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Old 10th February 2012, 10:01 PM   #121
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The problem with those may be the Ciss at min 2300 pF
be nice if same one more expert than me could clirify pro and con of this as far as (I think I know) this may efect the sound signature
The TO3P is certanly a bonus
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Old 10th February 2012, 10:10 PM   #122
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Yes, I would love to hear what Papa thinks.....
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Old 10th February 2012, 10:18 PM   #123
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EUVL,
In the simulations you posted, the response of the 2sk1530 looks a lot like that of a tube. Am I looking at this graph incorrectly or from the wrong perspective
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Old 10th February 2012, 10:40 PM   #124
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Quote:
Originally Posted by UKToecutter View Post
Has anyone considered using FQA36P15 and FQA28N15?
More current, why not?

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Old 10th February 2012, 10:41 PM   #125
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Input capacitance?
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Old 10th February 2012, 11:03 PM   #126
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Quote:
Originally Posted by Nelson Pass View Post
More current, why not?

Tanks Papa
The TO3P is very attractive.
And more current more voltage is certainly good.

But what would be the sound signature?
F5 sound really good and small compromise against above bonuses may be ok.

Why those are not used by Papa Pass is the big question.

Let me guess the answer.

Get a few and try...

Next big question
Naughty naughty little Alex want the F6.

Could you please titillate our soldering buds and give as a taste of what it would be like?

Many tanks

Al
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Old 11th February 2012, 01:36 AM   #127
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With a bunch of lateral MOSFETs on hand, I am going to build a couple of these -- although my Thors don't seem to have any volume deficit running bi-amped with F5's.
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Old 11th February 2012, 01:54 AM   #128
lhquam is offline lhquam  United States
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Nelson, help! Where the am I supposed to find the JFETs and MOSFETs to build this beautiful beast? It is even difficult to find SPICE models so I can simulate this in my "wet dreams".
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Old 11th February 2012, 02:06 AM   #129
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Quote:
Originally Posted by EUVL View Post
> The diode is voltage (or MOSFET drain current) dependent, acts like a clamp on the maximum voltage across R_source, but does introduce a sharp discontinuity when it kicks in, the latter being a bit like an amplifier's transition from Class A to Class AB.
Biased with some care, it actually delivers are reasonably smooth transition.

In any case, if you want this kind of current, you will have some mild
transitions unless you want to run 20 amps or more of bias.

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Old 11th February 2012, 02:16 AM   #130
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Quote:
Originally Posted by lhquam View Post
Nelson, help! Where the am I supposed to find the JFETs and MOSFETs to build this beautiful beast?
The train left the station...but LinearSystems is, hopefully bringing it back....those dreaded high Idss knock-off P-channel switching JFETs aren't necessarily dog-dreck, or you can use GR devices which work well in F5's. The knock-offs are about 20dB noisier. N-channel devices are readily available from Mouser.

...and SPICE models are generally available for the IRF and Fairchild MOSFETs, the JFET models are easily available, and Bob Cordell's book belongs right next to your copy of the Bible as it explains how to make MOSFET models.

Lateral MOSFETs have half the input capacitance of the vertical ones but less than a quarter of the steady state current carrying capacity.
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