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-   -   newbi chip amp questions. (http://www.diyaudio.com/forums/chip-amps/215933-newbi-chip-amp-questions.html)

iggy18 10th July 2012 07:00 PM

newbi chip amp questions.
 
I have a few questions about the tripath amps. I would like to build one for use in a portable audio solution powered by a 12 volt SLA battey. I will have four speakers wired up at 8 ohms and the biggest speaker requires 70 watts rms.

my questions are...

have any of you built one of these tripath amps and then powered it with a 12 volt battery? could you recommend one to me for this particular setup?

25 watts would work but I would like 50-100 watts. the chips I've found so far have been at most 25. are there any high powered tripath amps out there that you would recommend. (still, compatable with a 12 volt SLA battery)

i would like to have tone and volume control. the tripath amps i found haven't had these. is there a seperated chip or thing I could build that would give me control of the bass, treble, and volume with knobs?

thank you in advance for your help :D

picowallspeaker 10th July 2012 07:29 PM

Quote:

i would like to have tone and volume control. the tripath amps i found haven't had these.
Oh boy ! I think I wouldn't ever post such a link ..
But here it goes :
2.1 TK2050X2 50W+50W+100W Class D Tone adjust amplifier board | eBay
If you read : the lower the voltage , the lesser the output power :o

iggy18 10th July 2012 08:22 PM

wow, that looks like what I need. i just have to figure out how to chance 12 volts into 28 volts. thanks for the link!

johnr66 10th July 2012 09:16 PM

For a bridge amplifier and 4 ohm load, the best you can get is around 12 watts before clipping. You would have to use two of your 8 ohm speakers in parallel per channel. To get a clean 25 watts, you need a Vs of around 16 volts. If you can use two 12v batteries in series for 24v (around 25.2) you can get ~33 watts into an 8 ohm load.

iggy18 11th July 2012 01:27 AM

so basically, these little amps aren't so awesome with a 12 volt battery aplications? is there some little box or coil that could turn 12 volts into more volts? like how a stun gun turns a 9 volt battery into 20,000 volts?

johnr66 11th July 2012 03:04 AM

Let's say we have a perfect amplifier of the bridged tied load type (perfect in that it can swing from rail to rail on the output into a 4 ohm load).
(Vsupply/sqrt2)^2/RL = max out put watts before clipping.
So, (12/1.41)^2/4 = 18 watts

In the real world the amplifier cannot swing to the rails, so the output power is something around 12 watts. To get more power, you could lower the impedance if the amplifier can handle the increased current or raise the supply voltage. I've also seen rail lifting charge pump designs used as well.

To make a long story short, it is not the limitation of the particular amplifier, it is a physical limitation due to the supply voltage. You can certainly use a 12v to 24v converter to boost the voltage.

Arty 11th July 2012 03:03 PM

http://www.datasheetcatalog.org/data...ps/TDA1562.pdf
thisone uses class H to get you smewhere near 60 watt output power from a 12v SLA battery.
(4 ohm, naturally, from 8 ohm it will deliver less.)

Audio Designs With Opamps -2
and an exellent article on how to make tone controlls.
opamps are best at dual supply, but no reason why not just use a resistive voltage divider to power them, in this case.

volume controll can be a single pot.

johnr66 11th July 2012 04:47 PM

Quote:

Originally Posted by Arty (Post 3088680)
http://www.datasheetcatalog.org/data...ps/TDA1562.pdf
thisone uses class H to get you smewhere near 60 watt output power from a 12v SLA battery.
(4 ohm, naturally, from 8 ohm it will deliver less.)

That is exactly the chip I was thinking of when I mentioned the pump capacitors. It is rated at 14.4 volts which is the typical max voltage from the alternator of a running car. The loaded battery will provide an average of around 12 volts as it is being discharged. Output power will be significantly less, but still in the range of what to OP needs.

iggy18 12th July 2012 02:18 AM

Quote:

Originally Posted by Arty (Post 3088680)
Audio Designs With Opamps -2
and an exellent article on how to make tone controlls.
opamps are best at dual supply, but no reason why not just use a resistive voltage divider to power them, in this case.

I found a kit here Stereo Pre Amp with Tone Control

do you think this would be a good place for me to start?

I'm completely new to circuitry. I haven't even soldered anything yet. I'm just getting into it, and I'm having a hard time finding educational material for an introduction. I was thinking I might practice with this amp 41Hz Audio:AMP4 kit

combine it with the tone control and put it into a pair of these Google Image Result for http://gadgetsin.com/uploads/2010/08/handmade_pvc_pipes_speakers_1.jpg


I know it won't sound the best but it seems like it will be a fun project. what do you think?

Arty 12th July 2012 05:48 PM

oh boy.
i beg You, to read my post.

If, -as it seems so- You Sir are new to all and every aspect of electronics and speakers, please accept my advice.
There is a good reason behind it.
Start with something simple, something that is sure to be managed,
something that can be completed without major challange, to ensure the statisfaction of:
succesful creation.

What You are about to do is not particulary hard, but if its a first project, then You may fail.
Faliure is not a bad thing, as long as one manages to learn from it.
On the otherhand, faliure may take away the joy.
Success in a smaller project would yield quite a bost of moral, and still pays off with experience, a value -sadly- not apprecited nowdays.

The "i know it won't sound the best" part is actually verry wrong.
Even "junk" can be made to sound better than majority of commerical "stuff".

Please, describe what You wan't to do in the first place.
Is it an automotive Hi-Fi, a home Hi-fi,
what can You get Your hands on?
What tools You have acces to?
What is the budget You can spend?
Online stores where You can order stuff?

Those informations -when provided- will help to figure out a project that is fun, and yields results You may seek.


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