LOOK YOU 300B Headphone Amplifier
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You are right! This is not a SRPP, just like SRPP, which is the active load, I tried the upper arm tube is connected with the output capacitance of the cathode, I found that the gain is high, but after a lot of experiments, I found the sound as in the lower arm is good, I think the main reason is because the SRPP depends on the load design, my headset 300 ohm and 300B impedance of 700 ohms, relative theory, 300B has enough ability to drive the other arm, 300B is equivalent to a resistance, equivalent to a constant current source, can broaden the frequency response. Welcome to a lot of guidance.
Curious which headphone needs the voltage gain of this circuit...
Hehe, the general people will be curious about it, mainly for several reasons,
1.Acoustic impedance of 300B is low, without direct output transformer.
2.300B plate resistance power consumption is huge, very easy to burn, use tube instead of resistance, with the optimized circuit of this kind of structure is very wonderful.
As drawn it's not an SRPP - the output needs to be taken from the "cathode" (filament) of the upper tube in the pair. Also proper pushpull operation is only achieved with a specific range of load impedance.
Have you considered a white cathode follower configuration?
Not needed! , listen to a lot of music I think it is very good! It's easy to drive a 32 ohm.
Look, this is the frequency of the output voltage value, not the specialized equipment to multimeter, we look at
Bad frequency response.
There is a lot of effective miller capacitance (12AX7 driving 300B ).
A better driver stage and dedicated output transformer would yield superior results IMO.
No I don't think so. I think the transformer loss is greater, design capacity in the appropriate capacity will have a very good frequency characteristics. You certainly did not look carefully, you should pay special attention to the voltage input, this picture shows very good very flat curve, you certainly did not pay attention to the 17KZH-20KHZ voltage input is very low, because this is a mobile phone produced by multi difference frequency as can be imagined.... , so I now explain why the power level with 300B. 300B output impedance is low, for high impedance headphones is not what, it is easy to drive, which is the main reason for using 300B,In fact, we may be more inclined to 6DJ8 tube, the use of 12AX7 is because of his high magnification, a single tube can be completely driven 300B a little problem is not! , saving the amplifier series will also benefit the sound quality! 12AX7 amplification factor is high, so the audio details will be more sensitive!
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