Systemic Development > Amplification and Preamplification

Check out this tube collection

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ejk:

https://www.youtube.com/watch?v=VFHP_zvgaoc

rollo:
Still prefer a SET with Matched tubes. Hits ya right in the Soul.

charles

ejk:

--- Quote from: rollo on December 10, 2022, 08:35:35 AM ---Still prefer a SET with Matched tubes. Hits ya right in the Soul.

charles

--- End quote ---

So why the Warp 1?

Nick B:

--- Quote from: ejk on December 10, 2022, 01:52:10 AM ---
https://www.youtube.com/watch?v=VFHP_zvgaoc

--- End quote ---

Good video. I like watching Mikey…

steve:
I saw the video and wondered if I should address all the misinformation the author has posted.
I will probably be called the bad guy by some, but please read below for the scale of his nonsense.

The author's push pull (PP) description shows his virtual complete lack of understanding of electronics. His
description is for Class C, or B at the very least, Not class AB1 or class A in any sense.

He says half the signal is for one output tube and the other half of the signal for the other half of the
tube. Let's call the two output tubes X and Y.

He also states a gap in the signal between X and Y output tubes, and also notch distortion. (I hope he changes his video or deletes it.)

If his statements were true, by definition there would be no idle current for each tube. Class B is for slightly more than zero idle current, say 5ma to 10ma.

Class C is for well past cutoff, so obviously no idle current. Class C is
generally relegated to RF and industrial concerns, and certainly Not for even PA
audio systems, let alone any sort of high fidelity.

Class AB1 and A both utilize significant idle current by definition. Generally,
in AB1, output tubes run 1/2 to 3/4th of their plate dissipation at idle. 50-75ma
is typical for normal output tubes such as 6550s, KT88s, 300Bs. Smaller output
tubes will have less idle current.

Let's use 65 ma for each pentode output tube since those are readily published.
That means both output tubes X and Y run class A until each tube reaches their respective cutoff point, 0 ma.

That means a peak swing for each X and Y, is from 65ma to zero ma, and 65ma to 130ma.
That is 0 ma to 130 ma peak to peak, or the whole signal, thus class A. (A 6L6 is 60ma or so idle current.)

As such the output for a PP pentode stage is listed as 17.5 watts rms for class A1 operation at ~270 plate volts,
PP plate load of 5000 ohms.

Wired as a triode, the 6L6GC runs about half the output power, let's say only 5 watts
output rms just to be safe.

Most speakers are sensitive enough to peak into the 90s db spl on 5 watts rms
Class A power.

But even at a ridiculous 1 watt rms output, many speakers would be running
from middle 80s db to lower 90s db, or higher peak spl. There is no gap
between X and Y tubes as the author falsely claims.

Knowledge is power to decipher real science from hogwash.

There are several/many inherent problems with any SET amplifier by definition,
whether DHT, IDHT, or Solid State. That is for another topic.

I do like how virtually all vacuum tubes look, especially lit up.

cheers

pos

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