that most people wouldnt even be able to hear the difference.   Also, these new materials can be offset by simply
using stronger magnetics anyway.

 The speaker boxes themselves... are not actually what makes speakers sound that much better / different.  I found that out
early on.. when I was swapping various drivers, into different speaker boxes.   The most notably dramatic changes... were always
coming from Superior Drivers... not the actual Box Shape itself.

 The only exception, being in the type of speaker box:  Ported, Sealed, Passive Radiator, and Open Baffle.

 Unfortunately, I also learned that you cant just seal a ported speaker... and expect it to sound like a sealed speaker... when I
tried to Improve my 90s era Techniques speakers.  It seems that sealed speakers, require woofers that have an easier to move
spider... as well as much stronger magnetics... so that they can over-come the higher air-pressures, of a sealed cabinet design.


 I also bought one of those B0se Radio's at a thrift shop for like $30 (6 CD base unit included)..  mostly as a curiosity, about
their Bass Tube technology (similar to Transmission Line designs).   At lower volume levels... it sounds "OK" at best.  But at
med to high volume levels.. you get that same over-exaggerated, and artificial + droning  sounding Bass.  In fact, the louder
you push the system... the worse and worse it sounds.   Add to it, very poor highs.   The Mids were the only semi-decent
thing about them... and even they were nothing to write home about.

 The other bass extending method that seemed to work without sounding artificial, is the use of a well tuned Passive Radiator.
Ports simply create bass that is way too artificial sounding... in addition to causing other issues, like Port Chuffing, and other
distortions, from turbulence + inconsistent air volume/pressure issues.


 I also used to fantasize about 360 degree speakers (omnidirectional)... but after hearing those 360 degree Di-Pole tweeters...
and hearing how they can distort via time-delay issues...  as well as experienced Holographic sound from the EPIs 180 degree
spread.. I realized that things are not always what you would assume / expect.

 In fact, I did once build an Omni satellite prototype, from some cheap used drivers.  I had intended to try to create some
funnels full of resin, or find / make a Solid Concrete / Rock  Cone... to spread the upwards projecting tweeter... in 360 degrees...
But due to time and material constraints... I simply used Four, 4" dowels  (one per corner of the top of the speakers), and placed
a flat piece of wood on top.   This would allow the tweeter to hit the wood.. and be heard out of all sides of the speakers.

 Despite not having a Cone "director"... the design actually worked just fine.  You could easily hear the tweeter, from any
direction.  Obviously, it may have sounded better, with a Cone to direct the soundwaves more accurately... but they sounded
decent enough to use... so I used them for several months, as-is.. before I eventually got my EPIs.

 I suspect that since those tweeters were low spec... that they were incapable of producing the same kinds of issues, that they
Dipole Ribbon tweeters were creating.  As such, I then realized, that sometimes specs on drivers, do not always mean
that they are "Superior"  for the type of sound, and effects, that you may be after.   For example.. certain super-tweeters
may be able to handle extremely high frequencies... but at the same token.. may have a slightly artificial sound to them..
and often might be a little too  Hot / Harsh / Fatiguing.


 And finally, I will speak a little more about driver importance...  From when I tried to replace my foam-rotted Woofers,
on my Phillips Woox mini-system.

 I had some similar sized woofers from various other mini styles, like Sony, and Aiwa woofers.  Yet none of those woofers,
sounded ANYWHERE CLOSE to being as good, as the original Phillips woofers.  The sonys were especially bad... severely
coloring the sound, in a very bad way.

 After several attempted replacements.. I couldnt find anything that sounding remotely as good... so I started researching
the original woofers.   While many companies use cheap Chinese drivers... these Phillips woofers were made in a Taiwanese
company... that was known for its higher quality, higher-end audio drivers.  I believe Phillips specifically had these drivers
made to their exacting specs.  These woofers were unique in a few ways.. one of the main being, that they had much greater
EXCURSION abilities... to prevent them from suffering distortions, if/when the cone travels too far.  However, that alone, is
not what made them Sound better than all of the other woofers.  It was simply a much better quality woofer, all around...
and was tuned perfectly.   The difference between the Sony woofers, and these, was by a factor of 10.  Literally that
much difference in sound quality.

 As such, I had no choice, but to get the original drivers Re-Foamed.  I actually liked those speakers that much, that I spent the
$100 or so dollars, to have them refoamed.   Unfortunately, the Woox assemblies experienced foam rot, about 2 or so years
later.. and they become useless at that point.

 So... when I see people buying drivers from places like PartsExpress... I just feel the need to speak up about the fact... that
many of those drivers might have decent looking Specs.. but they might actually sound like Poo.   And no matter how good
your Box design might be... those drivers might not do them any Justice at all.   Then you will have speakers that LOOK like
$50k speakers... but only sound like $100 speakers.

 This is why I recommend buying or picking up USED drivers, that have a solid reputation, for Supreme Excellence in
performance and Reproduction.

 Hope that helps.  I wont rant any further     Maybe just post some other ideas Ive had...

 Anyway, it would also be cool to share some of your other ideas on speaker designs...  and or some of your experiments
 Maybe even some of your favorite speaker / headphone experiences.

