So, just thinking ahead a little... I was looking at the Podzuma project and rather liked the portability aspect of that project. The Podzuma in a nutshell is what i was looking for in the beginning. My thoughts using what i have right now and building something of a combination between the podzuma in a stage monitor type enclosure like the smithereens
I essentially want to use my Sirius receiver hooked up to a 5VDC transformer and use that for the primary source hooked up to a class T amp. This sure would be better than my current setup, 2 clunky speakers and a Sony HT receiver that weighs over 30lbs. I first got the idea today when i was at Princess Auto and i was in their surplus dept and had seen this Altec Lansing gaming speaker
The specs are as follows:
One 1" neodymium tweeter and one 6.5" midbass driver
Sound Pressure Level (SPL): 100 dB
Total Continuous Power: 40 Watts RMS
40 Watts @ 8 ohms @ 10% THD @ 80 Hz - 20 kHz
System Response: 50 Hz - 20 kHz (-10 dB)
Signal to Noise Ratio @ 1 kHz input: > 90 dB
THD+N @ 1kHz input @ 250mV RMS: 0.15%
Dimensions: 12.6" (W) x 10.4" (D) x 9.1" (H)
40 RMS watts at 10%THD?! Isn't that max output rather than max listenable output? sounds pretty bad to me anyways, didn't think it was worth trying.
So, just thinking ahead a little... I was looking at the Podzuma project and rather liked the portability aspect of that project....
What you propose is most definitely doable and can be had relatively cheaply if you DIY. You might even be able to use your existing JL speakers as mid-bass/hi-end speakers and stick a small DVC sub in the enclosure to reinforce the low end. Sounds like fun actually.
40 RMS watts at 10%THD?! Isn't that max output rather than max listenable output? sounds pretty bad to me anyways, didn't think it was worth trying.
Definitely MAX output and @ 10% THD, you're in potential clipping territory. That measurement metric is a waste of time.
Yea that's what i thought, $50 gets you squat these days. Here is a rough idea of what i propose to build.
Oh and did i mention im kind of a snob as a tradesmen? Most everyone ive spoken to thus far has laughed at my idea, they always say oh why dont you just by a Dewalt jobsite radio? To which i downright refuse for multiple reasons.
They use from what i can tell, a pair of poor quality high eff drivers that just scream when you crank it up. The amount of distortion is incredible, i hear framers and roofers down the road with their radios screaming and i can clearly hear all the distortion, just horrible sound. My theory is that the radios have made them deaf or they are simpletons that believe that louder is better. They arent the only bad jobsite radio though, they all are horrible IMHO. All the major brands Dewalt, Makita, Milwakee etc are poorly designed. Sure they are tough and can stand a few tumbles, but thats where all the engineering went into.
My personal favorite portable radio is the Audiovox Sirius SUBX2
Not perfect sound, but quite nice as far as im concerned, its a 3 way system and the bass is quite impressive for such a small unit. A pair of tweeters and mids and then a shared sub, well designed i think, just not very "tough".
The small sub idea makes a lot of sense, i would appreciated the added bass especially considering it tends to disappear in the unfloored empty houses i work in. Would the crossover be hard to modify to accommodate a sub?
I was looking at the Sure 4x100 t-amp, would that be a good choice for this sort of a project? Volume control would be required
The small sub idea makes a lot of sense, i would appreciated the added bass especially considering it tends to disappear in the unfloored empty houses i work in. Would the crossover be hard to modify to accommodate a sub?
I was looking at the Sure 4x100 t-amp, would that be a good choice for this sort of a project? Volume control would be required
There's a million different ways you could build a boom box, but I gotta ask you....how do you get satellite reception if you're working inside a house, for example? I have Sirius/XM and my in-house antenna sucks donkey nuts.....But that's a story for another day.....
Or even 2 of the Dayton subs with the VC's wired in parallel. That would make for a powerful boom box that would put any of the ones you showed to absolute shame!!
If you went that route, I'd suggest you box up the JL's in their own sub-enclosures (making them sealed). All you'd really need is a cap + coil for a passive low pass filter for the sub woofer. The inductor might be a bit costly however, depending on how low you wanted the XO point to be.
Ya... that reception is a whole other problem. Depending on where I'm working just having the antenna on top of the unit, works fine at full strength. Right now its literally sitting on top of my HT receiver in the kitchen I'm working in. In my own place though, that's another story. Main floor and top floor are generally ok as long as im close to a window, basement is a no go, antenna has to go out the window. It really is hit or miss, the antenna has 20' of coax so i can usually put it a few feet outside a window or door and it functions ok. What i have notice is heavy duty equipment in the area tends to affect reception somehow. I plan on building a gender bender and converting the SMB end to something like BNC on 50ohm RG-58, the antennas never last more than 6 months without needing a new end crimped on. This way i can extend the length if need be. They also make an outdoor antenna that is supposed to perform a lot better.
Ive been using this Sirius everywhere ive been working for about 4 years now and i dont think ive ever been in a house that i couldn't finagle reception. I still cant figure out why they dont make a rugged version of their boom box. its made of plastic and not very sturdy, ive gone through 3 of them so far... the last time i bought it from Costco, so maybe its time to exercise my unlimited return policy. Even with all the frustration, its worth it though, local radio tends to blow, the DJ's make me want to shoot myself in the face.
im working on a model of what im thinking i want to make, i will upload when it looks like something. I would also like to design this so that the coax's can be swapped out for something similar and not need too many mods to sound good. This might be a tall order but i think its worth doing, in case the coax's dont last.
im working on a model of what im thinking i want to make, i will upload when it looks like something. I would also like to design this so that the coax's can be swapped out for something similar and not need too many mods to sound good. This might be a tall order but i think its worth doing, in case the coax's dont last.
