Well this changes things This output transformer has a slightly different spec from the OT I pulled from a very similar Wollensak tape player and used in another amp. You can design a true class A single-ended or push-pull amplifier. As-built schematic with voltages. No, it is not a clipping circuit. So I don’t think it’s a ground loop this time. Snfoilhat , Apr 7, After the amp is checked out to make sure all is working as designed, then you test it into a speaker, using the most important pieces of test gear of all – your guitar and your ears!

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The overall gain is set by the ratio of the plate load resistor in conjunction with the internal plate resistance of the tube and the value of the cathode resistor. This, in conjunction with the usual 50uF filter cap, which has a reactance of Contrary to some attenuator manufacturer’s claims, there is no way to make an “automatic” impedance matching attenuator, or a folloower all” product. Are these safe to use with my Sabre?

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

This is because the plate dissipation is dependent on the average signal at the plate, along with the plate voltage, idle bias current, and plate load impedance.

At dB, the impedance is 15 ohms for a 16 ohm cab, 14 ohms for an 8 ohm cab, and 13 ohms for a 4 ohm cab.

Jeff GehringMay 28, The ‘wet’ channel is broken in at least 2 ways 1. Clashing folloqer tank I get reverb, but even at 10 on the reverb recovery, there isn’t enough gain. Can you speak a bit about grounding rules? You can use a load-line superimposed on the characteristics of the tube to determine the max plate voltage, idle current, and load impedance that will allow you to bias the tube to the optimum class A operating point.


The “driver” tube, or phase inverter as it is more appropriately known, is under no more stress than any of the other preamp tubes. Who are your favorite guitarists? Also thinking of changing the amp circuit. Then install folloqer power tubes.

I made a despairingly bad laptop webcam recording a little earlier, so maybe I can clean that up in Audacity, else I’ll have to record audio again sometime soon. That’s why it is a bad idea. SnfoilhatMay 6, As the note decays, the signal level decreases, and the midrange frequencies start getting “unclipped” either by the fact that their frequency band level is lower, or by phase cancellations due to the unequal phase shift with respect to frequency caused by tone controls and other RC phase shifts that occur in a gain stage and show up as a “dip” in the top of the square wave, which will move back and forth along the top as the fundamental and other harmonics shift the operating point.

I have high hopes.

What kind of resistors do you recommend for power supply decoupling use? Yes, my password is: The output transformer in a single-ended amplifier must be gapped to prevent DC offset in the primary from saturating the core.

I have highlighted some areas of concern. If the damping factor is very high, the amplifier more tightly controls the speaker movement.

The Amp Garage

Silver mica or polystyrene film capacitors are the best choices. Not enough to push me to redo it No going back on the tone stack now — the ink is dry. The problem is that it gets to be too much, and you end up with too much bass and treble boost and “hangover effects” as it was called in the old days of audio, and you get a flubby, fizzy tone at high levels of attenuation.


Do you revern a shielded connection from the Reverb pot to the lower PI input?

Which is the cathode follower? | The Gear Page

We have achieved transformerless all-tube spring reverb. The way the followwr is biased and the circuit is set up determines when the tube or tubes is on. This means it does not appreciably load the previous stage it is connected to, and the very low output impedance allows it to drive low impedance loads without much signal voltage loss.

These will fill all seven tube socket cutouts in a stock PR.

Fender 6g15 Reverb unit. Cathode follower. – The Amp Garage

But a suitable series resistor could do that. A truly reassuring ‘Hey, did I leave a ground point open? Then, on the bottom half of the sine wave, the other tube is on “pulling” while the first tube is off “idle”. The low impedance output of a follower is not a guarantee that sufficient current can actually be sourced, and moreover acts much more like a voltage source than a current source.