On Sun, 23 Feb 2025 23:30:41 +0000, TTman <kraken.sankey@gmail.com>
wrote:

Can anyone explain why the best ones seem to use germanium transtors, (
and 'matched pairs' at that)? Why not a simple op amp with back to back >diodes? Any circuits?

I designed the signal path for the Ryder amps.

https://www.thegearpage.net/board/index.php?threads/ryder-amps-cabs-from-the60s.663614/

They were named for a co-worker, Frank Ryder, who was also a small
plane aerobatic instructor. The only time I ever got close to motion
sick was after an hour flying with him.

The Ryder amp had a path that used a tracking diode clipper followed
by a diferentiator. They called it "bell tone", not fuzz. It had a
"long sustain", whatever that means.

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On 2/23/2025 7:04 PM, john larkin wrote:

On Sun, 23 Feb 2025 23:30:41 +0000, TTman <kraken.sankey@gmail.com>
wrote:

Can anyone explain why the best ones seem to use germanium transtors, (
and 'matched pairs' at that)? Why not a simple op amp with back to back
diodes? Any circuits?

I designed the signal path for the Ryder amps.

https://www.thegearpage.net/board/index.php?threads/ryder-amps-cabs-from-the60s.663614/

They were named for a co-worker, Frank Ryder, who was also a small
plane aerobatic instructor. The only time I ever got close to motion
sick was after an hour flying with him.

The Ryder amp had a path that used a tracking diode clipper followed
by a diferentiator. They called it "bell tone", not fuzz. It had a
"long sustain", whatever that means.

As a long-time guitarist my impression is that guitarists tend to be a
pretty conservative bunch, and often the reason for something being
considered "the best" tends to be because that's the way the classic
pedals were and those were the products that the great names of history
used.

Certain signal paths and devices are sacred, like communion wafers.

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In article <vpgb31$n7q8$1@dont-email.me>,
TTman <kraken.sankey@gmail.com> wrote:

Can anyone explain why the best ones seem to use germanium transtors, (
and 'matched pairs' at that)? Why not a simple op amp with back to back >diodes? Any circuits?

I suspect it's a combination of several factors. What follows is
speculation, not gospel :-)

As others have suggested: history and tradition. Musicians in the early solid-state era found germanium-based circuits which produced a pleasing
sound, the sound became popular, and other musicians who wish to adopt that sound find it easiest to simply reproduce the original circuits.

Voltage compatibility. Germanium has a lower transition voltage than
silicon (roughly 200 millivolts vs roughly 650). It's possible (I
speculate) that some early fuzz circuits were being used with
instrument pickups with low output voltages and no preamps... and they
wouldn't fuzz or clip if they had been built with silicon transistors
because the input signal levels were too low for that. (I once built
a passive fuzz-box for a classmate, using a simple anti-parallel
diode pair. Didn't work worth a darned.)

Switch-on behavior. I looked at some measurements that had been taken
of different varieties of germanium diode, and there's quite a
variation in the current-vs.voltage curves. Some "switch on" rather
more gradually than others... while today's silicon-based diodes tend
to switch on quite rapidly (a near-"ideal" curve). I don't know how
much of the variation in the behavior of the germanium devices is due
to variations in the diode structure itself, and how much is due to a relatively high series resistance. In either case, in many circuits, a slow-to-turn-on germanium device would tend to clip the signal more
gradually as the signal level rises, and thus would tend to have a
different balance of fundamental and odd-harmonic frequencies than a faster-switching device. This might give the musician more delicate
control over the amount of clipping/fuzzing being applied, compared to
a fast-switching diode/transistor which would clip quite abruptly when
the threshold signal level was reached.

If I recall correctly, germanium diodes (and transistor junctions)
are relatively "leaky" by modern standards, and both reverse and
forward leakage might affect the sound that they impress on a signal
going through them, I suppose. It'd probably depend on the circuit
in which they're used.

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On Sun, 23 Feb 2025 23:30:41 +0000, TTman <kraken.sankey@gmail.com>
wrote:

Can anyone explain why the best ones seem to use germanium transtors, (
and 'matched pairs' at that)? Why not a simple op amp with back to back >diodes? Any circuits?

This doesn't answer your question, but might offer a vague example of
the differences in the sound (distortion) produced by Ge vs Si
transistors:

"Arbiter Fuzz Face"
<https://fuzzcentral.ssguitar.com/fuzzface.php>
"They do sound different from the original Germanium versions, usually
with a more harsh and aggressive clipping as opposed to the "soft"
clipping characteristics of Germanium."

