The Boominator - another stab at the ultimate party machine

kristleifur · 2011-06-19 1:35 pm

Nahaz said:
I notice that the sound become very distorted on lower volumes than expected.
I verified that its not the speaker/box by connecting it to my home hifi system and here I can play fine to ridiculus volume levels with far less distortion than with my lepai/battery setup.

Also Ive noticed that if I max out the volume knob on the lepai the bass is non existant pretty much. Even if the source volume is turned down (not playing at max). If I lower the lepai volume knob to about 75% the bass comes back. This in itself is not a major problem the volume is far too high even at 75% when the source is maxed. But maybe it can give a hint as to what might be the cause of the distortion?

Weird! Might be an out-of-phase issue. I can't really imagine how exactly, but it sounds like the potentiometer is physically malfunctioning and causing the bass to bleed off into ground or the channels to cancel each other out. It's strange at any rate.

I'd jumper the potentiometer and see what happens then. Use an iPod or something else that has a built-in volume control.

If that fixes it, then the potentiometer is to blame.

Also suggest you buy a prebuilt Amp6 or Amp9 and swap it in for the Lepai 🙂 The Lepais don't exactly have a stellar reputation for quality.

Nahaz · 2011-06-19 1:53 pm

Pics:

I was not involved in selecting colors, logo or patterns, and I did not ask him to paint me inside the lid : ), He made that as a surprise.

Thomas (a friend and camp member) had full creative control and this is what he ended up painting.

kristleifur · 2011-06-19 1:57 pm

I like it 😀

Saturnus · 2011-06-19 2:19 pm

I love it. Bring it to the Boominator meet up, please.

Nahaz · 2011-06-19 2:23 pm

It's sort of a "cartoonish" steam punk look to it I think. Unfortunately there is a lot of dust and crap in the clear coating which does not look very good. But after all it is a Roskilde boombox, it will be scratched and get dirty sooner or later.

Nahaz · 2011-06-19 2:25 pm

Ill be there:

Tuesday, June 28, 2011 at 3:00pm
Agora G

ThokN · 2011-06-19 3:03 pm

Nahaz said:
Hello again, I finally got the boominator back after the paintjob.
So yesterday we had the first field test at a party.

I notice that the sound become very distorted on lower volumes than expected.
I verified that its not the speaker/box by connecting it to my home hifi system and here I can play fine to ridiculus volume levels with far less distortion than with my lepai/battery setup.

Also Ive noticed that if I max out the volume knob on the lepai the bass is non existant pretty much. Even if the source volume is turned down (not playing at max). If I lower the lepai volume knob to about 75% the bass comes back. This in itself is not a major problem the volume is far too high even at 75% when the source is maxed. But maybe it can give a hint as to what might be the cause of the distortion?

Measured voltage on the batteries today is 12.1V

I will continue testing with Trends audio amp with external pre amp (the trends audio can not reach the volumes where I have distortion issues with the lepai without a pre amp).
I will also test using regular power supply (not battery) to rule out power as the root cause of this problem.

But meanwhile it would be great if anyone had tips on what might be the problem.

I actually experienced the same thing, but with a small homebuild boombox with the SP-60/4's. I thought it was because of wrongly dimensioned enclosure, but now you have made me think twice... Is the amp really not capable of playing at 100 volume without distorting? That would be bad 🙁 Anyway, I think I will try to change the input caps to 0.47uF as recommended by Saturnus (I think..or V-Bro, don't remember), and hopefully that will remove some of the distortion.

Anyway, if it can help you, we tried to cut off the frequencies below 125Hz on the MP3-player, which helped, but didn't remove it completely.

I hope it was just the wrong dimensions, since I'm building a small box myself which I have used a lot more time on, but I will first have the speakers tomorrow and test Wednesday or Thursday to see if correct dimensions solves the problem. I can post the results here if you are interested.

BTW...What an awesome paintjob 😀

joak0068 · 2011-06-19 5:34 pm

So... I'm gonna ask, like many others, about the wirering 🙂

I have bought a 6W solar panel Rated 0.4A @ 14.5V.

Can i connect this directly to my battery, without a charge regulator?

I will be using 2 Yoasa 7,2Ah batterys, don't know if i should parralel them?

DanielClark91 · 2011-06-19 6:06 pm

joak0068 said:
So... I'm gonna ask, like many others, about the wirering 🙂

I have bought a 6W solar panel Rated 0.4A @ 14.5V.

Can i connect this directly to my battery, without a charge regulator?

I will be using 2 Yoasa 7,2Ah batterys, don't know if i should parralel them?

