F6 Amplifier

[buzzforb]

You just lost me

[Antoinel]

Originally Posted by buzzforb

You just lost me

• Can the bias circuit for the bottom FET Q2 [diy F6] simultaneously bias Q2A [as in my drawing above]. Most probably yes; because this lower bias circuit is referenced to -Vcc.
• Can the secondary transformer winding for the bottom FET simultaneously present an out phase signal to the gate of Q2A [as in drawing]. Most probably yes.
• So when Q2 is progressively turned on, Q2A is simultaneously and progressively turned off. And the reverse with signal phase reversal.

The simultaneous biasing and driving of Q1 and Q1A as in my drawing above is messy and will not cut it. However, there is hope from the quadrifilar Jensen.

• Bias Q1A using its independent circuit exactly like that used for Q1.
• Borrow a winding from the Front End circuit. Connect it to Q1A exactly like that for Q1; except reverse its phase to that presented to the gate of Q1
• Now Q1A and Q2A are most probably biased and signal phased for proper operation

Best regards.

[buzzforb]

I meant about the SIM. Lets say that all the above is true. What difference do you expect in performance. What does this bring to the table to warrant the change?

[Antoinel]

Originally Posted by buzzforb

I meant about the SIM. Lets say that all the above is true. What difference do you expect in performance. What does this bring to the table to warrant the change?

buzzforb; I do not know yet the answers to your relevant questions; but I will think about them. To start, I saved a Jensen and a bias circuit, and thus simplified the circuit; but what else gives in return?. It is easy for me to scribble a schematic, fumble and redo until it sits right. It is just a suggested bridge diy F6.

[buzzforb]

I am not trying to be crtical. My rip off circuit may be a waste as well, but i do know it has a few possible advantages. Balanced input, distortion reduction. THe main concern is that you may lose some of the harmonic tweaking from the original. That is, unless is can be achieved some other way. All this is hypothetical and unproven. I will try to get to it ASAP to see what happens. I will try first with lateral( i like them), then SS, then Cree, then IRF150

[Antoinel]

Originally Posted by buzzforb

I am not trying to be crtical. My rip off circuit may be a waste as well, but i do know it has a few possible advantages. Balanced input, distortion reduction. THe main concern is that you may lose some of the harmonic tweaking from the original. That is, unless is can be achieved some other way. All this is hypothetical and unproven. I will try to get to it ASAP to see what happens. I will try first with lateral( i like them), then SS, then Cree, then IRF150

I wish I was able to read [and appreciate] the schematic of your F6 bridge amp. It was fuzzy, and did not load or expand for me. My proposed schematic is not instead of yours; but rather a general idea to masticate.

[flocchini]

Originally Posted by buzzforb

I am not trying to be crtical. My rip off circuit may be a waste as well, but i do know it has a few possible advantages. Balanced input, distortion reduction. THe main concern is that you may lose some of the harmonic tweaking from the original. That is, unless is can be achieved some other way. All this is hypothetical and unproven. I will try to get to it ASAP to see what happens. I will try first with lateral( i like them), then SS, then Cree, then IRF150

Maybe start with the non degenerated F6 - not a bad sounding amp

Best

Bob

[buzzforb]

Just a few solder joints away. This weekend hopefully.

[Antoinel]

The objective of this post is to write the subject schematic which may appear unconventional or odd. But its value lies in the process used to write it so as to make it practical. I fumbled the design in my posts above. But; I hope that the attached is logically digestible and has minimal or preferably no errors. Still it is a paper exercise; just for the fun of sharing ideas. Please note the following:

• The FETs Q1, Q1A and Q2 have independent variable bias circuits. By comparison, the bias supply for Q2A is that of Q2. The bias supply of Q2A can also be independent for added flexibility.
• The phase of the signals on the Jensen transformer windings.
• The signal for Q2A. It originates in the front end winding at P1. It is then coupled by capacitor to the gate of Q2A. Note that this signal is in phase and preferably equal in amplitude at the gate of Q2A like for the gate of Q1.

Bottom line(s). I saved an extra Jensen, and a bias circuit. No signal phase or bias violations. It is a hypothetical bridge amp; albeit unusual. It may work for all we know. I may or not build it; but I had therapeutic fun reaching this junction.

Best regards.

[vtr]

Hi,

i have all parts for my f6, i will start with the unbuffered version driven my my rtp3 preamp.

anyone tried to modify with a symmetric input?


my idea is to use positive phase of regular input and neg phase input from secondary feedback connection.

or can i use only one primary, but then i will loose 6db gain according my transformer know how?

thanks