I build TDA2050 as per ESP. 5 Nos Amp on single heat sink size 4" x 12" All 5 amps are sounding good individually. As I read proper grounding is required for gainclone so I wish to verify.
Ground Point 1: Connects Input 22K+220pf AND 47uf 25V AND RC ground.
Ground Point 2: Connects Power Ground AND 1R 1/2 Watts AND Speaker Ground.
Above 1 & 2 ground points are connect with single wire.
NOW, I wish to connect those all 5 Nos amps to single PSU (transformer) which is the best way ? ( I HAVE ALREADY DAMAGED 4 NOS CHIPS AND ONE TRANSFORMER, I DON'T WANT TO TAKE A RISK THIS TIME !)
Option I : As attached picture, with this option I found lot-off wire in the system.
Or better option !
Ground Point 1: Connects Input 22K+220pf AND 47uf 25V AND RC ground.
Ground Point 2: Connects Power Ground AND 1R 1/2 Watts AND Speaker Ground.
Above 1 & 2 ground points are connect with single wire.
NOW, I wish to connect those all 5 Nos amps to single PSU (transformer) which is the best way ? ( I HAVE ALREADY DAMAGED 4 NOS CHIPS AND ONE TRANSFORMER, I DON'T WANT TO TAKE A RISK THIS TIME !)
Option I : As attached picture, with this option I found lot-off wire in the system.
Or better option !
Attachments
re post3.
You cannot get both 35V and 25V from the same PSU.
The lower LED is back to front.
What are all the extras for?
You need a transformer, a rectifier and a pair of smoothing capacitors.
The worst case voltage from your 24Vac transformer will be about 38Vdc (if regulation ~7%). You must not use a 25V capacitor across this.
Do any of the amplifiers drive a full range speaker or a bass speaker?
Then the +-4700uF is far too small for all those amplifiers.
The 4k7 resistors will dissipate just over 240mW. use 500mW or 600mW and stand them off the PCB, they will run warm.
You cannot get both 35V and 25V from the same PSU.
The lower LED is back to front.
What are all the extras for?
You need a transformer, a rectifier and a pair of smoothing capacitors.
The worst case voltage from your 24Vac transformer will be about 38Vdc (if regulation ~7%). You must not use a 25V capacitor across this.
Do any of the amplifiers drive a full range speaker or a bass speaker?
Then the +-4700uF is far too small for all those amplifiers.
The 4k7 resistors will dissipate just over 240mW. use 500mW or 600mW and stand them off the PCB, they will run warm.
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Then If I want I will have to use two transformer. But PB advised not to run 4ohm speaker cause IC run HOT. So, 18-0-18 would be good to run 5 Nos TDA2050 & 1 Nos LM3886.
if I use 18-0-18 transformer i.e. 25v +- . I should increase caps on PSU. Is 10000uf good to run those 6 amps.
Reply Post # 2, Pacificblue as you advised, I build bulb tester as I understood ( I am not electronics man so I cannot understand electronics language properly) Please find attached picture.
Before trying/powering all amps individualy I test all amps by ( speaker polarity tester ) touch (-) polarity to heatsink and (+) polarity to all points on PCB. Like (+), (-) and ground. If the speaker does not jump i.e. it is not short to heatsink. Even I test this-way for my damage chip it was jumping.
2nd test with ( speaker polarity tester ) If I touch (-) polarity to back-side of the IC, speaker jump only when I touch the IC's PIN no.3. And very little on PIN no.5.
After above test, I attached bulb tester & powerd only one amp. I found, bulb is not glowing and amp is sounding good. ( I could not understand why bulb is not glowing )
As per Post # 1 picture I wired all amp and powerd (Bulb tester is still attached) Bulb glow very little. WHEN I ATTACH DVD PLAYER ALL 6 CHANNEL OUTPUT TO ALL TDA2050 RC SOCKET. BULB GLOW VERY BRIGHT ( Is this normal ? )
BUT AFTER 5 MIN. I FOUND TRANSFORMER BECOME VERY HOT AGAIN.
I am confused why this happening. My one 18-0-18 transformer meltdown, I did not purchased new one. And this all I am trying with 12-0-12 5 amp transformer. Is that reason ?
ONE THING PACIFICBLUE, TDA2050 SOUNDS POWERFULL THEN TDA1554Q ACCEPT SWEET HIGH-FREQUENCY. BUT THIS CAN BE TUNED AFTER ALL AMPS STABLE.
Thank you & Regards.
Attachments
the bulb = off, tells you the connected circuit is drawing very low current. That is good.
The bulb glowing or bright tells you high current is passing. That is bad. There is a serious fault, if it is bright. Switch off and test for the fault.
If the transformer is HOT, then the fault is probably in the transformer wiring.
Disconnect all the amplifiers and bulb test the transformer and PSU.
You should be careful with that battery you use for testing. 1,5 V DC at the amplifier input can lead to high DC voltage at the speaker output.
