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Old 13th July 2008, 08:16 AM   #1
billr is offline billr  New Zealand
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Default 300B push pull amp

Hail

I posted a notice about a month ago in that i had scored a box load of 300s 845s etc.

I also have a pair of 5k potted transformers, a very hefty power transformer that needs a new home, and the wherewithal to build a nifty amp.

So it's time that something came of the assorted bits'n'pieces that I've got kicking around.

I'm fairly relaxed about design, and can design my own drivers.

What I'm generally interested in is the general merits of a couple of design options that I am tossing around.

I like the thought of driving the 300s with either of the following,

1. a power drive cct a la tubelab, or
2. cathode follower.

The 300B as i read it, has quite a bit of capacitance to overcome, I also like the idea of moving into A2 as well, hence the need for the above.

When it comes to the bits before the above, a couple of schmitts? or a simple two stage with a concertina or single stage then a concertina then a driver?

I've also got 10 IXYS 900V CCS devices, that I am keen to play with.


The options, the options?

Any thoughts and ideas most gratetfully accpted.

sorry if this is a ramble. Just looking for ideas, I've been searching the web for cct diagrams, there are dozens all seem to have their merits, interested on hearing other peoples ideas before I commit to far.

BIll
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Old 13th July 2008, 08:55 AM   #2
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Well, if you ever wanted to pioneer something unconventional....
Long Neck Pair of 6AS7 or 6080 low Mu Triodes ought to do it.
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Old 13th July 2008, 09:23 AM   #3
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Default Re: 300B push pull amp

Quote:
Originally posted by billr


1. a power drive cct a la tubelab, or
2. cathode follower.


3. Transformer phase-splitter

Would be my choice. A two stage design with no coupling caps.
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Old 13th July 2008, 04:57 PM   #4
GaryW is offline GaryW  United States
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Here's mine. It's been running as my main amp for several years now:
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Old 13th July 2008, 10:10 PM   #5
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Very nice. Love the 866s.

What are the 0.25ohms for?
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Old 14th July 2008, 02:47 AM   #6
GaryW is offline GaryW  United States
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Good eyes. They are current sense resistors for setting bias in each push-pull pair.

The 866's are nice. I had 83s in there and they were fine too, but the glow of the 866 attracts.
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