Some time ago, I wanted to build some reasonably high-powered "portable" HiFi speakers that I could lug around outside (when working around the yard) or bring to parties, etc.
My design goals were:
1) It should [obviously] sound better than your average store-purchased BPC (black plastic cr4p) deal found at Circuit City
2) It should have plenty of power to clearly play for extended periods in small outdoor settings
3) Capable of being powered from my 20v DeWalt batteries - so I can cut the cord when needed.
4) No frills, but it should accept basic balanced input so I can maintain clean sound when driven my my next project (portable HiFi mixer/pre-amp w/ bluetooth).
Anyway... the overall design and specs are as follows:
Each Speaker
-> 10" Dual voice coil subwoofer. 4 ohm per coil, 200 watt per coil. This driver covers 220hz on down.
-> Dual 3.24 inch midrange covers 220hz to 3400hz. These drivers were actually reclaimed from some old Polk Audio sat speakers that had rotted surrounds.
-> Single dayton audio 1" soft dome tweeter to handle 3400 on up.
The 10" was originally powered by a single TPA3116D2 (mono) chip amp - but that board just did not have the beans to really keep the sub going at high levels and would shut down at high volume. I eventually replaced the TPA3116 mono board with a TPA3255 (stereo) amp board. Since the entire speaker is designed to run with 16-24 volt range, I had to get the voltage up. So the TPA3255 amp is now powered with a cheap 500 watt DC-DC boost converter (bosting to 36 volts). This now gives me 150 per voice coil and is PLENTY. Easily stands up to most commercially purchased subwoofers found today (the extra large cabinet helps on the low end).
The two 3.25 inch midrange drivers are powered from ONE channel of a TPA3116 (stereo) amp, and the dayton silk dome tweeter is powered by the other channel.
I did build a time-delay circuit w/ a 555 timer (with fast reset) and optocoupler that ensures both the 3116 and 3255 amp boards are forced into mute mode until power levels are over 16V and 3 seconds have passed. This ensures absolutely NO power-on pop happens. I was especially concerned that the tweeter - which is connected DIRECTLY to the amp output could experience damage by any power-on pop that the 3116 is bad for.
All three channels of amplification (well, the sub is actually TWO channels).. are passed through a 12db/octave LR crossover design that was clobbered together from Elliot Sound products website (thanks!). I also built a balanced receiver (also from Elliots site) that can work in single ended when desired.
The back "amp plate" faceplate is 5mm MDF laminated in 3M vinyl (brushed titanium). The faceplates were built by cutting and engraving on the laminated boards. Result is a pretty professional looking plate. If I had to do it again, I would likely fnd a way to print the lettering on the vinyl with a transfer or dye sub printer of some sort.
The cabinets are 5/8" MDF (remember, these have to be somewhat portable!). The MTM upper speaker set are isolated in a sealed inner enclosure. The final finish is a spray-on truck bed liner that I buy by-the-gallon (water based).
The driver and mid range units all had ugly (basically no) outer trim/beauty ring. Thus.. I cut some custom beauty rings for each (again, on the laser cutter) and painted them satin black.
Finally... here come the pics:
My design goals were:
1) It should [obviously] sound better than your average store-purchased BPC (black plastic cr4p) deal found at Circuit City
2) It should have plenty of power to clearly play for extended periods in small outdoor settings
3) Capable of being powered from my 20v DeWalt batteries - so I can cut the cord when needed.
4) No frills, but it should accept basic balanced input so I can maintain clean sound when driven my my next project (portable HiFi mixer/pre-amp w/ bluetooth).
Anyway... the overall design and specs are as follows:
Each Speaker
-> 10" Dual voice coil subwoofer. 4 ohm per coil, 200 watt per coil. This driver covers 220hz on down.
-> Dual 3.24 inch midrange covers 220hz to 3400hz. These drivers were actually reclaimed from some old Polk Audio sat speakers that had rotted surrounds.
-> Single dayton audio 1" soft dome tweeter to handle 3400 on up.
