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-   -   P-P Katodfollower with 6c33c (http://www.diyaudio.com/forums/tubes-valves/152437-p-p-katodfollower-6c33c.html)

Ryssen 24th September 2009 08:37 PM

P-P Katodfollower with 6c33c
 
Have searched but havent found any info on this,what I know is that the gain becomes close to 1.and the driveswing must be more.'any thoughts on this ideas,fixed bias will be used,Schemas and reading..?

jechentau 25th September 2009 06:42 AM

what load will it drive? do you want to use a center tapped choke, center tapped symmetric autotransformer, or regular output transformer (will have quite strange specs)? this matters because plate voltage and idle current, bias and operation mode and required driveswing, can be optimized.

Ryssen 25th September 2009 01:59 PM

I am going to use a LL9213 P-P, a lundahls trafo,I have e.maild him about data,they are about 10-14 years old.
What is a center tapped choke good fore?

jechentau 25th September 2009 02:15 PM

ah, do you have a link to datasheet?


a center tapped choke would let one connect a speakerload directly, and symmetrically
to the cathodes of the tubes.

but with most speakers, that works best with many pairs of tubes ;p

or with some mosfets, like a member, susan parker, as i recall ;p though she used a transformer indeed.

may be interesting for you to search perhaps.

you will need to bias the "other way" though (depletion mode devices) ;p

Ryssen 25th September 2009 02:42 PM

Quote:

ah, do you have a link to datasheet?
Canīt find one on the net,I am waiting for mr lundahls reply then I will post it.
I searched the net on 6c33c and there is not much info on this,like how to calculate the drive swing for the 6c33c in this coupling,I know its going to be quite large.

Ryssen 25th September 2009 05:38 PM

The LL9213 is the same as LL1623
http://www.lundahl.se/pdfs/datash/1620_3_7_9202.pdf

And it is connected as 1,6k,but I guess that can be halved by using 8 or 4ohm
wich is it?
Anyone have cloue of the workingpoint of the 6C33 in this arrangement?

jechentau 25th September 2009 06:01 PM

well, i am not sure, but as is, it seems too high a load.

however sofar it seems that this thing is useable though, if rewired.

2 series 2 parallel primary seems to result in about 11:1 impedance ratio, which seems better in the ballpark.

the grid swing is the grid drive, on top of the output swing, iirc, in this case.

which may be more than 300 V

ths dude has a 5x 6c33 driving 8 ohm, for 20 watt out, with 2.5 to 1 turns, i believe a pair in pp can deliver the same, and with a higher ratio, (3.35 with that trafo), you may hit over 25 W class A.

http://www.super-otl-audio.com/Description.htm

since this amp has less cathode swing, his grid swing drive requirements are also less (maybe half, or less, afaik)


i have to think of more ;p

what to think of 155V, 350 mA, about - 50V, and 400 Ohm seen each tube? a bit over 200 V swing,54 Watt idle, class a inductor theorem 25% efficiency ~ 25 Watt out for pair?

seems about right, any expert opinion?

Ryssen 25th September 2009 07:41 PM

Quote:

2 series 2 parallel primary seems to result in about 11:1 impedance ratio, which seems better in the ballpark.

Like this?

http://i194.photobucket.com/albums/z..._07/LL1623.jpg

What will the Primary restans be then,at 8 ohms sec.


Quote:

the grid swing is the grid drive, on top of the output swing, iirc, in this case.

which may be more than 300 V
Is that 300v Peak to peak?

jechentau 25th September 2009 07:45 PM

i guess the windings thus yes, but let someone check.
8 ohms sec. will be about 880 ohms, or 440 ohm for each tube.

so the voltage could be a bit higher, and the current a bit lower, but same story

yes, peak to peak

again, let check plz ;p

actually the windings are suboptimal, can be better arranged for wider bandwith. i think

edit: actually it seems a trade off between bandwith, or dc balance, but for best bandwidth i guess one can best put both inner coils parallel, and both outer, and place those combos in series, with the middle as center. but let check.

Ryssen 25th September 2009 08:09 PM

http://i194.photobucket.com/albums/z...7/LL1623-1.jpg


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