Hi Voltwide
is there a compare table for some original coils and the Würth? i mean the saturation etc..
i know doctors compare list with a lot of coils but did somebody do this with some chinese coils e.g. this TPA3255 12,5 - 13,2µH coils.
better egulator???
Hi
next step will be the target to decrease the "noise" of the YJTPA3255 board.
is there a good replacement for the LM 2575T (12V) or LM2575S 15V --> LM317?(i will do some scope measurements on the weekend...)
as i keep sybic modification i stick to the datasheet figure 29 to use not the 22µH but i use the 220µH. So its correct or?
can you please give me a hint to change this regulator to an ultra low noise one?
thx
Hi
next step will be the target to decrease the "noise" of the YJTPA3255 board.
is there a good replacement for the LM 2575T (12V) or LM2575S 15V --> LM317?(i will do some scope measurements on the weekend...)
as i keep sybic modification i stick to the datasheet figure 29 to use not the 22µH but i use the 220µH. So its correct or?
can you please give me a hint to change this regulator to an ultra low noise one?
thx
Maybe this -
LT30451 + LT8608 Low Noise RF Audio DAC ADC Linear Power Module-in Replacement Parts & Accessories from Consumer Electronics on Aliexpress.com | Alibaba Group
it's an interesting product - a step-down buck regulator in combination with an LT3045 regulator. The only problem is that the maximum voltage of the LT8608 is 42V - just a bit low for the TPA3255. I imagine there's an alternative model in Analog Devices' extensive catalogue which could be swapped in?
hi linuxfan
thank you . i realized your post pages before...but 45 euro...?
42V is for me and i guees for home use enough😉
so i am not a regulator expert...single chip solution? - instead of the LM2575T or LM2575S......i am pretty sure they are not origin on my YJTPA3255 boards....
do you try the AVDD mod by abraxalito?
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I have all parts sitting on my work bench. Just need to find some spare time.
Yes, on reflection US$50 is quite pricey for that regulator, especially compared to the price of the Chinese TPA3255 boards.
For my own TPA3250 build I will use a TPS7A4700 regulator (from ldovr) with its own transformer, to power the 12V rail. I will be bypassing the input opamps, so I don't need 15V.
yes you are right - the cines TPA boards a chap and this regulator is nearly the same price...
AVVD
At the YJ boards there is no possibility to solder from the buttom side so you have to mount the cap on the top side. the access to the chip is under the heatsink.🙄 i try to solder smal cable there and its realy close to every pin but it works....just on the damaged board...will see next step..😀
noise compare 3251EVM vs YJ3255
Hi
I did some scope probes..
I use my psu - LRS 150-24 (28V) which i use for listening and try some measurement directly on the terminals of both boards. the psu is noisy.🙄 iput shorted amp on - 4R load
pic 1 +2 YJTPA3255 on / off
pic 3+4 3251EVM , YJ3255
opamp pin 5 = V+
here seems the YJ3255 better..
and directly at the + of the decoupling caps with a input signal of 100mVrms into 4R.
pic 5+6
YJTPA3255 are the original caps ... - 3251EVM
is the 30% more "ripple" the reason of slightly more noise of the YJ board??
128mV rms vs 101mV rms
Hi
I did some scope probes..
I use my psu - LRS 150-24 (28V) which i use for listening and try some measurement directly on the terminals of both boards. the psu is noisy.🙄 iput shorted amp on - 4R load
pic 1 +2 YJTPA3255 on / off
pic 3+4 3251EVM , YJ3255
opamp pin 5 = V+
here seems the YJ3255 better..
and directly at the + of the decoupling caps with a input signal of 100mVrms into 4R.
pic 5+6
YJTPA3255 are the original caps ... - 3251EVM
is the 30% more "ripple" the reason of slightly more noise of the YJ board??
128mV rms vs 101mV rms
Attachments
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AD8599 - opa1602 compare
Hi
after a burn in phase of my opa1602 board i find this opamp is not just cheaper its sounds nearly the same-slightly better.
what is technical the big difference of this opamps?
the boards are identically setup - 4R speakers "Disco M"
both YJ board give some noise if you switch on at the speakers and you go with your ears to the membranes.
please give me some information about CMRR,, PSRR. if i compare this datas in both Datasheet the opa1602 is better. Is that a value that could be effect the SQ??
pic 1 AD8599
pic2 opa1602
thanks
chris
Hi
after a burn in phase of my opa1602 board i find this opamp is not just cheaper its sounds nearly the same-slightly better.
what is technical the big difference of this opamps?
the boards are identically setup - 4R speakers "Disco M"
both YJ board give some noise if you switch on at the speakers and you go with your ears to the membranes.
please give me some information about CMRR,, PSRR. if i compare this datas in both Datasheet the opa1602 is better. Is that a value that could be effect the SQ??
pic 1 AD8599
pic2 opa1602
thanks
chris
Attachments
There is no evidence that burn-in of OPAs is of any significance for audible sound quality.
