Members gusfinley Posted October 14, 2005 Members Share Posted October 14, 2005 Well, I thought I would go to the local antique store and see if I could find some antique radios to convert into guitar amps. I happened across some old tubes. The tubes in them didn't match the boxes, and some of the boxes said "used" on them. Inside the Boxes I found a Siemens EL84, Siemens ECC83, and a RCA branded Brittish ECC83. They were $1.50 each so I snagged them!! I popped the EL84 and the RCA EL84 into my amp and fired it up. At first the ECC83 flashed, so I removed it and put in the Siemens ECC83. That one flashed at a shorter duration, I decided to leave it in and see if it would make some sound. It did. I put the RCA back in there and it still sounds good, too. I was just wondering if this flashing is something I should worry about - I'm sure it is. After the Flash, there is a nice yellow glow on the connections below the tube going to the pins, they glow about as bright as the heaters do. Even if the two ECC83 s are worthless, at least I've got a good EL84!! Link to comment Share on other sites More sharing options...
Members potaetoes Posted October 14, 2005 Members Share Posted October 14, 2005 if the british one flashed, that's normal, because it's likely a mullard and mullards flash. Link to comment Share on other sites More sharing options...
Members gusfinley Posted October 14, 2005 Author Members Share Posted October 14, 2005 Originally posted by potaetoes if the british one flashed, that's normal, because it's likely a mullard and mullards flash. Cool!! I was wondering if the flashing was a property of NOS type tubes. Link to comment Share on other sites More sharing options...
Members potaetoes Posted October 14, 2005 Members Share Posted October 14, 2005 Originally posted by gusfinley Cool!! I was wondering if the flashing was a property of NOS type tubes. it has to do with the heaters being in series or something. Link to comment Share on other sites More sharing options...
Members Dale B. Posted October 14, 2005 Members Share Posted October 14, 2005 Some of the RFT's I have flash as well. Link to comment Share on other sites More sharing options...
Members The Boogie Man Posted October 14, 2005 Members Share Posted October 14, 2005 Originally posted by gusfinley Well, I thought I would go to the local antique store and see if I could find some antique radios to convert into guitar amps. I happened across some old tubes. The tubes in them didn't match the boxes, and some of the boxes said "used" on them. Inside the Boxes I found a Siemens EL84, Siemens ECC83, and a RCA branded Brittish ECC83. They were $1.50 each so I snagged them!! I popped the EL84 and the RCA EL84 into my amp and fired it up. At first the ECC83 flashed, so I removed it and put in the Siemens ECC83. That one flashed at a shorter duration, I decided to leave it in and see if it would make some sound. It did. I put the RCA back in there and it still sounds good, too. I was just wondering if this flashing is something I should worry about - I'm sure it is. After the Flash, there is a nice yellow glow on the connections below the tube going to the pins, they glow about as bright as the heaters do. Even if the two ECC83 s are worthless, at least I've got a good EL84!! Don't expect too much for $1.50 but if they work good your in luck, I say get them tested. Sometimes cathode/heater or grid emission leakage causes that, becareful. Link to comment Share on other sites More sharing options...
Members conundrum Posted October 14, 2005 Members Share Posted October 14, 2005 Yeah, all my RFT's flash as well. Nothing to worry about. Link to comment Share on other sites More sharing options...
Members Dale B. Posted October 14, 2005 Members Share Posted October 14, 2005 Here's how Doug Roccaforte has it explained on his site: Have you ever noticed how some tubes like new old stock Mullard or Amperex 12AX7s "flash" brightly when you turn on the power? The answer is rather technical so bear with me. The two filaments have unequal cold resistances. When power is first applied, the filament with the lower resistance passes more voltage over to the other filament, which makes it glow brightly (Ohm's Law at work). As the lower voltage filament warms up, its resistance rises to the hot resistance of the other filament, allowing both to get equal voltages. This effect is pronounced in amplifiers with AC filament supplies because larger amounts of current are available for the tubes, DC filament supplies like those found in better hi-fi equipment tend to be current limited, reducing the opportunity to "flash." Link to comment Share on other sites More sharing options...
Members gusfinley Posted October 15, 2005 Author Members Share Posted October 15, 2005 Hmmm... looks like the 5814A's they had are replacements for 12AU7's - I'll be picking those up today.......... Link to comment Share on other sites More sharing options...
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