Adding a capacitor before the choke defeats the benefit of a choke input filter.
Hi Alex M
I'm agree with Joshua. Why do you use this cap ?
120µF is better (less oscillations) but slower.
I want to use polypro caps so I don't want to go to high values.
Guys, what would your ranking ;-)
Reduce ripple voltage
Have top class caps
Better impulse behavior
Improve dynamanic
Vincent
I'm agree with Joshua. Why do you use this cap ?
120µF is better (less oscillations) but slower.
I want to use polypro caps so I don't want to go to high values.
Guys, what would your ranking ;-)
Reduce ripple voltage
Have top class caps
Better impulse behavior
Improve dynamanic
Vincent
Polypro caps is an excellent idea, Allen used them in some of his models.
Parallel few and you can get any value you may choose, though LC with C being about 120uF looks like an excellent choice. If the PSU is in separate enclosure, have the last polypro cap in the amp's enclosure.
In either case, don't omit a Shunt Reg., either Allen's or Salas'.
splittin' da hair
ya mean - diff between cLC and CLC .....
It's either LC, or cLC, or CLC.
As I said a page or so ago, I chose that value for the first cap to tune the DC to 350V with the transformer secondary voltage I used, and it has the additional advantage of reducing ripple and choke buzz.
I felt at the time that using a first cap with 1/20 the value of the second counted as essentially still shunt regulated, since it is far below what you would need without the choke.
Just for interest, the 47uF cap I installed originally was a cheap 450V electrolytic. I plan to replace this with an SCR 630V polypropylene within the next few months (mainly for longevity and reliability), but I don't expect a big audible change since it is relatively isolated from the audio circuits by the choke, the second capacitor and the shunt regulator.
Alex
My mains transformer and choke were both from Variable Voltage Technology in the UK: a 300V 180mA transformer and a 10H 200mA choke. I note, by the way, that VVT have completely revised their range and no longer sell exactly the same items I bought form them, but still have a very wide selection and my experience dealing with them was very positive.
The regulator was Emile Sprenger's HPHV regulator, which has already been discussed in this forum. If you send me your e-mail address I can send you a copy of the construction manual.
Alex
I can't say I notice anything "special"! How long does the initial current peak last?
Alex
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Alex,
Could you please send me the circuit you are referring to in your post answering to Craig?
Thank you,
Evangelos
I am sure there is a simple answer to this, I must be missing something.
Allen writes "the attenuator must maintain the same impedance at all settings - pots are fine but some switches may not be". I would of thought the impedance would change when the resistance of the pot/switch is changed...?
Could someone explain this to me please?
Cheers
Charlie
Allen writes "the attenuator must maintain the same impedance at all settings - pots are fine but some switches may not be". I would of thought the impedance would change when the resistance of the pot/switch is changed...?
Could someone explain this to me please?
Cheers
Charlie