Recent Posts

41

Tube Amp Building - Tweaks - Repairs / Re: Can you tell the the frequency of a tone control is by it's resistors and caps ?

« Last post by tubeswell on December 06, 2025, 01:44:21 pm »

Basic formula for simple low-pass or high-pass tone filter:

 f = 1/(2Pi x R x C)

Where:
f is the frequency cutoff point in Hertz (at -6dB per octave)
R is resistance (in Ohms)
C is capacitance (in Farads*)
Pi is 22/7 (so 2Pi is 44/7)

*i.e., 100nF (aka 0.1uF) = 0.0000001F, 10nF (aka 0.01uF) = 0.00000001F and so on


For more elaborate circuits, use a combination of the above with voltage division and summed bode plots. (Merlin’s books are excellent for instruction on this.)

42

Tube Amp Building - Tweaks - Repairs / Re: Please do not use VPN's

« Last post by shooter on December 06, 2025, 01:42:34 pm »

2FA and voice recognition are the new hacker go-to's.  they can clone your voice and grab your 27/7 gazing-glass tracker "ID" for even more ways to exploit!

43

Tube Amp Building - Tweaks - Repairs / Re: Please do not use VPN's

« Last post by EL34 on December 06, 2025, 12:50:43 pm »

Nothing stops spammers and hackers from trying to register

They don't get past me 99.9% of the time

I can't tell what I do to investigate them and 2FA cannot do what I d.
SMF is the forum software and it does not offer that

44

Cabinets-Speakers / Advice on 12" speaker installation into closed box

« Last post by Khristophorous on December 06, 2025, 12:47:51 pm »

I really liked the ideas of using T nuts as that would give me the ability to swap the speaker out easily if I ever wanted to but once I got the speaker (Celestion V) and did a dry fit it looks like the distance from center to edge is about 8mm. That would be fine if I just use wood screws - but I am afraid the flange of the T nut, and therefor the spike would be setting right on the edge. I am really wanting to move on from this project and just play my damn guitar so I am real close to just using plain wood screws but I thought I would come make a post and see if anything came of it before I made a decision. Also, would white polyethylene foam be a good candidate for a DIY gasket? Thanks

45

Tube Amp Building - Tweaks - Repairs / Re: Can you tell the the frequency of a tone control is by it's resistors and caps ?

« Last post by pbman1953 on December 06, 2025, 12:45:34 pm »

The caps in the bass circuit are .1 & .047


While in the Fender tab, and based on the default caps in the calculator, where do you read the centered frequency?

46

Tube Amp Building - Tweaks - Repairs / Re: Please do not use VPN's

« Last post by tristanc on December 06, 2025, 12:42:19 pm »

How about implementing 2FA? I know it’s a constant arms race, irrespective of politics etc, to keep bad actors (and content) out.

47

Tube Amp Building - Tweaks - Repairs / Re: I think I had an idea for a "new PPIMV" that represent a Constant Load for PI

« Last post by kagliostro on December 06, 2025, 11:01:30 am »

For that use the pot must be Linear, not Logaritmic

Franco

48

Tube Amp Building - Tweaks - Repairs / Re: Testing Bad Filter Cap with a scope for 120HZ hum

« Last post by shooter on December 06, 2025, 10:55:44 am »

https://el34world.com/Forum/index.php?topic=32980.msg368863#new


both of you are probably chasing the same gremlin but from different mothers 

49

Tube Amp Building - Tweaks - Repairs / Re: I think I had an idea for a "new PPIMV" that represent a Constant Load for PI

« Last post by acheld on December 06, 2025, 10:22:18 am »

I like the idea but am skeptical that the pots would be so precise.   But maybe they are.  I guess linear pots would be close enough.

Interesting!  Let us know how that works . . .

50

Tube Amp Building - Tweaks - Repairs / Re: Please do not use VPN's

« Last post by acheld on December 06, 2025, 10:17:58 am »

Thanks for sharing that info.  Helps put things in perspective.