Tda 2003 sound quality.Show me your opinion!

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PetruV

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Joined 2012
Yes ,large offset causes escess curent and heat to be profuced,when i turn it on one chanell has no dc offset and one has 3 v help me
the tes bulb glows bright,but if i unplug the speaker from the problem chanell the consumption goes to normal
 
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Mihkus

Mihkus

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Joined 2012
Single or split supply?
Did you put diodes between Vee & Vcc? Maybe one of them is shorted...
I had lots of problems, one was same as yours...
My problem was noninverting circuit 3 100k R resistors and 22uf cap...
Had to find almost perfect fit 5% resistors...

BTW i didnt use diodes...
 
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PetruV

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Joined 2012
i fixed it,the resistor hooked up for nfb at pin 2 made bad contact. still dont understand how that pissed it off.
now the amp is idling cool without diodes,and the 25watt tes lamp is orange-yellow.sound is a very quiet though my phone outputs 0.2-0,3v and gain resistors are 22 and 1 k so gain must be 23
23 x 0.2 should be still 4.3 but it isnt even close,
 
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PetruV

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Joined 2012
Lamp is this bright AT idle and that huge heatsink is at 50c,hmmm,oscilation? my analog multimeter reads 4v when music is playng but it isnt that loud,maybe most signal is drowned by oscilation. i used 10r resistors and 104 caps in zobel,.
How could we fix this oscilation bug?.grounding is correct and worked this way in my tda2003.Ocassionaly the lamp gets a little dimer for a second.thanks in advance
 

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PetruV

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Joined 2012
mine is same now,but i decided to take apart the whole amp and put it back togheter these days,it will sure work if i do so,also is it ok to use 10r resisistor for zobel?
tsiros your heatsinks must burn,they are pretty small and only have horizontal fins!
 
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PetruV

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i have taken it apart and put it togheter and now its very cool,lamp doesn even light up,but still quiet,i will try to reduce current limiting
nope still quiet,25w lamp dosent light at all even when volume is at max but it is quiet,less than 1 watt
 
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PetruV

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Joined 2012
no longer quiet,but it seems to distort away after 30 sec on 100w,over a period which speakers go up and up untill it distorts away,sounds as if only one rail is present.
could it be because the rail voltage is going down,and the lm1875t acts weird on low supply voltages,or what. apart from this it works very well.
Tomorow i will start to design an amplifier based on 2sa1943 and c5200,with the help of you guys
yes,the voltage is going down because of huge offsets in both speakers
 
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PetruV

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Joined 2012
Works,perfectly just very hot,need new heatsink,very clear sound,it just needed 2 10k pull down resistors from input to gnd and works perfectlly.
Moral of the story? no matter how much you are a professional you will still make mistakes if you dont listen closely to the diagram in the pdf
 
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PetruV

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Joined 2012
it sounds a tiny bit better than tda2003,a little brighter in the trebble and more boomy in the bass,unlike tda2003 which is more precise,but lacks sometimes bass. altough the tda2003 keeps the cones in a better grip,lm1875 is a litlle unontrolled,mid end is same.
 
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PetruV

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Joined 2012
Dr_EM said:
I think it's meant to be 1 Ohm? Increasing it can cause instability/oscillation and this can certainly lead to the high operating temperatures you're experiencing. It'll impede the sound quality too of course.
Click to expand...

yes it wasnt ok,it works better with 1 ohm
Amp is now working,just needs transformer mounts,after some measurement i found out i get 10v ac,so i at least got my 25watts i asked for!
very stiff supply,22vdc or so,but sags maybe 2volts on max load,transformer is salvaged from an amp that is the cheapest you can buy,had it when i was 8 or so,heatsink is also from same amp,barelly warm on maximum load.i like it very much but it is too problematic for a begginer.
next stop?,designing an discrete amp togheter which will run on 20/0/20v dc!
 
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