TDA7294 + Power Transistors AMP (TDA7293 to come also)

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stingray72

Member
Joined 2014
39v transformer

i found out the answer shortly after i posted that but I couldnt edit it. I read so much info on this thread i got confused. I was considering the 7293 enhanced by the way. I looked into the enhanced version on his site just now and i was figuring a antek 32 32 500 va would be ok. Am I right? The 39 39 was a antek as well but I know now that 700va is too much after reading about someone on here frying stuff because of too much transformer. And I am a fresh never built an amp guy so go easy on me ha. Nice to meet you all.
 
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basi

basi

Member
Joined 2007
audiofil.hr
I read that the tda7293 explode if the negative rail is lost or does not come up before, and go down after, the other rails.
I only like explosions Coming from speakers as sound effects not the amplifier. :D

My solution to losing rails is to instal this on primary side of transformer and quickly trun of power if the rail loses.
http://www.ebay.com/itm/14173889989...49&var=440856277642&ssPageName=STRK:MEBIDX:IT
 
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A

AndrewT

R.I.P.
Joined 2004
That advert contains many lies.
Did you try to assess if any of the claims could be close to achievable?
Price is very good if that is what is important.
But I would rather have an amplifier that lasted a bit longer than 1second after switch on.
 
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S

stingray72

Member
Joined 2014
AndrewT said:
That advert contains many lies.
Did you try to assess if any of the claims could be close to achievable?
Price is very good if that is what is important.
But I would rather have an amplifier that lasted a bit longer than 1second after switch on.
Click to expand...

I knew the distortion rate was really bad so the power was way over estimated but I have zero electronic knowledge but definitely have a desire to learn.
 
A

AndrewT

R.I.P.
Joined 2004
P = Vpk^2 /Rload
Turn that around and you get Vpk = sqrt(2*P*Rload)
for 1500W into 8r0 dummy load that gives us 154.92Vpk
add on a bit for losses through the amplifier then add on a bit for sag in the supply voltage when high current is delivered and we arrive at a guesstimate of 165Vdc to 180Vdc as the likely supply rail voltage.
Rail to rail would be 330Vdc to 360Vdc. What about an allowance for mains voltage variation?
The 1943/5200 are rated @ 230Vce0
13Pairs of 150W devices ( the 14th pair are probably drivers) have a reliable maximum output power of around 650W
max supply voltage is stated as 135Vdc, that's 270V across the supply rails with 230Vce0 devices.
the cold Idc rating @ 150Vce is ~0.1A that gives a 13pair a maximum DC output of 1.3A when Vce equals 150V.
You need to learn how to dissect the specification to reveal the lies these retailers publish.
 
S

stingray72

Member
Joined 2014
AndrewT said:
P = Vpk^2 /Rload
Turn that around and you get Vpk = sqrt(2*P*Rload)
for 1500W into 8r0 dummy load that gives us 154.92Vpk
add on a bit for losses through the amplifier then add on a bit for sag in the supply voltage when high current is delivered and we arrive at a guesstimate of 165Vdc to 180Vdc as the likely supply rail voltage.
Rail to rail would be 330Vdc to 360Vdc. What about an allowance for mains voltage variation?
The 1943/5200 are rated @ 230Vce0
13Pairs of 150W devices ( the 14th pair are probably drivers) have a reliable maximum output power of around 650W
max supply voltage is stated as 135Vdc, that's 270V across the supply rails with 230Vce0 devices.
the cold Idc rating @ 150Vce is ~0.1A that gives a 13pair a maximum DC output of 1.3A when Vce equals 150V.
You need to learn how to dissect the specification to reveal the lies these retailers publish.
Click to expand...

Thank you for that short and precise answer.
 
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