FLEA PPP, all ecc99

[tinitus]

I would like to ask if this can be made work
am I on track, or complete wrong

its 3x eccc99 in total
output ecc99 have each half in paralel

[aardvarkash10]

I don't think it will as drawn. You appear to have the output pairs wired to oppose each other...
For what I think you want you need to apply a bias voltage to the interstages and have both outputs on either phase connected to the same end of each interstage.

Bah - i'll draw it - it'll be quicker and clearer!

Crap drawing I know - inside the hatched area is an inverted repeat of the image shown...

[djn]

It sort of looks like an OTL. If you are going to use that many tubes, you might want to look at Tim Mellow's 25W OTL.

[tinitus]

Originally Posted by djn

It sort of looks like an OTL. If you are going to use that many tubes, you might want to look at Tim Mellow's 25W OTL.

hey, its only 3 tubes in total
you might call it ecc99 driving ecc99, PPP

Im trying to understand how it works
it may show that I dont

addvarkash
yeah, I think I made a mistake with interstage PP to PP
the two "out" to grids should be to PP output stage, and not to two paralel output
will try to redraw

[aardvarkash10]

you could simplify further. The ltp front end is superfluous. Both ITs can be driven from the same single anode as long as their secondary winding directions are opposed.

The cathode resistors in the outputs are also superfluous - bias should be set by applying a voltage to the IT secondary windings.

[planet10]

Could you not make it simplier yet by using a single interstage with a centre tap to feed the bias into?

dave

[aardvarkash10]

shure kould! I just figured the op was working with stuff they have...

[tinitus]

great info

Dave, I suppose it actually works the way you suggest, I just didnt know how to show ground connect
it is one single interstage trafo, PP to PP
but it could aslo be ordered SE to PP

http://www.lundahl.se/pdfs/datash/1660s.pdf

I will try and redraw with SE driver

aardvarkash
if starting from scratch, there would be better ways, other tubes, etc
thats what you were thinking, right
well, it is a triode driver
shouldnt have had any additional driver, from beginning
dont know why I chose to
maybe because something I read about odd order cancelling

also thought about dedicating it to a horn compression driver

possible 3kohm OPT http://www.lundahl.se/pdfs/datash/1664.pdf

[aardvarkash10]

hi tinitus - no - I haven't even looked into whether the schemo is actually feasible with the chosen tubes - that's your baby!

My way, you end up with one less ecc99 being used (the input ecc99 is shared between the two channels, one triode each).

The IT is already intended for phase splitting, so it seems superfluous to do it twice.

THe bias would usually be applied at the centre tap of the IT's secondary as Dave points out. You gain performance as there is no voltage loss across the cathode resistors since they are not there.

[Looneytunes]

Originally Posted by aardvarkash10

The IT is already intended for phase splitting, so it seems superfluous to do it twice.

If the IT is doing the phase splitting, is there any advantage to moving the IT to the input, before the first tube? (I've seen this on other designs.) Any disadvantages?

Looney