Portable Speaker System "Zen Visionary" with Sonic T Amp
After hearing my friends' Altec Lansing and iPod Hifi systems, I knew I wanted one of my own. I just didn't want to pay that much for either, so I made my own. Take a look at the pics here
I saw the designs for the Podzuma, and another system that featured cheap speakers mounted in a cardboard box. I didn't like the size or layout of the Podzuma and the cardboard one... well... lets just say I didn't want to look homeless when whipping that sucker out at my flag football, soccer, or ultimate frisbee leagues. I also decided I didn't want to put the battery inside the unit like the podzuma because I can use this indoors as well. The Podzuma is totally enclosed and the input is mainly from a 3.5mm audio jack, with mine I just hook up wires to the speaker terminals on the back. I don't have to worry about a battery or amp unless I take it outdoors.
I won't go into supreme detail regarding construction since I had the box glued for me. I did some circle cutting using a Dremel, a Drill and a hole saw once I got the glued box.
I knew that I didn't want to work with MDF as a speaker box due to having to paint, cover it, or use some really ugly gray or black felt like substance (used on many car stereo speaker boxes). So the next best thing was plexiglass. I scoured for some sheets on Ebay and got them for about 50. I didn't have to pay shipping since the seller was in the same general area and agreed to drive them over to me. Anyway, for a few extra bucks he glued the box together, while I got to cut out some circles and do some sanding.
I chose .375 inch thickness for the sheets and they measured 18 x 9 inches for 5 sheets. 4 of them made up the main rectangular portion while the 5th sheet was cut into two and glued onto the sides. Like I said earlier, the seller did the cutting and gluing of the box since he is a plastics manufacturer here in Texas. The total size of the box is 18.75 x 8 x 7.75 inches which is a little bit bigger than an iPod HiFi.
After I received the glued box, I cut out some holes. First off, the Circle cutter attachment for the Dremel isn't very accurate when used on plastic. I can't say how well it works for wood cutting since I haven't used it on wood, but I do know you won't end up with a perfect circle. So I didn't even use the circle cutter. What I found was that you can make a circle template on the plastic itself with a permanent marker and use the circle cutting bit, rotary guard attachment and trace the circle. You won't get a perfect circle either with that method, but it seems to work better for me. You can also go back and shave off the extra to get close. As long as you have a circle big enough for your speaker to fit in, it will cover up your imperfect circles once mounted.
The hole saw I used for making the port openings. That will make a pretty nice circle, you just need to sand the inside to get it smooth. When drilling plastic, you need to lower the drill speed in relation to wood and metal. The bits get hot and too fast rotation speed will melt the plastic. Too slow, and you melt the plastic too because the friction ramps up due to increased contact with the drill bits or hole saw. It takes some practice but you can drill plastic without melting it. Just don't pull the trigger on the drill all the way.
Anyway, I designed the box sort of like the iPod Hifi, but I added tweeters and woofers. The HiFi only uses 2 full range drivers and one woofer. I knew I didn't want that. I wanted a tweeter, mid and woofer setup. I also placed the speakers on the sides so that you can hear the music better if you aren't directly in line with it. That is one of the problems with the Altec Lansing, iPod HiFi, and Podzuma. The speakers on those are all front firing, which they sound fine if you are in front of them, but if you move laterally in relation to the speakers, they become harder to hear when you are running around on a playing field.
So I decide to mount the tweeters front side with one woofer. The Midranges I side mounted and the remaining woofer is on the rear. Now when you run around you can hear music on most of the fields. And obviously the farther away the lower the volume, but at least you can still hear it.
The battery is a DIY Li-Ion. I decided on Li-Ion because they are smaller, lighter, and they can be charged more quickly than a Sealed Lead Acid battery, and in the long run will be a hell of a lot cheaper than C or D size batteries used in the Apple HiFi. The Li-Ion celles were 8 loose 18650 size 3.6v with soldering tabs and 2400mah rating. I soldered 4 cells in series to yield 14.4v and 2400mah. After soldering I tested the voltage, and got about 16.3v. The cells real world output was about 4+ volts per cell when fully charged. After use, the output will fall back towards the 14.4v gradually. I repeated the process the same with the remaining 4 cells and ended up with 2 packs of 2400 mah, 14.4v. So I then paralleled the 2 packs to yield 14.4v and 4800mah. Once I made the 8 cell pack, I tested the voltage again to make sure I had done it correctly. If I got anywhere over 16.3v I knew I messed up. So the moment of truth came and it measured exactly at 16.3v. I also made a voltage regulator using an LM317T and two resistors, since 16v will short a T Amp. I have mine set at 13.85v output and it sounds just fine. I did have to use a small heatsink on the LM317.
