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Tech: Amp question |
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Subject: RE: Tech: Amp question From: Sandy Mc Lean Date: 01 Nov 08 - 07:40 PM or 50L6 (8 pin base with key slot.) |
Subject: RE: Tech: Amp question From: Bernard Date: 01 Nov 08 - 06:33 PM Output valves in push-pull amps were usually EL84 (15w) or EL34/KT66 (50w). The Vox AC30 used four EL84s in dual push-pull, self-biasing configuration, and the AC100 used a similar setup with four EL34s. ECC83/12AX7 were usually used as pre-amp valves, and had a tendency to go 'microphonic' - if you tapped them, you'd hear it through the loudspeaker. Quite handy for acoustic feedback... |
Subject: RE: Tech: Amp question From: Raptor Date: 01 Nov 08 - 04:52 PM Thanks folks |
Subject: RE: Tech: Amp question From: Mooh Date: 01 Nov 08 - 08:16 AM Raptor..The folks over at the Canadian Guitar Forum may have some additional expertise. www.guitarscanada.com Peace, Mooh. |
Subject: RE: Tech: Amp question From: John J Date: 01 Nov 08 - 07:41 AM It's a long time ago since I used these but I recall the 12AX7 / ECC83 as being a twin triode for low frequency (AF) applications. It wouldn't be used as an output device - not for anything other than very low power (headphone output), more likely use is in a pre-amp stage. John |
Subject: RE: Tech: Amp question From: JohnInKansas Date: 31 Oct 08 - 06:36 PM The "two tube" description suggests a pretty "primitive" amp; but the discussion at one of the links indicates later dates of production than a "just two tubes" circuit would suggest, and indicates that one of the "tubes" might be a 12AX7 which was, in fact "two tubes in one" with two separate plates and a separate and independent grid for each of the two plates, allowing the tube to function as a "two channel" or even "two stage" amp. So the "two tubes" may function as at least three gain channels/stages. Early to late 60s amps most likely would have used the two sides of a 12AX7 as a "push-pull" amplifier stage with one channel boosting the signal while it's on the "plus" side of the cycle, and the other during the "minus" side, but this arrangement usually used a center-tapped output transformer with each channel from the tube driving "one end of the wire" into the output xfmr. Note that the amp cited as using this tube may not be yours(?). A possibly pertinenent question would be whether you need/want information to "make useful," or are mainly interested in finding "provenance" for the amp as a "collectible." If you intend to try to use the amp, the note by a couple of posters regarding common absence of a (power) transformer in amps from this builder should be noted. Some amps in this era just connected the line power directly thru a rectifier with "dropping resistors" and capacitors to get the DC voltages needed inside. A "fault" in the wiring could cause the user to "glow 'till the fuse blows" so the apparently common practice of adding an "isolation transformer" (and a smaller than "wall-circuit-value" fuse) to the power side might be worth some consideration. John |
Subject: RE: Tech: Amp question From: GUEST,popstudioguitar Date: 31 Oct 08 - 09:08 AM You can find more info at http://sites.google.com/site/pepcotubeampinfo/ |
Subject: RE: Tech: Amp question From: Raptor Date: 21 Oct 08 - 06:07 PM Its on that page you linked to. It's called the arc 801. |
Subject: RE: Tech: Amp question From: Richard Bridge Date: 18 Oct 08 - 07:33 PM There was a DA Pine who built amps in Dartford Kent UK until about 20 years ago - but that would make the "made in Canada" label unlikely. |
Subject: RE: Tech: Amp question From: treewind Date: 18 Oct 08 - 01:59 PM http://www.fenderbronco.com/id14.html Search that page for Pine - which suggests you should try googling for PEPCO too A. |
Subject: RE: Tech: Amp question From: GUEST,Gene Date: 18 Oct 08 - 12:10 PM YOU MIGHT FIND MORE INFO AT: http://www.fenderbronco.com/id14.html |
Subject: Tech: Amp question From: Raptor Date: 18 Oct 08 - 08:38 AM I just bought an amp at a garage sale with a 12" speaker and 2 tubes in it the faceplate is gone and I don't know what it is. I does say Pine Electronics on it somewhere as well as Made in Canada. Any Ideas? Raptor |
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