Hi Blackdod
for me the main porblem is the recommended max. voltage what the chip can handle.
LM1875 +/- 25V (max +/-30V)
TDA2030 +/- 18V
so if we plan to use 18 -0 -18V AV transformer we will get about 18*1,41 = 25V without load und under load less - but too much for the LM1875 fake = TDA2030...so first test the chip
so i hope we get a TDA2050
chip
for me the main porblem is the recommended max. voltage what the chip can handle.
LM1875 +/- 25V (max +/-30V)
TDA2030 +/- 18V
so if we plan to use 18 -0 -18V AV transformer we will get about 18*1,41 = 25V without load und under load less - but too much for the LM1875 fake = TDA2030...so first test the chip
so i hope we get a TDA2050
chip
Attachments
I´m also quite surprised and I found it interesting to share
This just convinces me that the fake "LM1875" that come in these kits are really the TDA2030. Apart from the physical differences between the two (slits on the sides)
For other hand, in the TDA2030 data sheet you can see a maximum power of around 15W with a +/- 16Vdc power supply... if I´m understanding the graph correctly.
º
Hi
You have to look at the figure 4 graph its about 0,5% distortion. figure 5 is about 10% distortion...nobody want to hear this
16V at 8R impedance gives 12WATT
16V 4R impedance gives 18W
so yes this is the max voltage for that chip.
thanks! this is a warning fo me if i get my kits deliverd and i see the fake with the slits on the side
chris
Attachments
Hi
You have to look at the figure 4 graph its about 0,5% distortion. figure 5 is about 10% distortion...nobody want to hear this
Actually, the distortion at these levels does not matter. If you are listening to efficient speakers (or headphones like me) you will probably have become deaf before perceiving the distortion.
Hi
the only thing i can think about is without destroying every chip i will get is to look at the power consumption at a defined voltage and compare that.
so i can use my lab supply and set a voltage and tehn compare.
i am thinking about the Id graph TDA2030 Figure 12, TDA2050 figure 14. the current graph at 16V has not a big difference....but i am not really sure.
chris
the only thing i can think about is without destroying every chip i will get
is to look at the power consumption at a defined voltage and compare that.so i can use my lab supply and set a voltage and tehn compare.
i am thinking about the Id graph TDA2030 Figure 12, TDA2050 figure 14. the current graph at 16V has not a big difference....but i am not really sure.
chris
Hi
as i wrote in post 9 i got a LM1875 kit by amazon but with missing resistors.......claim = money back...ok
the LM1875 is without slites on the side. another pic shows a 1875 with broken leg. this is without slite on the side.
chris
as i wrote in post 9 i got a LM1875 kit by amazon but with missing resistors.......claim = money back...ok
the LM1875 is without slites on the side. another pic shows a 1875 with broken leg. this is without slite on the side.
chris
Attachments
kit from aliexpress...TDA20xx
Hi
additionally i ordered some kit from aliexpress.
the LM1875 is a fake = it has the slites on the side, this kit is complete and use elna 10µ cap (the small red) and the nichicon gold 47µF. no screw or isolator for the chip is included. the paper shows 2 pages. 1 is the schematic the other side is chinese with some hints i guess.
i soldered all components except the chip TD20xx. this week i plan to test the ali kit to be sure which chip i got
chris
Hi
additionally i ordered some kit from aliexpress.
the LM1875 is a fake = it has the slites on the side, this kit is complete and use elna 10µ cap (the small red) and the nichicon gold 47µF
. no screw or isolator for the chip is included. the paper shows 2 pages. 1 is the schematic the other side is chinese with some hints i guess.i soldered all components except the chip TD20xx. this week i plan to test the ali kit to be sure which chip i got
chris
Attachments
Exactly Chris, I bought 4 of those kits on eBay. They come with the same components, instructions, package ... that you describe.
It will be interesting to read your impressions.
In my case, the only thing I have replaced in two amps with components purchased from an official distributor have been the 220uF capacitors (Nichicon KW).
Jose
It will be interesting to read your impressions.
In my case, the only thing I have replaced in two amps with components purchased from an official distributor have been the 220uF capacitors (Nichicon KW).
Jose
Hi Jose
yes you are right the caps are 100µF/50V at this kit. should be 220µF.
i will try this configuration.
link where i bought it:
20W HIFI LM1875T Mono Channel Amplifier Board Stereo Audio Amplifier Module Kit for DIY Integrated Circuits-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
chris
yes you are right the caps are 100µF/50V at this kit. should be 220µF.
i will try this configuration.
link where i bought it:
20W HIFI LM1875T Mono Channel Amplifier Board Stereo Audio Amplifier Module Kit for DIY Integrated Circuits-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
chris
cost of houding increase...
Hi
as i posted in #96 my plan was to use a "better, bigger" little bit more expensive housing. i decided to ordered 2 cases.....other projects are waiting for some housing too..
now i get a letter and i have to pay extra taxes. 27,01Euro. 2 cases with delivery 86,46.....so one housing cost about 58 Euro...i love to live in Europe
chris
Thanks rabbitz for sharing your experience..
i re checked the housing and other parts:
at Aliexpress - -"my" preferred housing cost about 47 € with shipping.
