Howdy. Nice walkthrough. One might consider connecting a plastic cap. of say 1 uF in parallel with the main filter cap. That should knock down the noise on the rails. It might also cure any tendency to oscillate. Regards.
Well if you look at the datasheet for that IC, the THD is already at 10% when you reach 2W Peak. Nasty! So yea, that IC is pretty bad. Your VPP is roughly 10.5v, and you have a 12V input so that is correct, as you have some drop across the output transistors.
+Bogdan Serban Wrong. The capacitor, unless it is totally underdimensioned (not the case in this video) will deliver one constant voltage, U = (√2) * U_P. The capacitance does not matter. In the video you see the output power does not change at all.
Kevin Livingston correct. In power supply filter capacitors you only need to know two things. 1... The voltage rating on the capacitors must be higher than the transformer secondary output... How high you ask? As high as you can afford... Just as long as it's never lower.... 2. The capacitors capacity should be high as possible... According to what size will fit and of course what your wallet can afford.... Also... I guess that you can safely say that there's a third rule of thumb... And that will be the ESR value of the capacitors you choose... The ESR value needs to be as low as possible for the type of capacitors you will be using... There will be many different options available from different brands... Make sure that you pick the one with the lowest ESR value for the voltage and capacity... Try to aim for 105° temperature rated capacitors... These will last longer.... Happy capacitor shopping :)
Power output depends on voltage, a higher filter cap will give more peak power but little extra continuous power. That chip also has a very poor spec, not really HiFi even on a good day!!
sorry this question is unrelated to the video** just wanted to ask you this before i go ahead and make any decisions, ive got a camera that the previous owner has said that he used sony mini dv tapes and panasonic mini dv tapes. Which are both the 'me' style lubricants, and i also have the same style sony tapes. Do you think it would be fine to go ahead and start using the camera without a head clean? (since im using the same 'me' style sony tapes)
+vancscoot If the camera is not displaying any video issues, then no need to clean. Remember that to much video head cleaning can wear out the heads! As far as tape usage, if I remember correctly, Sony tapes are not good, causes issues with its lubricates, Panasonics are recommended, this is all I use in my tape cameras...another thing, don't mix tapes as each one uses a different formulas of lubricates, stick with one brand / type.
+JacksJunkDotCom ok thank you, sorry i was talking about getting the heads 'professionally cleaned' and not the cleaning tapes. But i only have sony tapes left so i might just get the camera 'professionally cleaned' then switch to a different brand of tape (tdk) ? would be the best?
+vancscoot Yes, by all means, use what you have, just keep my recommendations as food for thought. Have the camera serviced and you should be good to go! :)
Thanks Dr 😊 I’m a complete novice and been researching the effect of increasing the capacitance of power filter caps in old amps and although everyone says you can do it to a certain degree, they warn that you could damage other components if you exceed original capacitance too much And not provide a soft start function! In your experience, is this true? I was thinking of putting two 15000uFs in place of the two existing 6800uF ones. Could that cause issues? It seems you More than doubled original specs successfully. Thank you so much for your help.
Indeed increasing the capacitance of the filter capacitor too much can cause damage. When turning on power, the capacitor is charged. This creates a current spike, the higher the capacity, the bigger the spike. If the spike is too big it can destroy for example the rectifier diodes. For the experiment shown in this video these considerations did not matter. If the bigger capacitor had caused damage, I would have repaired that and used a smaller capacitor. Obviously this is not a good strategy when you want the amplifier to work reliably. In your case, I would say increasing the capacitance from 6800 µF to 10000 µF should be fine, but don't go any higher than that! 15000 µF is likely enough to cause damage!
@@DrCassette thank you so much 😊 I’m gonna go with what the Dr ordered 😊 and no, I will not hold you responsible in any shape or form if I end up burning down the house! 😊 Been checking out your other videos and Already have a better understanding than when I posted the question! Thank you.
HI and thanks a lot for the very interesting video. I have a question. What kind of impact would have a change in the VA of the transformer ? could that give more power ? i am thinking of modding some old amps i have at hand and i would like to understand if it would be better to upgrade the power supply transformer or the power supply capacitors in order to get some more slam in the sound (i.e. dynamics). Thanks a lot again.
As shown in the video, bigger capacitors will increase dynamic peak power. A bigger transformer could increase continuous RMS power, but generally amplifiers are designed in such a way that the output power of the transformer matches the output stage, meaning a bigger transformer won't make a difference because then the output stage is the bottleneck.
@@DrCassette Hi and sorry to jump in after so long time but i sincerely love this video. I wonder what would be the outcome with an even bigger cap. i mean .. will there be a point at which adding more uF gives no practical benefit ? i am about to recap some old amps and big and good ones are very expensive Could a value of 20mF per rail per channel be seen as a limit ? thanks a lot again. Kind regards, gino
The filter capacitor is connected to the DC power supply of the amplifier, where there can be fluctuations in the voltage as demonstrated in this video. However, to hurt the capacitor you would have to apply a fairly constant reverse voltage. The supply voltage may fluctuate, but it will never go negative. So the filter capacitor will be fine.
The TA8229k is only capable of about 1W max at 1% THD. Beyond that threshold, the distortion goes sky rocket to 10%. The data sheet says it's just a portable amplifier nothing too fancy. But nevertheless, its worth buying 13000uf capacitor just to run a chip amplifier.
