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Old 30th January 2013, 10:39 PM   #101
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I meant 6j11p, had a look around and they seem to be the same thing. They are listed as an ef180 type and to me look very like a higher dissipation (4.9w) 6j9p, with higher heater current. The anodes look just like 6j9p-e's ie tanks! If thats the case they should be well worth looking at!

Enzo
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Old 30th January 2013, 10:53 PM   #102
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Indeed they are built like a tank. I've seen them listed as E280F equivalent also.

Verstuurd van mijn GT-N7000 met Tapatalk
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Old 9th May 2013, 06:54 AM   #103
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Default GM70 C3G/6B4G

I did try C3G triode as input/driver tube (gain about 42) to the interstage xformer but I did not like the sound, compressed, loss of dynamic, still not bad sounding for SE amp. With C3G (triode) as input and 6B4G as driver/interstage the sound is more powerful, more dynamic, the sound is satisfying.
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Old 3rd November 2014, 09:43 PM   #104
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Enzo, what happened at the end, which one was the winner?

The 6e5p is for me one of the best, but need one more stage or preamp to drive correctly big triodes.
High gain penthodes strapped as triode have the problem of the oscillation is mandatory heavy grid stopper > 5k cap 90pf g1 to ground help,


Very interesting link,
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Old 11th November 2014, 07:22 PM   #105
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I stayed with the 6e5p, I designed but didn't build a direct coupled 4p1l driver, then bought some extremely cheap 300b's so robbed the output transformers and ps caps from the gm70. The 300b has a 4p1l filiment biased cap coupled and sounded better than the gm70, apart from the bass where the gm rocked.
Building se 4p1l, 6hv5a spud (sounding promising) and 833 spud! So busy. Must finish 6av5/6cb5a push pull too!
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Old 11th November 2014, 08:42 PM   #106
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Quote:
Originally Posted by enzoastro View Post
Building se 4p1l, 6hv5a spud (sounding promising) and 833 spud! So busy. Must finish 6av5/6cb5a push pull too!
Enzo
833 spud??? Is that an oxymoron?

6E5P is a perfect single stage input/driver for the 833, BTW. The higher mu of the 833 helps a lot.
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Old 12th November 2014, 10:04 AM   #107
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833 spud??? Is that an oxymoron?

6E5P is a perfect single stage input/driver for the 833, BTW. The higher mu of the 833 helps a lot.
Hi Magz, your 833 is biased at 32v (247-215), is right that 6e5p give 30v per 1v but without preamp you are in the edge to have good headroom you will must have a gain 45mu. ( the next station 6s45pe )

In my 211 biased at 60v need at less a gain over 80, Only in one stage the 6j51p have the stones to drive correctly but my next station will be 3 stages to feel relax.

Maybe the next with two tubes and three stage will be the ECL tubes tP as ECL82
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Old 12th November 2014, 10:34 AM   #108
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Thought that might raise some eyebrows lol ��
Again some cheap tubes came my way, I'm not sure the 833 can ever sound as good as more well known tubes but I've never heard an 833 so I thought I'd build a small, cheap if comprised amp to dip my toe. Not words often used with 833s... I have power supplies I can rob from my gm70 / 6hv5a amps that are good for 1100-1200v @ 2-300ma so that's the ht per monoblock. I also have smp @ 16-20A 12v and 20A inrush limiters for the filiments. The sticking point is the se opt. Budget build precludes 240 each hammond so I looked to China and have been quoted 180 delivered for a PAIR of 75 w 330ma 2500v 4.5k opt. I don't say they will rival tango....
I use speakers with 40w power handling (2x 301 axiom 16 ohm parallel / channel) so don't need/want more than that. My rough calcs say ~ 1v in equals 1watt out so 40-50v via tubelabs powerdrive should suffice. My 4p1l preamp puts that out so spud it is. Kudos to the quarter ton 833 builders but I plan on being able to lift my monoblocks without help.

Last edited by enzoastro; 12th November 2014 at 10:37 AM.
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Old 12th November 2014, 03:05 PM   #109
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Originally Posted by celsius235 View Post
Hi Magz, your 833 is biased at 32v (247-215), is right that 6e5p give 30v per 1v but without preamp you are in the edge to have good headroom you will must have a gain 45mu. ( the next station 6s45pe )

In my 211 biased at 60v need at less a gain over 80, Only in one stage the 6j51p have the stones to drive correctly but my next station will be 3 stages to feel relax.

Maybe the next with two tubes and three stage will be the ECL tubes tP as ECL82
Yes, I'm using a preamp, so putting in a little more signal is no problem. Plus, it helps my preamp feel needed...
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