That 1K should not be getting hot..you have 12mA going through it according to your schematic. It should be dissipating only 0.14 watts and it's a 5 watt resistor. Maybe ever so slightly warm after 5 minutes.
The 100K will be dissipating ~290/100,000 x 290 = 0.84 watts so warmer but not so you can't touch it after 5 minutes.
Hope that helps.
The 100K will be dissipating ~290/100,000 x 290 = 0.84 watts so warmer but not so you can't touch it after 5 minutes.
Hope that helps.
Ok. Thx for that calculation. I will check better tomorrow. They do take a while to heat up, maybe 3-5min. I'm gonna play music n hour n then check them again.
They will never be empty, as it is an exponential decay. They will be sufficiently discharged for safety after a number of time constants e.g. after 3 time constants they wil be about 5% of the previous voltage. Time constant = CR, where C is the sum of all PSU capacitances and R is the bleeder resistor. You have about 200uF so 100k will give a time constant of 20 secs; it will be safe to touch after about a minute. Note that this sort of calculation should form part of the PSU design process.Max Martin said:
Bleeder resistors are used for safety, so they must be chosen carefully, be in mind that a 1W metal-film resistor, over about 350V tends to open, and you will haven't a bleeder resistor anymore.
As a rule of dumb, I use 270K/3W metal-film resistors up to 350V, and two in series up to 700V, In this case you could use two 180K/3W in series for C1, the same for C2, and 270K/3W for C3...C6, just in case L1, or R2, or R3, or R4, or R5 were open (rare but possible), however you should adjust (lower) the value of R2 to compensate that power loss.
I greatly admire your knowledge and thank you so kindly to pass it on to a beginner like me. I really learn something.
Thx Popilin n DF96!
My kiwame carbon 5w are rated 700v. Is it enough with one then instead of two in series?
Any advantage using 370k (or 2x180k)?
You think 100k is too low?
I change rectifier today at the same time i changed psu caps 2x150uf. Now the pre is dead silent. I guess some the extra uF was needed?
I was little nervous before i pushed powerbutton to measure. I had to rewire the whole socket and psu-wiring... Took 6 hours
Anyway, can't say that SQ became much better but now there is a more refined calmness and quitness between notes. Can't say if it's rectifier or caps though.
Thx Popilin n DF96!
My kiwame carbon 5w are rated 700v. Is it enough with one then instead of two in series?
Any advantage using 370k (or 2x180k)?
You think 100k is too low?
I change rectifier today at the same time i changed psu caps 2x150uf. Now the pre is dead silent. I guess some the extra uF was needed?
I was little nervous before i pushed powerbutton to measure. I had to rewire the whole socket and psu-wiring... Took 6 hours
Anyway, can't say that SQ became much better but now there is a more refined calmness and quitness between notes. Can't say if it's rectifier or caps though.
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Good to know you are learning, but nothing to thank, we are here to help each other.
BTW, the one who really knows a lot is DF96, not me.
Brand resistors sounds expensive to me, so I use the cheapest ones, but if yours are rated 700V is good and you could use single resistors.
Ohm's law, V=iR, tells us that with 100K and say 300V, current is 3mA, for HV PSUs 1mA is more efficient (less waste power), so 300K or closer normalized value (270K or 330K) is OK, use Ohm's law with every voltage and do the same calculation, i.e. R=V/i (R=XXXV/0.001A)
I change rectifier today at the same time i changed psu caps 2x150uf. Now the pre is dead silent. I guess some the extra uF was needed?
I was little nervous before i pushed powerbutton to measure. I had to rewire the whole socket and psu-wiring... Took 6 hours
Anyway, can't say that SQ became much better but now there is a more refined calmness and quitness between notes. Can't say if it's rectifier or caps though.
I know cases where people can hear the difference between Valve and SS rectification, but I don't believe between two valve rectifiers if correctly used, I bet that more capacitance did the trick.
Congratulations for your preamp, also looks very nice.
Just noticed above duncan psu/sim is the old one. Here is what i use now.
And sorry for the little blurry images. I'm always in a hurry=)
Thx for your positive comments. It's coming to an end soon this pre. I wonder who elses fingers scratching to build this. I think the one who does will be more than happy.
I'm still waiting for my GE 5670W to arrive from the states. It's the tubes left to try out to see if i can get a slighty improvement in the area "move my heart/soul/coherent-sound" i'm looking for. Other words, little more tube sound. Also if other tubes doesn't do it then i will try cap/res in cathode again with film caps.
B+ is 282V with 270R cathode res. Voltagedrop a bit too high compared to the diodes, diodes= 1.7V 270R= 1.75-1,8V (about...)
And sorry for the little blurry images. I'm always in a hurry=)
Thx for your positive comments. It's coming to an end soon this pre. I wonder who elses fingers scratching to build this. I think the one who does will be more than happy.
I'm still waiting for my GE 5670W to arrive from the states. It's the tubes left to try out to see if i can get a slighty improvement in the area "move my heart/soul/coherent-sound" i'm looking for. Other words, little more tube sound. Also if other tubes doesn't do it then i will try cap/res in cathode again with film caps.
B+ is 282V with 270R cathode res. Voltagedrop a bit too high compared to the diodes, diodes= 1.7V 270R= 1.75-1,8V (about...)
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Popilin:
You remember you said my input impedance was 39K in my poweramp? I thought to myself how did you come up with that nr?
Now it hit me, you looked at the schematic at the resistor! but it is wrong! It's says 39K but it's 510K!!! What does this change? Regarding coupling caps? Can i safetly change this down to 100K in worst case?
You remember you said my input impedance was 39K in my poweramp? I thought to myself how did you come up with that nr?
Now it hit me, you looked at the schematic at the resistor! but it is wrong! It's says 39K but it's 510K!!! What does this change? Regarding coupling caps? Can i safetly change this down to 100K in worst case?
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