832 TWEEKS

Post by **Nick** » Fri Feb 27, 2009 5:07 pm

Yes, you could do what you are doing NOW with the c3g, but as you posted a link to the original circuit, I assumed you were talking about replacing the driver stage in that with a c3g.

pre65 · Post by **pre65** » Fri Feb 27, 2009 6:07 pm

Sorry to confuse !

This is what i am trying to achieve.

http://i111.photobucket.com/albums/n146 ... uit002.jpg

Are the 1K resistors shown by the 832a grid on the original circuit likely to be grid stoppers ?

If Shane has a 200v mains transformer then this circuit would do his project as well.

I dont know how to work out the values of resistors marked with a question mark.

shane · Post by **shane** » Fri Feb 27, 2009 6:46 pm

My transformer has 200v and 260v windings. Would there be any advantage in using 260v, and if so, what mods would be needed?

Mike H · Post by **Mike H** » Fri Feb 27, 2009 6:59 pm

Eeek, that cathodyne will have feeble output if just biased from 0V.

Needs to be more like this:

The 'gain' could be a shade over 0.9, but the input impedance can be very large.

Not sure if it will work wired as pentode either, usually only triodes are used like this. C3G could be wired as triode though I presume

.

shane · Post by **shane** » Fri Feb 27, 2009 7:05 pm

Yes, but the whole point of the exercise is that you don't have a dedicated phase splitter valve.

pre65 · Post by **pre65** » Fri Feb 27, 2009 7:09 pm

The second triode in the double triode normally fitted is the phase splitter,but as Shane says,with this common cathode, or cathode coupled phase splitter that Nick educated us about the phase splitter valve is eliminated.

Makes for a very simple circuit that seems to work !

Mike H · Post by **Mike H** » Fri Feb 27, 2009 7:26 pm

Oh I see, sorry didn't see that!

As you were then

Post by **Nick** » Fri Feb 27, 2009 8:20 pm

What value and voltages are you using for the 300b.

pre65 · Post by **pre65** » Fri Feb 27, 2009 8:45 pm

The 300b was going to be based on the circuit you drew up for Colins amp,but I now have a version from Mark using the C3m.

In essence its the same as the one used for the KT66 SET which is shown here----

http://i111.photobucket.com/albums/n146 ... uit001.jpg

but on the 832a the HT is less @ 270 V

andrew Ivimey · Post by **andrew Ivimey** » Fri Feb 27, 2009 9:30 pm

what is point?

pre65 · Post by **pre65** » Fri Feb 27, 2009 9:40 pm

andrew Ivimey wrote:what is point?

To get a better performing amp using bits to hand !

Both Shane and I have C3g and VR tubes in our spares box and we now know it works.Keep it simple stupid !! (KISS)

James D said that a VR tube with C3g improved the bass (amongst other things) and he was right.

And D-cos I can,and I want to.

More wine Vicar ?

Mike H · Post by **Mike H** » Fri Feb 27, 2009 11:27 pm

Don't mind if I do

pre65 · Post by **pre65** » Sat Feb 28, 2009 11:56 am

If necessary, i would be prepared to go to a higher HT !

The "new" version would probably be a new build rather than cannibalise the existing one.

Post by **Nick** » Sat Feb 28, 2009 12:06 pm

Try:

C3g Anode load 6k8 5W
VR150 load 7k5 5W
c3g Cathode resistor 68R

No resistor in series with 10H choke, 47uf 385v cap after choke.

pre65 · Post by **pre65** » Sat Feb 28, 2009 12:11 pm

Nick wrote:Try:

C3g Anode load 6k8 5W
VR150 load 7k5 5W
c3g Cathode resistor 68R

No resistor in series with 10H choke, 47uf 385v cap after choke.

BRILLIANT !!

Thanks Nick.

audio-talk

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