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Old 9th January 2007, 09:17 PM   #11
Manu is offline Manu  Europe
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Thank you very much Mr. Pass
and a Happy New Year
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Old 9th January 2007, 09:17 PM   #12
Lovan is offline Lovan  Sweden
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Zen Mod:
I see. Thanks for the headsup!

Grey:
Good to see that it's not only me who thinks that
Why have the multiplier at the end instead of the beginning?

Nelson Pass:
Why not use a BJT? then it would only be about 1.4W (2*0.7)?
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Old 9th January 2007, 11:17 PM   #13
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Bipolars work just fine. Go for it.
For that matter, you can use anything you happen to have in your junkbox--MOSFETs, even JFETs work just peachy (as long as your current requirements are modest). If you need more current and and can get by with just an N-ch device, then there are power JFETs.
Note that the "speed" of the device isn't really relevant, since all you're amplifying is DC and most anything can handle that.

Grey
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Old 10th January 2007, 03:19 AM   #14
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Quote:
Originally posted by Vix


As I understood, usually there were some small capacitors (220uF elko bypassed by a 1uF film) after the capacitance multiplier (zen v3 and v4 for example).

I use 33,000//0.22 uF

(for my Zen V5)
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Old 11th January 2007, 01:18 AM   #15
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Quote:
Originally posted by Babowana


I use 33,000//0.22 uF

(for my Zen V5)



Misprint of 33,000//4.7uF
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Old 11th January 2007, 04:16 AM   #16
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Incidentally, for those who have commitment issues...(a lot of guys around here, right?)...or want to experiment:
Note that it's easy to lock the voltage in a capacitance multiplier. A basic capacitance multiplier uses a voltage divider to "set" the output. So use a switch. Put a Zener in the position between the control element (Gate or base) and ground instead of the resistor. Instant simple regulator.
Turn the amp off. Flip the switch to lock the voltage. Turn the amp back on.
Two caveats, neither all that difficult to deal with. First, the resistor between the rail and the control element needs to be chosen to bias the Zener decently--generally a few mA will do the trick. Second, the pass device will need a heatsink if you're going to be dropping much in the way of voltage. In extreme cases, you might want to consider paralling pass devices to help dissipate the heat.
This will give you an easy way to compare capacitance multipliers and simple regulators sonically, for very little money.
Why?
Why not?

Grey
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Old 11th January 2007, 04:28 AM   #17
Lovan is offline Lovan  Sweden
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Great idea Grey!

What happens if the rails have different regulation i.e different hfe for the npn and pnp?
As in capacitance multiplier not in zener regulator.
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Old 11th January 2007, 04:44 AM   #18
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Quote:
Originally posted by GRollins


This will give you an easy way to compare capacitance multipliers and simple regulators sonically, for very little money.
Why?
Why not?

Grey

Good idea

Why not combined one, i.e. multiplier plus regulator, at little cost of voltage loss?
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Old 11th January 2007, 05:06 AM   #19
Lovan is offline Lovan  Sweden
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Babowana: I presume that was the way Grey was thinking with just having a swith to put in the zeners in parallell to the cap.

Rod have an idea to the multiplier too. A second order filter:
http://sound.westhost.com/project15.htm
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Old 11th January 2007, 05:18 AM   #20
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Quote:
Originally posted by Lovan


Babowana: I presume that was the way Grey was thinking with just having a swith to put in the zeners in parallell to the cap.

You are right. It sounds so.


By the way, when you put the big cap after the multiplier or
the regulator, I highly recommend to bypass the big cap with
nice 4.7 to 10uF film. I get better high frequency sound from my Zen5
with the bypass film cap (probably, my big elec cap had bad ESR
value?)
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