Wow , as well as him not having enough power to run the circuit - - - look at the circuit ! Not too good ,
man !! No nothing (compensation , decoupling).... nothing. Alibaba circuit ??
Yeah , I second a little chip-amp tda 2050 , or other TDA's direct coupled.
Edit , my last PC speakers were LM1875 running off the internal small +/- 30V SMPS. Plenty loud.
OS
man !! No nothing (compensation , decoupling).... nothing. Alibaba circuit ??
Yeah , I second a little chip-amp tda 2050 , or other TDA's direct coupled.
Edit , my last PC speakers were LM1875 running off the internal small +/- 30V SMPS. Plenty loud.
OS
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If you have access to used equipment, failed computer printer+copier+fax machine appliances come with a 30 v or 36 v power supply of 3 or 3.5 amps. Each plugs in the wall. If the - were not safety grounded you could stack two of those plus to minus and have a pretty capable power supply for 2 channels. I pay $2 for those at my local charity resale shop.
Per OStripper this schematic is pretty basic. Feedback direct from the speaker line to the op amp input 3 is an invitation to oscillate driven by radio interference. 14 turns .5 mm hookup wire wound around a china marker or 8 mm dowel series the speaker could really help that. Feedback line goes inside that. If still oscillates, I'd try 50 to 100 pf parallel R2. And for RF pickup from the input, I'd put 100 to 130 pf to analog ground between c1 and r1. Of course, needs a grounded steel or aluminum case to also keep the RF out. I use portable steel file case with a square hole cut to allow the heat sink to be outside.
I built an LM1875 amp point to point wire and both channels motorboated about 10 cycles/sec. You really need a circuit board just like in the TI datasheet. Unfortunately all the ones for sale are speaker burners, dual supplies with the IC hooked directly to the speaker. There is a single supply capacitor coupled circuit in the datasheet, but nobody on ebay, amazon, or aliexp will sell you that pcb unless you supply a gerber file. My speakers cost 20 times what one of these diy amps cost.
For a circuit with about the same parts but actually works (I built 2 point to point) and sounds good see apex6 https://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-42.html
Nobody will sell your a pcb for it though unless you supply a gerber file.
Per OStripper this schematic is pretty basic. Feedback direct from the speaker line to the op amp input 3 is an invitation to oscillate driven by radio interference. 14 turns .5 mm hookup wire wound around a china marker or 8 mm dowel series the speaker could really help that. Feedback line goes inside that. If still oscillates, I'd try 50 to 100 pf parallel R2. And for RF pickup from the input, I'd put 100 to 130 pf to analog ground between c1 and r1. Of course, needs a grounded steel or aluminum case to also keep the RF out. I use portable steel file case with a square hole cut to allow the heat sink to be outside.
I built an LM1875 amp point to point wire and both channels motorboated about 10 cycles/sec. You really need a circuit board just like in the TI datasheet. Unfortunately all the ones for sale are speaker burners, dual supplies with the IC hooked directly to the speaker. There is a single supply capacitor coupled circuit in the datasheet, but nobody on ebay, amazon, or aliexp will sell you that pcb unless you supply a gerber file. My speakers cost 20 times what one of these diy amps cost.
For a circuit with about the same parts but actually works (I built 2 point to point) and sounds good see apex6 https://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-42.html
Nobody will sell your a pcb for it though unless you supply a gerber file.
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What is that ?? i've NEVER had anything oscillate unless I was making my analog synth circuits ?
LFO's and VCO's (better planned oscillators) accurate oscillators. you must know the oscillator to avoid it.
Class D (Hypex) is VERY interesting to me , fully out of phase self oscillating amp , with the output duty cycle
of said oscillation modulated with the audio ! I'll oscillate for 400 watts !!
(below) One big loud freakin' oscillator !!! 🙂
OS
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If he has a split secondary , just double up ( or join the CT for 50V). And use a capacitor coupled OP stage.
I hear they have a nice sound. All the old 70/80 radio shack amps were cap coupled.
the Bipolar equivalent is the "bootstrapped" VAS , where you inject the "cap" sound before the OP stage.
BUT , unless you have a super nice /stable (like my Sonance Sanken EF2) OP , easy to fry a speaker.
BTW , that is why the Sonance has real simple fast DC relay at the OP .....
OS
If the OP decides to start from scratch, could any of the diyaudio store amps be recommended? Which one would be closest to what he was planning to build (but hopefully better)? Would the ACA mini be suitable?
Nah , Alibaba chipamp...
I can't believe the OP posted circuit. Not dangerous , but "childlike".
His PS would not run a class A amp !
His power supply would be bare minimum for my "pitchfork " headphone amp.
He needs to scout the dumpsters for some big toroids !
Wish he was local , I have 1-150VA 35-0-35 and a 200VA 40-0-40 in my junkbox. I'd give it away.
OS
I can't believe the OP posted circuit. Not dangerous , but "childlike".
His PS would not run a class A amp !
His power supply would be bare minimum for my "pitchfork " headphone amp.
He needs to scout the dumpsters for some big toroids !
Wish he was local , I have 1-150VA 35-0-35 and a 200VA 40-0-40 in my junkbox. I'd give it away.
OS
What is your DC offset at the output? I wonder if there is enough leakage current through C1 to set the DC input of the op amp to zero?
OP ought to go ahead and build that on a perfboard. Everyone who “thinks” they are going to become a PCB designer should have the practice doing things like that first. They may not be expensive anymore but reordering things three times till everything is right is. Do a few of those, and you’ll know a little more about what you’re doing when you sit down with a CAD tool.