There are several midbass/extended range speakers that play very smoothly up to 4.5k, and a bunch of tweeters that you can cross at that point. I'm hoping the XO's I sent work out with the JL's. You certainly could retrofit other driver combos with those XO's, but it will be a hit-or-miss proposition. It's like buying a pre-fab XO from Madisound or PE and thinking it will work with any driver combo. Obviously that's never the case and you will readily get flamed here for suggesting that any prefab XO is "good enough" LOL.
Seriously, though, you don't need to aim for perfection with a boom box that you're going to use on site. Crap....make it sound decent and make it go loud and last a full workday on a single charge and I think you could call it a success.
I'm a carpenter too, and I've been using a JVC Sirius receiver mounted on an old 1st generation Milwaukee jobsite radio for about six years now. It's not too bad compared to the DeWalts and the newer stuff, but it sure has its limitations. It has 5.25 woofers and separate tweeters. I usually end up stringing an antenna outside. Fortunately, I found a source for cheap replacement antennae some years ago and still have a few spares. Yes, reception is hit or miss unless you are in a metal building in which case forget it and just string the antenna outside. (Check out the orbits of the three "loitering" Sirius satellites if you are into that sort of thing. Pretty neat stuff.)
I'm currently working on a replacement, and I've got most of the parts gathered. Got an Indeed amp exactly like the one in that other thread, and it's amazingly good. I have some old "truck boxes" I've always liked, 10" woofers and some Motorola zingers. I hooked those up to the little amp and I think I'll be able to crank it plenty loud. I didn't believe the specs on that Indeed amp when I bought it, but I can crank it all the way up and it does not sound bad. I also have a Lepai exactly like the other amp in that thread, from PE. The Lepai sounds good till you turn it up too loud, then it turns to jagged nastiness. That would be very bad on a jobsite because there is always someone turning up your radio when AC-DC or something like that comes on. Yikes. No comparison in the two amps above low levels. They both sound remarkably good hooked up to better speakers. I'll put some midranges and some proper tweeters in the truck boxes before I take them to work. Mostly I do trim and cabinets, so I don't need to light up the neighborhood.
Power will be from a 17ah AGM battery out of one of those jump start boxes, with a switchmode supply set to about 13.6 volts so as not to harm the amp. I figure it's just like the charging system in a car, with constant voltage keeping the battery full but not cooking it. Power is always getting interrupted for one reason or another, and that battery should run the system for quite a while. One annoying thing about the Milwaukee setup is when the AC power gets cut, it takes ten seconds or so for the battery to kick in and power everything, which causes the satellite radio to go through its booting up routine. Not a big deal but annoying when it happens several times in a day. I have had great luck with AGM batteries in my van, both under the hood and in the back, powering a big inverter. Spillproof and actually pretty hard to hurt unless you cook them.
Ok so this is kind of a good news bad news sorta thing... Im afraid i kinda shat the bed here... once i pulled the tweeter contacts off the main contacts i hooked them up and... they are shot, like big time shot. i dont know why i couldn't tell before, i knew something was off but not totally sure what. One of them doesn't even read resistance... CRAP!!
Ok, for the gooderish news, i happen to have a sorta similar pair of speakers to swap in for testing. A pair of Alpine SPS-170A coaxials(link). Yes the specs are different, and so are the sensitivities for that matter, but im kinda stuck for the moment. I did play with these speakers in the boxes before and they were VERY bright, hard to listen to at close range. I have one hooked up to the crossover and im gonna see what happens, hopefully they will improve the sound. i'll check back in a while with more news.
Good to hear others are working on jobsite radios, i really wish there were some higher end ones available, oh well i guess thats why DIY is so popular.
I forgot to mention that i just got a 500watt computer power supply for $60(Link) to power my JL Audio amp. It is rated for 34A at 12v and seems to do well with this amp cranked with a 12in sub hooked up at full gain. For now this will be what i am building with. I dont think i can get better than this $400 amp in the DIY category, if others think i can i would like to see what would go up against it.
Whats even better is that i need 5v as well to power my Sirius sportser receiver, and computer PSU's output both 12v and 5v, perfect.
you had me sweating bullets there for a minute... i didnt want all this effort to be in vein.
I stuffed each enclosure fairly full with stuffing... is there a particular feel or density i should be going for? I want to make sure im doing a pretty fair A/B comparison.
That computer power supply looks like a nice solution. I've got a good old Kenwood car amp gathering dust. Thought about using it for my project but the power supply was what stopped me. I hadn't thought of using a computer supply. Uh-oh. This might be turning into one of those projects.
Any favorites for testing? ive been going through different ranges of music i enjoy in the best formats i can find. My first thoughts is that the speaker with the crossover just sounds easier to listen to. Sounds like everything is kinda even if that makes sense? The one without is giving me a massive headache, that tweeter is peircing, i dont think i can test as is much longer.
So the L-Pad seems to make a large improvement. As far as the rest of it, im just going to have to listen to more music and see what i think.
you had me sweating bullets there for a minute... i didnt want all this effort to be in vein.
I stuffed each enclosure fairly full with stuffing... is there a particular feel or density i should be going for? I want to make sure im doing a pretty fair A/B comparison.
It's sort of trial and error with sealed or ported enclosures. You want to absorb any midrange that's bouncing around the inside of the cabinet and then jetting back thru the cone (selaed) or the vent + cone (ported). I'd try 8oz and 16oz and then listen for the the scenario that yields more bass.
I would still suggest trying to port the cabs to get better bass extension.
The PSU works well, much better than the 50a car charger/booster i was initially testing with, it would cut out when i was pushing the low bass as high SPL. Hot wiring the PSU is pretty easy, generally just jumping the green to a ground turns it on.
Re: Cheap speaker recomendations
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Originally Posted by jgleadall