Same applies to some technical data - which might differ - but at levels far below audibility.
Certainly this does not apply to the golden ears who hear differences far beyond any measurements due to their extraordinaire unrivalled capabilities superior to the average deaf humans.
Same applies to some technical data - which might differ - but at levels far below audibility.
Certainly this does not apply to the golden ears who hear differences far beyond any measurements due to their extraordinaire unrivalled capabilities superior to the average deaf humans.
ok.
.....still an audible difference in some boards or DAC...etc..
@burn in
the parts are stored a lot of time nobody knows how long....for me a usage of the "burn in" process is to come into a stable status.
listening and compare is for me a mandatory part. yes i know its a subjective thing...my personal advantage is that i absolutely do not care which money its costs or which brand the caps are or what opamp is installed....so i have no peronal relation or emotion in that
after a nice compare and a high sound level album with a punchy sound (Trettmann/kitschkrieg/megaloh - title Anorak..and a lot of others 😎😀.)
i got loud cracks!!!..and the amps getting nearly silent - a kind of attenuation + some cracks...
i remember me that at the YJ boards the thermal paste at the power chip- TPA3255- is too much under the heatsink.
--> heatsink away and clean it with a pcb cleaner 3 times! and let it 5 min work in .......then clean it.
now its gone
i got loud cracks!!!..and the amps getting nearly silent - a kind of attenuation + some cracks...
i remember me that at the YJ boards the thermal paste at the power chip- TPA3255- is too much under the heatsink.
--> heatsink away and clean it with a pcb cleaner 3 times! and let it 5 min work in .......then clean it.
now its gone
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i am 47 years old...my ears are burned 😉😉😀😀😀😀😀
really i sitting during a week about 5-8 hours listening music...not just for compare test 🙂..i know my equipment.
amp7 8R config...input spikes ???
Hi
for my 8R board i am finished but i got in my lab some clipping led flashing. so i do not use a speaker in the lab. with no input signal but amp powerd on i got at 28V in 8R some oscillation from 8 Watt to 11watt power consumption-so i checked the inputs- pin 1 or directly after the 10µF input cap on the right channel i got following pics.
pic 1,2,3 are pics directly on the R channel input cap - no input signal
pic 4-5 showing if i set 200mVrms input on both channel - some spikes are more than 2V !!!😱 so the clipping goes flashing and the consumption of the amps jumps into 55-70Watt shortly ...as i see on my rigol DP832 psu😱
i re solder all input caps again and the smd 10k resistor...is this a typical oscillation because of this 22pf at the opamps??? if yes i have to change these bastards...
Hi
for my 8R board i am finished but i got in my lab some clipping led flashing. so i do not use a speaker in the lab. with no input signal but amp powerd on i got at 28V in 8R some oscillation from 8 Watt to 11watt power consumption-so i checked the inputs- pin 1 or directly after the 10µF input cap on the right channel i got following pics.
pic 1,2,3 are pics directly on the R channel input cap - no input signal
pic 4-5 showing if i set 200mVrms input on both channel - some spikes are more than 2V !!!😱 so the clipping goes flashing and the consumption of the amps jumps into 55-70Watt shortly ...as i see on my rigol DP832 psu😱
i re solder all input caps again and the smd 10k resistor...is this a typical oscillation because of this 22pf at the opamps??? if yes i have to change these bastards...
Attachments
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The traces are smeared. Maybe some oscillation. You might vary the time base of your scope until this smearing is synchronized and some kind of periodic oscillation becomes visible.
yes i will try.
the period of the 1khz signal is too short to show this. i saw the 1khz jumping up and down......
thank you
i try to check what happend with the board.
here are some voltages directly on the output pin of the LM2575T..😱
yellow trace
pic 1 is DC measurement
pic 2 is AC
pin 4 shows nothing??
....now the board is dead...no power...i think the regulator died......🙄🙁
because i haven´t got a LM2575T-12 at home is it possible to mount for pin 1,2,3 a 7812???
thanks
chris
here are some voltages directly on the output pin of the LM2575T..😱
yellow trace
pic 1 is DC measurement
pic 2 is AC
pin 4 shows nothing??
....now the board is dead...no power...i think the regulator died......🙄🙁
because i haven´t got a LM2575T-12 at home is it possible to mount for pin 1,2,3 a 7812???
thanks
chris
