NOS 7581A - what's the REAL value of these?

11 Gauge · June 12th, 2008, 12:19 PM

I've got a pair of low mileage NOS Philips/Syl 7581A's that I always chalked up to being a slightly more rugged (and more powerful) 6L6.

I come to find out today that these things are now considered grail tubes. Some folks are even comparing them to KT66's, which just seems silly to me.

They are slightly impressive sounding - the only reason that I haven't gotten rid of them over the years. Maybe I just haven't heard them in the right amp.

Any thoughts? A google search resulted in all kinds of contradicting information, so I guess most of it is B.S.

Wally · June 12th, 2008, 05:30 PM

IME, if you are looking for big, articulate, complex and rich tones; the 7581 is THE 6l6-type tube to have. The best TR I have had was a '65 into which I had put a set of NOS 7581's along with some EV's. That amp was sold for big dollars even though it was not mint....very good but not mint. T he sonics sold it, and he had to pay me large to get it. IT was worth the 'weight'. (8^)

JimiBryant · June 12th, 2008, 06:08 PM

I've got a set of those Sylvania 7581As but I only like 'em in one of my amps -
and they're GREAT for ultra-clean headroom - but I can't figure out why I
don't like these in any of my Fender amps or my JTM45, so there ya go.

in my Music Man RD50 combo with a Weber California 10" they can't be beat.

Tim Swartz · June 12th, 2008, 10:04 PM

I think the Sylvania/Philips 7581A is just a renamed 6L6GC STR (dual getter variety often branded Mesa, Fender, Groove Tube, Peavey, GE, RCA, etc...). This tube was in everyone's catalog as it was probably the only 6L6 being mfg in the US in the '80s. GE had a short bottle variation named 7581A/KT66.

mad dog · June 14th, 2008, 08:48 AM

I've tried 7581A and the original variant, think it's the 237 STR Sylvania, in several amps. In a couple BF Fenders, probably the best tubes I've heard. In a couple other amps, tweed pro type Sewell and Ampeg Gemini II, I actually prefer JJs.

I'd heard the buzz on these, assumed they'd automatically be the best in any 6L6 amp. But every amp is different. It pays to experiment. There are lots of good tubes around. Sometimes the right ones for an amp are not the one's you'd expect.

Big White Tele · June 14th, 2008, 12:28 PM

I had a new set of Phillips 7581's and tried them in my Dual Pro, and a 66 Twin. Didnt care for them in either amp. I actually prefered the GT 6l6ge's.

June 12th, 2008, 12:19 PM	#1 (permalink)
11 Gauge Friend of Leo's Join Date: Mar 2003 Location: The East Coast Posts: 2,761 10 Photos	NOS 7581A - what's the REAL value of these? I've got a pair of low mileage NOS Philips/Syl 7581A's that I always chalked up to being a slightly more rugged (and more powerful) 6L6. I come to find out today that these things are now considered grail tubes. Some folks are even comparing them to KT66's, which just seems silly to me. They are slightly impressive sounding - the only reason that I haven't gotten rid of them over the years. Maybe I just haven't heard them in the right amp. Any thoughts? A google search resulted in all kinds of contradicting information, so I guess most of it is B.S. __________________

June 12th, 2008, 06:08 PM	#3 (permalink)
JimiBryant Tele-Afflicted Join Date: Sep 2007 Location: Chicago Chicago that toddlin' town Age: 46 Posts: 1,495	I've got a set of those Sylvania 7581As but I only like 'em in one of my amps - and they're GREAT for ultra-clean headroom - but I can't figure out why I don't like these in any of my Fender amps or my JTM45, so there ya go. in my Music Man RD50 combo with a Weber California 10" they can't be beat. __________________ I am very proud of the fact that I'm so humble!

June 12th, 2008, 10:04 PM	#4 (permalink)
Tim Swartz Tele-Afflicted Join Date: Mar 2003 Location: Michigan - Tweenst the Great Lakes Posts: 1,775	I think the Sylvania/Philips 7581A is just a renamed 6L6GC STR (dual getter variety often branded Mesa, Fender, Groove Tube, Peavey, GE, RCA, etc...). This tube was in everyone's catalog as it was probably the only 6L6 being mfg in the US in the '80s. GE had a short bottle variation named 7581A/KT66. __________________

June 12th, 2008, 05:30 PM	#2 (permalink)
Wally Friend of Leo's Join Date: Mar 2003 Location: Lubbock, TX Posts: 3,608	IME, if you are looking for big, articulate, complex and rich tones; the 7581 is THE 6l6-type tube to have. The best TR I have had was a '65 into which I had put a set of NOS 7581's along with some EV's. That amp was sold for big dollars even though it was not mint....very good but not mint. T he sonics sold it, and he had to pay me large to get it. IT was worth the 'weight'. (8^)

June 14th, 2008, 08:48 AM	#5 (permalink)
mad dog Tele-Holic Join Date: Jun 2005 Posts: 702	I've tried 7581A and the original variant, think it's the 237 STR Sylvania, in several amps. In a couple BF Fenders, probably the best tubes I've heard. In a couple other amps, tweed pro type Sewell and Ampeg Gemini II, I actually prefer JJs. I'd heard the buzz on these, assumed they'd automatically be the best in any 6L6 amp. But every amp is different. It pays to experiment. There are lots of good tubes around. Sometimes the right ones for an amp are not the one's you'd expect.

June 14th, 2008, 12:28 PM	#6 (permalink)
Big White Tele Tele-Meister Join Date: Aug 2005 Location: Canadian Rockies Posts: 230	I had a new set of Phillips 7581's and tried them in my Dual Pro, and a 66 Twin. Didnt care for them in either amp. I actually prefered the GT 6l6ge's.