another email going public

[dave slagle]

not sure where this fits but here is another private discussion going public (with permisison of course)

I prefer TVC over AVC because of isolation feature of the tranny. This
might improve the ground loop in certain system. However, does it sound
better than the AVC?, it is questionable. I wish I have an opportunity to hear both.

Personally I see the use of a transformer to break ground loops the result
of poor design. Proper grounding techniques eliminate the need for fixes
later on.

I can do both, but much prefer the sound of the AVC which is why I recommend
that approach.

I also interest in a pair of Armophous SE output tranny which can fully take advantage of KR 300BXLS and possibly a pair of 1:1 IT tranny too.
I would like to produce from 15 to 18W. According to the recommended data, this would require 500V plate-cathode, 110mA plate current and -105 V grid with output impedance is about 615ohm.

The big choice you have now is what load you want to work into? I'm sure I
can come up with something that fits your needs.

I am debating whether I should use
parafeed or series feed tranny for this.

I am not a fan of parafeed, particularly for output stages. I like simple
circuits with predictable results.

Attached is the current amp I have. Currently I have a separate preamp to drive this amp. This time I want to build a three stages amp with the intent of eliminating the separate preamp.

A wise move. The more you can pair things together the less problems you
have down the line since you can control what happens between stages and prevent people from screwing things up down the line

My plan is to use 6SN7-56/27-300B or 5687-56/27-300B

I would look for something a bit beefier than the 27 to drive the 300B...

Also what's your recommendation and suggestion?

I prefer higher current drivers. So I like the 5687 as an input tube, the
triode wired 46 or 10 seems a better choice for a driver, particularly for
one of the high power 300B's.

I tried both Magnaquest parafeed tranny. One is the colbalt used in 26 preamp and one is the nickel output used in the amp above. I liked the sound of Nickel output very much. However, for some reason on the scope both of the tranny do not look very good.

Measurement is a very difficult subject. I fully encourage measuring and
reporting back on every detail of everything I do. Measurements are never
wrong, but often they are mis-interpreted.

They produces damped/ringing on the rising edge of the square wave. They also produce some hump around 55Khz. I just wonder if these are typical of the parafeed or any series output tranny.

Much more info is needed to determine the cause. If we end up working
together, I'll gladly do what I can to get you the results you desire.

dave