Six amplifiers on a 120 VA transformer could be asking too much of the transformer.
If the amplifier is reproducing music on all channels, the light bulb must become bright, because more current flows. It is important that the bulb stays off or remains dim, when the amplifier is powered, but no music is playing. In that condition you can make all necessary measurements to make sure there is no fault. Once you are sure that everything is working correctly, you can remove the bulb tester and check everything with music.
Six amplifiers on a 120 VA transformer could be asking too much of the transformer.
If the amplifier is reproducing music on all channels, the light bulb must become bright, because more current flows. It is important that the bulb stays off or remains dim, when the amplifier is powered, but no music is playing. In that condition you can make all necessary measurements to make sure there is no fault. Once you are sure that everything is working correctly, you can remove the bulb tester and check everything with music.
All amps sounding music but not clean, If I mute the volume, some sound comes like VOU VOU VOU VOU VOU VOU ( Sorry I can not describe ) I have added RF filtter. It's not HUM. This sound does not come when single amp running. Should I purchase new transformer 18-0-18 2Amp.(available to my supplyer ) 12-0-12 transformer is not sufficient ? How big smoothing capacitor I should apply ?
Your description sounds like a phenomenon called motorboating. That is a result of unwanted feedback, which leads to some kind of oscillation.
It is possible that you get that effect, when leads or traces are too close to each other. The speaker signal can e. g. couple into the input signal, and produce such an effect.
Try to group the wires according to their function. E. g. power supply, speaker, line level. Then separate the groups from each other. Power supply wires should not run in parallel with line level signal wires. Speaker wires should not run in parallel with line level signal wires. The distance between speaker and power supply wires is not as critical, but it is always good to separate them as well.
Review your amplifier with that in mind. If you have the PCBs very close to each other, the traces can also couple into each other through induction. Bring as much distance between the wire groups as you can, where they run in parallel. You need less distance, where the wires cross paths at right angles.
The best solution is to take all line level signal wires to one side, all speaker wires to the opposite side and the power supply wires at a right angle to the others, i. e. upward, downward, towards the front or towards the back. You will need to look, how you can best do that in your amplifier case. When there is not enough space to keep the wires separate, you can try shielding them with metal plates in between. That is however not very effective at low frequencies, unless you can get your hands on the very expensive mu-metal. Try grounded copper (e. g. untreated PCBs) or aluminium.
The transformer should not degrade the sound at low listening levels. It could become an issue at high listening levels. A transformer should have a power rating at least as big as the combined output power of all amplifier channels.
It is possible that you get that effect, when leads or traces are too close to each other. The speaker signal can e. g. couple into the input signal, and produce such an effect.
Try to group the wires according to their function. E. g. power supply, speaker, line level. Then separate the groups from each other. Power supply wires should not run in parallel with line level signal wires. Speaker wires should not run in parallel with line level signal wires. The distance between speaker and power supply wires is not as critical, but it is always good to separate them as well.
Review your amplifier with that in mind. If you have the PCBs very close to each other, the traces can also couple into each other through induction. Bring as much distance between the wire groups as you can, where they run in parallel. You need less distance, where the wires cross paths at right angles.
The best solution is to take all line level signal wires to one side, all speaker wires to the opposite side and the power supply wires at a right angle to the others, i. e. upward, downward, towards the front or towards the back. You will need to look, how you can best do that in your amplifier case. When there is not enough space to keep the wires separate, you can try shielding them with metal plates in between. That is however not very effective at low frequencies, unless you can get your hands on the very expensive mu-metal. Try grounded copper (e. g. untreated PCBs) or aluminium.
The transformer should not degrade the sound at low listening levels. It could become an issue at high listening levels. A transformer should have a power rating at least as big as the combined output power of all amplifier channels.
If you want your final amplifier configuration to have good performance at the maximum rated power output, you would want to use a transformer with higher VA rating. Also good would be a higher output voltage, regulated down to what you need.
You could choose the minimum capacitance (per rail) to use, for unhindered bass response down to frequency f, with:
C ≥ imax / ( πf∙(Δv - (ESR∙imax)))
which was derived in the post at http://www.diyaudio.com/forums/power-supplies/216409-power-supply-resevoir-size-169.html#post3320547
and gives the capacitance value, C, that would be required in order to supply the current for one half-cycle of a sine signal of frequency f (in Hz), with 0-to-peak amplitude imax Amperes, while causing the voltage across the capacitor to dip by no more than your choice of Δv Volts.
imax = √(2 ∙ P_rated_rms / R_load)
With the C equation above, you could first let ESR = 0, then calculate C, then find the ESR for that C at frequency f, then recalculate C with the ESR you found, and you might need to iterate like that until C does not change significantly.
