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

[dsdjoy]

Hi,I am considering to build it, and am wondering about how it sounds.Do have first listening experience with Babelfish J2 ?Is it an improvement, compared for example with F5 ?Kind regards,Oliver

[Zen Mod]

Hi,....

Hi !welcome to the forum :rolleyes:B. J2 is in finishing stage - final pcbs populated and I hope that I'll soon find some time to put them together with rest of mechanic parts ( PSU , heatsinks ) and listenI was thrilled with prototype ; just as information - my prototypes are always mono , where I'm trying concepts and changing things to make entire package better .... according to my needs and knowledge .when I'm ready - I make pcbs and eventually make final tuning of some part values ; it's anyway always needed changing actual physical layout of electrical circuit .I remember that I was thrilled , first time hearing notes from Babelfish J mono prototype ;also - I was pleased when I made first F5 ( that one was stereo) , in Ikebana style (point to point , rudimentary PSU ) ;but - I was stunned hearing first tune sung with mono Babelfish J2 prototype I hope it's helpful ;anyway - Generg will soon make his B. J2 , so you'll have another one , this time objective opinion .

[sp300b]

...anyway - Generg will soon make his B. J2 , so you'll have another one , this time objective opinion .

...and me, myself and I

[Zen Mod]

[Zen Mod]

naah .....now waiting for shipment from Shuro ..... MOX 1R/3W

[Manu]

Superbe !Manu

[Magura]

Superbe !Manu

Looking for a new project Froggy? Magura

[generg]

anyway - Generg will soon make his B. J2 , so you'll have another one , this time objective opinion .

very glad to hear I will see PCPs soon .............. and more glad to be called objectif! I have my MOX 3W 1 Ohm already, even a 10W variant from Mundorf also coming from Schuro.many THXs Zen Mod

[sp300b]

naah .....now waiting for shipment from Shuro ..... MOX 1R/3W

[scope]

Zen, koji si stavljao razmak rupica za:-otpornike-3W otpornike-i koja je dimenzija plocice

[Zen Mod]

Zen, koji si stavljao razmak rupica za:-otpornike-3W otpornike-i koja je dimenzija plocice

10mm za MF (15mm za R32)23mm za 3Wto su sve dimenzije direktno iz lib , s tim sto sam maltene sve korigovao velicinu padspcb je 80x110

[generg]

what is this? LOOK AT THE PICTURE

genergs swimming chaos babelfish J2 works!

Dear Zen Mod I want to thank you very, very much for your work exploring the J2! Without you, we would still wait, eager to clone Papas J2 and not knowing what to do with the Semisouth R100 bought over a year ago.

Maybe we can start discussing a little bit your circuit. Why did you take BD 140 instead of double or triple j-fets Sk170 and R9 trims the current through the inputstage?

R12 makes the offset zero and with R25 we can regulate the bias of the output stage?

When I bought the green (you always choose the color of hope) LEDs, they asked me if I wanted the 3mA version or the 20mA type, I suppose 20mA is the right choice!

Why do you connect back the emitter of Q8 to the BD140?

By the way my Q7 and Q8 get a little bit hot, correct? I did not always the best versions of parts, for instance only BD140-10, or Bc556B or of CN17 only a smaller version, is that problematic?

Of course I keep the best resistors and the best caps and the best for your final version of boards coming soon!

The sound: like a shark in the sea!

all the best for you!

[Zen Mod]

what is this? LOOK AT THE PICTUREgenergs swimming chaos babelfish J2 works! ,..........

.......Maybe we can start discussing a little bit your circuit. Why did you take BD 140 instead of double or triple j-fets Sk170 and R9 trims the current through the inputstage?.......

why wasting 2SK170 , when with two-bjt-CCS you have very nice CCS , with superior Tempco .

R12 makes the offset zero and with R25 we can regulate the bias of the output stage?....

with R9 set 20mA through input LTP ( exactly 9V4 across R3 )both R12 and R25 are influencing Iq and offset ; start with R25 at zero , trim R12 to desired Iq , then fiddle offset with R25

........When I bought the green (you always choose the color of hope) LEDs, they asked me if I wanted the 3mA version or the 20mA type, I suppose 20mA is the right choice!Why do you connect back the emitter of Q8 to the BD140?.

20mA type is good ; they're operating here at 5mA ; nice value , considering both internal resistance , tempco and noiseQ8 ? base of Q8 via R24 and base of Q5 via R2 are connected to neg PSU, via R21

.....By the way my Q7 and Q8 get a little bit hot, correct? I did not always the best versions of parts, for instance only BD140-10, or Bc556B or of CN17 only a smaller version, is that problematic? .

put some little heatsink to Q8 ; Q7 is maybe just warm ; difference between BD140-10 and BD140-16 , same as between 556B and 556C are just in Hfe ; do not even bother .....

