TDA 7293 vs STK4192 + newbie questions
Im new to audio systems as well as this forum. I hope this thread is in its appropriate forum , if not kindly relocate it to wherever it is deemed appropriate.
I have an old bunch of speakers and amplifiers ( both working ) from my grandfather. Unfortunately , due to the amplifier being : mono , discreet transistor based ( 2n3055 and sort) ,a cassette player input, lost schematics , im planning on building a new amp.
Getting to the point , I have :
1. 2 towers , each consisting of ( 1x Tweeter - 50W(max) 8ohm , 1x Mid- 20W 4 Ohm , and 1x Woofer - unknown wattage, 9 inch dia , 8 ohms). Now my grandpa claims that the system was 80W , so i would say that the woofer can handle a min of 40W. In addition , the tweeters 50W is its peak i guess , so its RMS would be lower . (Pics attached)
2. 1 x 30-0-30 Transformer , 4A ( I guess, it used 6A diodes in its bridge rectifier)
3. 1x 15- 0 -15 Transformer , I guess 500mA
I have a few questions , hope they arnt too noobish :
1. Any opinion on the STK4192 vs the TDA7293 in terms of audio quality , stability , heating and component quality) ? I also have alternate low powered options like the tda2030/40/50
2. Isnt i better to set a constant gain in the IC while modulating the voltage via a potential divider or op amp amplifier in the input to prevent oscillations?
3. By Power = V^2/R , the max power 2x 8 ohm speakers in series can draw if i use my 30 -0 - 30 is approx 500W. But neither the amp nor the speakers can handle it. So , am I supposed to control the Wattage via the output voltage( setting the peak voltage via the gain or some IC function)?
4. If the above is true , then the efficiency with supply of -45 to 45 V and a peak output of just 40V would see a lot of heat since at leat the tda7293 is a class AB
5. Is it worth it to keep the 30 -0 30 around? or should i replace it with a 12 -0 -12 5 Amp ? Im trying to minimze the budget by reusing the old stuff.
6. Is a 80+80W system too loud for a 300 sq feet room?
Thanks! hope these questions are clear and not too noobish!
PS : I have attached the pics of the speakers . If anyone can guesstimate or identify them , it would be great.
Rather than buy a new power supply just don't turn the amp up full.
A living room doesn't need many watts.
I get by on a couple of watts from a USB DAC into a Fane 12-50WRMS speaker.
Combine your TDA2030/40/50 idea with your 12-0-12 5a transformer idea for a doable project. The voltage is 'less lethal' that way and the expense is small.
It is probably necessary to have that bit of practice, and a considerable amount more caution before using that 30-0-30 transformer! But, if you wanted to know, a chip amp that can use that, was probably made by STK. There's some pre-built boards pop up on ebay every so often.
Or, over in the discrete amplifier forum and diyaudio store, the Honey Badger can work with the 30-0-30 transformer. That's overkill for 300 sq ft.
This link contains some answers to the voltage vs parts questions: Building a Gainclone chip amp power supply.
37 volts peak is 26 volts RMS which if applied across 8 ohms would dissipate 84 watts. So a 70 to 80 watt amp is feasible given a suitable 30-0-30 transformer.
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