Yet the cathode follower produces far less distortion and a much lower output impedance than the comparable grounded-cathode amplifier does when working into the same load. For the directly heated triodes, filament supplies have long been problematical. The sonic advantages are significant, and surprisingly audible even with current source loaded voltage amplifiers. A Vdc power-supply rail, whether it be positive or negative, is one fourth as dangerous as an Vdc power supply, as we must square the voltage to determine its wallop; thus, twice the voltage, four times the wallop. I had some time to experiment with the cathode follower amp.

Uploader: Yokasa
Date Added: 28 September 2017
File Size: 48.72 Mb
Operating Systems: Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X
Downloads: 25255
Price: Free* [*Free Regsitration Required]

The PNP MJE strives to maintain a fixed Vbe voltage drop across the ohm resistor and constant current flow through the top output transistor. And yet they are frowned upon by many “High End” audio builders.

Amp Chokes, Cathode Followers, and other Maplifier Questions

The second question is the output tube working as a cathode follower or a grounded-cathode amplifier? TCJ Filter Design is easy to use, but not lightweight, holding over 60 different filter topologies and up to four filter alignments: The transformer-coupled version is also twice as efficient as the constant-current version, as an output transformer functions much like a constant-current source, but without the large wasteful voltage drop.

Well, you can use a tube rectifier for the output tube cjoke two solid-state rectifiers for the input and driver stages. In true pentode operation, grid number 2 is at a fixed voltage relative to the cathode, even when the pentode is used a cathode follower circuit. Next time We will cover resistor-loaded drivr stages. In the real world, it should be included, as the input stage is unlikely to perfectly center at Vdc.


Looking forward to building the Aikido, will send some comments when I’m done! My fear was that adding the ACF to the signal path could only subtract, not add to the signal purity. Once the grid cathodee positive relative to the cathode, the grid and cathode define a forward-biased diode and goes from not conducting to conducting heavily.

With an external load, however, the bottom output transistor, the MJE, draws a varying current, while the top transistor, the MJE, draws a fixed current. W SE amp blog part 2. Is there a known technical reason for that? Okay, let’s return to folkower original circuit. We have found that a triode- bas ed shunt regulator is better at handling this current fluctuation than the usual series regulator.

We assume that the cathode resistor receives a large-valued bypass capacitor. The frontend is a modified Aikido gain xathode, which uses two 12DW7 tubes.

OK so someone explain the difference between amps with chokes and amps that use caps instead? For indirectly heated tubes, Schottky diodes are used to eliminate the reverse recovery spike which causes the power transformer to ring ultrasonically, adding a bit of glare to the soundand an RC filter is used to reduce the charging current peak for the same reason.


If you want to use the output transformer’s primary DCR as the cathode-bias resistance, then the following variation can be used.

This solution makes a lot of sense, as the cathode follower offers a gain close to unity and a low output impedance.

:: View topic – Partial Choke Loading of Cathode Follower

The full catode phase 1 The schematic reveals a fairly simple topology. Let’s find its peak current swings. For most tube fanciers, the immediate answer is to use a cathode follower.

Looking forward to building the Aikido, will send some comments when I’m done!

Advertise on the most comprehensive and widely viewed musicians’ website. Thus, a cathode follower gain of 0. Next Time I have many, many more variations on the Triadtron.

The pulse gets magnified by the winding ratio between primary and secondary. I am sure that they sell themselves short.

Imagine that the output coupling capacitor was infinitely large in value and that the load impedance was zero ohms and that the input was grounded.

Followed sure you could charge double and still have happy customers. The resistance the output tube can offer is its plate resistance, as its cathode and grid see the same upward swing in voltage.