So it’s a twofer! Carbon film resistors are a good compromise between the low noise and excellent stability of metal film and the subjective “warmth” of carbon composition. Which applies even more to PI stages: This will cause the primary DC currents to cancel out, so you don’t get transformer saturation. This usually leads to cracking of the epoxy seal around the lead entry points, which can allow moisture into the capacitor, leading to drift and potential failure.

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If there isn’t one, install a metal shield plate on the reverv underneath the open side of the chassis. Another drawback of the post-phase inverter master volume is that it reduces the effectiveness of a presence or depth control. In a cathode-biased amplifier, the cathode is at a positive voltage, somewhere around V with respect to ground.

The cathode follower: the tech secret behind classic tube amp guitar tone? – Hughes & Kettner BLOG

May 30, I need to save them for a build that revebr cobbled from cqthode. Note that this will only work if you bias the amp into class A, because you will only be running one side, and it will clip if biased at class AB or class B. And yes, TriAmp has a cathode follower! At 7 on the dial the resistance between the lug 1 and the wiper is about 40k; between the wiper and lug 3 ground is about 10k. White has no color, but it still sounds better than black, so there.

We’ve added some “new” guys to the moderator crew. The presence of a phase inverter tube does not cathlde mean the amplifier is class AB, just as the presence of a cathode resistor doesn’t automatically mean the amplifier is class A. This is not a problem that is unique to PC boards, as some “gurus” would have you believe. It gets a bit shaky when you are dealing with push-pull, which uses tubes in pairs deverb quartets, or more, always in multiples of twoor single-ended, which uses one tube or more, but they are in parallel with the first one, not in push-pull.


Still working on preamp layout. Triode mode, with its higher damping factor, makes the amplifier less responsive to speaker changes, so it sounds vollower a bit less “tubey”, and also lowers the power output.

It can help certain tubes survive longer in CF stages.

So I removed the 7-pin sockets at V6 and V7 and installed octals. That’s very close, minus the reverb path, to my Hammond special.

A zener diode is simply a diode that has a designed-in “breakdown” reverse voltage that is fairly tightly controlled. The Gear Page is run by musicians for musicians.

However, the problem is that people associate “gain stages” with, well If you run into a reactive load, you can’t easily see how much power the amp is putting out, because you have to take into account the frequency-dependent impedance of the reactive load, and there is a cosine of the phase angle to be taken into consideration to calculate revrrb real power. Electrolytic capacitor life fo,lower not infinite.

Is is a clipping circuit? Classic tube tone, cooked up with the finest ingredients and the tastiest traditional recipes, all xathode to go right out of the box: The distortion is less than in class B, but more than in class A. You can see by the thin crescents of white on my control cutouts that the rear plate shifted slightly while clamping. I must be getting old – that’s what ctahode father said about the music I like!.


This will cause the primary DC currents to cancel out, so you don’t get transformer saturation. You probably have your favorite Master volume circuit, but wired as you have shown, I’d probably use nF to couple to preserve bass at lower volume settings. At any rate, it is always a good idea to check the operating conditions of the tube circuit on a scope to make sure things aren’t getting out of hand.

Cathode-follower clipping plus Valvewizard’s cheap current source reverb driver amp

Another factor in amplifier damage from attenuator use is when the amp is run into an attenuator that is not properly impedance matched to the amplifier.

Apparent loudness is a different subject entirely, and depends on a lot of factors. The Matchless reverb does work fine, so yes, you will probably have to cascade the recovery stages.

Open-circuit voltages are always higher than loaded secondary windings.