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-   -   Push-pull implemented with KT88 (http://www.diyaudio.com/forums/tubes-valves/222936-push-pull-implemented-kt88.html)

regiregi22 5th November 2012 03:42 PM

Push-pull implemented with KT88
 
Hello,
I am planning to build a push-pull KT88 based amplifier. I would like to make it operation type selectable by using a switch, so I can operate the tubes at Triode, Ultralineal or Pentode, depending on my PWR needs, and mostly for audio comparisons purposes. Fixed bias provided by extra turn on xfmr.

I could use a different tube rather than KT88, but what the h*ck, it's among the best tubes in its power rating. I haven seen some pcb boards (like pmillet's) that come very handy if testing and breadboarding, but it will be a final assembly, not an amplifier to experiment, so I will P2P it.

What is a common, high-end, not very complex schematic to use? I don't really care if it is a complex desing, but life's such, that simpler ones use to be the better ones. I don't really need to be able to select between triode, UL and pentode, that's something I am able to put in by myself :)

If you were about to build ONE, with these requirements, what proved schematic would you implement?

Thank you and best regards,
Regi

SandyG 5th November 2012 04:00 PM

Look to the Dynaco schematics with modifications to the driver board, a ton of them floating around, for the Monoblock's look for the MKIII amps and for a stereo version the ST70. Lots of transformers from several sources and I think just an update to the driver and you will have a simple good sounding amp.

Sandy

regiregi22 5th November 2012 08:30 PM

I have had a look at that, seems quite interesting

www.triodedick.com/pdf_files_td/Bill_En.pdf

tinitus 5th November 2012 09:34 PM

Quote:

Originally Posted by regiregi22 (Post 3229564)
I have had a look at that, seems quite interesting

www.triodedick.com/pdf_files_td/Bill_En.pdf

Mono Bill or Mono Bill II are later KT88 designs

don't know if its true, but I got the impression that the KT88 quality could be an issue

boywonder 6th November 2012 03:01 PM

In addition to the Bill/Mono Bill, here are a few more:

Mullard 5-20 topology with PP KT88's:

http://www.diyaudio.com/forums/tubes...pp-blocks.html

Mullard 5-20 topology with MOSFET followers:

http://www.diyaudio.com/forums/tubes...n-mullard.html

Differential front end with MOSFET followers:

http://www.diyaudio.com/forums/tubes...c-ab2-amp.html

regiregi22 15th November 2012 07:08 PM

Quote:

Originally Posted by tinitus (Post 3229653)
Mono Bill or Mono Bill II are later KT88 designs

don't know if its true, but I got the impression that the KT88 quality could be an issue

Why? Ain't KT88 good enough performers?

tinitus 15th November 2012 07:39 PM

Quote:

Originally Posted by regiregi22 (Post 3242963)
Why? Ain't KT88 good enough performers?

ahh, yeah, I guess they are ok
I meant, a KT88 may not be all good just because it says KT88 on the bottle ;)
hope its ok to call it a good alround performer and 'middle of the road', so to speak

regiregi22 15th November 2012 08:32 PM

2 Attachment(s)
I think I am going with Triode Dick's, but I can't find anything related to output transformer impedance, power and other characteristics on its website. Do you know what is used in the original design or should I just calculate it?

Link to the translated website:
Bill Part 7

tinitus 15th November 2012 09:25 PM

monobill 2 schematic shows 5K6

regiregi22 15th November 2012 09:31 PM

OK! Thanks!


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