SemiSouth power Jfets .......... FW J2

[generg]

no success today, I just prayed and switched on, ............ even the LEDs did not burn, the offset was good, the Iq was rising.....batsch a sparkle and I switched off.... what a hollow sound, big hole sound.... enough for today, tomorrow I will look again! (the second half of the PC-board I used for the second channel, I remarked too late, has many fine connections I did not see in the beginning, some I killed, maybe not all. Or something stupid)

[Zen Mod]

good luck !repetitio est mater studiorum:cheers:

[generg]

Thanks!

[generg]

The good message, both channels work!

the bad message: connected both channels to pumpkin, I have for the first time an oscillation in one channel .......

so still no stereo, only double mono! IHHHHHHHHHHHHHHHHHHHHHHHH...

now I drink two espresso and ................ go on!

btw Sonidos are waiting, wooden horns arrived yesterday!

[Ја sam sam]

btw Sonidos are waiting, wooden horns arrived yesterday! 

Wooden horns   , give us pictures  .

[generg]

I changed the earth conections.. oscillation away..... still to much hum....

but I was coming from Pumpkin with F4, I have to reduce the gain of Pumpkin and have to use shielded cable in the input..............

but hearing louder musik.................... stereo now.......... fantastic , totally different from F4!

[generg]

Hi stoN Kold, nothing extraordinary, sp300b build them some years ago and showed very good pictures! Mine are in a raw condition... the plan is from Sonido and is a little bit different from the plan on the webpage, they changed some dimensions to make it better. I could post the new plan, if wanted .....but of course for you a picture , still no driver mounted .......... next week I will build them up, today I will only hear Babelshark J2!

[generg]

the next ......

[Zen Mod]

....I have to reduce the gain of Pumpkin......

........

off course !!

having preamp with full blast gain for follower stage - connected to 1V5 declared input of amp is almost certain disaster ...... as leaking gas from stove

.......

but hearing louder musik.................... stereo now.......... fantastic , totally different from F4!

when we'll see some pics of speakers ?

edit: I see that you were faster with pics than me on keyboard

[Zen Mod]

btw.go back later , after 10 albums , and tell us more about sound

[generg]

........ the separation of the different acoustic sources in depth and width is so fantastic, every source has its own place ....and to say something critical: my room is very small, I am only 2 m away from the speakers and may be all is a touch to near in this unused presence not used from F4 ..... may be I will play with the gate stoppers later and hear if I can find a good value for me.

[generg]

"having preamp with full blast gain for follower stage - connected to 1V5 declared input of amp is almost certain disaster ...... as leaking gas from stove " Dear Zen Mod, what is the lowest value for the feedback resistor in Pumpkin you can recommend?

[Zen Mod]

.......and to say something critical: my room is very small, I am only 2 m away from the speakers ....... .......

considering that - little Sonidos may be complete solution for your room , without any need for augmentation from low sideyou'll be surprised both with amount of SPL and physical volume of sound "body" , coming from them

"having preamp with full blast gain for follower stage - connected to 1V5 declared input of amp is almost certain disaster ...... as leaking gas from stove " Dear Zen Mod, what is the lowest value for the feedback resistor in Pumpkin you can recommend?

leave R1 & R3 at 10Ksay that gain of ~ 3,9 to 4,7 (11,8db to 13,4db ) will suffice in that case - alter both R5 and R6 to 39K ( max 47K)check offset after change

[generg]

Thx Zen Mod,the sound is panoramic, very wide, but the sources itself stay precise, are not blown up, and between the sources is something you cannot grap easily ..... interaction?o.k. enough honeymoon for today!good work Zen Mod!

[Zen Mod]

......good work Zen Mod!

you had some doubts ?

[generg]

For the ultimate in resolution, I initially defaulted to FirstWatt's stunning J2 amplifier. It renders Yamamoto's 300B SET even with the most transparent output bottles by Synergy Hifi or Shuguang Black Treasure comparatively thick, slow and opaque. Expecting potential hairsplitting and the need to hear the tiniest of details from these very fast and translucent widebanders, Nelson Pass' SemiSouth power JFETs were my keenest microscope.from http://www.6moons.com/audioreviews/yamamoto10/passive_2.htmlwhat did I say............!

[Zen Mod]

I'm more interested in your own words and opinion , than in Srayan's

[generg]

yes master, did you remark the similarity?

[Zen Mod]

yes master .......

[Zen Mod]

just finished torture test of amp on "regular" pcb'cause I still don't have these MOX 1R/3W , mounted plain carbons - 2WPSU - biggie Donut via Variac ,Graetz , 2x33mF SpraguesR9 in ( factory preset) mid position , R12 and R25 on min/short positionvoltmeter on output for offset ; goal is zerovoltmeter across any 1R source(drain) resistor ; goal is 1V for 2A Iqboth inputs groundedfired up , due to cascodes in front LTP everything came to life at approx +/-15VdcIq around 1A5 , offset around 350mVup with PSU at approx +/-18Vdc check and set voltage across R3 to 9V4 ( that's 20mA through LTP)fiddle with R12 - offset to zeroVariac - full PSU voltage +/-22V5 again R12 - offset zero R25 - fiddle .. go to 1V across 1R done;torture test - everything with and without dummy load ;5 mins in full clip ( almost rectangle ) at 500 , 1K , 5KHz ; with or without dummy loadbrown out 30 secondsbrown in 30 secondsasymmetrical PSU voltage ( +18V5 / -22V5) ; little hum in speaker but offset stable sound - mono on test speaker - naked Philips 12" FR ------ gorgeous !

[stein]

[Sync]

Ma nist ti ne verujem...dok to Sloba ne sastavi i protrese. Tek onda pravim.