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  1. 6

    Bias voltage by Cap

    The JCM900 bias circuit, aka Ampeg bias circuit, is a totally different animal. The Carvin bias circuit uses the impedance of the .047uF capacitor in series with the resistance of the 100K resistor to form a voltage divider. You can get nearly the same result by replacing the .047uF capacitor...
  2. 6

    Marshall major tone question

    The cathodyne has no DC reference for its grid. The bias winding has no ground reference for its center tap. The balance resistors in the second filter stage are not connected properly.
  3. 6

    Marshall major tone question

    There are slight differences between some of the Majors, but this is the basic idea. The OT has multiple secondaries that connect to the "Christmas tree". I have never been able to convince anybody to disconnect their OT and analyze it for me, so I drew the OT with a continuous secondary.
  4. 6

    JMP 2204 NFB. Which tap?

    I'm not very well versed on Marshall differences like this, but I do know that the transconductance of EL34's and 6550's is nearly identical so that the tube type doesn't justify changing to different secondary taps. Maybe they wanted the Americans to have amps with more NFB?
  5. 6

    JMP 2204 NFB. Which tap?

    Good guess, but the NFB has to do with gain and not with maximum power. If the OT primary impedance of the 50W amp is twice as much as the primary of the 100W amp and the 50W amp has half as many of the same power tubes as the 100W amp, then the gain at the primary will be the same in both...
  6. 6

    JMP 2204 NFB. Which tap?

    This one shows it on the 4 ohm tap.
  7. 6

    Marshall MAJOR 200 REPLICA Project

    This one is more accurate. The OT secondary is shown as a continuous winding, but really it has multiple windings that are combined externally.
  8. 6

    Speaker Jack JCM800

    Unswitched mono jacks used to be readily available, but I don't know about these days. The ones in Marshalls are unmolested.
  9. 6

    Bands with 2 drummers?

    By far the easiest way for two drummers to stay in sync is to adopt linear timing. Drummers are known for taking the easy way out and for playing with non-linear timing. They seem to be more agreeable to a second drummer than to a metronome pounding them through headphones. James Brown had...
  10. 6

    Do you believe in UFOs?

    The classic Greys are biobots that are mass produced by one species of aliens. There is a larger, ugly being that is sometimes reported by abductees and that is the actual alien. Kind of like the white guy who stays in his locked vehicle while natives drug a large, mammalian carnivore. I...
  11. 6

    Do you believe in UFOs?

    You might have communism confused with totalitarianism. The two forms of government are diametrically opposed and both Stalin and Mao were ruthless, iron-fisted totalitarian dictators. Their primary motivation for killing their own citizens was to eliminate opposition. There is a connection...
  12. 6

    Do you believe in UFOs?

    For a no-nonsense, scientific examination of the Roswell incident, I would direct your attention to "Crash at Corona" by Berliner and Friedman. The interstellar police and the distances are unlikely to be publicly verified in any of our lifetimes if ever.
  13. 6

    Do you believe in UFOs?

    Really? Are you actually considering that I might be right? I have read scientific, medical, and academic journals all of my adult life and they have all steadfastly avoided the subject. I still subscribe to a couple and I would be very surprised if they ever addressed the issue.
  14. 6

    Do you believe in UFOs?

    There is an interesting human behavior that I have observed for pretty much all of my life. When they are scared, stressed, terrified, etc., their normally rational behavior disappears, facts and logic are ignored, and they crack jokes. One night at band practice I went outside and saw a UFO...
  15. 6

    Do you believe in UFOs?

    Beats me. I don't watch that kind of drivel. I did have two real-life jokers in black suits following me night and day for awhile in my younger days. They seemed to be trying to intimidate me because they made it very obvious that they were there.
  16. 6

    Do you believe in UFOs?

    An alien craft from a different planet was shot down by the interstellar police for violating interstellar law prohibiting interference in the affairs of indigenous species (us). This happens all the time, but this time the military's recovery and cover-up team was busy with another crash over...
  17. 6

    100watter 4 El34, 240VAC mains how much fuse ratings?

    The power transformer steps up voltage and steps down current in accordance with the turns ratio between the primary and the secondary. As an example, say a transformer has a 120V primary and a 400V secondary. The voltage step up is 1V:3.33V and the current step down is 3.33A:1A. 4A at the...
  18. 6

    Mojotone Effects Loop V2 sounds terrible

    Another neat feature of the Mojo loop is that it loads your tone stack with 500K when there isn't an optional trim pot. The loading is 333K to 1M with a 1M trim pot that has one leg grounded and the wiper attached to the 0.1uF input capacitor.
  19. 6

    Mojotone Effects Loop V2 sounds terrible

    A couple of strokes on a calculator will tell you what the Send circuit will do. With 250Vdc on the Drain, there will be about 125Vdc on the Source because the 1M/1M voltage divider puts 125Vdc on the Gate. 125Vdc divided by 47K equals the idle current of 2.7mA. The AC load is the 47K Source...
  20. 6

    Mojotone Effects Loop V2 sounds terrible

    Granger has a newer version that is really small. I don't know what the circuit is on the new one, but the one in the picture you attached is like this: The trim pots are a pretty good idea, but the design makes poor use of them. I like their T-shirts.

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