There might be an effect with this DIP-packages in a noisy environment. The enclosure shown is made from plastics, so no overall shielding there..
cheers again, I received my amp today, finally! and what a beautiful and small amp it is! It plays very well right out of the box and I was surprised by its power despite of size :-o
looking forward for my modifications, lets the tuning begin! 🙂
Just started with simple listening tests and measurements and it did 2x30W@8R with default 24V PSU with no mods so far, very nice! Still waiting to receive my 32V power supply so I am very curious what the differences will be, after modding opamps, capacitors, cooling and power supply.
This is my first class D amp and it is unbelievable how low heat it produces :-o
The audible noise-floor of the amp is very quiet indeed as was refered many times here, but after measuring it on scope it produces 200-300mV 450kHz inaudible noise, so not very good in that terms, but maybe this is the class D feature, or not proper output filter?
looking forward for my modifications, lets the tuning begin! 🙂
Just started with simple listening tests and measurements and it did 2x30W@8R with default 24V PSU with no mods so far, very nice! Still waiting to receive my 32V power supply so I am very curious what the differences will be, after modding opamps, capacitors, cooling and power supply.
This is my first class D amp and it is unbelievable how low heat it produces :-o
The audible noise-floor of the amp is very quiet indeed as was refered many times here, but after measuring it on scope it produces 200-300mV 450kHz inaudible noise, so not very good in that terms, but maybe this is the class D feature, or not proper output filter?
I had to prepare the orders for the parts so opened the amp... pfff what a dissapointment, as nice it is from outside so ugly it is from inside 😀 I am surprised it didn't blow up, check the images and the solder work on the PCB, never seen such a awful soldering, there are probably no shorts just thanks to soldering mask, so this was a ticking bomb of some sort...
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Wiliks
The usual thing for Chinese noname manufacturer. For some reason, more well-known Chinese manufacturers as SMSL or Topping do not make amplifiers with this chip.
The usual thing for Chinese noname manufacturer. For some reason, more well-known Chinese manufacturers as SMSL or Topping do not make amplifiers with this chip.
I meant of course not about the chip. Now there is no choice, only this noname manufacturer made an TPA3250 amplifier. I think that SMSL or Topping or other well-known manufacturers would make a better quality board and amplifier at all. But for unknown reason other manufacturers did not make amplifiers with TPA3250
hi Wiliks
Yes some reflow solder dots are looking as "cold" solder points....its looks too dull
....resolder it again.
the hand made solder dots looking more shiny but they are not cleaned --> pcb cleaner or slightly scratch away...
Yes some reflow solder dots are looking as "cold" solder points....its looks too dull
....resolder it again.
the hand made solder dots looking more shiny but they are not cleaned --> pcb cleaner or slightly scratch away...
Finally received the capacitors I ordered more than 2 months ago.
Very fast film caps with 400V dV/dt in V/us.
Used them for the post filtering after the coils.
Sound is much much cleaner!
Very fast film caps with 400V dV/dt in V/us.
Used them for the post filtering after the coils.
Sound is much much cleaner!
These film caps are not "faster" than any other caps. 400V/us is the allowable slewrate. And that is just number, that no realworld class d-amp output filter will ever produce.
i would not call fx audio as "no name" this company is existing since 2011深圳市飞想数码科技有限公司
ok the hompage is strange and not actual. but the 502spro is really the only one with the tpa3250 chip and lets says...according to your pcb... fx audio has a "quality control issue" 😉😀
the fx tube 01 get good feedback...as i read...
chris
foil on the opamp
Hi
yesterday i did the first test with foil over the opamps. i do not ground it...is it necessary?
foil like this:
Anpro 15M Kapton Tape Klebeband Selbstklebend Kupferfolie, EMI Abschirmband Kupferfolie Kupferband 2.54cmx15m, EINWEG: Amazon.de: Baumarkt
yesterday i pus 150mVrms into the amp, its runs with LRS10-24 set to 24V. on 8R i get about 1,5 Watt per channel with the 1 o clock volume setting.
3 minute i check with my temp tool the difference of the housing of both opamps = difference of temp of the opamp with/ without foil was 32°C and 38°C
so the opmap for R channel has the foil- opamp for L channel has no foil, scope at pin 4 and pin 1 -GND and outA
pic 1 with foil
pic 2 no foil
pic 3 speaker output R channel with no signal (opamp with foil)
pic 4 speaker output L channel with no signal (opamp without foil)
pic 5 19khz at R channel sp output
pic 6 19khz at L channel sp output
Hi
yesterday i did the first test with foil over the opamps. i do not ground it...is it necessary?
foil like this:
Anpro 15M Kapton Tape Klebeband Selbstklebend Kupferfolie, EMI Abschirmband Kupferfolie Kupferband 2.54cmx15m, EINWEG: Amazon.de: Baumarkt
yesterday i pus 150mVrms into the amp, its runs with LRS10-24 set to 24V. on 8R i get about 1,5 Watt per channel with the 1 o clock volume setting.
3 minute i check with my temp tool the difference of the housing of both opamps = difference of temp of the opamp with/ without foil was 32°C and 38°C
so the opmap for R channel has the foil- opamp for L channel has no foil, scope at pin 4 and pin 1 -GND and outA
pic 1 with foil
pic 2 no foil
pic 3 speaker output R channel with no signal (opamp with foil)
pic 4 speaker output L channel with no signal (opamp without foil)
pic 5 19khz at R channel sp output
pic 6 19khz at L channel sp output
Attachments
today i start o give the opamp L channel near the potentiometer a foil too.
the temp behavior is really the same = better both opamp give me with 150mVrms and the volume knob at 1 o´clock the same temperature...its about 32°C...ok thats fine
now the compare at the same opamp = L channel opamp pic yesterday and today
pic 1 without foil 19khz
pic 2 with foil 19khz
pic 3 without foil 19khz speaker output
pic 4 with foil 19khz speaker output
no really big findings...?
the temp behavior is really the same = better both opamp give me with 150mVrms and the volume knob at 1 o´clock the same temperature...its about 32°C...ok thats fine
now the compare at the same opamp = L channel opamp pic yesterday and today
pic 1 without foil 19khz
pic 2 with foil 19khz
pic 3 without foil 19khz speaker output
pic 4 with foil 19khz speaker output
no really big findings...?
Attachments
I dont think these mods are worth it as the changes are negligible. If you want some more advanced and further tuning do a best cooling possible and raise the switching frequency of TPA... or change the surrounding capacitors for better ones etc...
I am looking forward to do so, already ordered... just waiting for supplies to come in 🙂 also now I am searching for some 5mm aluminium plate to crew from the bottom to get cooling from the enclosure 🙂
I am looking forward to do so, already ordered... just waiting for supplies to come in 🙂 also now I am searching for some 5mm aluminium plate to crew from the bottom to get cooling from the enclosure 🙂
Put better copper plate. Copper has a thermal conductivity of almost two times higher than aluminum.