The sound: like a shark in the sea!

tell me more .....

[generg]

dear Zen Mod

Trimming successfull, all values o.k.

Sound, please give me some more time, but like a said very fluent like the water, very quick and dynamic like the shark and precise like his teeth.

I have also up to now only one channel, some more J74 are coming next days. Also in two, three days Sonidos are build up and I can compare with the Thiel SCS4.

happy life being retired.......

[Zen Mod]

ZM knows Bahnhof:buehehe:

[generg]

ZM knows Bahnhof:buehehe:

O.k then you may also know if I could take for Q8 a BD140 as well?

[Zen Mod]

naturlich

[generg]

some more impressions....still hearing mono, it is surprising how perfect one channel only sounds, you miss nearly nothing.The bass has the quality of F5 or better, but I did not like F5. Coming from Accuphase it had the same way of details but a bit stressed. Babelfish combines all the qualities I found in the different F series (F1, F4,F5).Of course every new amplifier makes aware of new details never heard before, because they all sound different and we do not care for the details that got lost.Babel J2 has the articulation of F1, but a more fluent combination of details.The highs are excellent, the clash of drums comes stunningly perfect ......

[Zen Mod]

[generg]

before we one more question please Zen Mod , I omitted D2-D5 in the beginning of signal path. Nelson omitted it in F1j.You implemented it for safety?One more comment to the sound, then I stop. As Zen Mod knows I modified BA-1 with Semisouth R100 and was immediately impressed by the changed sound. These new parts are really worth their money.The problem with BA-1 was, that the CCS was still IRF240, so the interaction may be not optimal. Also the front stage was not optimized for SSR100 and was not necessary, pumpkin was enough.I don´t know if pumpkin could drive the SSR100 optimal and I did not know if the matching of 6 SSR100 per channel was good enough. Later I changed the CCS IRF240 too into SSR100, the sound changed again, but consonants got edgy and some drum strikes were to pronounced (distortion? Nelson had reasons to change to Mu-follower.)So I am happy to know that the frontstage of Babelfish J2 is optimized for SSR100 and I have to match only a pair of these expensive parts.Indeed besides the typically SSR100 sound per se, the frontstage Zen Mod developed gives more drive to the SemiSouths than ever!

[Zen Mod]

before we one more question please Zen Mod , I omitted D2-D5 in the beginning of signal path. Nelson omitted it in F1j.You implemented it for safety?

call me cautious repair man :Viannen_loungelizard:I had my share of repairs , where someone plug input cables without touching chassis with hot tip before .I drew them from habit , but without intention to really put them on pcb .

As Zen Mod knows I modified BA-1 with Semisouth R100 and was immediately impressed by the changed sound. These new parts are really worth their money.The problem with BA-1 was, that the CCS was still IRF240, so the interaction may be not optimal. Also the front stage was not optimized for SSR100 and was not necessary, pumpkin was enough.I don´t know if pumpkin could drive the SSR100 optimal and I did not know if the matching of 6 SSR100 per channel was good enough. Later I changed the CCS IRF240 too into SSR100, the sound changed again, but consonants got edgy and some drum strikes were to pronounced (distortion? Nelson had reasons to change to Mu-follower.)So I am happy to know that the frontstage of Babelfish J2 is optimized for SSR100 and I have to match only a pair of these expensive parts.

CCS is CCS ; black box , if you ask me - and putting SSouths in CCS is waste squared ; you can make it even with bjts if you wish . under condition that you make good , not mediocre one .problem was probably in some other area - but now I can't take a look at BA1 schm ..... too much multitasking lately , and I have just one dumbe kopf

Indeed besides the typically SSR100 sound per se, the frontstage Zen Mod developed gives more drive to the SemiSouths than ever!

naah - what I did is just Babelfish-ing Papa's bread crumbs

[Tea-Bag]

Oops.

I ordered http://search.digike...rds=516-1310-ND for my LED's. Think they are 2mA typical.

This might explain why they are flickering a bit with a signal pumping into it?

Congrats Generg, I am a further bit behind. Have a nasty cold.

I have one channel with minimal offset, .750v across source resistors, the other is offset of 10v, and it biases to 1.8v quickly. Something wrong with it, it didn't respond to R12 or R25 fiddling at all. Maybe swapping out LEDs will get me further down the road..

I do need to take some serious measurements of both channels and present them here.

Generg, Once you go full range driver, I think you'll be happy. What implementation for Sonidos you going to use, BLH, OB?

Tea-Bag