I like your videos always - they are so natural and not so highly optimized like others ... just showing what you will show us and talking about your ideas - that's great!
Hi JAT, John, As a regular viewer, I always look forward to new uploads. You have a really interesting channel. Being self taught in electronics, you can't beat the voice of experience and years of practice. I hope all is good. Take care, C.
Simple electronics theory; the ripple voltage Vr = I/(fC), where Vr is ripple voltage, I current drawn f 2 x mains frequency and C capacitance. Increasing the capacitance decreased the ripple voltage allowing the amp to get nearer to the voltage rails.
Just your first comments, if the content is interesting and the video isn't a potato people will watch. I'm 6 years later cos I'm curious about this exact thing lol. But ill check your subs shortly hope it's grown for you bud! 😊
A good compromise would be to use the same transformer, the voltage drop on the AC side will not be that great. Then use a separate bridge and smoothing capacitors for each channel. Obviously if one channel is already pulling the rails down, the other amplifier has less to play with even before it starts being driven. I bet you will be close to that 20 watts, one channel driven. Try it.
The reason for the voltage drop is the insufficient power of the transformer, and the same reason why the overall power boosted for 20 percent just by adding a larger capacitors, because the capacitors acts like a power reservoirs and help the transformer to deliver power almost to the limit , but i doubt that if you put two bridges and two smoothing caps you get a 20 WATTS per channel, simply because if transformer have e.g. 30 WATTS it cannot give 40 WATTS no matter what you do.
thank you for sharing an informative video ! i have kenwood ka2000 vintage amp! it is 13wt/ch at 4ohms. there are 2200uf at 50Wt and 1000uf at 30Wt caps at power supply ! how much i should increase the capacitance and power for optimal results ! thank you !
I always felt like big caps, aside from smoothing the current would give a bit more dynamic power due to them having more reserve power for peak output of whatever you're listening too. I'm probably completely wrong haha but guess we'll find out.
What capacitors can you recommend for an AV RECIERVER with a pair of power supply capacitor of 22.000uf at 85v??? The caps are 15 year old. Any high end recommendations?
hi john I was looking at the VHM-314 v2 and VHM v3, and i noticed the V3 has much bigger capacitors, would that mean the bt reciever could handle more bass spikes when listening to music? what are the benefits of a bigger cap?
Can through hole filter capacitors in a power supply be improved by increasing them to a greater capacity to make the power supply quieter and more efficient especially in guitar amplifiers?
It is a 25.2 volt, 2 amp CT (12.6v per side). Finding a 3 or 4 amp transformer would be better. If you want more power using 8 ohm speakers, I'd get a 36v CT transformer.
Of course it would be better. I found 2 pretty good 4 Ohm/8 Ohm/16 Ohm table (voltage ^-> wattage and amp ^-> wattage). If im right with that voltage the max output current can be 3,7-3,8 amp with 4 Ohm load.
John, is there any difference in sound with using 1x10.000uF and 5x2.200uF? I understand paralleling caps will reduce ESR and is generally better? Thanks!
If you have the room, more caps are better. If you work a powerful amp hard into low impedance loads, the caps can actually heat up due to the ESR, so more caps in parallel will be lower ESR and higher surface area. For normal listening, I doubt there would be one bit of difference in the sound as long as the negative feedback has control over the amp circuit.
If i replaced the filter capacitor on my magnavox 14 watt receiver with one that has a voltage capacity of 70 volts[the present capacitor has capacity of 45 volts] would my wattage output increase considerably?
Ooo you are the master. Sir, I have a dream to build an audio system sounds clear, crispy and better than BOSE. What are the things I need to consider while assembling an amplifier for powerfull home audio. Please share your experience.----------------------should I build it using two mono amp with two separate toroidal transformer . Waiting for your opinion. Thanks in advance.
Oooooh Bose! :D Yes, you might do a bit better going with separate amps and transformers. I'd still put them inside the same case unless you want them totally individual.
Bro I got an older 80 amp STINGER power supply that I sucked the life out of before I knew what I was doing man I know it's the caps it still works it's just weak idk could you fix mine sometime?
I followed your earlier video "Filter capacitor influence on amplifier" and want to know that does a 2 Ampere transformer actually delivers only 50℅ of its rated capacity ?
Because of the higher output voltage after full wave rectification and filtering, the actual continuous current that can be delivered is less than the transformer's current rating. It depends on how it is set up, but it is more than 50%. Using a filter choke can improve current capacity.
"How do you measure ESR?" = with an ESR Meter. You can suitable simple ones from Ebay for $15 or so - just look for the multi-device electronic testers with the blue dot-matrix LCD screens that are often called transistor testers.
Ingegeral larger caps will hold up the rails better. Be careful to use good low ESR caps, they really do a better job. Also avoid Chinese caps the are of questionable quality, stick with Japanese caps.
@@userPrehistoricman You always have to count on losing at least 2V across a linear regulator and you then need to add on the maximum ripple voltage to ensure each regulator stays in regulation (you obviously need a positive and a negative regulator). Switching regulators are not suitable for audio use. Given ±17V rails into 4 Ω, the peak current drawn is possibly 4A or 3A rms to deliver the maximum theoretical output power of 36W. With 10,000μF capacitors, the peak ripple can be as much as 3V (VC=It). The commonest linear regulators like LM317 and LM337 can only deliver 1.5A, so you need a booster transistor in each rail. With all that complication, you'll lose maybe as much as 5V out of each of the 17V rails. Instead of a theoretical maximum output power of 36W rms (17V x 17V / 2 x 4 Ω), you get a theoretical maximum output power of (12x12)/(2x4) = 18W. It's really not worth halving the power available from the transformer just to have the regulation.
If you have no losses, then a single-ended output swinging ± V volts into R ohms can't possibly output any more than V² / 2R watts rms. No amount of trying can get more than 18W rms out of ±12V rails into 4 Ω. The most voltage you're likely to get out of a 12.6V-0-12.6V ac transformer is ±17V dc (that's 36W max without losses into 4 Ω or 18W into 8 Ω).
Since the power supply is independent of the amplifier, the resistors bleed off the charge from the capacitors when it is unplugged from power and not connected to the amplifier.
@@JohnAudioTech may i know the values? Love it implement it in my designs. Also try using capacitance multiplayer in your designs.. i dont have an oscilloscope to measure frequency response and distortions. Your videos give quite a bit of insight ! Thanks for doing these videos..
@@Vtrontv At 3:29 they look like Brown-Black-Red = 1K. Since the rails are about ±17 that would dissipate 0.29W in each resistor, so 1/2W or 1W resistors are needed if I read the markings correctly. In the case of 10,000μF capacitors, the discharge time constant would be 10 sec, which would be okay.
Is it true what Petroci Gabor commented on one of Your videos: "Large caps cure noise, but on the same time damping dynamics by first reservoir caps esr dissipation factor. If you have too much filtering, you loose reaction time. Loose high end, loose accuracy."
You are correct. Most music is short pulses of drum beat which would let you get by with small caps but some music has long sustained bass which would need better continuous power.
I meant that it seems you don't need to increase VA of your transformer, and it's definately a good idea to replace those caps. I am curious why I have never seen your amp made on an etched pcb? From my experience it's easier to make a good layout that way.
