| Circlotron |
| Can anyone point me toward some stuff dealing with cathode follower class A type output stages? I imagine these would have some unique properties over more common type of o/p stage. |
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| 316a |
Hello ,
I've been pondering over something similar using 7236/5998a and mains toroids as output trannies which should work rather well . Driver stage is the main hiccup !
316a |
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| Circlotron |
| quote: | Originally posted by 316a
Hello ,
I've been pondering over something similar using 7236/5998a and mains toroids as output trannies which should work rather well . Driver stage is the main hiccup ! 316a |
Hi 316a. Driver stage - yeah, it's gotta swing lots of volts doesn't it? Maybe bootstrapping it's dc rail from the output tube cathode would help. I assume you would use a parafeed setup when you use a toroid as an output tranny - it won't give very good bass response with dc flowing through it. There is no airgap in the core. Uhh, actually did you mean single ended or push pull class A? :scratch: You just gotta post the results when you get it going, ok?
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pedroskova, that would be good if you would email me the pdf. Thank you. :) Thanks for the link too. |
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| 316a |
Push pull works fine with toroid outputs , DC cancels . Working on a toroid amp at present but not a CF one , remember the 'power' long tailed pair output stage I posted a while back ?
316a |
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| 316a |
That's the chap ! But I'll be using a depletion mosfet instead
316a |
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| Circlotron |
| quote: | Originally posted by pedroskova
Anthony Dockrill had an article in Valve discussing a 10Y driving a parafed CF 6L6GC in tetrode mode. No longer up on the web, but I could email you the pdf. |
Here you go then -> gpratt@alphalink*com*au
Just change the asterisks to dots. |
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| Brett |
| quote: | Originally posted by 316a
remember the 'power' long tailed pair output stage I posted a while back ?
316a |
I built a 12E1 PP using an almost identical biassing scheme. Op points were 240Va-k, 120mA/tube, -34V , 5ka-a using a battery biassed 820 on a big sink. Got about 12W out of it. Took it apart to use the PS components in something else, as it was a bit hard on the chokes I had at the time. Sounded very good for a lash-up.
Which depletion mode MOS are you going to use? The DN2450?
Cheers |
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| 316a |
Hello ,
I'll be using a simple DN2540 first then a cascode with a 2540 TO220 and TO92 . Like the 'hot'n'low' opearting point for 12E1 !
316a |
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| choky |
interesting to say-old geezers from old books use to say that triode like to see at least 3Ra even if load is cathode connected.
that's why CFs are most linear when they are CCS loaded.
I pay that price once-when I was brave enough to put 600:600 xformer in cathode :nod: :scratch: |
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| fdegrove |
Hi,
| quote: | | that's why CFs are most linear when they are CCS loaded. |
There's a small raft of different CFs out there but either way it's hard to make a "Joe Average CF" more linear than it is already.
Oh well not all CSSs are made equal either...
A CCS will linearise virtually any circuit...whether you like the result or not is an other issue altogether...
Making generalisations like that is not going to help you nor anyone else...
Cheers,;) |
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| Circlotron |
| quote: | Originally posted by pedroskova
Anthony Dockrill had an article in Valve discussing a 10Y driving a parafed CF 6L6GC in tetrode mode. No longer up on the web, but I could email you the pdf. |
Got it. Thanks. :nod: Interesting that he refers to it as tetrode mode but it is really in triode mode because the cathode is moving up and down while the plate and screen are staying put, i.e. plate and screen are doing the same thing. For tetrode mode, the screen should move up and down with the cathode but at a fixed voltage above it, while the plate stays still. Only read that recently, didn't realise it mysef until then. |
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| choky |
| quote: | Originally posted by fdegrove
Hi,
There's a small raft of different CFs out there but either way it's hard to make a "Joe Average CF" more linear than it is already.
Oh well not all CSSs are made equal either...
A CCS will linearise virtually any circuit...whether you like the result or not is an other issue altogether...
Making generalisations like that is not going to help you nor anyone else...
Cheers,;) |
interesting-most apealing way to make any stage in tube amp or preamp (for me,off course) is to use single triode and xformer,hehe-in any order you want or can;
I know that is not best way in any case,but I just like sound made with lotsa iron
:goodbad:
accent was on right Rload,not on CCS.I like CCS in heater circ,but I realy don't bother much with implementation of same in cathode or anode.
but,what is important-is good to know and try various ways in achieving to make good stage.
(that's why I asked for some schmtc;) )
for me seems that more important are some other things for good stage.like operating point,slew rate,etc etc are;
in fact ,I almost hate most of SRPP designs,even real CCS loaded-I can't say much more except that sound made in that way is sorta boring :devily:
be well! |
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