So now I proceeded to solder the PCB protection circuit to the 8 cells. Please note that DO NOT EVER USE Li-Ion or Li-Poly batteries without a PCB protection circuit. Otherwise you can have a fiery mess. The PCB will prevent over charging and excessive discharge of the battery, which in turn prevents the battery from catching fire. Anyway, you solder the pcb to several junctions of the battery, where the cells meet at the + and - terminals. You also solder connections to the + and - input/output wires. This way it can monitor the charge and discharge levels of each individual cell. If the PCB senses too much voltage coming in from the charger, or the battery is nearing capacity, it automatically cuts off and no more power is sent to the cells. The same for discharge. Once the cells fall below a certain voltage, it cuts off so you don't damage them. I added an optional "Fuel Gauge" PCB that has a series of 5 LED's to show the remaining charge/discharge level of the battery. All 5 light up when it is 100%, 4 light up for 80%, 3 for 60%, and so on. There is a tiny button you push to light them up, they stay on for 10 seconds and turn off automatically.
If you plan on making your own pack, you need to buy the cells with soldering tabs. It will save you time and grief, because it makes connecting the cells easier. You also need to buy a pre-made PCB circuit. You can find those online at places like www.batteryspace.com I guess you could make your own, but at only 5 bucks or so, the time and effort and calculations you have to do aren't worth it. You also need battery bars, these connect the cells together at the + and - terminals. You can find some online at some Hobby shops like www.towerhobbies.com, or you can go to your local RC Car/Boat/Plane store to buy some. YOu need to get the right size though. For 18650 size Li Ion cells I used Novak Micro Bars. They are silver plated pure copper bars and are perfectly sized. I also used no loss connectors for the battery, charger, and input on the amp. I used Deans Ultra Connectors because you can't accidentally reverse polarity since the connector will only fit one way, so no worries about blowing an amp or shorting your battery due to reversed polarity. And I do have to add that I love the size of that battery. Its smaller than the case of the amp and about the size of 2 Zen Vision M's stacked to together.
The Amp is a Sonic T Amp. I reboxed it using a plexiglass box used to hold autographed baseballs. It fits perfectly, and you can remove the top for easy acces if you want to mod the board. It is mostly stock, but I removed the crappy wires and used some expensive silver coated/plated interconnect wire for the battery and speaker connections. You'll only need a foot or so at the very most so you can get away with getting a very low quantity. I also changed the pot knob to an aluminum one and changed the red LED to a blue one.
I will get rid of that amp for a better sounding Amp 6 Basic from 41Hz. I didn't picture that one because I haven't finished the plexiglass box for it yet. ONce I get it done I will post pics of that one. Thanks again Jan for making great amps cheap!!! Get one at www.41hz.com if you don't already know about them.
The audio source is a Creative Labs Zen Vision M 30gb model. I named the speakers after the MP3 because I figured there's a Podzuma floating around, why not have a Visionary floating around too?
Regarding run times, at full charge I have yet to drop below 80% after about 4 hours of playing at various volume levels. I can max out volume on my Sonic T amp without clipping on almost every song when setting the volume level on my MP3 player at its highest volume levels. The sound quality is great, and it doesn't clip compared to my friend's Altec Lansing and iPod Hifi. It was cheaper than either of those systems too, it just needed a whole lot of time to construct and design. But overall I am very satisfied with it as are the people who have heard it on the football/frisbee/soccer fields.
A definite cool factor. Looks great. And great advice in your post.
I guess I don't agree on the side firing midranges, but maybe I'd be proven wrong in actual field testing :)
Why not separate chambers for each side?
Sealed back midranges?
Raintalk, thanks for posting
First off let me state that I am a newbie when it comes to audio. Believe me I wrestled with the idea of front or side mounting the mids for a long long long time. Did I forget to mention long? Everything says to mount them front, but that is only in relation to a fixed listening position. Cars, ampitheaters, home theater, and whatever else, your standard listening position doesn't change (except for moving your seat). But while running around in the free air with nothing for the sound waves to reflect off, you won't hear the music as well which kind of defeats the purpose of having a portable speaker system unless you stay in a fixed position.
I tested 2 speakers by bringing them to my fields. First I pointed them in the same direction straight ahead towards the field and jacked the volume up as loud as possible. Then I tried positioning them so that they angled out. The difference to me was readily apparent. So it was then I settled on side mounted mids.
As far as not separating into chambers or not using a partition. I also thought long and hard about that. My first design was to build two smaller boxes and then connect them with a clear acrylic piano hinge. I decided against that because it was too complex and cost prohibitive.
I could have chambered the box, but man, plexiglass is hard to work with. With the way I set it up, I would either have to make a few small pieces and glue them together at right angles, or use one larger piece at approximately 45 degrees between the two woofers. And trying to sand the edges to get the angles correct is a pain in the butt. Also, trying to get the exact height of the inside of the box correct is truly tedious work. Plastic is pretty hard to work with, and trying to get the height of the piece so that it is sealed and fits well is very difficult (at least for me).
