TPA3116 Modifications

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Hey guys,

I just looked at this thread on PE (TPA3116 2.1 Amp - Step by Step Modifications -

Techtalk Speaker Building, Audio, Video Discussion Forum
) and unsure if anyone can assist?

I'm particularly interested in the:
There are two 1uf signal coupling caps between the L-R input volume pot and the chip's input. With the chips impedance impedance (30K w/gain set at 26dB), these caps form a 1st order HP, F3 = 5hz. The schematic has a table with cap values for increasing that F3 relieving the L-R speakers from some bass duty.
I'd love to get the tweeters to crossover at around 100hz, would this be doable at all, not quite sure if I can replace some caps as per the original article? Would certainly be much cheaper than mucking around with buying three crossover modules! Unfortunately my schematic and audio knowledge is relatively low compared to my soldering knowledge!


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If you can locate the input caps for the Satellites you should be able to install lower value caps to drive up their low frequency cutoff somewhat. But there are a few caveats...

1) Reducing the cap values from design specs could have an effect on the noise floor of the amp and might also raise some minor stability issues.

2) If the caps are surface mounted it's going to be a real pain to change them.

I would suggest you change 1 cap first, compare the channels and if all is good, do the other one.

If you hit a problem put the original cap back and look for another solution.
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It is worth a try, even as you will only get a 6dB/oct high pass, this will take quite some load away from you satellites. If one had the schematic for this amp, it would probably be possible to use another capacitor in one of the OP-amps stages. This makes a 12dB filter, which is usually a very good choice for 2.1 HIFI systems.

Please be aware that the 3116 chip is not a sub woofer amp, as it´s output is limited. It only has more power than the other two channels, if the woofer has lower impedance!

The very optimistic 100 watt rating is only near to reality, if you have a 24 volt power supply (5-6 ampere would be fine) and use a 2 ohm woofer, or two 4 ohm in parallel.

If you, maybe change the often fake TI OP-amps for real NE5532, you should have a very fine amp.
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