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In Reply to: RE: Time to tackle the High Voltage Power Supply posted by Cousin Billy on January 01, 2016 at 10:28:40
In the previous posts picture.
Regarding the 'ELMACO' OR 'HAITI' 600 ohm resistors. If I was to change these, but I only have 560R and 680R, which would work best. And why?.
-as Banat has pointed out, there presence is. The actual values are not.
What is happening is they provide a return path for the bias on the power tubes and also reference the output section to ground potential. Since the actual bias current is very slight, the values of the resistors is not critical. However it is important for them to be able to handle some power, in case the amplifier is given a signal without a load- then these resistors *are* the load and will heat up.
The 600 ohm 3 watt value has proven pretty steadfast over the last 30 years or so.
"Regarding the 'ELMACO' OR 'HAITI' 600 ohm resistors. If I was to change these, but I only have 560R and 680R, which would work best. And why?. "
Would you care to give a clue, such as what the schematic is, or what amplifier you are talking about?
I'll get to your question after this first picture.
A few years ago I had a friend build 'risers' for my MA-1 amps.
In hindsight, 3" was not enough.
Good gosh are those 200uF Mundorf Tubecaps big!!!!
Let's get to cpotl
In this next picture, I have removed the orange drop cap and the 7.5 Ohm resistor. These two appear to make an RC circuit. A quick calculation puts the corner frequency at 212,314Hz. I will assume this RC filter filters out the Utility Companies ~200000Hz carrier signal. This signal is how different power stations 'talk' to each other.
I am not an electrical engineer.
The 'front' of the RC circuit is connected to the HV caps, and the 'back' of the circuit is also connected. This is through the 600 Ohm resistors.
I need help in understanding this.
The original HV power supply caps are directional?.
The new ones will not be. They are 'film'.
Question: Does current and voltage pass in both directions in the 'old' capacitors?
Do the 600 Ohm resistors connect the power, coming to the caps from the transformer, to the RC circuit, therefore 'cleaning' the power to the HV caps?
If yes, then any value around 600 Ohms will work.
-That orange 0,1uF in series connected with 7,5 0hm power resistor forms output Zobel network which appear connected in parallel with amplifier output two terminals ,
-Those two 600 ohm power resistors are ground reference resistors for Circlotron OPS , and if they are not connected in proper way as is was originally from A-T manufacture your amp will make booom and fail !
-Further I think that those big Mundorf capacitors do not belong there ,
electrically maybe but physically don`t ,
- Personally I will never modified those great OTL amps in your way .
Happy New Year and all the best !
"Art which does not have the appearance of art is true art."
- Old Roman saying -
I hooked up an old driver, played some music, and no smoke.
Measured the chassis in a number of spots. Wanted to make sure I didn't have a 'leak' anywhere. Big smile on my face.
Can't wait for my CuTF's to arrive. Can't wait to finish my new speakers.
2016 is gonna be a great year.
Too bad the stock market is taking a hit.
If we look at the picture in the previous post.
My grey wire is coming off a tag strip. A green/yellow striped wire is running from there to the transformer. I think Ralph called this a 'ground' reference wire. It doesn't matter what it's called. There are obviously other wires coming to the tag strip. This all on one side.
Here's my question;
Is voltage 'coming' from the this tag strip, and into my capacitors?
Or is voltage 'going' to the tag strip?
Which direction is the voltage travelling through the HV supply caps?
Another technical question.
If these coupling caps connect the 'top of the differential cascode' (V2) to the 'driver tube' (V4), then the voltage travels from V2 to the driver tube V4. Yes?
Plate of the top tube in the dual-diff cascode to grid of the driver tube, yes. Where else could the signal voltage (AC) flow but from one node to the other? You might want to observe the directionality indicated by the color-coded leads of the Vcaps.
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