In Reply to: Power supply without indutive reatance posted by Aldovan on January 28, 2004 at 05:38:39:
An equivalent amount of filtering would be done by a 7.5k resistor... but, obviously then you'd need a much higher initial B+.
Stick to the original parts list since you are obviously new to this.
Anyway, what operating point are you going to run the 6080's at? And what output transformer are you using?
Aldovan like to use mono supply for stereo amp.
Let see two 6080 at 80mA each section that ended with 320mA total
just for output tubes.
Now 7.5K resistor at 320mA must be at least 1500W and will drop 2400V.
Even with one 6080 at SE one section for each channel we get at 160mA
250W and 1200V drop.
Joelt that is one of the great ideas I have ever see in my life.
> > Joelt that is one of the great ideas I have ever see in my life.> >
I said "for an equivalent amount of smoothing". I did not say one should implement a 7.5k resistor.
Z = 2*pi*f*L = 7539 ohms impedance.
But like you and others said, you don't have to have that much of a series impedance - about 100 ohms with larger capacitors can suffice.
First off, the formula is for reactance X, NOT impedance (which is
the VECTOR sumation of DC resistance R, reactance of the capacitance, Xc & reactance of the inductance XL in the circuit).
So you mean the reactance XL of the inductance is 7.539-ohm. Strictly
speaking, the calculated impedance of a 10H inductor should be XL + DCR, assuming the stray capacitance inside the inductor is negligible to induce additional Xc & vector shift.
So, why 120Hz? How are you so sure that this is a full wave rectification. It could be half wave or bridge-type (double full wave) rectification.
Back to the issue, while XL is to suppress AC rippling of the HV,
larger the better, provided the too big henries would not 'ding' up
overshoots from the filter caps. We must not confuse with its DC resistance which should be lower the better to reduce the undue DC voltage drop throughout the HV circuit.
Here comes in the application of active or passive regulators to provide the voltage drop required by the load plus stablization, without which filter chokes & resistors alone can't achieve.
Good "impedance" listening
This is fun! So you got me, I said impedance when I should have said reactance. So what is the impedance of an ideal inductor I wonder? Oh,that's right, the impedance of an ideal inductor is equal to its reactance.
So would you be so kind as to calculate the impedance of a 10H choke with 50 ohms DC resistance? R theta form will be fine, or real and imaginary components, your choice. Now that you've done that, compare it to the 7.5K that is calculated using ideal inductance values.
Seems like just guesstimating was fine and dandy. Something about orders of magnitude.
Sorry I didn't show my work.
So where did you get your electrical engineering degree?
First off, please qualify your OWN meaning of "ideal" inductor?
An inductor with purely inductance, no DC resistance & no stray capactance? Is there such an animal around??? You may as well tell us
how to design or where to get an "ideal" amp with zero distortion &
Secondly, what is R "theta". R is always linear, no vector angel! My goodness! I must have missed a lot. Is there such a vector R around???
If you want to involve the vector angle of the stray capacitance, spit it out clearly, for the sake of those less knowlegeable than you.
Thirdly, what is "ideal" inductance? Inductance itself ia a magnitude
qualification of an inductor or a coil, in simple language, unit 'henry'. Are you telling us an inductor comes with X "ideal" henries & Y "unideal" henries?
IMO, it is your over"guesstimating" or confusion or what? One can get
this basic electrical knowledge from high school. Otherwsie, I got
to re-study my electrical engineering discipline back to college.
WE can't read your mind right every time. Please present your lofty ideas precisely & concisely. On behalf of whoever read your posts, thank you.
Good 'sober' thinking & listening
Jan 30, 2004.
PS: I have told you the formula of calculating impedance. Did you read? Nobody is infallible. If it is an error or overlook, just admit it. No big deal. Please don't re-direct attentions. It won't bring
I was referring to 2 different ways of notating complex numbers - (radius, angle) or (real, imaginary).
Example: (1, 90deg) in (R,theta) form = (0, 1) in (real,imaginary) form.
I thought you were familiar with that notation. My bad.
Now, as for the impedance of a 10H inductor with 50 ohms series resistance, the answer I was looking for was (7539, <89.62deg), which is equal to (50, 7539). Most people will agree that for first order approximations, (7539, <89.62deg) can be represented by (7539, <90deg).
So you learned all this in high school? Wow, must've been some good high school. All I learned was Ohm's Law in High School.
As much fun as this exchange is, I feel we must call it quits. All of our arguing has boiled down to misunderstandings due to language differences.
It's just tube amps, after all.
Calm down... :-D
Don't argue over the last decimal - as long as one is right within 5% that is high quality.
I know "cheap-jack" is a dickhead, but to argue - no matter how tight one are - is a perfect waste of time and effort...
Where will the world end if everyone is nitpicking?
So, "dickhead" is the "nature" English yuor nom teaches you. Right?
I wanna tell her "Par" english" is so fu.k..g "unpossible" !!!!!
EQUIVALENT FILTERING at first (won't be the same with a 7,5k either but thats another story) .....he could just get a value that will drop the b+ the same as would the choke. That would be something closer to 75ohm.
That could get him to build his amp and later add a choke.
I already own a 5H 600mA choke, all ready to be installed in the P-P amp I'm building. However, that choke is so bl**dy heavy that I'm thinking of trying a resitor instead. A PSUD2 simulation seems to indicate that the ripple would be quite small if I use enough smoothing capacitance. A 30 ohm 15W-20W resistor might seem a bit ugly, but it would be a heck of a lot lighter than all that iron.
Just wondering, though - if I use 50uF directly after the 6D22S rectifiers, then a 30 ohm resitor, then 470uF as a reservoir capacitor, is this likely to stuff up the 6D22S? I know 50uF is safe, but will 30 ohm provide the rectifiers with enough protection from the 470uF?
