Google traductor fail 😀
Thank you.
So for 6 ohm speakers, a 2x24V R-core transformer is good?
R-Core 2x24V
I think I need one transformer per channel.
With 30Vcc at 6 Ohm, the output power is 60W. What is the consumed power? What is the efficiency of the LM3886?
hello.
if your max. p-out is 60 watt then the transformer should have a bit more - 80watt and more............120w or so looks very well.
greets.
if your max. p-out is 60 watt then the transformer should have a bit more - 80watt and more............120w or so looks very well.
greets.
I made a calculation but I don't know if it is true.
Transformer total voltage: 24V+24V = 48V
Speaker impedance: 6 ohm
Amperage: 48/6 = 8A
Power required: 24V*8A = 192W
+ Heat dissipation (35W in my case): 192W+35W = 227W
I think that 250-300VA would be good.
</SPAN>
Transformer total voltage: 24V+24V = 48V
Speaker impedance: 6 ohm
Amperage: 48/6 = 8A
Power required: 24V*8A = 192W
+ Heat dissipation (35W in my case): 192W+35W = 227W
I think that 250-300VA would be good.
</SPAN>
Hi,
your amplifier does not draw a continuous load.
On sinewave test signals each supply rail supplies between 0A and 1.4*Aac.
The smoothing capacitors and decoupling meet the instantaneous demand for current.
The transformer charges up the smoothing capacitors to match the average current demand at that time.
A good rule for sizing a mains transformer to power a ClassAB amplifier is:
Select transformer VA to be one to two times the total maximum power of the loads.
Two channels of 60W chipamps is a total maximum power of 120W.
A suitable range of VA for that two channel amplifier is 120VA to 240VA.
It will work with transformer outside this recommended range.
A low power single channel chipamp putting out 30W of maximum power could run on a 30VA to 60VA transformer. But performance will be compromised by the varying voltage coming from the transformer as it tries to meet average demand. The transformer regulation is mostly to blame for this poor performance for low VA transformers.
Many suggest a minimum VA for power amplifier use is 120VA to 160VA, where the regulation is much improved.
your amplifier does not draw a continuous load.
On sinewave test signals each supply rail supplies between 0A and 1.4*Aac.
The smoothing capacitors and decoupling meet the instantaneous demand for current.
The transformer charges up the smoothing capacitors to match the average current demand at that time.
A good rule for sizing a mains transformer to power a ClassAB amplifier is:
Select transformer VA to be one to two times the total maximum power of the loads.
Two channels of 60W chipamps is a total maximum power of 120W.
A suitable range of VA for that two channel amplifier is 120VA to 240VA.
It will work with transformer outside this recommended range.
A low power single channel chipamp putting out 30W of maximum power could run on a 30VA to 60VA transformer. But performance will be compromised by the varying voltage coming from the transformer as it tries to meet average demand. The transformer regulation is mostly to blame for this poor performance for low VA transformers.
Many suggest a minimum VA for power amplifier use is 120VA to 160VA, where the regulation is much improved.
Hi,
as pointed out by Red, National's graphs showing Power dissipation vs Power output for various loads is far more informative than an efficiency figure.
as pointed out by Red, National's graphs showing Power dissipation vs Power output for various loads is far more informative than an efficiency figure.
According to the graph:
For 30V @4 Ohm, power dissipation is 47W
For 30V @8 Ohm, power dissipation is 25W
For 6Ohm, I think it will be ~36W
So my 60W amplifier, plus the 36W of heat dissipation give a consumed power equivalent to 96W.
But I think that the chip or the speaker have other electrical looses?
Note: I ordered the chips, some resistors and a good soldering iron.
I want to try different resistors value for the gain, and to have a DC offset as small as possible.
I buy : 680R, 1K, 10K, 20K, 24K, 30K, 68K, 91K.
For 30V @4 Ohm, power dissipation is 47W
For 30V @8 Ohm, power dissipation is 25W
For 6Ohm, I think it will be ~36W
So my 60W amplifier, plus the 36W of heat dissipation give a consumed power equivalent to 96W.
But I think that the chip or the speaker have other electrical looses?
Note: I ordered the chips, some resistors and a good soldering iron.
I want to try different resistors value for the gain, and to have a DC offset as small as possible.
I buy : 680R, 1K, 10K, 20K, 24K, 30K, 68K, 91K.
that's it.
~96W when the amplifier is feeding your 6ohm speaker with 60W.
The speaker might give out a peak of 200mW to 20W of acoustic power, depending on efficiency. What ever is not acoustic power becomes heat.
My speakers efficiency is 0.3% 😀
With 60W, they can produce 180mW of music.
104dB with only 180mW !!
The electricity is impressive 😛I'm now trying to find some caps.
µF, ESR, Volts. Is there another important characteristic?
I have found Mundorf M-Lytic caps (50V, 22000µF, 14mOhm) they are good? I can find better caps for this price ? (27€ - 37$)
µF, ESR, Volts. Is there another important characteristic?
I have found Mundorf M-Lytic caps (50V, 22000µF, 14mOhm) they are good? I can find better caps for this price ? (27€ - 37$)
hello.
good electrolytic caps come along with a datasheet,where you can read:......
the purpose (audio-video-entertainment),ratings/temperature, ripple current,esr (at different frequency's),sometimes esl......dimensions(snap-in 10mm lead distance preferred for pcb).........and so on.
there are many reliable manufacturers like panasonic,bc,epcos-siemens,nichicon,............
i presume mundorf is a good one.
greetings
good electrolytic caps come along with a datasheet,where you can read:......
the purpose (audio-video-entertainment),ratings/temperature, ripple current,esr (at different frequency's),sometimes esl......dimensions(snap-in 10mm lead distance preferred for pcb).........and so on.
there are many reliable manufacturers like panasonic,bc,epcos-siemens,nichicon,............
i presume mundorf is a good one.
greetings
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