Yes.

You should parallel the two batteries to form a 14,4 Ah 12v battery (acting as one big battery)

Kostecki · 2011-06-19 8:26 pm

Kostecki said:
Our boombox is as close to being finished as it can be. It's assembled, painted and everything, but yesterday when we had assembled everything we discovered a tiny little crack on the raised part of the "kantophæng" (don't know the english word) on one of our bass units.

It looks like this: http://dl.dropbox.com/u/170632/crack.png

Are there an easy fix for this?

I'm sorry for "double-posting" but i can't just let my question drown since i really need some clarity on this 😱

Saturnus · 2011-06-20 8:59 am

Kostecki said:
I'm sorry for "double-posting" but i can't just let my question drown since i really need some clarity on this 😱

What material is it? Those driver look like the suspension is made of some kind of synthetic rubber. In that case head to your local hardware store and ask how to repair it but you might get away with just using a small strip of extra strong duct tape. Or regular duct tape and one component contact glue.

Boissez · 2011-06-20 12:14 pm

Battery musings...

Hello everybody, first time poster here. :wave:

I've been reading back and forth in this thread (and around the webs) but I have a hard time gauging what kind of battery life to expect from different battery solutions.

What I wan't to build is an 'airline-friendly' setup (must fit in overhead compartment, max 5-6 kg). It's somewhat more classic than the boominators here but I'm looking for a setup that can double-duty as a real audio player when travelling - so stereo is a must.
Here are the components I'm considering so far:

- Hifimediy T1 or T2 (TK2050) - (not sure which to get 😕 )
- 22.2V LiPo Battery (ca. 4000 mAh) + balanced charger
- 2*JBL control 1Xtreme monitors (have those already) 8 Ohm, ~90db

My (totally unqualified) guesstimation is that I can count on about 2-3 hours battery @max and 20-30 hours @ more conversational levels.

Question is now... Am I completely wrong? And what would you suggest I do differently to optimize battery life?

PS: I apologize in advance if this is the wrong place to post this. I simply figured that people in this thread would have a great deal of experience with class D's + batteries.

Saturnus · 2011-06-20 1:25 pm

Boissez said:
My (totally unqualified) guesstimation is that I can count on about 2-3 hours battery @max and 20-30 hours @ more conversational levels.

That's slightly optimistic. 2 hours @max should be doable but only 10-12 hours @ very low volume.

I'd advice to get much more sensitive speakers though as those you have will probably mean you use way too much power by needing to turn it up higher.

Boissez · 2011-06-20 2:29 pm

Saturnus said:
I'd advice to get much more sensitive speakers though as those you have will probably mean you use way too much power by needing to turn it up higher.

I was fearing somebody would say that... But thank you for confirming my fear 😉

Problem is that tiny efficient speakers are few and expensive - not something I'd travel with. Frankly, I haven't found any other speaker that really beats these in terms of efficiency vs size/weight (they are only 2.35 kg each and 23x15x14cm).

It does trigger another question though: would using a smaller amp help? I know these are supposed to be ~90% efficient - but does efficiency drop noticably when it plays at say 10% volume?

Otherwise I guess that I'll just have to tone down expectations and try to fit a larger battery to the amp. 😉

Wubbaz · 2011-06-20 2:45 pm

Sorry for asking this again, but I am in doubt of how I should make the central connection point.. just take all plus wires to a buttsplice and then take all the minus wires and then into a buttsplice? Red is plus, blue is minus

Thanks!

Saturnus · 2011-06-20 2:52 pm

Correct. Except for the small change. Note the connection on the batteries.

Wubbaz · 2011-06-20 6:15 pm

Saturnus said:
Correct. Except for the small change. Note the connection on the batteries.

Cheers, Saturnus! Just need to fit the HP-10W's and the electronics, then I'm finished.. won't be able to paint it before Roskilde 🙁

But thanks alot for all the help you have been! Really appreciated 🙂

donnib · 2011-06-20 8:51 pm

Phaedras · 2011-06-20 11:57 pm

donnib said:
(...)

Wow, thats a lot of links gathered, good job 🙂

I notice you also added a link to my cabinet blog entry - i'm glad its helpful 🙂

Phaedras · 2011-06-21 12:28 am

I would like to remind people of the Boominator Meet-Up @ Roskilde Festival. Its Tuesday the 28th of June, at Agora G @ 15:00 (3pm)

Meet-up!

Also, go check out the Boominator facebook page for pictures and stuff 🙂

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The Boominator - another stab at the ultimate party machine

kristleifur

Nahaz

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kristleifur

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