F5 Cascoded - an alternative for my interest in the Balanced F5 - Page 2 - diyAudio
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Old 22nd January 2011, 09:58 AM   #11
juma is offline juma  Germany
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I look at your PCB in post #1 and it's a bit crowded with 150R/3W feedback resistors.
I planned that PCB for 3x150R/2W feedback resistors since I can't buy locally 100R/3W ones.
You can use 2x100R/3W to avoid crowding.
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Old 22nd January 2011, 10:59 AM   #12
Zen Mod is offline Zen Mod  Serbia
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Papa meant on small cascoding bjt's , not on outputs

he gave another important tip - keep strong and firm biasing of them

you already have that in those posted schematics , all over variouss F5 threads

sabath - I meant on wattage of feedback resistors , in case of max PSU voltage
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Old 22nd January 2011, 11:46 AM   #13
tinitus is offline tinitus  Europe
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I deleted my post, to avoid further confusion
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Old 22nd January 2011, 01:09 PM   #14
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I've also been following the balanced F-5 thread with much interest. Previously, I had been interested in some posts of F-5 with more power and ideas for doing it, where cascode, multiple outputs, etc were discussed.

Cascoding very much interested me, both for the F-5 as well the BA-2. Cascoding questions seemed to be a little above my understanding, so I decided to sit back, read other threads on the topic and see what I could learn. Thanks for posting this, I'm still very intersted in the balanced F-5, but this thread will hopefully be the one the clears up the cascoding process up.

Meanwhile, I play the F-5 in a system where the gain is adequate, and am happy. The F-5 is what it is, and is exceptional as that. While my first reaction was, "Wow, I should would like this in a high power version" I dont know that the result would be as enjoyable. Many times with commercial amps, I've noticed that when there is a 60 watt version, a 100 watt version and a 200 watt version, the less powerful version seems to sound the best....within its power range. Similarly I fear that higher power/gain versions wont have the same magic.
Hopefully this thread will not only be an in general learning experience for me, but will also allow me to understand cascoding, so thanks!

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Old 22nd January 2011, 01:50 PM   #15
flg is offline flg  United States
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Old 22nd January 2011, 02:56 PM   #16
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Originally Posted by NYCOne View Post
I'm not sure I follow the "caps to ground" - I have the caps where your diagram suggests. I can change this if I misinterpreted your figure.
That would be the "fewer parts" edition. The cap from
base to base achieves much the same thing as the base
currents cancel each other.

This is a bandwidth issue, the object being to prevent
the cascodes from degrading the bandwidth due to high
impedances on their bases.

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Old 22nd January 2011, 03:14 PM   #17
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Tanks Zen

realy apreciated
As NICOne say (quote what time is it ......

Hope ranting and rawing bout (well how shuld I put this...) is over

Nycone yust did it again you started a briliant tread mate.

Be back in a Jffy got a pcb IDEA to share
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Old 22nd January 2011, 03:24 PM   #18
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Originally Posted by flg View Post
Thanks, always enjoy info on Pass. I've read that one from someone else's recommendation. Nice read, but didnt leave me in a place to be able to implement as I am inexperienced in design. I can follow the idea, I can identify parts and am fairly good with a soldering Iron. I follow directions well, I just am no where near taking an idea like cascoding and applying it to an existing amplifier without guidance.

Thanks for the comments,
much appreciated,


Last edited by Russellc; 22nd January 2011 at 03:31 PM.
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Old 22nd January 2011, 03:36 PM   #19
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F5 PCB triple (reminding me of last time I left a bike under a buss)

Ernos cascode in this version.
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Old 22nd January 2011, 03:38 PM   #20
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(where diid I steal this?)

Balanced F5 triple
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