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Re: Dumble cathode values...


 
10/28/1999 6:06 AM
Bruce
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Re: Dumble cathode values...
I guess I was being a little elusive.  
The point I was making Ken, is the Numbles Amps seem to have more B+ delivered to the plate loads of first stage preamps then most people normally think about.  
Therefore, that current is built in.  
Personally, with a simple RC coupled 12AX7, I like to see around 190vdc to 210vdc on the plate and idling around +1.2ma or so.  
Bruce
 
10/31/1999 7:49 PM
Andy Fuchs
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Nobody "owns" any values. A designer decides what gives him the sonic or electrical objective he desires. "Randall the Vandal" (my reason for the name is obvious) borrowed (or stole) almost everything he did from the Fenders he started out modifying. The values are clearly listed in the RCA manuals. Yes, Edison stole this whole light concept from the sun....a
 
11/1/1999 3:01 AM
Aaron V.
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Actually, Edison 'bought' his light idea.  
Henry Woodward (a Canadian med student) patented the first incandescent electric bulb/lamp. A little bit later he sold part of the patent to Edison, who refined it to make it much more effecient.  
Just a bit of histroy :)  
 
Aaron V.
 
10/28/1999 11:09 AM
Steve A.
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Trace:  
 
    I believe that some of the amps you mentioned aren't using a 12AX7 for the preamp tubes (which would explain some of the oddball values you find in the Pittman book). If you think 3k3 is high take a look at the Marshall MV preamp on this site: it uses an Rk of 10k on the second stage. Dennis Kager also used a 10k cathode resistor for the second stage bypassed with a 0.047uF cap on his Pignose G40V (talk about bright... the amp would tear your ears off if it wasn't for the .001uF cap to ground on the wiper of the treble pot.)  
 
    FWIW I tried putting in a 10k pot in series with a 820R cathode resistor for this stage in my original Pro Maniac project last year. I was expecting some big changes as I'd adjust the pot, but the differences were pretty subtle. I did notice that if the 0.047uF Ck cap was used with an Rk setting of ~2k2 or less, the signal would cut off very abruptly as it decayed. With a larger Ck cap (0.68uF or 1.0uF) it sounded pretty good with the Rk set over maybe 9k or under 2k7 (the middle range between 3k and 9k was nothing to write home about). BTW I believe that a plate resistor of 100k was used, with maybe 290vdc coming from the power supply and around 180vdc right on the plate.  
 
    According to the notes of our anonymous correspondent the Dumble amps supply a higher B+ to the preamp tubes than a typical modern high-gain amp (270vdc to 300vdc), but much less than a BF XXX Reverb amp (high 300's to low 400's). The first two stages have 206-209vdc on their plates while the two OD stages are running a bit higher at 227-229vdc.  
 
Thanks!  
 
Steve Ahola  
 
P.S. So you think that EVH was influenced by EC just as SRV was influenced by Albert King? "C'mon, Eddie, play some blues! Play some blues!" IMHO EVH was more influenced by guitarists like Harvey Mandel who quite possibly invented the fretboard tapping techiques used by the later guitarists like EVH and Yngie. I even hear a connection between EVH and Paul Kossoff or the guy in Bad Company, but not with EC...
 
10/28/1999 12:10 PM
jason
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quote:
"P.S. So you think that EVH was influenced by EC just as SRV was influenced by Albert King? "C'mon, Eddie, play some blues! Play some blues!" "
 
On VH1 they did a show called guitar gods and in speaking with Eddie he said Clapton was the only guitarist that did anything for him.(of course you know Eddie and his interviews!)  
jason
 
10/28/1999 1:24 PM
GFR
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Altough in most of his interviews EVH says Clapton is his main influence, I have one interview where he says it's Jimmy Page (that makes a lot more sense).  
 
And I hear a lot more of Freddie King in Clapton's playing than Albert King.
 
10/28/1999 6:27 PM
Steve A.
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GFR:  
 
And I hear a lot more of Freddie King in Clapton's playing than Albert King.  
 
    Definitely! Except for his AK "quotes" (like on "Strange Brew"), Freddy/Freddie was The King to EC. (It was "Freddy" on the King albums before 1966 but "Freddie" on and after his first record on Cotillion.)  
 
    If you like the blues he played with John Mayall (like on "Raw Blues"), you ought to check out Matt Murphy's work with Memphis Slim in the 50's (they recorded the original version of "Steppin' Out"). Sounds a lot like EC backing up the blues giants visiting England.  
 
    As for EVH, I was thinking more about his playing style and techniques, but I'm sure that he was quite impressed with EC when he was growing up (you know, learning the basics like trashing hotel rooms and blowing up guitar amps).  
 
Thanks!  
 
Steve Ahola
 
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