Id still drop the 193K for regulation, DCR, and filter Q related reasons. 10H and 400uF will give plenty smooth B+, especially for a pp amp.
with the 193M followed by 400uF, I'm simulating 398V with a hum of .27mA. I guess that's pretty solid. I'll probably save the 193K for later. What would those "regulation, DCR, and filter Q related reasons" be, btw?
The 193k adds more resistance, degrading regulation and bass performance.
Splitting the cap in two and adding another choke makes for 2 higher Q filters in cascade and more possible ringing.
Splitting the cap in two and adding another choke makes for 2 higher Q filters in cascade and more possible ringing.
Using a stepped load and/or tap in PSUDII is a good way to pick up ringing, which can happen with transients in a class AB amp.
ringing is bad, but are there ways to damp it down? or is using a minimalist power supply the only way? are diode networks between caps a way to do that?
Fundamentally the way to get a damped filter response is to add more capacitance and/or resistance.
How to calculate LC filter Q:
Resonance Frequency: Fres(low)= 1/ {2pi*[sqrt (L*C)]}
Fres(low) Q= (1/ Rchoke)*[sqrt(L/C)]
If we want to be more thorough, the load resistance across the capacitor also damps the resonance, and can be added to Rchoke via:
Rdamp= L/ (C*Rload)
Rload= VB+/ IDC + Rchoke
Q= [1/ (Rchoke + Rdamp)]*[sqrt(L/C)]
If Q is > .707 there will be a hump in the response of the filter. Q= .5 is critically damped. A Q > 2 is likely to lead to ringing. Look for it in PSUDII with the voltage across the choke in addition to the output voltage.
Each octave the low frequency resonance is reduced by gives 12dB more filtering.
With less than perfect diodes there is a time when no diodes are conducting during the 0 crossing as the foward voltage drop for the diode to conduct has not been overcome, the inductor tries to maintain current causing a voltage to develop. This is why some recommend 220nFish caps to ground in front and behind the choke as snubbers. Math courtesy Morgan Jones, Valve Amplifiers.
Damping of ringing in LC circuits.
Tube power supply design notes.
Rectifiers and transformers.
CLC power supply ringing.
How to calculate LC filter Q:
Resonance Frequency: Fres(low)= 1/ {2pi*[sqrt (L*C)]}
Fres(low) Q= (1/ Rchoke)*[sqrt(L/C)]
If we want to be more thorough, the load resistance across the capacitor also damps the resonance, and can be added to Rchoke via:
Rdamp= L/ (C*Rload)
Rload= VB+/ IDC + Rchoke
Q= [1/ (Rchoke + Rdamp)]*[sqrt(L/C)]
If Q is > .707 there will be a hump in the response of the filter. Q= .5 is critically damped. A Q > 2 is likely to lead to ringing. Look for it in PSUDII with the voltage across the choke in addition to the output voltage.
Each octave the low frequency resonance is reduced by gives 12dB more filtering.
With less than perfect diodes there is a time when no diodes are conducting during the 0 crossing as the foward voltage drop for the diode to conduct has not been overcome, the inductor tries to maintain current causing a voltage to develop. This is why some recommend 220nFish caps to ground in front and behind the choke as snubbers. Math courtesy Morgan Jones, Valve Amplifiers.
Damping of ringing in LC circuits.
Tube power supply design notes.
Rectifiers and transformers.
CLC power supply ringing.
OK, I finally got some measurements on my E550, and finalized a nice symmetrical layout for my amp. The primary winding for the E550 measured at .04 ohms. The 240V secondaries in parallel measured at 1.4 ohms, and 5.1 ohms in series. With an input of 122.4VAC, I measured 232V on the output in parallel and 465V in series. I'd have expected around 490V - is there a reason why the voltage might be less than this?
P.S. Does anyone know where I can get a 20x14" plate of 1/8" aluminum plate for less than $46 delivered to 02116 (Boston)? I'm having real trouble finding a good deal. I've heard that local newspapers might have some for free as a result of mistakes in the lithographic process..
P.S. Does anyone know where I can get a 20x14" plate of 1/8" aluminum plate for less than $46 delivered to 02116 (Boston)? I'm having real trouble finding a good deal. I've heard that local newspapers might have some for free as a result of mistakes in the lithographic process..
Tweeker said:
My current setup is as follows: the E550 followed by a hybrid bridge with two 6AY3's for the positive leg and doubled UF4007's on the negative leg. Choke is a 193M (10H 63R 300mA) and capacitance is 2x500uF 500V JJ cans. I fooled around a lot with stepped loads in PSUDII but never saw anything other than a gradual change in voltage to accomodate different current draws 🙂. Hopefully that means I'm in the clear. Having a plate transformer that puts out over 1 amp might help as well, right?
If you dont see any ringing at startup or with stepped loads you should be fine. A bigger plate transformer aggravates it, but 1mF is alot of capacitance as most tube amps go. Your measures indicate the E550 is conservatively built. You might bypass the elcos with a smaller value capacitor.
OK, cool. I'll probably bypass each one with a .047uF 1000V film cap, generic brand (though they count as one, right?). More updates to follow, as soon as I get that ($*%& plate. Also, I need to get a charger for my camera, to show you all my beautiful layout 
Actually the voltage is lower than expected, but the resistances are pretty low. I think youl be pretty close to the voltage you actually wanted though.
jon_010101 said:
But you'll hear products of intermodulation of your rippless with the signal, especially when it is loud.
the load? i don't really understand. the caps are directly connected to the load... ? isn't that the case with an LC filter?
so connect from the power caps to the opt centertaps, and bypass that wire with a small cap? what does that do?
sorenj07 said:
No. Just think about wires that have own resistance and inductivity. 😉
If your "ground" is on the last filter cap, bypassing load is equal to bypassing the cap. But if you ground and power sre somewhere else (forf example, on a PCB) connected with your last cap by wires, bypass better that "somewhere else" than the cap.
ok. what confused me was the fact that i have both filter caps connected in parallel right after the choke so it really doesn't matter which i bypass...
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