I got some Philips 7581A's on the way for my Rivera amp because Rivera recommends the Philips 7581A or 6L6GC STR Tall bottle Sylvania as the best old style
tube for the amp & they act like it's the same tube. I have read that they are the same tube because Philips bought out Sylvania & kept making the
tube just under the new name of 7581A instead of 6L6GC STR. Just wondering if they are the same tube or are actually different tubes. If they are the same tube
then they would be 30W tubes but if they are a real 7581A then they are 35W tubes and I need to know for biasing purposes. Thanks.
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Sylvania 6L6GC / Philips 7581A Same tube?
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 Idunknow |
Sylvania 6L6GC / Philips 7581A Same tube? |
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Posts: 7 (02/04/09 14:54) |
Last Edited By: Idunknow 02/04/09 14:57.
Edited 1 time.
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Old Tele man |
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Posts: 1435 (02/04/09 19:51) Techus Maximus |
...the 7581A is an "industrial / military" upgraded version of the "commercial" 6L6GC having exactly
same electrical operating characteristics, but higher rated plate- and screen-dissipation values.
"...Renovatio, non Exauguratio..."
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Idunknow |
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Posts: 8 (02/04/09 22:46) |
Yeah I knew that, Old Tele, I was just wondering if the Philips tube was a real 7581A. The info I was reading on another site seem to infer that it was the
same tube as the Sylvania 6L6GC just renamed by Philips when they took over Sylvania. I don't even know if any this is true I was just trying to make sure
that the Philip 7581A's I got are 35W tubes.
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Old Tele man |
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Posts: 1436 (02/05/09 21:37) Techus Maximus |
...can only know that by comparing their guts (thru the glass)...however, you are correct that 'some' 6L6GC and 7581A tubes were made on the same
production line, differing only in their labels, near the "end" of the vacuum tube era (circa middle 1980's), as it was cheapest way to cover
both ends of the market (commercial and industrial/military).
"...Renovatio, non Exauguratio..."
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Idunknow |
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Posts: 9 (02/06/09 11:50) |
Thank you. I will post a picture as soon as they get here. thanks again.
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Idunknow |
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Posts: 10 (02/16/09 02:25) |
Can you tell from this picture if this is a real 7581A or not?
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Psycho Bass Guy |
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Posts: 321 (02/18/09 08:05) |
That's a real 7581A, and JAN spec to boot (green bottle screening). I have a few of those myself, and yes, lots of late production Sylvania 6L6GC's
ARE true 7581's. 70's made Sylvania STR 6L6GC's will also operate at 7581 specs. I suspect the Philips 7581A IS the old STR design. I don't
have a curve tracer, but the STR's I have look and act just like their 'younger' 7581A siblings.
"I'm the fly in the ointment, the monkey in the wrench, the pain in your ass."
Psycho >^} |
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Idunknow |
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Posts: 11 (02/18/09 17:52) |
yeah I happen to get a pair of these new off ebay that the guy had bought from KCANOS about 5 years ago and never used them. It's good to know they are
7581A. Still looking for one more matched pair.
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Idunknow |
Psyco Bass Guy Jan Philips 6L6GC's ? | ||
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Posts: 13 (02/21/09 18:12) |
Psyco Bass Guy what you said got me wondering if these Jan Philips 6L6GC's I have are actually 7581A's or STR's. They
sound just like the 7581A's to me & look just llike them, to me anyway? What ever both are the best sounding tubes I ever used!
Last Edited By: Idunknow
02/21/09 18:15.
Edited 1 times.
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- The Break Room
- Fender Amps
- Tech Bench
- Tubes
- Speakers
- The Instrument Room
- Mesa Amps
- Marshall Amps
- Small Amps
- Boutique Amps
- For Sale
- Other Major Amp Brands
- Introduce Yourself
- Solid State Amps
- Effects
- Other British Amps
- Sound Reinforcement
- Recording
- Important Announcements
- Hammond Organs & Leslie Cabinets
- Shameless Promotion
- The Boiler Room
