Well done Wiliks🙂
do you have 2 amps or an other amp to compare?
can you made THD measurements?
chris
do you have 2 amps or an other amp to compare?
can you made THD measurements?
chris
Thks Wiliks, many would find your mod sharing helpful taking same path.
I am also using a supply of 32V, 1 thing bothers me is pop-sound resulting from sudden power-off. Did u face this issue?
I am also using a supply of 32V, 1 thing bothers me is pop-sound resulting from sudden power-off. Did u face this issue?
Hello,
which amplifier would be suitable for the FX502SPRO?
Or is that related to the supply of electricity?
Or with the modification of the device?
-> LM4562NA
-> NE5532
-> LME49720
-> LME49860
Great what you are doing ....
which amplifier would be suitable for the FX502SPRO?
Or is that related to the supply of electricity?
Or with the modification of the device?
-> LM4562NA
-> NE5532
-> LME49720
-> LME49860
Great what you are doing ....
Hi
the reason why we changed the opamps is because the origin are fake
i tried : LM4562, OPA2134 and the LM49720
choose your taste 😉
chris
2chermann:
I can measure THD but it will be pointless since I do not have 2 amps to compare: modified vs oem version
2forestgump:
i do not get absolutely any pop when turning off, but i got very weak pop when turning on
I can measure THD but it will be pointless since I do not have 2 amps to compare: modified vs oem version
2forestgump:
i do not get absolutely any pop when turning off, but i got very weak pop when turning on
Hi Wiliks
By using a Brickwal filter for 20khz (as Voltwide recommended😉) its not pointless its interesting for me ...please 🙂
I found the finished TPA3255 amplifier without power supply cheaper than the set with TPA3250 and PSU. Aliexpress TPA3255
Which one has better quality of components?
Which one has better quality of components?
sorry ...no idea:
actually its not easy to say
https://www.diyaudio.com/forums/class-d/287470-tpa3255-diy-discussion-design-etc-99.html#post5703783
cherman i will get to it during weekend, i'm quite busy atm
hansueli i think you can even find fxaudio tpa3250 without PSU as well, and yes tpa3255 is more powerfull and better amp, but its also bigger, and to release its full potential you need also bigger heatsink (from top as the thermal pad is on top there) and 48VDC and very strong power supply, which you can't hide to simple "notebook-like" brick as you can with TPA3250. And honestly i do not need 2x300W amp for my 30W PC speakers monitors 😀
petersv you can, but you would need some extra circuit for that.
hansueli i think you can even find fxaudio tpa3250 without PSU as well, and yes tpa3255 is more powerfull and better amp, but its also bigger, and to release its full potential you need also bigger heatsink (from top as the thermal pad is on top there) and 48VDC and very strong power supply, which you can't hide to simple "notebook-like" brick as you can with TPA3250. And honestly i do not need 2x300W amp for my 30W PC speakers monitors 😀
petersv you can, but you would need some extra circuit for that.
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Wiliks, for example: if turning-off is due to sudden unplug of the power supply, will there be any pop?
Sure, that won't be a problem, igf you could point me in the right direction for some info on this I would really appreciate it.
2aks: not sure about direct improvement, but the drawback is a bit more heat generated so you need good cooling, but I think in any switching circuit, the higher the frequency the better, right? you have to change the value of oscillator resistor, see datasheet.
2petersv: i dont know any specific one as i havent used it yet, but try to search for something like "audio switch" or or similar keyword, i think its basically simple OPamp that charge cap on very high impedance input of some flip-flop cmos.
2forrestgump: even unplugging power supply from wall do not produce any pop when turning off for me.
2chermann: Sorry for longer waiting but i got ill and had other duties... but finally i got to measurements and heh it was very tricky and complex to measure THD on bridge amp 😱
to measure and avoid ground shorting of bridged output, i was generating signal from my desktop to amp, amp to dummy load, and from dummy load I was recording on external creative sb x-fi connected to macbook powered by battery to avoid grounding and any hum. The problem was i was unable to check it on oscilloscope "on the fly" as all scopes I have are somehow grounded so i had to make reference decibel scale for measuring, I would need battery powered one to avoid another ground or do it all in opposite way and record/and scope on desktop and generate from notebook, but i dont like it as battery powered notebook is super quite for recording.
Another thing is that I even cannot use my standard sine wave ungrounded generator I normally use for power measurements, as that one have about 0,5% thd which is useless for thd measuring...
pff long story short, it was successful here are the results, I post direct links to images so you can zoom in:
it is also interesting to see slight 35kHz noise, probably switching power supply noise? or some switching regulator? or the TPA chip noise itself? not sure... or the 600kHz TPA switching frequency harmonics?
pure signal loopback from desktop to notebook:
10W@8R load
50W@8R load, slightly before clip
10W@4R load
80W@4R load
100W@4R load - I think here it started to clip slightly as thd jumped rapidly and didnt had scope attached
2petersv: i dont know any specific one as i havent used it yet, but try to search for something like "audio switch" or or similar keyword, i think its basically simple OPamp that charge cap on very high impedance input of some flip-flop cmos.
2forrestgump: even unplugging power supply from wall do not produce any pop when turning off for me.
2chermann: Sorry for longer waiting but i got ill and had other duties... but finally i got to measurements and heh it was very tricky and complex to measure THD on bridge amp 😱
to measure and avoid ground shorting of bridged output, i was generating signal from my desktop to amp, amp to dummy load, and from dummy load I was recording on external creative sb x-fi connected to macbook powered by battery to avoid grounding and any hum. The problem was i was unable to check it on oscilloscope "on the fly" as all scopes I have are somehow grounded so i had to make reference decibel scale for measuring, I would need battery powered one to avoid another ground or do it all in opposite way and record/and scope on desktop and generate from notebook, but i dont like it as battery powered notebook is super quite for recording.
Another thing is that I even cannot use my standard sine wave ungrounded generator I normally use for power measurements, as that one have about 0,5% thd which is useless for thd measuring...
pff long story short, it was successful here are the results, I post direct links to images so you can zoom in:
it is also interesting to see slight 35kHz noise, probably switching power supply noise? or some switching regulator? or the TPA chip noise itself? not sure... or the 600kHz TPA switching frequency harmonics?
pure signal loopback from desktop to notebook:
10W@8R load
50W@8R load, slightly before clip
10W@4R load
80W@4R load
100W@4R load - I think here it started to clip slightly as thd jumped rapidly and didnt had scope attached
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Thanks wiliks!🙂
i use a differential probe for scope but i think about THD measurements in the future....but actually i am busy + bike season has started...😉😀
chris
i use a differential probe for scope but i think about THD measurements in the future....but actually i am busy + bike season has started...😉😀
chris
it is also interesting to see slight 35kHz noise, probably switching power supply noise? or some switching regulator? or the TPA chip noise itself? not sure... or the 600kHz TPA switching frequency harmonics?
i am not an expert but i remember you are using the origin air coils and that power is maybe the limit of the aircoils?
let´s wait what some expert will write here...😉
chris
i am not an expert but i remember you are using the origin air coils and that power is maybe the limit of the aircoils?
let´s wait what some expert will write here...😉
chris