Douk Audio Amplifier Chassis General Aluminum Shell Pre Amp Enclosure DIY Box-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group
the other housing - Galaxy Maggiorato GX288 230 x 280 mm + delivery cost me 34 euro +
i have to buy a power socket with fuse with 4,4 euro +
%product-title% kaufen
i have to buy 2 x 2,5 C/W heatsink with about 2x5,5 euros..... - max high 50mm.
%product-title% kaufen
.so the price is nearly the same for me.
the 50VA is about 26 euro- 80VAis 33 €
the 120VA transformer. cost 35 €
-->......the housing and the 120VA/2x18V is ordered
chris
Hi
as i posted in #96 my plan was to use a "better, bigger" little bit more expensive housing. i decided to ordered 2 cases.....other projects are waiting for some housing too..
now i get a letter and i have to pay extra taxes. 27,01Euro. 2 cases with delivery 86,46.....so one housing cost about 58 Euro
...i love to live in Europe chris
First measurment from amazon kit
Hi
as i wrote a bought the kits at 2 different sellers. first is amazon (they forgot some resistors)the caps are as john audio tech show us. and but the lm1875 look optical good = no slits on the side...5 euro
https://www.amazon.de/gp/product/B0796QV12M/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
i mounted the kit on a small and long heatsink and start my first test at my lab supply. 12-0-12V without fire and burning so i use +/-25V per rail.
pic 1 idle consumption at +/-25V per rail - no signal, no load
25V / 0,05mA = 1,25Watt per rail
temp after playing around was 28°C and DC offset 3,6mV
after 20min amp on (no signal , no load) i get 32°C on the chip and 3,8mV DC offset
pic 2 my board...the heat sink should be stabilized
pic 3 sine wave at the scope-yellow in, blue with diff probe output
pic 4 100mVrms 1khz - consumption 4 Watts per rail - output is about 0,67Watt at 8R load
pic 5 is consumption per rail = 20Watt/25V
pic 6 is the scope with 600mVrms 1kHz and 8R load before clipping
so this chip looks real - maybe used but real 1875?
chris
Hi
as i wrote a bought the kits at 2 different sellers. first is amazon (they forgot some resistors)the caps are as john audio tech show us. and but the lm1875 look optical good = no slits on the side...5 euro
https://www.amazon.de/gp/product/B0796QV12M/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
i mounted the kit on a small and long heatsink and start my first test at my lab supply. 12-0-12V without fire and burning so i use +/-25V per rail.
pic 1 idle consumption at +/-25V per rail - no signal, no load
25V / 0,05mA = 1,25Watt per rail
temp after playing around was 28°C and DC offset 3,6mV
after 20min amp on (no signal , no load) i get 32°C on the chip and 3,8mV DC offset
pic 2 my board...the heat sink should be stabilized
pic 3 sine wave at the scope-yellow in, blue with diff probe output
pic 4 100mVrms 1khz - consumption 4 Watts per rail - output is about 0,67Watt at 8R load
pic 5 is consumption per rail = 20Watt/25V
pic 6 is the scope with 600mVrms 1kHz and 8R load before clipping
so this chip looks real - maybe used but real 1875?
chris
Attachments
Hi
the chip do pretty well. i did a test sweep with 100mVrms 10hz - 35khz (10sec) with my rigol freq.generator. this gives about 0,7 watt as posted before. after an hour the temperature on the chip was about 53°C. so with this isolator and this heatsink it looks good.
2nd test .after 30 minutes with sweep of 70mVrms i got 50°C on the chip.
so yes this chip are good.
lets see what the other lm1875 "fake" do = i guess its a TDA2030.
chris
the chip do pretty well. i did a test sweep with 100mVrms 10hz - 35khz (10sec) with my rigol freq.generator. this gives about 0,7 watt as posted before. after an hour the temperature on the chip was about 53°C. so with this isolator and this heatsink it looks good.
2nd test .after 30 minutes with sweep of 70mVrms i got 50°C on the chip.
so yes this chip are good.
lets see what the other lm1875 "fake" do = i guess its a TDA2030.
chris
aliexpress test
Hi
i mount the kit with the fake LM1875 (slits in the side) on a heat sink in my lab - its about 1,5K/W 5,5 euro
%product-title% kaufen
i guess its a TDA2030 so i used max 18V per rail.
DC offset is at -1,3mV
pic 1 is idle consumption
pic 2+3 are with 100mVrms 1khz into 8R
pic 4+5 are with 1450mVrms 1khz into 8R - before clipping = its about 12Watt rms
actually the chip is running at max power with my sweep 10hz-35khz...15 minutes and its about 46°C with this heat sink ......so there could be some room for more.
how can i check if this chip is e.g. tda2050 without damaging??? just go up with the rail voltage and pray
chris
Hi
i mount the kit with the fake LM1875 (slits in the side) on a heat sink in my lab - its about 1,5K/W 5,5 euro
%product-title% kaufen
i guess its a TDA2030 so i used max 18V per rail.
DC offset is at -1,3mV
pic 1 is idle consumption
pic 2+3 are with 100mVrms 1khz into 8R
pic 4+5 are with 1450mVrms 1khz into 8R - before clipping = its about 12Watt rms
actually the chip is running at max power with my sweep 10hz-35khz...15 minutes and its about 46°C with this heat sink ......so there could be some room for more.
how can i check if this chip is e.g. tda2050 without damaging??? just go up with the rail voltage and pray
chris
