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Old 22nd February 2014, 11:33 AM   #21
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okei. i that case, just juse the vishay parts
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Old 7th March 2014, 07:03 AM   #22
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I have a question about powersupply to Aleph 1.7 pre

my trafo gives about 66vac out,,,it gives messured close to 98 vdc out of diode and cap-
it is close to the 100v value off the panasonic fc caps


to give a bit lower volt i have placed 2 resistor in the ac line after the trafo (4.7ohm)
this give about 94vdc

Is it ok to use resistor in the ac line after the trafo ??? sound wise..data wise

Trafo is 240va

Bjarne
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Old 9th March 2014, 01:41 PM   #23
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Yes, you can use a resistor in the AC or after rectification. Papa himself did that with the A75 supply with resistors feeding the voltage doubler for the front end power supply. Just leave enough room between resistor and board for air to circulate and not burn your boards.

Some will say you are pushing a bit close to the capacitors' rating even dropping to 94V. You may find that you need to replace them sooner than you would with higher rated capacitors, say 20%+ over operating voltage. In home use this could translate into 10-15 years instead of 20+. I don't know for sure but I think we tend to go a bit overboard derating sometimes. Take a look at the datasheets to get a clue how the life might be affected.
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Old 9th March 2014, 04:24 PM   #24
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I think i must drop to use this trafo--the serie resistor have to be to big..some time in the night time i messure about 99v....this is not so good for the caps
instead i will use 2 trafo with a lower volt ..dual mono
i am building a Veteran Aleph ..so i can compare to KK board..just need some parts to finish it
on the Veteran board i use other resistor type...Vishay Ero caps (15uf 100v)
be fun to hear it
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Old 20th March 2014, 03:53 PM   #25
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Hi Folks,

can anyone help me figure out how to wire this :http://www.mouser.com/ds/2/128/c4-8997.pdf to a balanced ALPS pot please ?

Thanks ,Rich
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Old 20th March 2014, 03:57 PM   #26
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2 poles/decks for mono balanced
4 poles/decks for stereo balanced

12 positions/steps ( which is max for that type) is sort of barely enough for proper comfort

there are many on line switched attenuator tutorials and calculators ; you'll grasp it there
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Old 20th March 2014, 04:01 PM   #27
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Thanks Zen ,


I have been surfing Youtube ,but nothing . Perhaps I'm not typing in the right keywords . "how to wire a balanced input selector"

Perhaps a link if you have time ?

Thanks, Rich.
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Old 20th March 2014, 04:06 PM   #28
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ook ootoobe

- Google Search

Stepped Attenuator Resistor String Calculator - Neville Roberts

Logarithmic Attenuator Calculator

Resistor-Switch Attenuator Networks for Audio Volume Control

On Stepped Attenuators II
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Old 20th March 2014, 04:11 PM   #29
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Thank you .
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Old 20th March 2014, 04:23 PM   #30
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balanced route is having two poles phases : one + , one -

just imagine it as plain stereo , with + as R and - as L channel

so , wire it as plain stereo pot

for stereo balanced , that's as two stereo pots on one shaft

all that , speaking of common (meaning - usual ) L (shaped) attenuator

there are other types , but that one is good enough for starters
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