The DIY 2.1 amplifier. Should I build it? Would you buy it?

[tyger23]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Using the amps for different frequency bands as you do in this 2.1 amp might eliminate any potential "beating". I've just read what it says in the datasheets, but I don't know how much you can actually get away with in real-world designs. Also, I'm not clear on whether the "beating" is a power supply issue or an artifact of the residual switching frequency in the outputs.

So I was wondering whether you have been able to experiment with the stock amps or whether you went ahead and tried to synchronize the clocks.

Hey Neil - Beat tones are real. Very, very real and very, very ugly. Oddly enough, though - they're showing up in a manner I did not expect. I was expecting the issue to be power supply related, but it's showing up as a magnetics issue on these TDA7492 boards. If you look at the picture where the two boards are mounted, you'll notice the magnetics are all in a line and all very close together. This is a big no-no in class-D world (as I'm sure you know) because of coupling. I could prove it was coupling just by moving one of the boards away from the other.

Sure enough, the switching frequency between the boards is not sync'd and the magnetics are coupling, showing up as a high frequency whine. Fortunately, the revision of TDA7492 boards I have (rev 3.1) has a test point pulled out for the SYNC pin, and the rework was straightforward and relatively easy. Better yet - it fixed the issue ;).

I'm not sure if the TPA3116 boards will need to be sync'd or not - their magnetics layout is different. I'll have to check that later.

[NickJ]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

I have been lurking and following this (and promising myself that, no in fact I don't need another amp), but I just wanted to say that you are doing awesome work.

[tyger23]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

You can't parallel-mono drive the 3116 though can you?

Oh- now that I see what you meant to make the 2.1 kit, I understand and like it quite a bit! Is the amp case an available item?
Later,
Wolf

Wolf,

The TPA3116 was specifically designed to support parallel mode. Just a small, easy rework to the board is required.

The case is here and will require some holes drilled in the back panel to accommodate the sub volume and extra speaker posts:
http://www.parts-express.com/aluminu...689-d--320-326

[Wolf]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Oh - it IS possible to use one TDA7492 and one TPA3116, if you so desired. You don't have to match both amplifiers.

You can't parallel-mono drive the 3116 though can you?

Oh- now that I see what you meant to make the 2.1 kit, I understand and like it quite a bit! Is the amp case an available item?
Later,
Wolf

[tyger23]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Thanks! Good to know, although more expensive.
Changing subject, do you have T/S parameters of the AC130F1? If I remember correctly you built a pair of Continuum.

That board is slightly cheaper from the YJ website, although you need to also purchase the cable to go with it (I learned the hard way). Not sure how shipping affects things, though.

http://www.yuan-jing.com/tpa3116-cla...-board-50w-50w
http://www.yuan-jing.com/shielded-au...-2-54-3p-awg28

I never took T/S parameters on the AC130. Since I was just building the Continuum kit, I never worried about it. I'm sure those are posted somewhere on this forum, or Jeff may be able to provide them to you.

[Silver1omo]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

No worries. PE now stocks the YJ TPA3116 board I also designed the board for. The TPA3116 is (at least numbers wise) a better performer.

http://www.parts-express.com/yuan-ji...-50w--320-6554

Thanks! Good to know, although more expensive.
Changing subject, do you have T/S parameters of the AC130F1? If I remember correctly you built a pair of Continuum.

[tyger23]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Oh - it IS possible to use one TDA7492 and one TPA3116, if you so desired. You don't have to match both amplifiers.

[tyger23]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Now the amps are out of stock in PE and the one I ordered from flea-bay did not arrive :(

No worries. PE now stocks the YJ TPA3116 board I also designed the board for. The TPA3116 is (at least numbers wise) a better performer.

http://www.parts-express.com/yuan-ji...-50w--320-6554

[Silver1omo]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Now the amps are out of stock in PE and the one I ordered from flea-bay did not arrive :(

[ani_101]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

It's alive!!!!! (Said with an evil Frankenstein laugh.)

Performing quite well. The 100hz crossover point I aimed for (different than the 80hz point in the schematics) is spot on. I had to make a few changes, but nothing major. I'll post a build thread once the pots I ordered a month ago from China actually arrive.

[ATTACH]52435[/ATTACH]

That is NICE!

[tyger23]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

It's alive!!!!! (Said with an evil Frankenstein laugh.)

Performing quite well. The 100hz crossover point I aimed for (different than the 80hz point in the schematics) is spot on. I had to make a few changes, but nothing major. I'll post a build thread once the pots I ordered a month ago from China actually arrive.

[tyger23]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

The board just soldered up really quickly. About an hour and a half and I'm done. There were several things I noted as assembling it - I'll post my thoughts on it later. Some components are a bit too close to the edge, but some tape should fix that issue. I'm a bit annoyed that DigiKey advertised the banana jacks I bought as "standard". They're not - they're mini or maybe proprietary. Oh well - that's something to tackle later. For now, I've got to go back to my paying job so I can spend some time bringing these up tomorrow.

[Silver1omo]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Nice!

[djg]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Awesome.

[tyger23]

Re: The DIY 2.1 amplifier. Should I build it? Would you buy it?

Just FYI - the boards and most of the parts arrived today. I already see a few small (not insurmountable) issues:

1. For whatever reason, they didn't use my most up to date silkscreen. Not a huge deal - my name just didn't get onto the board ;).

2. The mounting holes didn't get drilled out. Not sure why. Not a big deal, I just have to take a drill to the board unexpectedly.

3. I think I laid out the potentiometers backwards (as in volume up = volume down). I can fix this by cutting the traces on the board and re-wiring it. Pain in the rear end, but do-able.

On the plus side, it mechanically fits into the chassis! Yeah!







Obviously, I still need to cut out for the subwoofer volume pot and the extra speaker jacks, but it's well under way.