The 10" was originally powered by a single TPA3116D2 (mono) chip amp - but that board just did not have the beans to really keep the sub going at high levels and would shut down at high volume. I eventually replaced the TPA3116 mono board with a TPA3255 (stereo) amp board. Since the entire speaker is designed to run with 16-24 volt range, I had to get the voltage up. So the TPA3255 amp is now powered with a cheap 500 watt DC-DC boost converter (bosting to 36 volts). This now gives me 150 per voice coil and is PLENTY. Easily stands up to most commercially purchased subwoofers found today (the extra large cabinet helps on the low end).
The two 3.25 inch midrange drivers are powered from ONE channel of a TPA3116 (stereo) amp, and the dayton silk dome tweeter is powered by the other channel.
I did build a time-delay circuit w/ a 555 timer (with fast reset) and optocoupler that ensures both the 3116 and 3255 amp boards are forced into mute mode until power levels are over 16V and 3 seconds have passed. This ensures absolutely NO power-on pop happens. I was especially concerned that the tweeter - which is connected DIRECTLY to the amp output could experience damage by any power-on pop that the 3116 is bad for.
All three channels of amplification (well, the sub is actually TWO channels).. are passed through a 12db/octave LR crossover design that was clobbered together from Elliot Sound products website (thanks!). I also built a balanced receiver (also from Elliots site) that can work in single ended when desired.
The back "amp plate" faceplate is 5mm MDF laminated in 3M vinyl (brushed titanium). The faceplates were built by cutting and engraving on the laminated boards. Result is a pretty professional looking plate. If I had to do it again, I would likely fnd a way to print the lettering on the vinyl with a transfer or dye sub printer of some sort.
The cabinets are 5/8" MDF (remember, these have to be somewhat portable!). The MTM upper speaker set are isolated in a sealed inner enclosure. The final finish is a spray-on truck bed liner that I buy by-the-gallon (water based).
The driver and mid range units all had ugly (basically no) outer trim/beauty ring. Thus.. I cut some custom beauty rings for each (again, on the laser cutter) and painted them satin black.
Finally... here come the pics:
Testing my balanced receiver circuit:
The pre-amp receiver and xover. Originally 2-way, I eventually added an extra low/high pass for the mid/tweeter since my original deisgn was going to use passive xover for the mid/tweet.
Here, as you see: my original design was a stereo 3116 for mid/tweet and mono 3116 for sub. All brackets were cut on my laser cutter from 5mm MDF
Here, I am bread-boarding the time-delay circuit than ensures there is no power-on pop from either amp. You will see each amp has a special thin green wire coming off it: this wire runs to the mute pin of each chip. I had to remove the heat sink and do some fine-soldering to "hack into" this feature. The circuit itself is a 555 timer one-shot (fast recover) design that powers an optocoupler: when activated, the optocoupler grounds the mute pins, which turns the audio output on. 3 second delay and a simple zener/transistor circuit ensures that as SOON as power drops below 16 volts, the mute is re-applied.
I spent the extra $$ on true ball bearing fans with a DC-DC buck circuit to run the fan slower (around 6 volts). This ensures dead silent operation and long life:
Here you can see the completed reciever/pre-amp circuit (now with the additional 3-way crossover) as well as the completed power-on delay / low power cut out circuit. You can also see the adjustable DC-DC buck converter for the fan:
The pre-amp receiver and xover. Originally 2-way, I eventually added an extra low/high pass for the mid/tweeter since my original deisgn was going to use passive xover for the mid/tweet.
Here, as you see: my original design was a stereo 3116 for mid/tweet and mono 3116 for sub. All brackets were cut on my laser cutter from 5mm MDF
Here, I am bread-boarding the time-delay circuit than ensures there is no power-on pop from either amp. You will see each amp has a special thin green wire coming off it: this wire runs to the mute pin of each chip. I had to remove the heat sink and do some fine-soldering to "hack into" this feature. The circuit itself is a 555 timer one-shot (fast recover) design that powers an optocoupler: when activated, the optocoupler grounds the mute pins, which turns the audio output on. 3 second delay and a simple zener/transistor circuit ensures that as SOON as power drops below 16 volts, the mute is re-applied.
