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help understanding amplifier schematic

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okz!...

@nigel you saved the poor amplifier long before it gets finished! i'll try to remember the speakers! :D

so as far as i understand i don't need any load resistors to the power supply... but i'm having a bit difficulty to calculate the exact voltage under load... i hope i'm not exceeding the 300VDC.

how can i calculate what i'm giving to the amp with 220VAC/250mA power supply... looks to me it's ~300VDC

@Audioguru i think you hate gramophones... right? :)
 
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A gramophone was an old record player?
I still have a very good one. It sounds great through my solid-state powerful very low distortion amplifiers. I haven't used it for about 20 years.
Your amplifier won't work with a gramophone as its input. The gramophone needs a preamp circuit.

I even still have a good quality cassette recorder/player. Remember them? I haven't used mine for about 15 years.

I play FM radio, CDs and MP3s. I have thousands of MP3s because my son bought a laptop computer from a disc jockey.
 
@Audioguru my comment was about if you hate oldies in general... :D tubes are interesting!
as well as many things that left behind due to modern replacements which are also interesting
and sometimes awesome.

@Nigel pls can you answer my last post?


A gramophone was an old record player?
I still have a very good one. It sounds great through my solid-state powerful very low distortion amplifiers. I haven't used it for about 20 years.
Your amplifier won't work with a gramophone as its input. The gramophone needs a preamp circuit.

I even still have a good quality cassette recorder/player. Remember them? I haven't used mine for about 15 years.

I play FM radio, CDs and MP3s. I have thousands of MP3s because my son bought a laptop computer from a disc jockey.
 
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@Nigel pls can you answer my last post?

There's no enough information to answer - initially the voltage depends on the exact AC voltage supplied under load, and also off load before the valve warm up.

However, I would'nt use 300V electrolytics on a nominal 220V supply - as a crude rule of thumb, multiply by 1.5V - giving 330V or so.

I would suggest 400V electrolytics.
 
well...i was hopping you could help for a more precise approach of what i'm going to give to the amp...

i did my calculasions based on the "1.41" so i guess it's close to 310VDC but as you also said i understand that this number is without load...

all the capacitors i'm going to use are rated at 400V the electrolytics are Nippon chemicon.


There's no enough information to answer - initially the voltage depends on the exact AC voltage supplied under load, and also off load before the valve warm up.

However, I would'nt use 300V electrolytics on a nominal 220V supply - as a crude rule of thumb, multiply by 1.5V - giving 330V or so.

I would suggest 400V electrolytics.
 
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well...i was hopping you could help for a more precise approach of what i'm going to give to the amp...

My crystal ball is away for service at the moment :D

The formula is 1.414 times the RMS voltage minus the voltage drop in the bridge (1.4V) - but you need to accurately know the RMS voltage first.
 
heheh... :D
from the infos i'm giving do you think i might push the tubes to their limits?


My crystal ball is away for service at the moment :D

The formula is 1.414 times the RMS voltage minus the voltage drop in the bridge (1.4V) - but you need to accurately know the RMS voltage first.
 
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the amp...
not yet finished
 

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It takes you back! :D

i'm doing my best...

well...maybe i could a little better because i think it wasn't very good idea
having the tubes kinda near to the transformers, though if i have problems i
think i can easily isolate them and still look nice because i'm going to cover all the upper part with a **broken link removed** painted black so the only thing you can see is the light comming from the tubes and not the isolation of the transformers! :D

@nigel about the 6.3V of the heaters what do you think if i twist the cables and also use 2 resistors 1k as voltage divider and connect the middle to the ground to reduce noise?
 
The output transformers appear pretty small so maybe they won't pass the hum frequency.
 
I did a simple power supply pcb to rectify the 220VAC of the transformer (which apparently gives 230VAC and not 220VAC as it says :rolleyes::rolleyes:) and i'm facing a problem!!! it keeps blowing the fuse to the primary! :mad:

the transformer is fine! the circuit is so simple and everything looks fine to me, just a rectification and 3 capacitors and i don't get what's wrong, i haven't placed any load to the output....
 
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What is the fuse values? Current rating and is it fast or slow?

Your amp looks very nice. I would not cover it.

(that almost sounds dirty)
 
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Thanks flat5! :)

ok the problem solved... i had a rectification bridge schematic near me so i can see the orientation of the diodes to avoid any mistake...but guess what!!!? :D the schematic had the bridge WRONG!

ok here's the schematic caused the problem and here's the power supply pcb i designed...

it's the first time i did my own pcb design and i felt a bit unsafe with high voltage that's why i did so big rails with so much space between them..probably it's good for 10A or more! :D:D

the wires are from teflon...because last time the wire where green cable is
was touching the nearby diode and almost got burned.
 

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I think you should use new diodes.
They have been subjected to heavy overload.
They don't cost much.
Anyone else think this is a good idea?
 
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