Cathode Follower Push Pull

[Mr. Moscode]

Another option is to use bigger tubes and turn the transformer around if driving 10K. 6FQ7s would be the next step up, or use 2 and parallel the triodes. Bigger tubes with bigger output caps and you can get rid of the xfmer.

It's getting more complicated. Generally less is more. 1/2 the parts count, no phase splitter, half the mucking up of the signal.
IMHO, balanced drive's biggest virtue is noise immunity, used primarily in studios and to drive twisted pair telephone lines. Today it's important now, with dimmers, smps, and led lights being annoyingly noisy.

I'm building a analogue constant current controllers to run my ceiling puck lights so I my radios can work indoors. Less efficient, 100% quiet.

 

[solkatten]

Is this a sane solution? To have long tailed pair that gets a balanced input to be loaded by a PP anode choke. T o swing high voltage for PP CF stage. Yoy may need elevates heathers. A anode choke is expensive, but you could use any center tapped primary from OPT or you can even put half the primary and half the secondary in serie to achive larger Henry. A 6n6p doesnt need **** load of henrys to function....

 

[abbey road d enfer]

Do you mean for driving the cath folloxer?
It's a solution, but costly. If you want to have the full output swing, there is no easy solution.
Another is using an insterstage xfmr, with the secondaries driving directly the output tubes between cath and grid.

 

[solkatten]

Yep I mean to drive the cathode follower I think the primary inductances of my cheap edcores 5CT:1 is 90H+90H . That should be enough for 6n6p long tailed pair.

 

[solkatten]

Because its PP it dont have to gapped so many cheap OPT would do

 

[solkatten]

You could use pri and sec in series

 

[Mr. Moscode]

Is there a goal for this project?
How's the frequency response and phase shift vs frequency so far?

 

[solkatten]

I have not build it yet. I think I will start with 6n1p concertina driving 6n6p PP cathode follower stage. Input will be standard SE varible gainstage. It would be fun to se how much better freq response and THD gets, when the transformer is driven by the cathode…

 

[Mr. Moscode]

Forgive my ignorance but what's a concertina?
How are you accomplishing variable gain? Input attenuator? Variable NFB?

 

[solkatten]

Look at the 6n1p tube in post 27 its concertin a phase inverter without gain. Varible negative feedback is the classic mic preamp input stage arrangment

 

[abbey road d enfer]

You could use pri and sec in series

90H results in 11kohms at 20Hz. No need for series connection, particularly because of coupling, each winding is seen as 180H by the tube.

 

[abbey road d enfer]

Forgive my ignorance but what's a concertina?

Concertina is an alternative name for cathodyne. The name comes from the fact that the plate and cathode are moving in opposite directions, like the bellows of an accordion. The concertina is a variant of the accordion.

 

[Mr. Moscode]

Concertina is an alternative name for cathodyne. The name comes from the fact that the plate and cathode are moving in opposite directions, like the bellows of an accordion. The concertina is a variant of the accordion.

Thanks. Is that a European term? I like phase splitter.

RE: Variable gain preamps done with variable feed back. Maybe in the musical instrument world using 1 instrument it's cool but my experience with that scheme for hi end stereos is it changes the feel of the audio signal. Depth of the soundstage, low level detail like reverb tails and room ambience are affected to my ears. The greater the NFB the greater the loss of what I've mentioned. The less NFB, the more open the sound is.
IMHO.

 

[Somkereki]

Concertina is an alternative name for cathodyne. The name comes from the fact that the plate and cathode are moving in opposite directions, like the bellows of an accordion. The concertina is a variant of the accordion.

Thank you! I didn't know this name either!

 

[abbey road d enfer]

Thanks. Is that a European term?

I believe it is, but not everywhere in Europe. I see the term in posts from Germany/Austria, Scandinavia and some Eastern Europe countries. In France and UK it's quite unusual.

I like phase splitter

I believe phase-splitter and phase-inverter are generic terms that do not belong to a specific topology.
The two most common PI's are usually referred to as cathodyne or long tail.

 

[Mr. Moscode]

I believe it is, but not everywhere in Europe. I see the term in posts from Germany/Austria, Scandinavia and some Eastern Europe countries. In France and UK it's quite unusual.

I believe phase-splitter and phase-inverter are generic terms that do not belong to a specific topology.
The two most common PI's are usually referred to as cathodyne or long tail.

Long tail is a diff amp with the cathodes' resistor going to a fairly large negative voltage so you can get a high impedance. You can also use a solid state current source to ground in place of the long tail and avoid the high neg voltage.

 

[merlin]

Is this a sane solution? To have long tailed pair that gets a balanced input to be loaded by a PP anode choke. T o swing high voltage for PP CF stage. Yoy may need elevates heathers. A anode choke is expensive, but you could use any center tapped primary from OPT or you can even put half the primary and half the secondary in serie to achive larger Henry. A 6n6p doesnt need **** load of henrys to function....

It would work, but expensive. Most people go the cheaper route of bootstrapping, or using voltage doubler power supply and running the driver stage off twice the HT voltage.

 

[solkatten]

It would work, but expensive. Most people go the cheaper route of bootstrapping, or using voltage doubler power supply and running the driver stage off twice the HT voltage.

I think I will go that route. The PP cathode follower at 150 Vdc and the PI at 300 Vdc. Also the tube before the PI have to be able to swing the full signal.

 

[abbey road d enfer]

I think I will go that route. The PP cathode follower at 150 Vdc and the PI at 300 Vdc. Also the tube before the PI have to be able to swing the full signal.

Depends of the type of PI. LTP has gain and can swing a large part of B+. Cathodyne would need 600v B+ at least.

 

[solkatten]

Depends of the type of PI. LTP has gain and can swing a large part of B+. Cathodyne would need 600v B+ at least.

Yes u are right. It takes a **** load of B+ for the concertina to do its job. I have to rethink.