I spent the extra $$ on true ball bearing fans with a DC-DC buck circuit to run the fan slower (around 6 volts). This ensures dead silent operation and long life:
Here you can see the completed reciever/pre-amp circuit (now with the additional 3-way crossover) as well as the completed power-on delay / low power cut out circuit. You can also see the adjustable DC-DC buck converter for the fan:
Cutting out a custom router template on my laser cutter. This template let me route out the entire recess needed for the MTM layout with perfect precision.
Here, I put my laser cutter to use to make a router template guide for the recess needed for the rear amp plate. Behind, you see my first attempt with the amp plate (using spray paint -vs- 3M vinyl).
Router template guides in action:
Here, you can see the V2 of my faceplate (made with the vinyl) and the final rear cut out that was done with the router template guides.
Testing the fit:
Align, drop the plunge router and go to town:
The end result (not shown is the basic circle recess templates I had for the outer circle):
The old Polk Audio drivers were originally designed to be rear-mounted in plastic boxes. I custom cut beauty rings and drilled holes through the basket. Once that was done, I cut off the old mounting tabs/ears (seen in the photo below) so they could be flush mounted from the front like normal speakers.
Same was done for the sub drivers:
Couple more router template guides with my laser cutter and:
Testing the fit:
Here, I put my laser cutter to use to make a router template guide for the recess needed for the rear amp plate. Behind, you see my first attempt with the amp plate (using spray paint -vs- 3M vinyl).
Router template guides in action:
Here, you can see the V2 of my faceplate (made with the vinyl) and the final rear cut out that was done with the router template guides.
Testing the fit:
Align, drop the plunge router and go to town:
The end result (not shown is the basic circle recess templates I had for the outer circle):
The old Polk Audio drivers were originally designed to be rear-mounted in plastic boxes. I custom cut beauty rings and drilled holes through the basket. Once that was done, I cut off the old mounting tabs/ears (seen in the photo below) so they could be flush mounted from the front like normal speakers.
Same was done for the sub drivers:
Couple more router template guides with my laser cutter and:
Testing the fit:
Next up, I purchased some EVA foam and - using the laser cutter - custom cut exact-fit gaskets for every driver and the rear amp plate.
Have I mentioned how useful even a cheap $300 laser cutter is?!?!
You would think them gaskets came from the factory:
Seriously:
Custom cutouts for the handles:
Assembling the cabinets:
You can see the isolation cabinet that was built so that the midrange and tweets are in their own sealed chamber:
Ready to seal up, plenty of bracing. I could have added more, but again - these have to be somewhat luggable lol...
Assembled and ready for primer, adding some solid wood bracing behind where the handle screws will go into as MDF is not that strong in regards of screws pulling out under force:
Primed and ready for final coat, not shown: I hit all edges with satin black spray BEFORE the bed liner application.
Application of the bed liner:
As you can see, everywhere the bed liner was NOT applied, it is still dead black. I pre-sprayed the entire thing with satin black then masked off the areas where everything mounts before hitting it with the truck bed liner.
Have I mentioned how useful even a cheap $300 laser cutter is?!?!
You would think them gaskets came from the factory:
Seriously:
Custom cutouts for the handles:
Assembling the cabinets:
You can see the isolation cabinet that was built so that the midrange and tweets are in their own sealed chamber:
Ready to seal up, plenty of bracing. I could have added more, but again - these have to be somewhat luggable lol...
Assembled and ready for primer, adding some solid wood bracing behind where the handle screws will go into as MDF is not that strong in regards of screws pulling out under force:
Primed and ready for final coat, not shown: I hit all edges with satin black spray BEFORE the bed liner application.
Application of the bed liner:
As you can see, everywhere the bed liner was NOT applied, it is still dead black. I pre-sprayed the entire thing with satin black then masked off the areas where everything mounts before hitting it with the truck bed liner.
Hard to see in this shot, but.. Not only is the sealed side stuffed with poly, but.. The vented side for the sub has been lined with felt glued to the inside walls. Since the "sub" plays rather high (around 200hz), I wanted to ensure there were no internal reflections that could color the sound too much.
I will get some more pics of the finished set up later this evening.
I did some basic tuning with Dayton Omnimic, but have not really measured them correctly with REQW. Honestly.. they sound REALLY good.
