Not sure if I'm missing something here, but at 14:40 you said you were going to simulate ESR, but then you put the resistor in parallel with the cap, not in series. Wouldn't that simulate leakage current instead of ESR?
You are correct! Oh no! I don’t know how many times I watched that video during the edit, but I think the brain hears what it expects to hear, not the actual words spoken. It’s too late to correct the video. I think I said the right words (leaky vs ESR) later in the video. Thank you for picking that up, Dazz. I have pinned your comment so people will see the corrected error.
@@theguitaramptech Without the electronic / electricity, our mechanisms do not move. Sir you are sage! Keep on spreading the knowledge and wisdom. Peace out from Virginia Beach, Va!
I know hum is bad, but the hum at the start of voodoo child (slight return) is kind of iconic, in a weird way. Like ‘woah if the background hum is that loud, sh!ts about to go down’
Woa Johnathan…you ‘da man! I have listened and soaked myself in that song since I was 12 and I had never noticed that hum. But, I reckon if it was ME who recorded with that hum, people would say “Chris, you sound like sh*t with all that hum”. Thank you Johnathan for making me listen!
That 9.1% increase you spoke of for My power supply is pretty accurate. say an AA1164 Princeton schematic calling for a plate voltage is 410 volts. add 9.1% and and you get a true voltage of 455 volts. The original Filter caps were rated for 450 volts. Now it shouldn't be a shock that wall voltages might even be higher than the 9.1%, say 124 instead of 120. A quick study should say that those 450 volt max caps are well beyond their lifting power. And, that should also give an indication to look at voltages at the bias cap and grid caps, etc and make sure the voltage demands aren't being exceeded. That is why looking inside a reissue, for instance, you will find the ratings of the filter cap voltage have increased from 20@450 to 22@500. Now, of course, this tidbit comes with a couple of questions. Newer transformers are wound with the higher voltages in mind, so no issue there. But if you are running a 1964 transformer, you are getting the full benefit of this higher current and voltage in your circuits. This makes higher plate values when you lower the current to set the bias on your output tubes. The question is, what would be a good and proper way to resolve this without ponying up for a new transformer? Perhaps higher resistance dropping resistors in the power supply area? And how would that effect the load on the transformer? as a side note, the Princeton Reissue shows a plate voltage of 440 also, so apparently they didn't do alot of work on the transformers. (don't think I didn't notice you calling me out as smarty pants) :p
HAHAHAHA! You cack me up, Alta. Your knowledge has raised a couple of very good points about capacitor ratings. Being in Sydney, I wasn’t aware that USA mains can get up to 124V. To get the plate voltages down a little, I would first look at a rectifier tube with lower B+. My favourite low B+ option is the 5Y3. As you said you can also use a dropping resistor, but the plate voltage would have iits voltage sag exaggerated relative to current draw as you now need to add the increasing voltage drop of the resistor to the rectifier. (Don’t forget to do your maximum power dissipation for that resistor and then double it. ) That won’t solve all your problems, sadly. 124v is a 12.7% increase. This means your filament supply will now go up from 6.3v to 7.1v. Your tubes WILL work at 7.1v, but they will be running hotter and their life will be reduced, and the power transformer will also be running warmer. If there is no such transformer as a 125V to 110v stepdown transformer in the USA, you may have to stump up for a Variac. Ouch.
@@theguitaramptech moving to different rectifiers is what I had used so far. it helps. Now, for a future project for your consideration, find a cheap Marshall g100r cd amp head, use the fender deluxe reverb circuit. Delete all but one input add in a channel switching board with its own power supply off the 6.3 volt winding. Utilize 99% of the original faceplate layout. Use the deluxe reverb power and output trans. you decide on 6v6 or el34 or even 6l6 output. Maybe consider those cheap russian 6n2p tubes with the modified heaters. Tone mods to taste. One I am kicking around right now myself. Actually hoping to use the Princeton reverb (simpler tremolo) as the (2) trem channel and a marshallesque setup in the first channel.
@@3MonkeysGarage that sounds like an interesting project. I so wish I had time but my priorities are customer repairs then videos and …lastly… come my toys. Let me know how your project turns out.
Hey Chris, for a newbie like me that was some learning curve..! Great video and so funny. I had my hand up a few times when you asked a question, so something must be sinking in..Take care and keep the info coming..Stay safe..Ed..uk..😀
G'day Ian. Yes, in the next chapter we will be looking at rectifiers in more detail. As you know, Sag is the symphony of individual elements not a solo performance.
Capacitors non polorized or electrolytic store's energy electrostatically Filter chokes or coils of wire store energy electromagnetically. Chris your pretty cool. Giving away knowledge in a practicle way that can be understood for the layman. Google sent me your video. You are much like uncle Doug of Danisonic but he never shows his face.
Thank you for that excellent suggestion, Willian. Yes, I quite often install a 0.1uF/630v film cap across a large electrolytic. As you know, it will not help with sag, but it will take over from the electrolytic when the noise is significantly higher than the electrolytic's main "job" of looking after 100/120Hz. Fellow Aussie, Dave from @EEVBlog, made an excellent video on exactly this practice. If you haven't seen it yet, you will find it very interesting. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-BcJ6UdDx1vg.html
When you say its a 20uf capacitor or whatever, do you actually mean that or is it 0.20uf? I wouldnt ask this if it wasnt for the fact that im an hvac tech and our 20uf capacitors are GIANT, like bigger than a tube. No offense meant!
I’m not sure which part of the video you’re referring to. If it is a filter capacitor, then yes 20 µF is appropriate. If it’s a coupling capacitor then it’s more likely to be .01 to .1uF. Your HVAC caps serve a different purpose to help start huge motors.
@@theguitaramptechThats so cool, thanks for the reply! That said i was just watching and at 7:34 you mention a 20uf capacitor - which would be maybe for a small compressor motor and i just cant recall ever seeing a capacitor that big in an amplifier. That said i now realize that: 1: this might just be an example 2: ive only owned like 3 tube amps, the largest (output) of which was 20w 3: those capacitors would usually have a smaller 5uf or so section for the fan motor (edit: which may increase their size) Still i am curious though if you want to bother elaborating. Great work on this series either way!
I hope this equation helps to clarify capacitors for you. The higher the energy stored, (usually) the larger its physical size (not always the case, but usually). The energy stored in a capacitor is a function of capacitance and voltage. Energy=1/2 x Capacitance x Voltage(squared).
