| How big of an amp can I make with this? - Click HERE for Original Thread |
| ew |
| Greetings, I recently picked up a rather large transformer 30-0-30 670VA & am looking to make a ridiculously large chip amp. Any ideas? |
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| SpittinLLama |
at 30-0-30 the supply voltage will be pretty high so you will probably need to run into 8 ohm loads unless you parallel some chips. If you went with straight LM3886 you should be able to get 6x60W into 8 ohms, give or take. So 360W of output power. If you wanted one large amp then you'd need to do 4xLM3886 bridge/parallel (BPA) or a 6 chip version, 3 in parallel on each side of the bridge. Just some ideas. Power output is a guesstimation.
-SL |
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| AndrewT |
Hi,
30-0-30Vac would be a good start for a 4ohm amplifier.
BUT
It would better suit a discrete design with that sort of voltage.
Parallel pairs or triplets of chipamps starts getting beyond the simple intention for using a chipamp.
working backwards from your transformer rating
670VA supports about 420W of output power.
This could be 210W+210W into 4ohm
but this needs 35-0-35Vac to get the necessary DCrail voltage.
or
140W+140W+140W into 4ohm. That is about perfect for 4ohm drivers and running on +-44Vdc
Ah! a three channel front of house amp for a 5.1 system. |
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| ew |
| the 140x3 sounds interesting & just oddball enough to get my attention. Would how many LM3886's per channel would such a beast require? thanks again! |
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| AndrewT |
Hi,| quote: | | Parallel pairs or triplets of chipamps starts getting beyond the simple intention for using a chipamp. |
how many? a lot! an awful lot!!
and the voltage does not suit chipamps.
Have another read of the datasheet, particularly the
supply voltage vs load impedance
and dissipation/heatsink vs (load + voltage). |
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| ew |
| Could the high voltage be taken care of by using a regulated ps? Also, could I use something like Brian GT's LM3886 Stereo Kit x3, one for each channel to keep things simple? Thanks again. |
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