Steeplejack ..... or how F8 met Mighty Babelfish M25 (& Schade)

[Zen Mod]

It started here : https://www.diyaudio.com/community/threads/scryer-or-how-f8-met-mighty-sissysit.388550/

After that one, couldn't avoid my own greediness to try this combo too

Though, clever as I am, God's ways are his own and Buddha is everywhere........ meaning - better name for this one would be Mad Hatter, you'll see from 4R load behavior ........

Ok, for starters usual set of graphic files

Schematic is aggregate, find separate ones for pure Mos and for Schade later

 

[Zen Mod]

Got them pcbs, then had some usual fun

 

[Zen Mod]

first pure MOS iteration, let's call it just Steeplejack

schematic

Facts:

OS Iq 1A75
Rails 23V5dc
Jfet Iq 7.7mA, 2SK2145BL used
second stage (BD140+BD139) Iq 20ma

 

[Zen Mod]

Proof is in Da Pudding, 8R load

call it Pinpoint Machine; sorta sweetish at 1W level, getting brutally detailed above

nominally 20W@8R amp, clipping around 18W

THD can be easily tweaked changing IRFP240 to (double xcoonductance) IRFP150; but no, wont do that, prefer Schade to add some Spice

 

[Zen Mod]

Proof is in Da Pudding, 4R load

Now things are getting wild, letting ZM to know that there is some Mightiness above his own ..... meaning - things are existing even when I can't find explanation

 

[Zen Mod]

Iq stable as rock
DC Offset starting from -200mV, fast climb to 0, steady and stable in thermal equilibrium

no pops/clicks/farts during power On, power Off

will let you know tomorrow how it sounds, when I invest several hours in that part of fun

after few days of amusement, will proceed with Schade arrangement

Life is Fun

 

[von Ah]

Nicely done! And very interesting differences between 8R/4R. Endless enjoyment at the OPLDF.

 

[Zen Mod]

yeah, nature of this amp is even showing in line-up of graphs ...... even if I uploaded them in logical sequence ( they're still that way when looking at post in edit mode), everything is mixed

will see can I edit it , step by step

edit: nope, edit time expired ..........

 

[Zen Mod]

listening today for 6+ hours

it passed, with flying colors ...... Miles Davis Fran - Dance album, one of those I know every note in ...... enormous soundstage, Miles's trumpet is very critical - many amps failed, bringing it in ear shuttering way

nope with Mad Hatter ..... anyhow, Steeplejacks, Mad Hatters and ZMs of this world are sharing same sort of Wakoosnesssssssss



I hear every bloody grain on master tape, while not just having both feet tapping but also headbanging ( my usual behavior on jazz concerts) ......

 

[Zen Mod]

again forgot to put funny Pumpkin Mascot on top

 

[Plott]

listening today for 6+ hours

Okay... it MUST be good

 

[Zen Mod]

ha!

just finished conversion to Steeplejack SET (Schade Enhanced Thingie), meaning that upper mosfet is connected in Schade arrangement

all measurements done, it's already singing, and as I could expect, everything is slightly more in the face (comparing to pure MOS) , while I can still hear Miles thinking how it could be better that I didn't wiped clean damn spectacles prior to gig, probably lesser trouble with stage reflectors



ZM is Happy Camper, Steeplejack SET is Poor Men's Scryer ...... even for this one 300B Fetishists can eat my liver

 

[G600]

I may have missed it, but what is your second set of ears thinking of this one?

And stop working on speaker cones (first pic), and publish MORE AMPS

 

[Zen Mod]

I may have missed it, but what is your second set of ears thinking of this one?

And stop working on speaker cones (first pic), and publish MORE AMPS

yup, me too thinks that I got lazy of lately, doing nothing

will visit my Buddy these days, to let him hear

 

[Zen Mod]

so, Proof is in Da Pudding, colorful part

Steeplejack SET, funny pics, schmtc

 

[Zen Mod]

Proof is in Da Pudding, gigglywiggly part

basic settings same as noted in post #3

Load 8R

 

[Zen Mod]

same, Load 4R

 

[Zen Mod]

all in all ........ pretty good approximation of Scryer measurements, shown (starting from post #5) here: https://www.diyaudio.com/community/threads/scryer-or-how-f8-met-mighty-sissysit.388550/post-7078135

even if I didn't stretch my self for uncomfortable task to compare Scryer and Steeplejack SET directly, gone by always giggly auditory memory, but more by general feel of ease, measure of feet tapping and Dia of headbanging circle, these two are close enough

besides, pleasure being certainly enhanced with fact that I made another one, and didn't end in heap of Gray Smoke

 

[Zen Mod]

just for fun, SMD parts, each enclosed in red rectangle

 

[Dendrobium]

Aaah, did not even finish LuDEF yet and you dangle new toy in front of eyes...life of greedy boyz never boring with you around
Also interesting how most expensive part is none of the transistors or "active parts" or anything, but the lt3092 current source (5-10$/pc).. (ok, if we ignore the 2SK2145)
Anywayz, congratulations on what looks like another 3 pointer