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Saturnus 9th July 2007 07:55 PM

Back from field-testing at Roskilde Festival which was the rainiest Roskilde ever! We got 100mm of rain in 4 days which made the mud ankle deep most places and knee deep some places.

It also meant that I didn't get much power from the solar cells but the batteries did last from Saturday evening until Friday morning playing 12-18 hours a day before needing recharging, so I think it proves that even if we had very little sun the solar cells did work.

The best of it was the literally hundreds of people commenting that it was the best sounding boombox ever. Rock solid bass. People where amazed to hear that it didn't any play subbass at all, it really sounds like it does. Neutral and natural midrange with good focus on both foreground and background details, and not least very natural voices. Suprisingly well rounded top end with only a miniscule of "piezo"-sound.

Also the front and back firing configuration surprised many people, they where walking past nodding their heads, and then when where past you could see them suddenly stopping up as if in confusion why the sound hadn't changed. Most turned around for a second look, and many just had to ask where the hell I bought it. :D

It still works, btw. I'll probably try to sell this one after a full check up and some minor tweaks, and make an even more crazy version next year with direct methanol fuel cells from


Originally posted by Nisbeth
Going to Roskilde? :D :smash:

I'm a surviver of Roskilde '07 but by God didn't I have times when I thought enough was enough.


Originally posted by sts9fan
Could you explain how the solar panels are connected? Are the always charging? Nice Job!
Since the total output of the solar is 8 Watts at best compared to the 168 Watts in the battery pack, the solar cells can easily be connected all the time, without damaging the batteries. Then it can also pump in every bit of solar power they recieve into the system.

The connection is pretty simple. The two solar panels on each side is connected in series with a diode so the batteries doesn't into the solar cells. Each solar panel has clearly marked solder points on the back. A schottky diode could be used but it's not critical. Then each pair is connected into a central plus and ground point that connects all the power.

The reason for seperating the two solar panel sets on each end is because people tend to sit on the boombox while it's playing and when placed like this there's a bigger chance that at least one of the sets will work.

And thanks. :)


Originally posted by v-bro
Wow, I bet it's louder than the one Pekar built! :bigeyes:

I thoiught you were going to use other drivers, but the efficiency of this setup is probably nothing to joke about either :D

It actually play so loud that you can't really sit next to it when it's playing at maximum volume, you have to move away a couple of meters. Then again, the sound quality is also best if you do exactly that since that gives you the most well distributed sound from the tweeters.

The other drivers I've been raving about is for next years version. ;)


Originally posted by TroelsM

May I ask where you bought the P.Audio HP10W's from?

Hej. It's tricky here in Denmark since the Danish distributer of P.Audio doesn't have them in stock, and is unwilling to order any unless you buy at least 10 pieces! The good side is that can order them in Sweden at or in Germany at at almost half the Danish retail price. Then you only have to either drive to get them or know somebody that is willing to send them to you.

Pano 9th July 2007 10:04 PM

Congratulations on your succesful test run! Always nice to get them out in the mud and know they really work. :D

FYI, here is the spec sheet for the 10" P.Audio driver.

I don't see this driver on any of the USA supplier's sites. Might have to dig a little more.

Saturnus 9th July 2007 10:50 PM


Originally posted by panomaniac
I don't see this driver on any of the USA supplier's sites. Might have to dig a little more.
The P.Audio HP10W is pratically identical to the Goldwood GW-1058 from which is around $32. A little tweaking of the boxtuning is neccessary but it's only a minor difference.

Saturnus 10th July 2007 07:25 AM


Originally posted by panomaniac
FYI, here is the spec sheet for the 10" P.Audio driver.

Oh, I forgot to mention that though the current specs of the P.Audio driver is the same the picture is an older version. The current version doesn't have a logo, and it has a smaller fine mesh dust cap that allows air to flow through it.

MortenJ 11th July 2007 09:45 PM

First, nice work! I too turned my head after your boombox on Roskilde.

Second: How do you manage the volumecontrol, is there a seperate knob for that or do you use the player for that?


Saturnus 11th July 2007 11:13 PM

Hi Morten,

I'm not sure what you mean by volume control, it's either on or off ;p

Seriously though, it's a fixed level headphone input, so volume is controled by the player attached.

Thanks fellow Roskilde Survivor. It was another great festival despite all the rain and mud.



Pano 13th September 2007 07:07 AM

Hey Saturnus

I saw your Boominator today in commerical form. :)

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It's an iPod boom box by Harmon Kardon. Looks as cool in person as in the photo. Very sturdy with clean lines. It is symetrical, looks the same front and back. Two speakers on each side. iPod dock on the top. Aux connections along the bottom. Claims to have "Digital Amplification."

Did not get to hear it play, no batteries, no iPod. But the basic idea is there. It's a way cool looking unit. So it seems you are in good company. But yours is BIGGER!

v-bro 13th September 2007 03:50 PM

Where are the solar cells?

Pano 14th September 2007 09:49 AM


Originally posted by v-bro
Where are the solar cells?
Yeah! They forgot the solar cells!!

Saturnus 14th September 2007 11:40 AM

Actually it looks like a cross between pekar's solar powered boombox and mine. I'm thinking about the centerhandle here.

But yeah, they forget the solar cells. And also with the slanted fronts I doubt they used one of main aspects of my boombox which is the magnet-to-magnet mounted bipolar speakers. Though just going bipolar in a boombox has some significant advantages of it's own, mainly that when used outdoors the "back"-mounted speakers will augment the bass response of the "front"-mounted speaker, and when used indoors they will augment the mid-high response as well, resulting in somewhat flat frequency response regardless of being used indoors or outdoors.

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