Babelfish F8

[ItsAllInMyHead]

^ Fantastic!!!

🙂

 

[Russellc]

I have several sets that are just over 9, will these still work in this circuit? ( Just in case I need another one!

Russellc

 

[Zen Mod]

@Russellc

that's covered in post #8

Post in thread 'Babelfish F8'

2024-10-24 11:01 pm

Lazy ZM, forgot to measure Rout/DF ..... but - who cares; see at FW site and slide down (no output cap)

gain is ~ 1V34pp to 8Vpp, meaning ~0V5rms for 1W@8R .......... call it 15.5db

some notes I made:




Jun 2024 schm; my setting Iq 1A8 all cases

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
2SJ74BL Idss 6.5mA

IRFP

drain resistor 680R + 500R trimpot; 680R fixed increased with 330R fixed (fast, instead of changing trimpot for 1K)

Ugs 3V54
U(680+330)=2V65 so I= 2.62mA...

• Zen Mod

• 

 

[chromenuts]

I wonder if I will regret not having this one 🤔

If I review my power JFET hoarding…I already have built F2J and a pair of Babelfish 2J…I stuck some unmatched Semisouth down in ACAs too.

I still have boards and parts to build LuDEF and the Jeff Young long board versions of J2 and F3

Once I turn my attention to bigger SIT amps I don’t know if I’ll turn back

Everything is about getting my act together with speaker projects right now

I just don’t want to be an irresponsible greedy boy 🤣

Anyone want to comment on what might set this one apart from what I already built or have to build?

 

[Zen Mod]

I can't help you with comment .......... biased heavily

except, you know that all my amps are the same ........

 

[jasonb84]

I am wrestling with this portion of assembly at the moment. Populating boards and time for trimmer pots.

What would have been the Idss of the 2SJ74 supplied by Zenmod in kit?

Would it be beneficial to preset trim pots to a value that would reduce additional turns needed to calibrate the amp?

Could someone provide some quick guidance on first power up and Iq set? Should I bother bringing power in slowly with variac if I am already confident in power supply and other parts of amp build seeing as its already in use with Aleph J boards.

 

[Zen Mod]

I believe setting procedure is already covered somewhere in thread

shorted input, one DVM across speaker terminal to observe DC Offset, second DVM across (any) big 3W resistor in output stage, just be sure that you have calculated proper voltage across resistor group in case, for intended Iq

no need for any special procedure regarding trimpots

you got from me JFets in mid-upper portion of BL range, so all good

 

[Zen Mod]

say that DVM is across R18; effective R is 277mR; target voltage is 500mV for Iq 1A8

if DVM is across R19, effective R is 600mR, target voltage is 1080mV for Iq 1A8

 

[ggetzoff]

Package arrived yesterday from deep behind the iron curtain from a windswept Mt. Zen….

 

[birdbox]

My package showed up Thursday! Yeehaw!

 

[gary s]

I am sure you will be both pleased with the results.

 

[Zen Mod]

good to hear

all sort of problems lately with shipping, from all sides

besides, I had hectic several days (life, tricky thing ), hope to collect some brains tomorrow

 

[ItsAllInMyHead]

It's a special amp.

And it still is.

 

[Zen Mod]

..... and 2SJ74BL JFets left for just 6 kits more



2SK2145 aplenty, so no shortage of Babelfish F8b

and bought 100+100pcs of VN2106 & VP2106 (in place of and better than TN/TP2640), so no shortage of Babelfish F8m

 

[tonyEE]

Now, pics showing proto phase, as proof that I didn't just dream of ........ though, never underestimate capabilities of dreaming

Not once I had problems solved while dreaming

Curse of Living a Dream

Alek!

Most of the people in these forums were not alive when this came out.

Some of us.... bought the album when if first came out. It was such a great time in my life... upperclassman in college, finally with a little bit of money, a nice Dual Turntable with a Stanton 681EEE, a Kenwood KA3500, ADS L810s, about 300 LPs... some lady friends... Music was breaking out... Couldn't afford Nelson's work ( who does? ) but...

Physics was Phun.

BTW... Nobody walks in LA.

Those were such great times. Music was re-awakening...

Remember when MTV actually played music videos?

The Hardest Part.

And of course

HEART OF GLASS.... CALL ME!!!

Remember the B52s? Devo?

Were you there when Devo first showed up at Saturday Night Live? I mean, that performance actually stopped the bong getting circulated... ;-D

It became such a different World.... Loggins and Messina with Fleetwood Mac on one hand... then you got the Blondie, B52s on the other.

Finally, found myself in '82 in Hollywood at the height of the New Wave Era.

It was Rodney on the Rock on Sundays at 8PM on KROQ....

And then.... CDs came out and the End Of The World with Rap came out and destroyed our audio lives for a few years....

( BTW, the chicks on that video I included... pfft... you should have seen SoCal at the time..... what a glorious time with great music and awesome looking chicks... heck... I married one... ) "Hey, babe... you wanna dance?" My romance was out of a Zappa song....

Got this LP too... of course... The US Festival...

 

[tonyEE]

I'll be back pronto, don't interrupt

View attachment 1372104

Are you related to @Cal Weldon ?


I'll be back....

BTW, always take the ring off of the cigar.... serious cigars smokers ALWAYS take the ring off the cigar. And, that looks like a little cigar... what? a 50x5? A little Robusto? Pfft.... If you wanna be MACHO, cigars start at 60x6. I even got some 7x70s.... Actually, I even got some 105x10 pyramides..

And then you got those truly long 60x10 cigars. They take two hours to smoke.

I started one of them once, going to work on a Sunday.. traffic was heavy. Left home, an hour later I could not feel my feet.... got to work in two hours just as I finished the smoke and I could not feel my body. Coworker in the lab asked "Tony, are you OK? You're white as a sheet!"

 

[Zen Mod]

Are you related to @Cal Weldon ?

yeah, we are brothers



we both spent many years in work in same manner, flying high ......

 

[Cal Weldon]