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Old 1st February 2012, 09:35 PM   #1
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Default Planning a new boombox-build, help needed!

I have to apologize in advance as this is probably going to be quite a lot of text with a bit vague content (and I'm also not 100% sure I'm in the right forum, but I saw the boominator-thread here so I went with this). Not exactly sure where I'm going with this as it kinda depends on the answers I get here. Please bear with me.

So before a festival last summer I decided to throw together a boombox. I was very much in a hurry and didn't think through the build enough, which, as we all know, rarely is a good thing. The build consisted of a Lepai TA2020+, 2* HP-10T (I know now that I should've gotten the W-ones instead, but they were out of stock when I ordered so I took a chance with the T-version), 2* QLM-1005 piezos and a 12V 7.2Ah battery. I put it all together and it got us through the weekend, but I wasn't satisfied with the sound. Whenever I turn up the volume above ~half of maximum on the amp, the bass sounds broken and it's all just bad noise. Not sure if I did something wrong build-wise or if I'm just using the wrong components.

I got the impression that I wouldn't need any filters when using the piezos, but I guess that's not true, is it?

Since that one festival I've only had the box for indoor-use (for which it's working pretty good as the volume needed isn't as high) and I haven't really had the time to try to fix whatever might be working incorrectly. Now I'm thinking about getting this fixed, and as the case on the current boombox accidentally cracked, I got a perfect opportunity to start over completely.

I'm pretty sure I can re-use the piezos, the amp and the battery, but are the HP-10T's to any use at all? This is my main concern and the direction this thread will head in will be based on this. If I'm able to do something good with the speakers I have, I'm basically just going to rebuild and refine the case (and filtering? ), with the help of you guys. If I'm way better off getting other speakers, I might either go for the boominator (if I can afford it) or, preferably, a more mobile one. I understand that the boominator probably is unmatched research-wise, so to speak, but I feel there should be some other, smaller, boomboxes that's also been well tried out?

I'm thankful for all the help I can get and again, I'm sorry if I'm not that clear with my thoughts here. I will try to be more concrete as soon as I've figured out what to do with these speakers. I'm trying to read every boombox-related thread I can find, but there are plenty and the information-level is pretty varying. I thought it'd be easiest for me to have this thread aswell, to gather everything revolving my own projekt.
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Old 1st February 2012, 10:10 PM   #2
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One piece of the puzzle maybe: That thing where the sound goes south when you turn up the volume, AFAIK that's a Lepai thing. Bad input circuit implementation. As far as I know at least, from skimming the Lepai amp thread here a while back. I don't know for certain, but I'm fairly sure you can somehow bypass part of the input section of the Lepai - and add a regular off-board volume pot if you need a volume control at the amp.
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Old 2nd February 2012, 06:42 PM   #3
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Quote:
Originally Posted by kristleifur View Post
One piece of the puzzle maybe: That thing where the sound goes south when you turn up the volume, AFAIK that's a Lepai thing. Bad input circuit implementation. As far as I know at least, from skimming the Lepai amp thread here a while back. I don't know for certain, but I'm fairly sure you can somehow bypass part of the input section of the Lepai - and add a regular off-board volume pot if you need a volume control at the amp.
Thanks, I will look it up. Would be a simple solution to a rather annoying problem
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Old 3rd February 2012, 07:43 PM   #4
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How thick, or thin, are the wires going from the battery to the amp?

If you are using thin and long wires - the battery might not be able to provide the current the amp needs
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Old 5th February 2012, 02:18 PM   #5
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Originally Posted by Phaedras View Post
How thick, or thin, are the wires going from the battery to the amp?

If you are using thin and long wires - the battery might not be able to provide the current the amp needs
I have the same issues when playing without a battery too, i.e. when I have the amp plugged into a wall-socket.

I don't have another amp available right now, so I can't really do any testing yet. But let's assume the amp is working as it's supposed to, would the speakers be able to play clearly at low-mid volume, even if something is wrong with them? Or would the sound be bad even at lower volume?
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