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Old 17th March 2012, 12:10 AM   #3301
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Quote:
Originally Posted by Zen Mod View Post
...btw - J2 vs. BJ2 - they're not so different ...... any difference is strictly intentional - it's not fun making things exactly as Papa does
Finished my J2 variant 3 days ago. Now we're talking!!

You know by now how satisfied I'm about this amp topology as we've a Serbian friend in common who called you this evening.

With my precious DTQWT MKII loudspeakers by Troels Gravesen I'm in heaven! I can't imagine that a F4 can do it better than a J2 variant, oh, it should be your Babelfish J2 mighty Zen Mod! Or any SIT-amp from Papa...

So, do a F4 have a chance against the J2 on efficient speakers? The low level detail from the Semisouth JFETs is beyond any FET-amp I've heard so far... Truly amazing and on par with the best SET tube amps I've heard but without their limitations...

Thanks to Papa for encouraging to DIY!!
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Old 17th March 2012, 02:41 AM   #3302
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My pleasure.

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Old 17th March 2012, 04:50 AM   #3303
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by Kim Bay Smidt View Post
..........
You know by now how satisfied I'm about this amp topology as we've a Serbian friend in common who called you this evening. .........
small world

Quote:
Originally Posted by Kim Bay Smidt View Post
......

So, do a F4 have a chance against the J2 on efficient speakers? ........
I think not

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Old 17th March 2012, 10:56 AM   #3304
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Good morning to all. Would it be plausible that a LU SRPp FE, biased slightly lower with higher rails, be able to match J2? EUVL found pretty nice sweet spot at lower levels. Drinving an crippled F4 of coure.
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Old 18th March 2012, 01:13 PM   #3305
Gyuri is offline Gyuri  Hungary
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I think the F4 is a real truth-machine.
What it involves, going to come out of it.
But it requires a preamp, that I not have.
I wonder what Papa used for this?
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Old 18th March 2012, 01:35 PM   #3306
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Take away the jfet FE an dyou have even more revealing machine.
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Old 18th March 2012, 02:10 PM   #3307
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a LU FE
Euh, any reference ?
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Old 18th March 2012, 02:18 PM   #3308
neoinc is offline neoinc  Singapore
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How exactly is it to build a crippled F4 with a BA3?

I thought of building them in modules and interconnect like a BA3 pre to a F4 power. The BA3 gain should be more than enough to drive a F4 properly from what i understand.

If someone could suggest a better way, I would be happy to learn it.
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Old 18th March 2012, 03:08 PM   #3309
flg is offline flg  United States
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I was thinking of trying something like you see below. This is only a start. I think maybe more thinking is in order around that 200 ohm resistor... Guess the front end needs some power too...
Attached Images
File Type: png BA3-4.PNG (20.6 KB, 518 views)
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Old 18th March 2012, 03:28 PM   #3310
generg is offline generg  Germany
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no biasing network for the output stage....?
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