Tube Rolling w/Crack

[Cmdr_DASh]

Hello fellow addicts,

I just finished building my Crack on Sunday night (late night project when kids are asleep). Still need more hours to burn it in and my low frequencies just opened up. Loving it, fantastic kit and great manual!

I'm new to tubes and I like the ones that came with the Crack a lot. I'm very curious about the tubes I got, year of production, factory, etc. Could you help me out?

• 12au7 is Sylvania GMS AJR made in USA
• 6080 is a Philips 6080WC JAN 34167 USA, 8539 AAZ

[Jay]

I can't help you with the tubes, but nice work on your Crack.  Welcome to the world of tubes.
Jay L.

[Cmdr_DASh]

I can't help you with the tubes, but nice work on your Crack.  Welcome to the world of tubes.
Jay L.

Thanks Jay! Tubes are so hot! ("cool" doesn't seem to be the right word for it)

[Paul Birkeland]

• 12au7 is Sylvania GMS AJR made in USA
• 6080 is a Philips 6080WC JAN 34167 USA, 8539 AAZ

The 6080 is likely from the 39th week of 1985.  There are identical 6080s from the same time period with the same construction and the same color of printing that are labeled as Sylvania tubes, so that is likely the producing factory.  The lack of 5 acid etched dots (GE) and the acid etched stop sign (RCA) pretty much leaves Sylvania as the producer by the process of elimination.

The 12AU7 is a Sylvania gray plate. The letter codes on those Sylvania tubes are believed to be lot codes, but they haven't been connected to any specific dates that I'm aware of.

[Cmdr_DASh]

The 6080 is likely from the 39th week of 1985.  There are identical 6080s from the same time period with the same construction and the same color of printing that are labeled as Sylvania tubes, so that is likely the producing factory.  The lack of 5 acid etched dots (GE) and the acid etched stop sign (RCA) pretty much leaves Sylvania as the producer by the process of elimination.

The 12AU7 is a Sylvania gray plate. The letter codes on those Sylvania tubes are believed to be lot codes, but they haven't been connected to any specific dates that I'm aware of.

Thanks a lot Paul, that's what I was looking for! (and I managed to find my post moved in here too , phew I was thinking I broke a forum rule and post got deleted)

I've been reading this thread and I got the tubes in the picture on an impulse (which rarely happens)... I just had to see the difference. All I can say right now is that I left the Gold Lion in and I'm not sure I can take it out ... it's too good.

[attmci]

Thanks a lot Paul, that's what I was looking for! (and I managed to find my post moved in here too , phew I was thinking I broke a forum rule and post got deleted)

I've been reading this thread and I got the tubes in the picture on an impulse (which rarely happens)... I just had to see the difference. All I can say right now is that I left the Gold Lion in and I'm not sure I can take it out ... it's too good.

Unfortunately, these are all ......

[amerk84]

I built the Crack + Speedball amp a few years back and of course love it. Last year I rolled in a Brimar CV4003 input tube. Now looking to "upgrade" the power tube. Any recommendations?

[djspacewhale]

so someone on eBay is selling both an RCA and Sylvania 6AS7G with returns available - can anyone comment on the sound of these tubes? haven't rolled any power tubes, and stock for me is Philips JAN 6080WC

[L0rdGwyn]

I built the Crack + Speedball amp a few years back and of course love it. Last year I rolled in a Brimar CV4003 input tube. Now looking to "upgrade" the power tube. Any recommendations?

I built my Crack back in December and I've spent the last two months rolling power tubes and 12au7's (no time to waste!).  I've rolled the stock 6080, Mullard CV2984, Tung Sol 6AS7G, Tung Sol 7236, and Tung Sol 5998.  IMO, and like many other people on this forum, the 5998 is the very best of the bunch, best air, soundstage, detail, clarity.  If you are patient, you can get one for $75-100 on Ebay, but more often you will see them going for around $150.  A more budget friendly and more readily available upgrade is the Mullard CV2984, which is a very nice tube for around $50 on Ebay.  If you search this thread, this has been discussed ad nauseum but these two tubes are very often recommended.

Hope that helps!

[Kitchener]

So I went on eBay.
I’m still waiting on my Crack kit (any day now, ordered 25.12!  ) but I was determined to not let a minor detail like that deter me from getting a head start at tube rolling.
-gotta be prepared!

Here’s the thing:
The listing said RCA Clear Top 12AU7($20 for a pair), the tubes themselves say zilch.
Have a look at the attached photos.

They look like what Google says Clear Tops should look like, but there are no logos or other markings on the tubes.

Is there any reason to be apprehensive about stuffing these in my amp down the line?

[Paul Birkeland]

Those are RCA clear tops.  If they test well, they should work well in the Crack.

[Kitchener]

Super, thanks, Paul!

Yeah I’ve read quite a few recommendations for the Clear Tops so I figured it couldn’t help to get a couple for posterity 

[djspacewhale]

so I was told to try a 6sn7 with one of the Garage1217 adaptors, and it came today with a Raytheon 6sn7gt which extends lower than the stock GE 12au7a and has a wider soundstage, yet with a lot more distortion and a bunch of microphonics, plus I think it looks stupid as the adaptor is misaligned and every 6sn7 seems to look just like a big rod, and a not insignificant part of tubes for me is the look of them so I'm going to try flipping this forward and just getting a better 12au7. I'm looking at moving my power tube from a Philips JAN6080wc to a Sovtek 6as7g, and moving that GE 12au7a to... something. I've heard good things about new tung sols and mullards, though I've heard myths about rca clear tops even if they're a bit pricier, not to mention tung sol's NOS 5998's. can I get any recommendations on tubes to move to? I like a somewhat warm sound (crack and hd650s yea) and the wide soundstage of the raytheon is super fun, tho I also don't like the music to sound too smeary and to retain its detail and punch.

[buldogge]

There are Tung Sol 7236s on eBay right now for ~$30...great buy.

I wouldn't give up on the 6SN7s so easily...I run mine with the same adapter and a TS Mouse Ears...but...I also have tried Sylvania GTB, Ken rad VT-231, and NU Black Glass...all different, and frankly, I enjoyed them all (other than the GTB) more than the supplied 12AU7.

Having said that...I never bought/rolled any additional 12AU7s.

Also..If you want to try something different for aesthetics...you could pair a Melz 1578 (6SN7 equivalent, metal base) with a TS 7236 metal base.

I liked the cheap 1950's Soviet 6N5S quite a bit...but...I like the gain/clarity on the 7236 quite a bit more!

Good luck...Have fun.

-Mark in St. Louis

[Paul Birkeland]

and moving that GE 12au7a to... something. I've heard good things about new tung sols and mullards, though I've heard myths about rca clear tops even if they're a bit pricier

Why not get a real Mullard tube?  There are plenty of used but good vintage Mullard 12AU7s for under $20.