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Author Topic: My hybrid: jfet-Tube Sziklai-> classD pwr  (Read 1943 times)

jfetter

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My hybrid: jfet-Tube Sziklai-> classD pwr
« on: June 30, 2017, 05:28:17 PM »
Working on a new one now with some improvements, ie compressor so D amp never approaches clip.

 As-built zip attached.

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jfetter

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Re: My hybrid: jfet-Tube Sziklai-> classD pwr
« Reply #1 on: June 30, 2017, 05:37:00 PM »
Opps this is the jfet-mos front end. The above zip is tube-p-mos.


armkon

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Re: My hybrid: jfet-Tube Sziklai-> classD pwr
« Reply #2 on: July 10, 2017, 04:15:19 PM »
how your preamp works? i plan to do same thing with class D power amp

jfet stage -> tube clean channel (fender like) -> buffer with efx loop -> class D amp

jfetter

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Re: My hybrid: jfet-Tube Sziklai-> classD pwr
« Reply #3 on: July 10, 2017, 05:06:49 PM »
it sounds just peachey. all day yesterday in hi-fi mode with r&b and blues. The stereo summer was too low for CD outputs but worked fine with dragonfly. changed from 680 to 2.2k.

you wont have much headroom using a single jfet front end. if using with the Sz pair then lots of headroom. guitar needs 5v PP input range without clipping. i would do the tube/fet front end.

the bias pot allows setting harmonic content to max 2nd, max 3rd or a mix. For hi-fi max 2nd or simply lowest THD.

armkon

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Re: My hybrid: jfet-Tube Sziklai-> classD pwr
« Reply #4 on: July 12, 2017, 01:00:57 AM »
yes, but i will use full 1 tube with 280-330V anode voltage for fender preamp :) not with low values on regural extra transformer for tube stage only ;) and before it i will add extra gain stages with jfets ;) That my plan ;)

so J-fet (3-4 stages) -> (280-330V loaded full tube preamp) Fender Bassman or twin -> Class D PA