These pictures were taken a few weeks back - since then, I upgraded the mono 3116 amp for a 3255 amp w/ DC-DC booster (36V). The overall tuning is slightly "smiley face" (level of W-M-T). I also added a low end shelf around 55hz. I often listen to various electronic artists (Deadmou5, Ennja, Odesza) and love having an extra 3db bump on that super low end. That filter was added passively on the PCB (taken from the linkwitz riley site directly).
Nearly 300 watts peak available to each sub (proven by measuring each coil up to clipping under 80hz test and the scope). Another 30-40 watts to the midrange and another 30-40 watts to each tweeter. Plenty of SPL for reasonable outdoor use.
I am overall really happy with them and have been enjoying the hell out of these speakers now for the past few weeks.
I will try to get some actual measurements up with the speakers in free-air (I have a HUGE front yard)... I am honestly a bit curious how they perform. Even if they show to be off a bit - I am not that sure I will want to screw with the tuning a whole lot.
They may not be audiophile grade - and I am sure even my ageing dahlquists will do many things better. But for something I plan to lug around at times, they do pretty good.
I did some basic tuning with Dayton Omnimic, but have not really measured them correctly with REQW. Honestly.. they sound REALLY good.
These pictures were taken a few weeks back - since then, I upgraded the mono 3116 amp for a 3255 amp w/ DC-DC booster (36V). The overall tuning is slightly "smiley face" (level of W-M-T). I also added a low end shelf around 55hz. I often listen to various electronic artists (Deadmou5, Ennja, Odesza) and love having an extra 3db bump on that super low end. That filter was added passively on the PCB (taken from the linkwitz riley site directly).
Nearly 300 watts peak available to each sub (proven by measuring each coil up to clipping under 80hz test and the scope). Another 30-40 watts to the midrange and another 30-40 watts to each tweeter. Plenty of SPL for reasonable outdoor use.
I am overall really happy with them and have been enjoying the hell out of these speakers now for the past few weeks.
I will try to get some actual measurements up with the speakers in free-air (I have a HUGE front yard)... I am honestly a bit curious how they perform. Even if they show to be off a bit - I am not that sure I will want to screw with the tuning a whole lot.
They may not be audiophile grade - and I am sure even my ageing dahlquists will do many things better. But for something I plan to lug around at times, they do pretty good.
Fabulous project! I can imagine the immense pride you have in your creation. The laser work is super cool. As is the integration of many different elements. Well done. 😎
Some pics of the upgraded TPA3255.
I was having issues with static charges (even with pullup resistors) holding the mute of the 3255 on or off and so.. I have my exisitng time delay circuit controlling a simple 24v relay (seen at the top). This physically keeps the positive of each voice coil connection disconnected until the delay circuit turns it on. The black stuff you see smeared all over the place is Great Stuff silicone (which is electrically safe, BTW). It serves to help prevent excessive vibration of the larger components (and hopefully avoid solder joints vibrating apart). The vibration those 10" subs can induce can be pretty violent when I got the electronic music cranked.
Here you can see the 400(?) watt DC-DC boost converter. It now resides where the mono 3116 amp previously was. I got it set right around 34 or 36 volts (don't recal off hand) - but purposely limited it so each VC can never get more than 150 watts (which is more than plenty).
I was having issues with static charges (even with pullup resistors) holding the mute of the 3255 on or off and so.. I have my exisitng time delay circuit controlling a simple 24v relay (seen at the top). This physically keeps the positive of each voice coil connection disconnected until the delay circuit turns it on. The black stuff you see smeared all over the place is Great Stuff silicone (which is electrically safe, BTW). It serves to help prevent excessive vibration of the larger components (and hopefully avoid solder joints vibrating apart). The vibration those 10" subs can induce can be pretty violent when I got the electronic music cranked.
Here you can see the 400(?) watt DC-DC boost converter. It now resides where the mono 3116 amp previously was. I got it set right around 34 or 36 volts (don't recal off hand) - but purposely limited it so each VC can never get more than 150 watts (which is more than plenty).
I'm thinking about a laser cutter for quite a while now - your post dropped the last stone 🤓
How capable is a 10W cutter compared to a 20W? Is this MDF for your template, how thick can you cut?
I already have an Elegoo printer, so their cutter seems a good addition.