So basically it came down to too much work. If I had the time, money, and this wasn't my first time working with plexiglass, then I would definitely go ahead and do my original design or chamber the box.
The easiest solution is as you suggest sealed back mids. I will definitely get some later on, or maybe I'll get some baffles for the current ones. Anyway thanks for the tip. If you could hear it, I think you might like they way it works.
Very nice work! Very nice indeed. Thanks for showing us that.
You are going to be really happy with the way your AMP6 sounds compared to the Sonic Impact. :) If you can add a little heat sink to the AMP6 chip, it will be happier. Anything metal should do.
Do you think you will mount the amp inside the speaker box? Sure would be a lot easier to use. You've got plenty of room in there.
What are your drivers? I know some of them, but not all.
Again, very cool box!
Re: Portable Speaker System "Zen Visionary" with Sonic T Amp
I like to make the plexiglass case as u did, I will have to check out the homedepot....
Thanks Pano, anything coming from you is a compliment. Mounting the amp inside is something I am considering. I would probably go with the Amp 32 if I do. So tiny!!!
The drivers are Digital Audio DAMD 50's they are 3 ohm impedance, 93dB sensitivity, range is 35Hz-5Khz
The Audio Art mids are supposed to be 95dB sensitivity, 4 ohm, and 70Hz - 10Khz
The GMI tweeters are supposed to be 103dB sensitivity, and are 4 ohm, don't remember the range offhand though.
Gychang, if you want to make your own custom box using plexiglass sheets, you can get a cheap plastic/acrylic cutter at home depot. Anywhere from 3-7 bucks. You have to run the blade across the surface several times in order to get a nice clean cut. Also, you will have to file/sand the edge after you cut the plastic if you want them to fit flush when gluing.
In regards to the adhesive, you will have to use Methylene chloride based adhesive. Don't bother with anything Cyanoacrylate (CA) or anything Silicone based either. The CA is just regular superglue which will turn the plastic white and won't be perfectly clear if you mess up. The Silicone based glues don't stick well to plastic either. Epoxy might be fine, but the don't dry clear which defeats the purpose of using plexiglass or acrylic. Let me know what help you need and I'll do my best.
Try IPS Weld On adhesive, they make several formulations. They are plastic specific and work by softening the surface a little. the plastic then "welds" together and actually forms a stronger joint. They will dry clear and if done properly will leave few bubbles.
thanks, I will duplicate your efforts.
After further experimentation, and to increase airflow from the port tubes, I sealed the midranges and I rounded the edges of the port tubes. I removed the tubes and tapered off the edges of the tube using a dremel tool and routing bit. After getting it somewhat rounded, I then used some 600 grit sandpaper to smooth it out. To finalize it, I then took my butane torch and heated the edges of the tube to get it glass smooth.
(Note, when working with plexiglass, to get the super clear edges you keep sanding by increasing the grade of the paper. I.E. going from 600 to 1000 grit > 1500> etc. Once satisfied with the smoothness and if you get tired of sanding, you can then finish off the edge of the sanded area with a torch. Don't get too close or heat too much otherwise the plexiglass or other plastic will bubble and or bend. Experiment first with the distance from the flame and how quickly you move the torch on a scap piece and you'll be fine. ANyway, the flame will heat the surface and melt it slightly leaving a glass smooth surface)
To seal the mids I removed them from the case and used some thin sheet of tin to seal them up. I first stuffed some acoustic filling in the openings so the sound doesn't echo and I don't get too much vibration. I then sealed them up using some tin I cut out and used some silicone adhesive so there is no air leakage. I did have to make one small concession since one of the holes in the basket has to make room for the speaker wires from the cone to the soldering tabs mounted on the basket. For this I had make a larger opening in one of the tin coverings so that it the wires wouldn't short on it, but it did leave a little opening for air to enter and exit, but again there was acoustic filling so it should help with that.
So now the air flow out the port tubes is a lot greater, since all the pressure is relieved by escaping through the port tubes and not used to move the mids.
I also have stopped using my Sonic T Amp and use the 41Hz Amp 6 Basic exclusively. I can tell you without hesitation that the bass is markedly better with the Amp 6 Basic that the T Amp. I also increased the gain of the Amp 6 by using some 82K ohm resistors in the feedback loop. In the kit you are supplied with 56K resistors, but with my usage, if you maxed out volume you could hear it with out clipping, but the volume level was about the same as a Sonic T Amp. With the extra gain, you do increase the max volume level (although I cannot tell you how much) and you can get the amp to clip somewhat at the uppermost limit.
Pics of the now reboxed Amp 6 Basic, and the newly sealed mids will be posted, just click on the link at the beginng of this thread if you want to see them.
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