My guess(tm) is "harsh and aggressive clipping" translates into more
high order harmonics for Si. On an oscilloscope, that would look like
a rounding of the sharp corners of any fast risetime waveforms.

A few decades ago (about 1967?), I would try to repair almost anything
for anyone who walked (or crawled) into the shop. I don't recall the
maker or model of the fuzz pedal but it looked something like this: <https://reverb.com/item/84878514-vintage-60s-70s-jen-fuzz-tone-bender-guitar-pedal>
Notice the $2,200 asking price. The basic problem was that all the
knobs and potentiometers were bashed in by gorilla with a very heavy
foot. Oddly, the switch survived. After replacing the knobs and
pots, I found that the Ge input transistor was blown. I couldn't find replacement in Ge, so I substituted a Si transistor. The owner paid
me but soon claiming that it didn't sound right. I soon found a Ge
transistor. I couldn't hear the difference but the owner claimed that
the Ge transistor sounded "better", whatever that means.

As for using an op amp and diode clipper, it's possible. However, my
guess(tm) is that the typical buyer is trying to imitate the sounds
produced by the name brand players. It's quite easy to produce a
linear and low distortion device using modern components. Reproducing
the strange noises and non-optimal sounds belched by a device full of sub-optimal components, is actually quite difficult. For example, how
does one design something that has the proper "presence" and
"ambience"?

Note that some of the effects projects at:
<https://fuzzcentral.ssguitar.com>
use op amps and back to back diodes (usually Ge). You might try
building one of those.

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

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On Mon, 24 Feb 2025 09:39:58 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

My guess(tm) is "harsh and aggressive clipping" translates into more
high order harmonics for Si. On an oscilloscope, that would look like
a rounding of the sharp corners of any fast risetime waveforms.

Oops. That should be:

My guess(tm) is "harsh and aggressive clipping" translates into more
high order harmonics for Si. On an oscilloscope, that would look like
a sharpening of the corners of any fast risetime waveforms.
~~~~~~~~~~

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

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On Sun, 23 Feb 2025 16:04:47 -0800, john larkin <JL@gct.com> wrote:

On Sun, 23 Feb 2025 23:30:41 +0000, TTman <kraken.sankey@gmail.com>
wrote:

Can anyone explain why the best ones seem to use germanium transtors, (
and 'matched pairs' at that)? Why not a simple op amp with back to back >>diodes? Any circuits?

I designed the signal path for the Ryder amps.

https://www.thegearpage.net/board/index.php?threads/ryder-amps-cabs-from-the60s.663614/

They were named for a co-worker, Frank Ryder, who was also a small
plane aerobatic instructor. The only time I ever got close to motion
sick was after an hour flying with him.

The Ryder amp had a path that used a tracking diode clipper followed
by a diferentiator. They called it "bell tone", not fuzz. It had a
"long sustain", whatever that means.

Low damping, so the tone dies away slowly.

Joe G

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On 2/24/25 02:19, bitrex wrote:

On 2/23/2025 7:04 PM, john larkin wrote:

On Sun, 23 Feb 2025 23:30:41 +0000, TTman <kraken.sankey@gmail.com>
wrote:

Can anyone explain why the best ones seem to use germanium transtors, (
and 'matched pairs' at that)? Why not a simple op amp with back to back
diodes? Any circuits?

I designed the signal path for the Ryder amps.

https://www.thegearpage.net/board/index.php?threads/ryder-amps-cabs-from-the60s.663614/

They were named for a co-worker, Frank Ryder, who was also a small
plane aerobatic instructor. The only time I ever got close to motion
sick was after an hour flying with him.

The Ryder amp had a path that used a tracking diode clipper followed
by a diferentiator. They called it "bell tone", not fuzz. It had a
"long sustain", whatever that means.

As a long-time guitarist my impression is that guitarists tend to be a
pretty conservative bunch, and often the reason for something being considered "the best" tends to be because that's the way the classic
pedals were and those were the products that the great names of history
used.

Certain signal paths and devices are sacred, like communion wafers.

yeh, things like new old stock silk wound wire done by naked virgins
under moonlight in the amazon jungle delivered wrapped in tweed and then twisted in a certain way named after some guy that did it 50 years ago,
is the way to really get the right "tone"

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