Hi, this circuit is really popular in Bangladesh among users of the system for small events. they don't care quality sound they just need to roar for 12 or 15 inches speakers.
I bought a PCB to explore with, and I believe I should strive to make it better.
This board is what I've chosen because it's produced locally and is quite affordable. If a small adjustment would enhance the sound quality, individuals who have already invested in the board will save money as there would be no need to buy a replacement.
The majority of people that build these kinds of systems in our country lack training and are ignorant of concepts like bias current, DC offset, etc. as A hobbyist I would like to assist those who are looking for better-quality sound.
Do you guys believe that the circuit is well-designed and should I work on it?
I bought a PCB to explore with, and I believe I should strive to make it better.
This board is what I've chosen because it's produced locally and is quite affordable. If a small adjustment would enhance the sound quality, individuals who have already invested in the board will save money as there would be no need to buy a replacement.
The majority of people that build these kinds of systems in our country lack training and are ignorant of concepts like bias current, DC offset, etc. as A hobbyist I would like to assist those who are looking for better-quality sound.
Do you guys believe that the circuit is well-designed and should I work on it?
Attachments
Error! The base of Q4 must be connected to the collector of Q2.
The scheme has been traditional since the 70s.
The choice of a pair of transistors Q6\7 (insufficient power) raises a question.
R14 should be bypassed with a capacitor (like R15).
The scheme has been traditional since the 70s.
The choice of a pair of transistors Q6\7 (insufficient power) raises a question.
R14 should be bypassed with a capacitor (like R15).
Last edited:
RV1-balancing LPT.
RV2-setting the quiescent current.
Requires DC power supply: +40V\0\-40V
10a (max) no less than 200W (for two channels).
RV2-setting the quiescent current.
Requires DC power supply: +40V\0\-40V
10a (max) no less than 200W (for two channels).
Makes it look like something new and exciting, when there is in fact nothing new under the sun.
Fast forward 20 years and it will indeed be new again. When the entire world has heard nothing but 12 volt rail class D amplifiers and 2” speakers claiming 800 watts PMPO for a decade this is going to sound like a bomb going off in the room.
Fast forward 20 years and it will indeed be new again. When the entire world has heard nothing but 12 volt rail class D amplifiers and 2” speakers claiming 800 watts PMPO for a decade this is going to sound like a bomb going off in the room.
It’s just been done to death already. “Is this any good” depends entirely on your particular implementation. It can work well or it can suck. Drawing it upside down doesn’t make it any different.
Doing idiotic things like using 2SC2073 TO-220 drivers in the diff pair doesn’t exactly inspire confidence.
Doing idiotic things like using 2SC2073 TO-220 drivers in the diff pair doesn’t exactly inspire confidence.
The whole consumer electronics sections of every megamart is full of the garbage described. TV sound bars that replace the 1" speaker of modern TV with 3". Home theater systems with 5 channels of garbage. Wild wattage claims for the same. The only sound equipment store in my tiny city of 2000000 is Best Buy that will not demo anything. The Peavey dealer went broke, and the surviving bar/church sound installer pushes Bose, which there is not enough red ink to describe. A church I left played their wood piano through a $5 microphone and Yamaha voice only PA speakers. A system guaranteed to satisfy the deaf old men that run the music program.
I'm listening to the excellent HDTV sound on PBS this week (concerts, Foreigner now, Arrival next) through a toslink-line level converter, then a 75 watt Peavey warehouse amp driving some Salvation Army resale speaker with 1", 2", and 6.5" drivers. Cost $10 for 2. Has a boom box bass profile, as David Weems describes it, but is way better than the competition. All I could afford in the months after my local unemployed house painter carried off $2000 of retired bar band equipment, eveything dynaco, 2500 LPs, 220 CDs, even all the **** FM radios.
At least the Bangladesh thumper the O.P. documented could put out an honest ,1% distortion 80 watts.
Did you read the initial post?
The guy is just asking for help to improve a schematic sold as a consumable in Bangladesh, he is not asking for a dissertation on what is good or bad, just something to improve this ancestral thing.
If he just used transistors intended for their purposes. BD140 VAS and a small signal input pair. Even BD139 input diff pair is a little silly. You don’t need ”something big to keep it from blowing up” there. If you get fakes and THAT causes a problem it’s on you.
If the only thing you can find or afford are fake output transistors and drivers then reduce the power supply to +/-30 volts and simply live with the amount of power it generates that way. It won’t blow up if you use all generic parts that way - including TIP3055/2955 outputs or whatever is inside fake 2SC5200’s. Higher supply rails simply require The Real Thing. There is no getting around that.