So first, my Elegoo is the 20W version. It will cut 5mm MDF on (almost) 2 passes at 8 to 12mm per second. I usually run 3 passes to ensure a clean cut. That said, a 10W would likely do it as well IF you have air assist and run an extra pass (or two).
When I was shopping, the Elegoo was over $100 cheaper (at the time) than the other leading 20W model (the X-Tool). To be completely honest, if I had to do it again, I think I would go with the XTool over the Elegoo. My Elegoo laser cutter has been excellent - and the build quality is of no issue. The problem comes in: the details.
1) The built-in "air extraction" system is actually pretty useless and all that extra orange plexiglass and bulk just get in the way when you are trying to align the laser to the material.
2) The filter quickly gets dirty and serves virtually no useful puropose. I have removed mine completely.
3) Due to #1, the ability to manage the cables and air hose to the laser head is horrid. The air line itself has no easy way to be held out of place without impeding the ability of the laset head to travel all the way to the left. Cable managemenet is just bad.
4) After market support, add-ons and future expandability seem much more robust with the XTool. Accessories seem cheaper, too.
All that said, my Elegoo HAS been rock solid in terms of performance. I can easily cut 5mm MDF (often in 2 passes). I have attempted to cut 1/2 inch MDF but the result is not great. After the first 1/4 inch of the way through, you essentially have to re-adjust (focus) the laser - otherwise it just starts charring the middle due to out-of-focus. Higher-end (professional) cutters (which cost thousands) do this automatically. No so on a sub-$1000 unit.
What I often do when I need a router guide that is a bit thicker than 5mm is: just cut two guides out of the 5mm. Once cut, I can stack them and glue them together.
I would certainly go with a 20W if finances allow. You will not regret it - and the price of the 20W units has come down since I purchased mine.
I am actually thinking of making another plate amp - except the next one will be out of solid aluminum plate. I may have a local CNC shop do the cut-outs and then I can print the lettering onto the plates w/ the 20W and Cermark spray.
If you are not doing fancy fan vents (as I currently have) and are only doing round holes for volume knobs, etc - then the laser cutter is all you need:
1) Cut out the plate (to size).
2) Print the lettering and bulls-eyes/circles where the holes for switches/knobs need to be drilled
3) Spray the plate with Cermark
4) Fire up the laser machine and do the marking
5) Once done, clean off the Cermark and drill out the holes w/ a small drillpress or hand drill. You already have the center marks and sizes written on the plate, so drilling is easy.
Some people in the aviation circles are using their laser cutters to make custom back-lit panels. They take frosted white acrylic panels and paint the surface with satin black spray paint. Once the paint dries, they place this in the laser cutter and not only can you CUT the material, but where you "write" the letters, it is actually removing the paint and exposes the frosted white (or green) acrylic. You end up with a black panel and white or green lattering that can have a LED placed behind it for super nice lighted panel effect. Similar to how a McIntosh faceplate looks.
I have also use my laser cutter for:
-> Cutting out custom inductor spools. Using PVC pipe for the inner tube, I can cut out MFD "washers" of any size that fit perfectly around the PVC pipe (cut to any length I need). Since I can buy 14 gauge magnet wire super cheap here in MX, I can make any inductor I need for next-to-nothing.
-> Making custom gaskets for the drivers, connection jacks, etc
-> Support brackets/pieces
-> Custom info plates that state wattage limits, impedance, etc
I also use mine to make one-off boxes of any size (electronic project boxes). The price of the plastic project boxes is getting out of hand - and I never find the exact size I need. With my laser cutter and online box SVG generators (Boxes.py, Makerbox, etc) - I can have a custom electronics box of any size design I need in half an hour or less.
I plan to pick up a Creality K1 Max 3D printer later this year. Between a 3D printer and laser cutter, the cool stuff one can fabricate at home is truly insane.
Here are some pics of some quick-n-dirty enclosures I made for some TPA3116 mono amp boards a while back:
You can even get fancy and build the main box as seen above, then finish it off with a custom aluminum (or backlit acrylic) faceplate.
-Dean
You can even get fancy and build the main box as seen above, then finish it off with a custom aluminum (or backlit acrylic) faceplate.
-Dean