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Old 22nd November 2005, 06:14 AM   #1
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Default Portable Class D Power! Choices?

Hi all, I've been perusing this section for a while trying to determine which class D amp is for me...

Basically i want to make a good quality, reasonably loud, portable stereo.It will run off a ipod 80% of the time, so audio perfection is never going to be the goal, but i'd still like it to sound nice.

So far i've come up with a PAE 8" woofer, and vifa tweeter that should go together alright, and both have about a 90.5db sensitivity. Also it should have a decent low end extension, as the 8" has a Fs of around 35Hz.

My next step is to chose the amp to run it...It needs to:

- Run off a 12v SLA battery (best value source of power)
- Get reasonably loud (outside this is) so no room gain etc. But obviously not "party" levels.
- Sound nice!
- Easy to make
- Cheap-ish

So far the number one candidate seems like a "Charlize" but i was wondering if there were some class-d amps that traded a LITTLE of the sound quality for a little more power?! Or is the Charlize still a pretty good bet. (I like the price, and its premade, i jsut worry about its lack of power!)

Thanks for the help!
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Old 22nd November 2005, 09:48 PM   #2
Pano is offline Pano  United States
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Your problem isn't quality vs. power, it's voltage/power.

Running from 12 volts you'll never get much power, the T-amps do all they can to give you the maximum. That's around 15 watts.
If you want more power, you need more voltage. Car amps chop up the DC, bump it up thru a transformer, then turn it back into DC.
That's how they get the higher powers. That, and "marketing magic."

So if you need more power, like for outside, you need higher voltages. How you get them is up to you.
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Old 22nd November 2005, 10:37 PM   #3
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A good deal right now is the Blaupunkt pa2150
Search around, you'll find them for under $100 USD for 150W x2 full range.
Much cheaper than you could make one.
But maybe bigger than you're looking for.
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Old 22nd November 2005, 10:52 PM   #4
BWRX is offline BWRX  United States
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I don't mean to peddle what I have up for sale in this forum but I have a good match for your requirements.

I've got 2 assembled amp3's for sale that would work great with your battery supply and your speakers. Even better is that you could biamp your setup - one amp3 per channel - for more power and more output.

http://www.diyaudio.com/forums/showt...068#post758068

Contact me through the forum if you're interested. I'd probably give you a little discount if you wanted both of them since I just want to get rid of them right now.
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Old 22nd November 2005, 10:55 PM   #5
indoubt is offline indoubt  Netherlands
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You cannot bridge these tripaths (AMP3 and alike). You might however get a little more out of them if you just use one channel.

I'm running an AMP3 on 14.3 Volts at the pins and it is really quite loud. Maybe it will be sufficient
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Old 22nd November 2005, 11:05 PM   #6
BWRX is offline BWRX  United States
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I was saying that he use one amp per speaker and have each channel of the amp drive a separate driver. So one channel of an amp3 would drive the tweeter crossover and tweeter and the other channel would drive the woofer crossover and the woofer. Same for the other speaker. That way you have more power per channel than if you were using a single amp for both channels.

I believe that would qualify as truly portable hi-fi.
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Old 23rd November 2005, 10:37 AM   #7
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I don't really think a car amp would be the best choice as it would be a lot less efficient than class d amp, like the tripath chip ones. It would obviosuly be a lot louder, but then i'd need a full size car battery! Things will be getting a lot less portable!

Its not meant to be ear-bleeding loud by any means, just about the same as those all-in-one cd/radio/tape players that run on 8 D cell batteries. (Why is it so hard to comapre volume levels in words?!)

Basically the whole point of the project is to make something that sounds a bit better than the all in in stereos that are available. (You know the ones that have a pair of little 3-4" full range speakers in the plastic molded enclosure)

BTW is there anyway of using a multimeter on the speaker termials to analyse how many watts an amp is putting while listening to music.
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Old 23rd November 2005, 11:04 AM   #8
Pano is offline Pano  United States
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Quote:
Originally posted by Andres83
it would be a lot less efficient than class d amp, like the tripath chip ones.
There are Tripath amps made for cars, but they are likely bigger than you want. The DC/DC conversion uses power, too.

Quote:
BTW is there anyway of using a multimeter on the speaker termials to analyse how many watts an amp is putting while listening to music.
No easy way, no. You can do it with pure tones, though.
But you would need to know the sensitivity of the speakers. Maybe a better bet would be to use a sound level meter. Find the level you like, then you can start to calculate how much power you'll need for your drivers.
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Old 23rd November 2005, 11:09 AM   #9
Pano is offline Pano  United States
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BTW, which Peerless 8"? The 850490? Pricey, but very nice.
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Old 23rd November 2005, 11:17 AM   #10
Kenshin is offline Kenshin  China
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Quote:
Originally posted by Andres83

Its not meant to be ear-bleeding loud by any means, just about the same as those all-in-one cd/radio/tape players that run on 8 D cell batteries. (Why is it so hard to comapre volume levels in words?!)
These are no more powerful than 10 watts.
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