 Cheers

[Xiaou2]

Ideas:


=======================
More Driver = Less Micro-Distortions
=======================

 One of my ideas... to create potential for less Micro-Distortions, was to use more drivers... but also, to use
a more complex crossover system, to split the workload up.

 Less work per driver = less chance for micro-distortions.

 As such... rather than having a single Midrange... maybe have Two.  One crossed at the mid to high ranges of the
midrange frequency band.  And the other, being crossed from mid to the low frequency ranges.

 Additionally, using at least two woofers.  One woofer, being crossed towards the Upper / Mid-Bass frequencies,
and the Other being Crossed towards the Mid to Lower frequencies.

==================================
Electronic Switching - To reduce Workload Distortions
==================================

 Another additional experiment... might be the use of Timed Alternations.  Every Nth of a second... switch to a different
driver set.  In this way... you would be reducing the workload in a slightly different kind of way.  This alternation tech,
is what was used in the original Surround Sound amps.  As every Nth of a second.. they rip audio from the track, and
push it to the Rear Channel Speakers.   In that particular case... the audio was actually designed to push
Rear Channel Audio... and to different speakers.  However... it might actually be interesting to try using the same
method... to a different driver set, in the same speakers.

 Obviously, using a standard surround amp, is probably not Fast enough... and as such, you may need someone to
specifically design custom electronics, for faster and more frequent switches (seamless / undetectable).

 I suspect B0se used such electronic methods, to improve their  "single driver"  performance abilities.   But by
using superior drivers, and more drivers in total... it might make for some very interesting results.


======================
Multiple Passive Radiators per Box
======================

 A good passive, can really improve the bass response.  That said... Ive always wondered if it would improve
things even further, if you had Passives on every Side of a cabinet.  Thus, rather than getting a single bit
of action from one side... you are getting Four blasts at the same exact time (5, if you count the woofer or sub).

 That said, maybe the left speaker should not have a right facing passive... and visa versa for the right speaker.
Thus, potentially making the bass even more "directional".  Not sure it that even matters.


===================
Expanding Spherical Speakers
===================

 Ive also wondered, about making speakers that are similar to a Beach Ball... so that when the drivers
fire... the entire Ball Expands... sending out sound in every single direction at the same time.

 The main issue might be in designed drivers that are not effected by the air pressure, that is trying to
continually push them outwards.

 Or... to use a material that maintains its spherical form, without needing a lot of air pressure... YET,
is still flexible enough to expand.

 Another issue, is that you may have to make an internal framework, as otherwise, the drivers would be
so heavy, as to distort the ball that it was mounted into.

An Alternative Design...

 Might be to use multiple Passives that are built into a solid ball or hex shaped box.  So when one driver fires,
all of the passives also fire, in every direction.

 That said... for high frequencies, you still may need multiple tweeters.  At least One per side/direction.
Hard to say.

==================
Extended Ceiling Speakers
==================

Due to space limitations, Id once thought of an idea for making ceiling mounted speakers.  But instead
of hanging 4 separate speakers... thought about making long narrow speaker boxes, that are mounted
to each side of the walls ceiling (in the corners of the walls, between wall and ceiling).

 The drivers might be mounted at a 45 degree angle... making the boxes a little more Triangular,
so that the sounds spread further into the center of the room.  The large sized boxes, might
greatly extend the bass producing capabilities (though, Id still want them sealed, and potentially
to use Passives too).

 You might also want the same style of boxes, for the front and rear..  thus, the entire Ceiling, would be
like one giant speaker, surrounding the entire room.

 This type of design might not work that good... as directionality detection, and spread-width.. might
be an issue.

=============
Bass Shaker Boost
=============

 Some very powerful Subwoofers are decent, but to get hard hitting vibrations, you need them
at extreme volume levels.  By adding Bass Shaker Transducers to the base of each speaker,
that might be an interesting experiment, to be able to feel and detect vibrations from different
areas of the room... and with lower overall volume levels.

 That said... vibrations on that level.. could potentially distort high frequency drivers
accuracy potentials... making it unsuitable for Audiophile grade listening.

 That leads me to another idea...

====================
Free Hanging Tweeters / Mids
====================

 Some of the higher end audiophile speakers, do things like Separate the Tweeters from the main bulk
of the Cabinet, and place it on top, in a very Narrow enclosure.  I believe this is to reduce distortions from
both vibrations, as well as waves hitting the area around the tweeter.

 What if you hung the tweeters/mids from a slightly stretchy material... Like Rubberized Hoses.  Or using
metal cables... with shock absorbing Springs / Material  on each end.

 While you could hang them from your ceiling... that might look odd, and those cables would be very long.
Instead... you could have a beam that goes from the rear of the speakers... up to a foot or so above the
main cabinets... and the tweeters / mids are hung from that L-Shaped or C-Shaped Beam.

 You would likely need at least three cables per driver, to prevent twisting from any great air movements.

 The question would then be... Are the benefits, worthy of the differences in design?

[Xiaou2]

Quick Example of Suspended Driver Design

Tweeter
Mid
Dual Woofers
Two or Three Passive Radiators
Possible use of a Sub