1000 Watt LM3886 Or TDA?
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 7th May 2012, 02:14 AM #1 binsky3333   diyAudio Member   Join Date: Sep 2010 1000 Watt LM3886 Or TDA? Hello everyone! I am a bit curious as to how to get high power out of some LM3886 or TDA chips. I am looking into buying a 1600 watt 8 ohm sub woofer and was wondering how i can put around 1000 watts into this. I was looking at using a lot of LM3886 chips/kits. I ran across the BPA200 schematic and was wondering if something like this would work. Bascially 2 x 4 LM3886's in parallel and then bridged. Would 2 x 8 LM3886's in parallel then bridged add more power? Or would that just split up the load? Thanks in advance!
 7th May 2012, 03:35 AM #2 gootee   diyAudio Member   Join Date: Nov 2006 Location: Indiana There are some basic power equations that impose some limits. Power to a load R will be P = VČ/R which is equivalent to P = IČR. Those expressions are valid for DC and for RMS AC. We can also solve them for voltage and current: V = √(P R) and I = √(P/R) So, for 1000 Watts into 8 Ohms, V = 89.44 Volts RMS V peak = (√2)(V rms) = 126.5 Volts peak That's more voltage than the chipamps can handle. The only way to get that much power with a lower voltage would be to lower the R value.
binsky3333
diyAudio Member

Join Date: Sep 2010
Quote:
 Originally Posted by gootee There are some basic power equations that impose some limits. Power to a load R will be P = VČ/R which is equivalent to P = IČR. Those expressions are valid for DC and for RMS AC. We can also solve them for voltage and current: V = √(P R) and I = √(P/R) So, for 1000 Watts into 8 Ohms, V = 89.44 Volts RMS V peak = (√2)(V rms) = 126.5 Volts peak That's more voltage than the chipamps can handle. The only way to get that much power with a lower voltage would be to lower the R value.
Wow thanks for the great information! I guess it looks like im either gonna have to find a 4 ohm sub or wire two of these in parallel. I can't even think of a chip amp that's capable of putting out 100 volts. I know the lm3886 is capable of about 40 volts... but does anyone know how many volts bridged? I guess I would only be able to achieve 500 or so watts at around 40 or 50 volts with the lm3886. Anyone have any other amp suggestions?

Thanks!

 7th May 2012, 11:33 AM #4 KatieandDad   diyAudio Member     Join Date: Nov 2011 Location: UK Bridging the 50W LM3886 may develop about 200W in Bridge Mode. I posted an article at Maplin Sub-Woofer Project which explains the maths behind bridging amplifier modules. You'll need to drill down to Post #4 Last edited by KatieandDad; 7th May 2012 at 11:36 AM.
diyAudio Member

Join Date: Nov 2011
Location: UK
That doesn't compute with the article that I posted above.

Their maths shows that you can get 4 x the power of a single amplifier module.

If their maths is wrong then I will eat my words.
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Last edited by KatieandDad; 7th May 2012 at 12:16 PM.

 7th May 2012, 12:23 PM #7 AndrewT   diyAudio Member   Join Date: Jul 2004 Location: Scottish Borders Their assumptions are wrong. That invalidates the maths. __________________ regards Andrew T.
 7th May 2012, 12:31 PM #8 binsky3333   diyAudio Member   Join Date: Sep 2010 Sounds like 49811 is what I need. It seems as though the max I can get out of a 3886 is around 400 watts. Using the bpa200. Is it possible to bridge two 3886s, then bridge another 2 and then bridge the outputs from the two bridged sets?
AndrewT
diyAudio Member

Join Date: Jul 2004
Location: Scottish Borders
Quote:
 Originally Posted by binsky3333 ........... It seems as though the max I can get out of a 3886 is around 400 watts............
No, max is ~68W
Quote:
 Is it possible to bridge two 3886s, then bridge another 2
No, I explained the options by referring to the BPAx00 arrangements.
__________________
regards Andrew T.

 7th May 2012, 12:39 PM #10 KatieandDad   diyAudio Member     Join Date: Nov 2011 Location: UK 400 Watts is certainly pushing the limits of any assumptions in the maths. 150W in bridge mode is certainly possible. More can be achieved into lower impedance loads with paralled LM3886s. But why would you want to go down that route with easilly available Class D amps that can do 600W.

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