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F6 Illustrated Build Guide
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Old 15th January 2018, 03:41 AM   #1021
dcbingaman is offline dcbingaman  United States
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Looks like the Ciss of the IXTH64N10L2 is 3650 pF vs. 7500 pf for the IXFN140N20P. Probably easier to drive.
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Old 15th January 2018, 03:44 AM   #1022
dcbingaman is offline dcbingaman  United States
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Maybe the Ciss of these pucks is why the XA-25 has three stages vs. two......input , driver, output......just a guess.
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Old 15th January 2018, 03:57 AM   #1023
dcbingaman is offline dcbingaman  United States
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Just looked on 6 Moons site for the XA25 preview....it shows a photo of an IXFN60N80P. Looks like a N-Channel Enhancement HiPerFET with ratings of Vdss=700V, Id25=53A, Rds=140mohms. And get this, Ciss=18nF !! Wowee-Zowee !!
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Old 15th January 2018, 04:39 AM   #1024
2 picoDumbs is offline 2 picoDumbs  Australia
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Quote:
Originally Posted by 6L6 View Post
Can the driver/phase splitter stage drive the input capacitance of those devices? The pucks have almost 7x more Ciss, the IXTH64N10L2 is 3x

I'm not asking the question just to make a point, can anybody shed some light here?

Already done on IXTH64N10L2, with excellent results.
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Old 15th January 2018, 04:40 AM   #1025
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Quote:
Originally Posted by dcbingaman View Post
Just looked on 6 Moons site for the XA25 preview....it shows a photo of an IXFN60N80P. Looks like a N-Channel Enhancement HiPerFET with ratings of Vdss=700V, Id25=53A, Rds=140mohms. And get this, Ciss=18nF !! Wowee-Zowee !!

Don't compare apples with oranges.
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Old 15th January 2018, 05:07 AM   #1026
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F6 Illustrated Build Guide
which means one thing is source follower , another thing ......... non source follower



F6 is ...... non source follower

regarding XA25 , we already have few ( at least one very successful ) threads about
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Old 15th January 2018, 05:14 AM   #1027
dcbingaman is offline dcbingaman  United States
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I got it. My guess is, based on the descriptions in both the 6Moons and the new Stereophile review, that Pass is using complementary MOSFETs in the driver stage (IRF240 and 9240's to drive the two IXFN60N80P's in opposite phase (like a bridged circuit).

The amp is advertised as delivering 25 w/channel into 8 ohms, but put out 80 w/channel on the bench before clipping. Pretty impressive. Pass replaced 28 IRF MOSFETs in the XA60.8 with 2 HiPerFETs and got better sound in the process. Pretty cool. I need to hear one of these things.
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Old 15th January 2018, 05:43 AM   #1028
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as I said , there is a (F4 beast something ...) thread ........
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Old 15th January 2018, 05:49 AM   #1029
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Something in the air again.

Hahaha
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Old 15th January 2018, 05:59 AM   #1030
dcbingaman is offline dcbingaman  United States
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Thanks, Zen Mod - I will take a look.

I just built an F3 (using Chinese boards from eBay - actually nicely laid out), and am halfway through building a Pass Sony VFET (although I think I'll need a couple shots of Balvanie Scotch before I put power onto those pixie-dust containing VFETs).

I have all the parts to build an F5 Turbo V.2, but I am looking for the next thing to try. (I've also built a lot of toob stuff, but, that is really like restoring Model A Fords.....nothing works without GOOD output transformers which are getting harder to find.)

I am driving a minty pair of Spendor SP-1's which are 8 ohms and reasonably efficient. They work really well with a Pass Aleph 5 (60 wpm), but the Firstwatt amps are a little to small.

I am looking for something with the power of the Aleph but with a triode transfer function....the IXFN140N20P SE circuit might be just right for the Spendors, BUT a push-pull variant using these new HiPreFET pucks might be better still.

Anyway having just retired after 39 years at Boeing, I am looking to get into a little mischief.
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