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Old 6th October 2006, 01:47 PM   #1121
eLarson is offline eLarson  United States
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"Wow! This is going to take ALL DAY to build."
-- attributed to Remus upon seeing the plans for Rome.
Would a woodchuck bother to chuck MDF?
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Old 7th October 2006, 05:23 PM   #1122
Zen Mod is offline Zen Mod  Serbia
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Originally posted by jacco vermeulen

I think he meant Rome, Georgia.

ya mean-Paris,Texas?
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
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Old 27th November 2006, 08:03 PM   #1123
rgrav is offline rgrav  United States
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Default fet cascoding

Mr. Pass, I found your latest vfet amp in Audio Express interesting. I have some of Sony's older complemetary vfets that I was thinking of cascoding. You used a mosfet to cascode to the vfet. My question is whether a bipolar would work as well as a mosfet for the cascode, especially in not contributing a sonic signature that would mask the vfet. In a complementary pair of outputs, how does the mosfet behave as a cascode in the crossover region where the mosfets are nonlinear but bjts like Toshiba's 1302/3281 are very linear? I'm going to dig out your old Audio Amateur cascode 60W amp to study it's circuit for this project.
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Old 28th November 2006, 09:46 PM   #1124
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There's not a lot of difference between using a Mosfet
or a bipolar for the cascode transistor in my book. I
used a Mosfet because I have them laying around like

The cascode transistor imparts very little of its own
character into the signal. With a Mosfet, 100% of the
current through it comes through the cascoded gain
transistor, and the only influence it has is the small
variation in voltage on its Source, which in turn has
a small influence on the the gain transistor, mostly

With a bipolar, some of the current is sent off through
the Base, so you lose maybe 1% or 2%, but even that
is mostly linear, and doesn't have a lot of effect.

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Old 3rd January 2007, 11:33 PM   #1125
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Default Mr. Pass

I thought the idea with using an IGBT operated common base was because signal current does not have to pass through any NPN junctions, but rather a continuous slab of "N" material. Is the capacitance (if any) in a bipolar transistor enough to degrade audio frequencies?
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Old 3rd January 2007, 11:47 PM   #1126
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All electronic parts have some amount of capacitance. The degree to which it creeps into the audio spectrum depends on the impedance the capacitance sees.

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Old 18th January 2007, 12:29 PM   #1127
Stefano is offline Stefano  Italy
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Default No more news?

Hi to all!!!
It would be time for something new, when there'll be a new Zen version?
Let's make something special
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Old 20th January 2007, 12:39 AM   #1128
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Yes, it's about time.

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Old 20th January 2007, 05:14 AM   #1129
flg is offline flg  United States
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Old 20th January 2007, 09:34 AM   #1130
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Originally posted by Nelson Pass

Yes, it's about time.

I am ready to produce PCB
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