Or, using an approximate expression for ESR,
ESR = 0.02 / (C x VR), where VR = Voltage Rating of capacitor, and substituting it into the first equation, you could use:
C ≥ imax ((0.04πf / VR) + 1) / (πf∙Δv) [approximate, for electrolytic cap, only]
If we assume that the charging pulses would always be sufficient to recharge the capacitors as much as needed, then the two equations above would become the two equations below:
Capacitance Needed for a Sine Down to Bass Frequency = f, at Max Rated Power:
(1) C ≥ ( (imax ∙ f ) / ( 2 ∙ fmains )) / ( π ∙ f ∙ (Δv - ( ESR ∙ imax )))
(2) C ≥ (( imax ∙ f ) / ( 2 ∙ fmains ))∙(( ( 0.04 ∙ π ∙ f ) / VR ) + 1) / ( π ∙ f ∙ Δv ) [approximate, for electrolytic cap, only]
where VR = Voltage Rating of capacitor.
-----
But, for it to be truly "bulletproof", for any signal shape, including DC at the maximum rated peak sine voltage and current, you would want to use:
C ≥ (imax∙Δt ) / (Δv - (ESR∙imax))
which gives C as the capacitance that will allow only up to some desired maximum rail-voltage dip Δv when a specified maximum rated current imax is pulled out of the cap for a specified time Δt.
In this case, for a full wave bridge rectifier, we would use the time between charging pulses as Δt, i.e. Δt = 1/2f, where f is the AC mains frequency (50 Hz or 60 Hz), giving:
Capacitance Needed for Worst-Case Signal Shape, at Max Rated Power:
(3) C ≥ ( 1 /( 2 ∙ f )) ∙ imax / (Δv - ( ESR ∙ imax ))
Or, using the same approximation for ESR as was used before:
(4) C ≥ ( imax / Δv ) ∙ ( ( 0.5 / f ) + ( 0.02 / VR )) (approximation, for electrolytic capacitors ONLY)
where VR = Voltage Rating of capacitor.
Note that if the ESR is not much lower than the desired Δv / imax (which is also the maximum impedance we want the load to see), then the required capacitance value would be excessive.
Cheers,
Tom
You could choose the minimum capacitance (per rail) to use, for unhindered bass response down to frequency f, with:
C ≥ imax / ( πf∙(Δv - (ESR∙imax)))
which was derived in the post at http://www.diyaudio.com/forums/power-supplies/216409-power-supply-resevoir-size-169.html#post3320547
and gives the capacitance value, C, that would be required in order to supply the current for one half-cycle of a sine signal of frequency f (in Hz), with 0-to-peak amplitude imax Amperes, while causing the voltage across the capacitor to dip by no more than your choice of Δv Volts.
imax = √(2 ∙ P_rated_rms / R_load)
With the C equation above, you could first let ESR = 0, then calculate C, then find the ESR for that C at frequency f, then recalculate C with the ESR you found, and you might need to iterate like that until C does not change significantly.
Or, using an approximate expression for ESR,
ESR = 0.02 / (C x VR), where VR = Voltage Rating of capacitor, and substituting it into the first equation, you could use:
C ≥ imax ((0.04πf / VR) + 1) / (πf∙Δv) [approximate, for electrolytic cap, only]
If we assume that the charging pulses would always be sufficient to recharge the capacitors as much as needed, then the two equations above would become the two equations below:
Capacitance Needed for a Sine Down to Bass Frequency = f, at Max Rated Power:
(1) C ≥ ( (imax ∙ f ) / ( 2 ∙ fmains )) / ( π ∙ f ∙ (Δv - ( ESR ∙ imax )))
(2) C ≥ (( imax ∙ f ) / ( 2 ∙ fmains ))∙(( ( 0.04 ∙ π ∙ f ) / VR ) + 1) / ( π ∙ f ∙ Δv ) [approximate, for electrolytic cap, only]
where VR = Voltage Rating of capacitor.
-----
But, for it to be truly "bulletproof", for any signal shape, including DC at the maximum rated peak sine voltage and current, you would want to use:
C ≥ (imax∙Δt ) / (Δv - (ESR∙imax))
which gives C as the capacitance that will allow only up to some desired maximum rail-voltage dip Δv when a specified maximum rated current imax is pulled out of the cap for a specified time Δt.
In this case, for a full wave bridge rectifier, we would use the time between charging pulses as Δt, i.e. Δt = 1/2f, where f is the AC mains frequency (50 Hz or 60 Hz), giving:
Capacitance Needed for Worst-Case Signal Shape, at Max Rated Power:
(3) C ≥ ( 1 /( 2 ∙ f )) ∙ imax / (Δv - ( ESR ∙ imax ))
Or, using the same approximation for ESR as was used before:
(4) C ≥ ( imax / Δv ) ∙ ( ( 0.5 / f ) + ( 0.02 / VR )) (approximation, for electrolytic capacitors ONLY)
where VR = Voltage Rating of capacitor.
Note that if the ESR is not much lower than the desired Δv / imax (which is also the maximum impedance we want the load to see), then the required capacitance value would be excessive.
Cheers,
Tom
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