TLDR: If you have extremely sensitive speakers the first watt is phenomenal-- there is magic in there. There is significant and noticeable distortion when these are pushed to what I consider normal listening levels (loud) on 88db-ish speakers. I moved on to a TI TPA3220 EVM after these mods and it blows it out of the water in every metric. But costs 10x as much.
Disclaimer: this is a hobby and I find it fun to futz and all of my testing is done by subjective listening, take it with a grain of salt.
I tried to get every ounce I could out of these little boards after being pretty turned on by their stock setup-- I find them preferable to the 311x series and still do, warts and all. After much trial and error this ended up being the best sounding set of tweaks to my ears:
-Dual Meanwell 28v/5a SMPS with Full Wave rectifiers for each board (This is sort of my default power bank for testing boards)
-3x3300uf caps for primary DC input (yeah yeah inductance)
-0.68uf WIMA input coupling caps sounded best to me (the pics are different caps, try your own!) it's important to make sure the negative terminal coupling cap is attached to the PCB between PIN3 and the ground plane soldering location that the SMD cap was removed from. Will not work if connected directly to your negative cable, though positive (signal) will just fine.
-Set one board as MASTER and the other as SLAVE by putting a 39Kohm resistor between PIN32 and PIN10. Set the SLAVE by connecting PIN33 between both boards. This had the most dramatic ROI of any alteration.
-Replaced the output LC filter with various types, the best being 15uh/.68uf to my ears and mood. This is fairly simple to do and probably second best ROI if you're interested in playing with these boards.
I agree with danielwritesbac's assessment that there is some old school transistor vibe to these chips. That 70's Sansui/Marantz lushness is there, like a pantyhose filter on a camera lens. Very listenable. You stop caring about the set up and start enjoying the music.... then you turn it up and disappointment kicks you in the teeth. Especially because, for me, these sounded terrific with rock such as The White Stripes and Royal Blood. The 8932 just doesn't have the guts before very noticeable distortion cripples the fun. I haven't looked yet because, well, time and life, but hoping NXP has an offering with a bit more muscle in the same family. If they don't wish they did. (Just looked, seems they do, the 8954. Boards are $50. Got the 8932 for $3.50 ea., if you want to pay around 5x less a lot of people will be happy with the 8932. It's a the audio equivalent of a Civic with a few simple mods.)
All of my testing is done with the same PSU, TONE1 DAC and either a PEC or ALPS 20K pot. Moving on to 3221s/3225s!
Disclaimer: this is a hobby and I find it fun to futz and all of my testing is done by subjective listening, take it with a grain of salt.
I tried to get every ounce I could out of these little boards after being pretty turned on by their stock setup-- I find them preferable to the 311x series and still do, warts and all. After much trial and error this ended up being the best sounding set of tweaks to my ears:
-Dual Meanwell 28v/5a SMPS with Full Wave rectifiers for each board (This is sort of my default power bank for testing boards)
-3x3300uf caps for primary DC input (yeah yeah inductance)
-0.68uf WIMA input coupling caps sounded best to me (the pics are different caps, try your own!) it's important to make sure the negative terminal coupling cap is attached to the PCB between PIN3 and the ground plane soldering location that the SMD cap was removed from. Will not work if connected directly to your negative cable, though positive (signal) will just fine.
-Set one board as MASTER and the other as SLAVE by putting a 39Kohm resistor between PIN32 and PIN10. Set the SLAVE by connecting PIN33 between both boards. This had the most dramatic ROI of any alteration.
-Replaced the output LC filter with various types, the best being 15uh/.68uf to my ears and mood. This is fairly simple to do and probably second best ROI if you're interested in playing with these boards.
I agree with danielwritesbac's assessment that there is some old school transistor vibe to these chips. That 70's Sansui/Marantz lushness is there, like a pantyhose filter on a camera lens. Very listenable. You stop caring about the set up and start enjoying the music.... then you turn it up and disappointment kicks you in the teeth. Especially because, for me, these sounded terrific with rock such as The White Stripes and Royal Blood. The 8932 just doesn't have the guts before very noticeable distortion cripples the fun. I haven't looked yet because, well, time and life, but hoping NXP has an offering with a bit more muscle in the same family. If they don't wish they did. (Just looked, seems they do, the 8954. Boards are $50. Got the 8932 for $3.50 ea., if you want to pay around 5x less a lot of people will be happy with the 8932. It's a the audio equivalent of a Civic with a few simple mods.)
All of my testing is done with the same PSU, TONE1 DAC and either a PEC or ALPS 20K pot. Moving on to 3221s/3225s!
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Did you clean up the VDDA rail (pin8) with extra decoupling? Mine play jolly loud without noticeable distortion with that mod enacted. Otherwise yeah, too much HF hash.
VDDA is fed by VPA which has an additional 9900uf, left the smd caps for low ESR and less likely damage. Unless I'm missing something you're referring to?
Ahh I see what you're talking about. The extra capacitance is on 20/29, pin 8 is too inaccessible with the other mods.
Maybe I'll give it a go if I ever go back to the 8932s. I've moved on to the 32xx boards and a bloating budget.
Maybe I'll give it a go if I ever go back to the 8932s. I've moved on to the 32xx boards and a bloating budget.
I had a whole lot more than 9900uF on mine (on pin20/29) and that didn't allay the HF harshness. Only when I realized pin8 was the sensitive spot did I get the alluring sound I have now. This design has regulators for both sets of supplies : Transformer input TDA8932 mono amp