I like the look of the impedance curve of this model
https://www.lii-audio.com/product/o...total-full-range-and-exquisite-sound-fast-10/
That is something to keep your eye on when deciding. Of course listening is paramount but when that isn't possible a flat impedance curve will let a tube amp sound its best.
L1... L4 is an interstage push-pull transformer. They are connected by the K statement.
Bear with me here... So its coupled thru this transformer. The L1 and L2 being driven by the first stage are driving L3 and L4 to provide input to the output stage. Is this correct?
Will add this - EL84 PP amp with 89dB effficient speakers was dead silent.
The same amp with 96dB eff. speakers - I can hear its noise floor easily with ear in the big 12" wide mid horn.
kmtang,
What a genius circuit!
Correct me if I am wrong, please.
I could not expand your schematic in Post #55, therefore my analysis of your circuit may be wrong.
It looks like you are sending an unbalanced signal to:
A CCS and parallel cathode coupled phase inverter/driver input stage, which inverts the signal and applies it to the push pull primary of an interstage transformer.
The interstage transformer secondary is connected in phase, to provide an unbalanced signal to the 300B grid.
The advantages of your circuit are:
The interstage transformer has balanced current in the primary, so the laminations do not need an air-gap (less turns, smaller wire length, less laminations, and tighter primary to secondary coupling).
The input stage CCS and cathode coupled circuit reduces the 2nd Harmonic Distortion (at least partially cancels the 2nd HD).
Since the 2nd harmonic distortion has been reduced, there is very little interaction between the driver's low 2nd harmonic distortion with the very 300B's very moderate 2nd harmonic distortion.
This seems like a real good way to get that single ended sound!
Was this your purpose?
To avoid the large reduction of the total 2nd harmonic distortion.
In a practical way, the only 2nd harmonic distortion that is heard is from the 300B.
Correct?
If I somehow understood your topology,
Then I would be interested to know how many other readers noticed or understood your very interesting design.
Readers, speak up please!
It is a Mean thing to say that Karl Friedrich Gauss was an Average man, who was Centered on his Gaussian Curve.
What a genius circuit!
Correct me if I am wrong, please.
I could not expand your schematic in Post #55, therefore my analysis of your circuit may be wrong.
It looks like you are sending an unbalanced signal to:
A CCS and parallel cathode coupled phase inverter/driver input stage, which inverts the signal and applies it to the push pull primary of an interstage transformer.
The interstage transformer secondary is connected in phase, to provide an unbalanced signal to the 300B grid.
The advantages of your circuit are:
The interstage transformer has balanced current in the primary, so the laminations do not need an air-gap (less turns, smaller wire length, less laminations, and tighter primary to secondary coupling).
The input stage CCS and cathode coupled circuit reduces the 2nd Harmonic Distortion (at least partially cancels the 2nd HD).
Since the 2nd harmonic distortion has been reduced, there is very little interaction between the driver's low 2nd harmonic distortion with the very 300B's very moderate 2nd harmonic distortion.
This seems like a real good way to get that single ended sound!
Was this your purpose?
To avoid the large reduction of the total 2nd harmonic distortion.
In a practical way, the only 2nd harmonic distortion that is heard is from the 300B.
Correct?
If I somehow understood your topology,
Then I would be interested to know how many other readers noticed or understood your very interesting design.
Readers, speak up please!
It is a Mean thing to say that Karl Friedrich Gauss was an Average man, who was Centered on his Gaussian Curve.
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Hello 6A3summer,
Yes, your understanding is correct. Thanks for your detailed explanation of the circuit. In fact, the driver stage can be switched for either RCA or balance in. The driver stage gain is reduced by half with RCA in. A line input transformer can be used to convert the RCA input to balance. Also, we can use either 1:4 or 1:5 transformer if extra gain is required.
The PP driver stage provides exceptional low harmonics for both evens and odds. I am so surprised that the amp sounds so good from this PP=>SE amp. The friends were amazed how nice it is.
Johnny
Yes, your understanding is correct. Thanks for your detailed explanation of the circuit. In fact, the driver stage can be switched for either RCA or balance in. The driver stage gain is reduced by half with RCA in. A line input transformer can be used to convert the RCA input to balance. Also, we can use either 1:4 or 1:5 transformer if extra gain is required.
The PP driver stage provides exceptional low harmonics for both evens and odds. I am so surprised that the amp sounds so good from this PP=>SE amp. The friends were amazed how nice it is.
Johnny
