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Old 24th April 2012, 09:00 PM   #11
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Quote:
Originally Posted by sreten View Post
Hi, All 12V T-amps are already bridged output and you cannot bridge them, rgds, sreten.
counts volts on fingers and yes. Only about 4volts RMS, you're perfectly right. should have done that before, So, how are we going to get the best out of a stereo amp; biamping? Or just assume one side not working doubles battery life?
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Old 24th April 2012, 09:22 PM   #12
dangus is offline dangus  Canada
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Maybe it's a good idea to reverse engineer the power supply of a common Behringer or Mackie mini mixer to adapt it to 12V. You can't buy the parts to build one as cheaply.

Is there a mixer in Behringer's line of Mini devices? Those are very compact, but I suspect they all run off AC wall-warts. The BEAT800 phono preamp/beat counter uses a 1/2 wave rectifier to produce + and - rails from a 9V AC input. You might get away with substituting +12 and generating -12 or so with a DC-DC converter, if sharing a DC common with the power amp and other stuff isn't a problem. Otherwise, maybe an off-the-shelf DC-DC converter (isolated), or replace the rectifiers with faster ones and generate transformer coupled 9VAC somehow.
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Old 3rd July 2014, 06:13 PM   #13
jtay is offline jtay  United States
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Hello, I'm a newbie and looking to do the same thing. However, for me it's not so much about the money as it is what I get for the money. I was about to lay $500 out for a Roland Street Cube EX and learned that it didn't have phantom power for my mic of choice which adds another $50-100.

So I began the search for the best coaxial, high efficiency (preferably 99 dB or higher to maximize battery power) with the biggest frequency response (covering woofer, mid, tweeter frequencies all in one speaker) and light weight for ease of transport. Not long ago this would have been considered a pipe dream but not now. It looks as though I have found the perfect speaker for the ultimate busking amp. It's not cheap, $520 plus shipping but considering it meets all of my requirements, I'm willing to cough up the $$$:

http://beyma.com/uploads/ftp/Fichas_.../000000591.PDF

I will pair this speaker with a 12V class D car amplifier (I will use 8 AA battery pack = 12v) and a battery powered (requires 3-9 volt) Behringer XENYX 1002b mixer all of which I will fit in a medium size roller suitcase. Then just unzip suitcase and start playing.

However, my shortcoming is understanding why said speaker manufacturer recommends using Beyma FD2XA two way crossover? I thought one advantage of using a coaxil speaker was because they typically don't require crossovers? If someone could explain this to me I would greatly appreciate it. Also, another point of confusion is the LF is 8 ohms while the HF is 16 ohms. Although I may have this figured out? 16 ohms cuts your amp power in half as compared to 8 ohms which makes sense as the wattage capability of the HF is typically much less than the LF. Is my thinking regarding this issue correct?

Any and all advice is appreciated. Thanks in advance!
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Old 3rd July 2014, 11:33 PM   #14
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Don't think AA batteries will last long powering a car amp. A small chip amp like a TA2020, yes... car amp, no...
Look at rechargable batteries, like a decent SLA or LiPO, and perhaps consider a MiniDSP for crossover
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Old 4th July 2014, 12:47 AM   #15
JMFahey is offline JMFahey  Argentina
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Agree.
Quote:
12V class D car amplifier (I will use 8 AA battery pack = 12v)
Battery life will be measured in minutes.
For street/subway busking the absolute minimum is a 12V 4.5AH Gel/Sealed/Alarm lead acid battery (what Fender Amp Can, Pignose Hog 20 and similar commercial amps use) , and if you stand an extra pound weight, a 12V 7AH one which surprisingly costs the same or less, being the most popular one.
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Old 4th July 2014, 01:15 AM   #16
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Get real .......
https://www.youtube.com/watch?v=kVAZIDFMRXY
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Old 6th July 2014, 10:06 AM   #17
jtay is offline jtay  United States
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Default Thanks guys for your input!

I don't know much about batteries and just now learning. What I do know is the Roland street cube EX uses a 12volt battery pack made out of 8 AA batteries and it powers a class D amplifier which is what car amplifiers are. So I assumed it can be done ? And, if not, then I will have to go to another type battery as you suggested and maybe even a 12v deep cycle battery?

Here are some interesting links regarding batteries:

Make a 12V Battery Pack With AA Batteries | DoItYourself.com

Battery Capacity

I also have another breakthrough. Thank God, Yamaha wised up and recently came out with their 12v mixers. Now I can use the same battery or pack or two packs (one for mixer and one for amp) to run the mix-board. Here is the one I will use. Much better quality than the Behringer too!

Yamaha MG06X | Sweetwater.com

Thanks for the link on the bicycle generator too! Amazing stuff! Gives me hope that I can design the ultimate busking rig.

Comments are much appreciated! Keep 'em coming!
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