Bought a TPA3116 : Notice static at mid-higher volume

NattyBoh

Member
2016-02-22 1:58 am
So I bought this: New Silver HiFi 2 0 Stereo Output Digital Power Amplifier TPA3116 50WX2 | eBay Cheap I know, but I noticed a few things... If there is no audio going thru it, there will be some static/electronic noise coming thru the speakers. Also when playing, I noticed that the audio ( the song being played ) will have a weird alteration to it. Its hard to describe, but Im thinking its something maybe to do with heat? I dont see how though as it runs pretty cool. Maybe this is a common problem on both account above? thanks!
 

bullittstang

Member
Paid Member
2013-05-09 2:14 pm
Ft. Worth, TX
Have you made sure your RCA's are clear of any PSU bricks? I had a similar hiss/noise that was due to a cheap RCA cable and it's close proximity to a laptop brick. I changed the RCA to a better shielded one got rid of most of it, then rerouted the wire farther away from the PSU and got rid of the remaining noise. Just a suggestion to try.
 

mrWagner

Member
2006-10-27 1:34 pm
I'm also testing with this amp.
You can find more about it in the main TPA3116 topic as "breeze".

I also have hiss. Tried to put more caps directly on the power legs, but didn't help.
Replaced the input cap, didn't help.
Powered it with lab supply, didn't help.
Then lowered the gain and it helps with the hiss. Doesn't "solve" it, but lowers considerably.

It runs cool as without sink at low volume the chip was 32°C for me (about 22°C room temp).
Probably if the analog power input was not directly connected together with the digit power, it wouldn't have so much noise. It helped with other TPA3116 amps, but here the connection is under the chip, so you don't have much chance to separate them.
 
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What sensitivity are your speakers that you get noticable hiss? My tannoys are 88dB. I run the same (WLX/Breeze) board in a home built case fed by a Raspberry Pi + DAC. I get no noticable artifacts or hiss. I'm running it off an old IBM Thinkpad SMPS - 16V. The RPi runs off either a Nokia phone charger or other 5V uUSB power supply.

J.
 

trashcanz

Member
2016-01-14 8:49 pm
I thought 50k pots were the correct value to use for these amps due to the tpa3116 wiki here on the forums. The dual chip tpa3116 has a 50k pot stock that I changed to an 50K ALPS blue. At 36db gain, there was a loud hiss after passing the first quarter of the pot's range. There were little usable volume range. However, there was no hiss throughout the range of the pot after I changed the gain of the amplifier to 26dB.

I have been using alpha 10k linear pots that doctormord recommended. No hiss at all when used with tpa3116, tpa3118, tda8932... at any gain level.
 

No, NOT that one - and here's why:

1) that's a MONO potentiometer. You need a stereo potentiometer for a stereo amplifier: the potentiometer needs to have 6 pins, and the one you linked has only 3 pins (it's a mono pot).

2) That's also a linear pot: although linear pots will work, it would be better to use logarithmic potentiometers - the volume change will be more "natural".

In short, something like this:
10K Ohm Logarithmic Dual Rotary Taper Potentiometer A10K 10KA Pot Alpha | eBay

That's the one drmord also recommends :)
 
maybe this will help explain.

I've been swapping betwen a solid state vol control (pga2311 style) and a relay r2r style atten (which is passive if you don't add a buffer between its output and the tpa3116/8 input).

the relay atten I'm using (my own delta1) has a variable output z, just like a pot does. the usual config for a vol pot is to feed the previous stage into both ends of the pot, then take the wiper as the output of the pot and the ground (end) wire. as you vary the pot, you do vary the output z.

it seems this affects the TPA amp.

when I use a pot, the output z varies in a smooth and regular fashion. its a simple linear device.

but many relay attens (mine, for example) jump around on output z as some resistors engage and some are bypassed. its binary and so you get a pattern of ONs and OFFs and it does NOT climb or sink in a regular fashion. as you get binary rollovers, for example (31 to 32 or 7 to 8) you see a huge change in relays and configuration and you HEAR the noise level jump (and stay) at that point until you change to some other vol value.

I was hoping I could run the relay atten directly to the tpa, but today's test showed that's a really bad idea. the noise level variations that seemed random (binary but seemed random) was too annoying.

the pga output is inherently buffered, constant z and low z on output. any change in hiss is due to the internal op-amp of the pga being more noisy as the gain is increased. but its smooth and does not jump in strange annoying binary jumps. to me, that makes it so much more usable.

the same kind of noise issue is with a pot, though. its not jumpy, but as you vary the control the output z varies and this messes with the input stage (it seems) of the tpa.

moral: use a buffer if you use a vol control the amazon/ebay board I got that had a vol control didn't have a buffer (most don't). therefore, midway it was very noisy and hummy and when set to full volume (when input is shorted to output on the pot) that was the least amount of noise.

its not the amp, really. its how you do the atten before the amp. it does matter!