Run it through PSUD 2 , 6D22 is on the list of rectifiers . I doubt you'll exceed peak current capability as these valves are tough . Don't use resistors , you'll only end up with a higher impedence power supply or nasty pulses through the transformer if larger electrolytics are used
Finally, you start talking sense with me.
First off, who started this flame war. Surely it was NOT me. You initiated this nasty personal attacks on me since day one.
I only retaliate whoever spits in my face. In this part of the world, we call it "you scratch my back, I scratch yours". I just squared it out. Now you feel the pain of my retaliation. Have you ever try to put yourself in my shoes of this nasty peronal attack victim?
I don't need to know how experienced you are in your DIYs. This is not my job. I am too busy for such 'gossipping, or 'reverse social
carnibolism'. But for personal attacks on me, I vow to persue total
If you have read in between the lines of my fire-backs to you (I though your native Englsih should be good enough for thst), you should know I really don't need you to present your own designs here in AA. There is nothing wrong with battery bias. In fact, it is an
The "xenophobic cynical" comments I made to you just let you realize how ridiculous you were to have openly challenged me on this & that. You don't need to do so but you chose to do it, repeatedly. Apparently, you didin't mind upsetting people out of nothing? IMO, you are 'something else'. But, why?
I'm sure this is NOT English traditional culture as I know quite a few English friends in U.K. They are all so nice & considerate. I still recall while I was on business trip in Midland, England, I was singly invited by a good friend there, to join his Christmas dinner at home with his big family. There I was honoured with 'carving the beef' which only the master of the house is entitled to do so there.
In fact, one of my best audio friends here in Canada is an English businessman with a mouthful of strong English accent. I am now in the process of upgrading his beloved all-triode line amp & #32 two-tube SE monoblocks, which he bought for big big bucks from an ex-engineer of Sonic Frontiers who custom-built for him, a couple years ago. I am not happy with the sound at all since day one.
His rig also includes a Thorens TT/Sonic Frontiers phono booster, a Quad CD player/control unit, & 6 1/2" Lowther in local-made horn cabinet built to Lowther specs. My first successful step was to have the expensive preamp replaced with my own dirt-cheap hand-built line-amp. He is very happy already as the sound is now all 'set free' & open up, rather than like 'playing in a nutshell' before. But, not yet.....
Let's be down-to-earth (I use this English phase used so often in
U.K.), there is nothing NEW under the sun. Unless I miss a lot, I have NOT seen any tube circuitry that is new to me yet. CCS? I read tons of these circuits in many Japanese DIY journals decades ago. Parafeeds? RCA & WE published those many many decades ago. If a DIYer comes up with a tube amp circuit & tell me it is an OWN design. I
would suggest that whoever to get it patented right the way. "HAHAhahah. I gonna laugh my head off".
Subjective tweaks "that can not be proved or have any tehnical
How are you so sure? Have you ever tried it? You know how many
DIYers tried it out with audio improved results?
Please answer me this very often asked question about tube amps.
"Why a tube amp measured some 5% distortion can sound so much
better than a solidstate amp which meassures far far better?"
So what "technical foundation whatsover" can explain this?
If my English is written not mother tongue enough, you native English
need polish, bigtime, so as to prevent back-fires.
Good "polished" listening
Jan 23, 2004.
PS: Hopefully, I won't get shot 'point-blank' again out of the blue.
470uF after just a 3 0Ohm resistor....hopefully someoene else will reply....otherwise do as I do..and just try it...
Bas, The choke is deliberately over-specified at 600mA. The mains tranny HT is nominal 359-0-350v, also rated at 600mA but the amplifier will not need all that juice: probably only 330mA or so. The 6.3v secondary windings can tolerate between them 20 amps but the load (including the 6D22S rectifiers) will only be 12 amps. So, I'm playing safe regarding power supply capacity.
I agree with you that I could just try using a resistor instead of a choke and I probably will, but I don't want to wreck the 6D22S by using too high a capacitance so I thought I'd ask first. Actually, I'll probably split the power supply at that point; following the rectifier and 50uF smoothing capacitor, I'll use two 47 ohm resistors, each followed by 220uF smoothing capacitor, one feeding the left channel and the other feeding the right channel.
This is going to be a class A P-P amplifier (EL34s strapped as triodes, about 15W per channel), so power supply "stiffness" (low impedance) is not a prime concern. If it were, I'd probably be using SS rectifiers. Fatbottle is probably right about the noisiness of a resistor-smoothed PS so I should really the choke anyway; but, with the massive power tranny, two big (50W) OPTs and this heavy choke I can hardly lift the chassis. I don't want to do myself an injury! Besides, I'm hoping that any noise in the PS will be largely cancelled out by the fact that every stage in the amp will be balanced, because the design uses push-pull topology throughout.
It has been my experience and honest opinion that any "cost cutting or weight curtting" you do in a triode amp's power supply, be it SE, P-P, A1, balanced or whatever, is DIRECTLY heard, with a negative effect, in the final overall performance.
There is no substitute for building the "very best supply you can", if you seek real sonic quality.
A high quality choke employed as the input filter is highly beneficial and should be used for several reasons, but primarily .........because it controls the current waveforms of the diode, versus its voltage waveforms.
Resistances (in place of inductance) in the early stages of a power supply, is IMHO and generally speaking, a far worse choice.
Of course you can elect to compromise your design, but it is helpful to know what is ideal and where you are compromising.
Its your listening experience .......and your choice to live with. But you will spend far more time listening to the final result, than lifting it !!
Fair comment, that's the sort of advice I was seeking. Thanks! I've already planned and drilled the chassis assuming that I will be using the choke, so I'll bite the bullet. Just have to be careful lifting it.
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