Power amp with TDA2050 and BD249/BD250?

[Aleksandar]

Ok, so first of all hello to everybody here  8| So I have these chip and transistores spare in my junkbox and I thought I could upgrade my  TDA2030 10-15w practice amp  that I built some years ago. Now, I have this schematic for TDA2030+BD243A/BD244A current boost or something hybrid amp design that would suppose to deliver 40W into 4Ohm load at +-22V. I don't have a scanner so I can't post the schematic right now, but maybe someone could tell me if I could just use TDA2050+BD249C/BD250C instead or would I have to change the values of the other parts as well? For the power supply I have two transformers to consider: 2X18(center taped 36v?) and 2X24 (not quite sure about Amps though, the 2X24 one is over 2A i think) so would those be suitable, could all that work, and how much output would I get out of it? Is it worth bothering or should I just swap the TDA2030 with TDA2050. For the TDA2030 amp I used 2X9V transformer and that was too much for the chip so I put two 9V zener diodes to have exactly 18v for the power amp section. For TDA2050 I'd just remove those diodes so I guess it would work fine for some 25w amp into 8Ohm load. So what do you guys think?

[J M Fahey]

Hi aleksandas.
Since you are comitted to upgrade your amp  :tu: and you will have to replace power board and supply, including the transformer, you might as well go straight to an LM3886 or similar amp and supply.
You would work and spend about the same, an many will be able to help you, you may even get a kit.
Just a thought.

[Aleksandar]

Thanks for the sugestion J M! Actualy, I had the LM3886 planned for another project in which I'd include that FET blackface preamp, and I'm still hesitating between the LM3886 and the TDA7294 for the power amp section. As for the amp mentioned in the first post, here is the schematic for the original version with TDA2030+BD243A/BD244A. The file is of really poor quality so I'll write the values down, starting from left to right:
C1=2,2mF(16V); R1=47kohm; R2=1k8; D1,D2=1N4148; R3=47kohm; C2=47mF(16V); R4=1k8; R5,R6=2,2 ohms; C4, C5 and C6=100nF; C7,C8=22mF(40V), R7=1ohm;C3=220nF, and protection diodes are 1N4001.  Simple circuit, but since I.m not very familiar with designing and what not, I thought I could use a second opinion

[J M Fahey]

Well, if you already have everything, test it.
I don't know the supply voltages.
Do you already have the transformer?
Because it is more expensive than all the other parts combined.
If you have to buy it, go straight to one of the LM3886 options.
In theory the TDA7294 is better; in practice the 3886 is well tested, and the board simpler, also easier to mount; the 7294 is more complex (the pin assignment is downright *stupid*, why pins that go together have others between them? If they go together, why aren't them *internally* joined saving pins and complexity?) STUPID designers.
I warn you, Teemu doesn't like this kind of IC Boosted circuit  at all.

[Aleksandar]

Well, I have three transformers that are center tapped. One is already in the amp with 2030, its 2x9(18v, 1,7A), then 2x18(36v)- that would be suited for LM3886 eventually, and 2x22(44v) which would go with TDA7294. In this TDA2030 amp that I built I have a 10" speaker in it, so lately I'm  considering just swapping the 2030 for 2050 and removing the two 9V zener diodes that I put in to stabilize the supply to 18V, because after the filters it goes up to 24V, which would do well for the TDA2050 and give me some 25W rms- nice little practice/recording amp. But still curiosity eats me about that TDA2050/BD249-250 combination
Now, for the TDA2050 vs LM3886 thing- I've heard that although 3886 eats 2050 in output power, some think that 2050 sounds a bit better, and I must admit that I really like how this TDA2030 sounds. I had the preamp running another amp, and when I put it with 2030 it really came to life somehow, with well pronounced mids in a certain way, and I' d like that sound, but a bit boosted...