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Big Bad Bob Big Bad Bob is offline
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Default Triode Naming Convention

On 2020-10-09 15:20, Phil Allison wrote:
FFS give up posting wild guesses as fact.


which ones?

It's not like I haven't built a bunch of guitar amps since I was a
teenager, both tubes AND transistors, nor seen a number of schematics,
nor reverse engineered a Fender amp to build a custom amp based on
Fender's circuits because someone wanted me to, nor having played guitar
since the 1960's, nor having re-worked the electronics on guitars a few
times [including putting a 5 pos switch on a Hondo strat copy that had a
3 pos switch for a friend], yotta yotta.

OK - which of the things I said were "wild guesses" ?

keep in mind that the tech manuals said something I'm agreeing with.
YOU are disagreeing with the tech manuals, and after I provide several
examples based on what I've seen (particularly for older amplifiers,
where this would be more relevant), you say that I'm "posting wild
guesses as fact".

So, since I never actually DID that, then you're welcome.

A typical old amplifier:
http://www.thevintagesound.com/ffg/s..._5c3_schem.gif

(in this case 75k - I've seen as high as 220k, but on average, input
resistors on the shared input are around 100k, which if you think about
it, isn't a whole lot different from 75k or even 68k when you average it
all out)

A typical guitar (strat):
https://wholefoodsonabudget.com/wp-c...-center-6b.jpg

https://tinyurl.com/y6dew9vv

shows volume and tone controls are 250k. I have seen as low as 50k, but
typically 100k as I recall.

This one shows 1M volume controls on the guitar:

https://wholefoodsonabudget.com/wp-c...iagram-12s.jpg

I'm sure you'll see LOTS of variability. Some old guitars [I used to
have one] even had ceramic pickups. And you also have pedal output
impedence. So the variability is pretty wide here.

My guess is that a pre-amp would be designed such that any noise
generated by an audio tube's filament would be minimized based on a very
wide range of possible inputs, single guitar, two guitars, ceramic or
dynamic pickups, 50k or 250k or 1M volume controls, etc. etc..

So if I happen to "ballpark" the values, you should be able to see why.

And I still accept what the tube spec sheet says about hum on one of the
triodes being slightly higher.