Tube Rolling w/Crack

[lordnikon]

I purchased an RCA Black plate 6AS7G (probably dated 1950/60s) and it sounded like crap imo.  I'm not sure if I got a defective tube (though it was tested prior to purchasing) it sounded muddy compared with the Philips JAN 6080WC tube that came with my Crack kit. The difference was astonishing. The analytics were gone and sounded "ordinary", nothing magical about it.

The driver tube I'm using is a Telefunken 12AU7 ribbed plate. (Fantastic btw)

[JamieMcC]

Early 1950's Tung-sol 5998 Clear top!

I am actually quiet chuffed with this find, it was in with a bunch of various different untested tubes so took a bit of a gamble with it. First try it didn't work no sound no glow on the heaters 

I pulled it out and had a look to see if I could see any internal damage then retried it ah ha heaters are now glowing and sound but slightly muffled and occasionally dropping out and in on one channel. 

Pulled it out to check the pins and they were totally black with some kind of hard carbon or oxidation type of residue. Ten minutes of pin scraping with a xacto knife and a little buff with scotch brite pad later gleaming pins reinsert deep breath and a sigh of relief tubes now working perfectly and its a beautiful sounding tube what a result! 

(https://www.head-fi.org/content/type/61/id/1123319/width/350/height/700/flags/LL)

(https://www.head-fi.org/content/type/61/id/1123314/width/350/height/700/flags/LL)



 

[kscwuzhere]

Retrofitted my crack to run the 5687 on 2 toggle switches and all I can say is WOW! I currently have the Raytheon JRP 5687WA and it has done wonders for my set up. Before the mod, the two tubes I found myself using the most were my Telefunken e80cc and my RCA long black plate 12bh7a D getter.

The Telefunken e80cc really brings out the highs for the hd650s (removing all veil) and has a quite impressive overall soundstage. Instruments are full but blend into each other a little bit (compared to the 12bh7a and the 5687). The overall sound signature is balanced with the hd650s and the bass is tight yet lush (missing from the 5687).

The RCA black plate 12bh7a is one of my favorite tubes because of its wide soundstage and its overall lushness. The bass is lush like the e80cc but isn't quite as tight as it feels looser making it "tubier". The 12bh7a makes the beyerdynamic T1s extremely balanced but doesnt quite have the same extension in the highs that the e80cc and the 5687 has that the hd650s need.

Finally, the Raytheon military spec JRP 5687WA. This is the most 3 dimensional sounding tube I've ever heard. The hd650s sound incredibly large and as a result instrument separation has become pretty incredible too. The one downside of this tube is its lack of bass presence. The hd650s are a generally bassy pair of headphones and the raytheons recess it quite noticeably. While still being incredibly tight and fast, its lack of wholebodiness (in the bass) is a little disappointing. Besides the slightly recessed bass the tube is incredibly extended and balanced and I'm going to roll my crack with some other 5687s/equivalent to hopefully bring that bass back to life.

[John EH]

Got my 421A in the mail today.  Looks beautiful, sounds better, tests good.

Happy man today.

[Paully]

I imagine that should bring you a nice decade or so of musical enjoyment.  Nice!

[John EH]

Might last longer than that.  My TV7 says the Triodes test 60/63 where 40 is the minimum acceptable value.   This is a mighty fine tube and it's real well balanced and it makes beautiful treble that I just wasn't quite satisfied with before.

Of course it literally cost more than a stock Crack does but who cares?  This sounds AMAZING!

[Paully]

If it makes you happy, I have no problem spending more on the tubes than the amp.  I mean I can't actually do it myself, but as a concept it sounds fine to me!

[John EH]

Not sure why this excites me but it does.

[Paully]

Lol, so many comments, so little time!

[mcandmar]

I want your tube tester, proper bit of kit!

...nice tube too by the way

[kscwuzhere]

So after retrofitting for the 5687 I decided to roll the 7119 equivalent as it seems to be a very well regarded tube (Doc B. loves it). The Amperex 7119 is so far the best tube for my hd650s. The sound signature is brighter than the raytheon 5687, the bass is more extended and significantly airer but not quite as tight as the 5687, and the mids are lusher. Overall the tone is extremely enjoyable as it really gives the hd650s some treble energy with absolutely beautiful separation and imaging. Each instrument demands its own area and instruments dont bleed into each other at all. I tried this tube with the onelivewire's beyerdynamic T1's and even though it definitely sounded impressive, it wasn't as good as a match as the raytheon as the tube was too bright for my liking.

[lordnikon]

Got my 421A in the mail today.  Looks beautiful, sounds better, tests good.

Where did you buy it? I've been looking all over for them.

[John EH]

Where did you buy it? I've been looking all over for them.

eBay.  I literally have been trying to get one for years.  I usually bid $200 or $225 and lose every single time.  There are some on eBay that I believe to be quite questionable regarding authenticity.   Anyway i found this one and threw caution to the wind and bid $275  as it started creeping up there I thought for sure somebody else would get it but it ended exactly at $275.  So by my estimation I overpaid for it but I can't get the Sennheiser HD650's off my head since I got it.

Oddly enough I have some pretty epic 12AU7's and I think the best match for this tube is the cheap RCA clear top.  With other 6080's a Mullurd box plate CV 4003 was best.  For whatever reason I don't care for Telefunken tubes in the crack.  WE421A with orange label Clear Top = Best.

[John EH]

I want your tube tester, proper bit of kit!

...nice tube too by the way

I work for the government.  Few years ago I was at a repair / overhaul facility in North Island San Diego doing a project on an Aircraft Visual Landing Aid.  There it sat.  I asked the boss about it and he told me they had actually just stopped using it because the last piece of gear with a tube in it, a ships gyro, had just been transitioned out.  It had just been overhauled and calibrated as well.   They told me I could have it.

[NightFlight]

eBay.  I literally have been trying to get one for years.  I usually bid $200 or $225 and lose every single time.  There are some on eBay that I believe to be quite questionable regarding authenticity.   Anyway i found this one and threw caution to the wind and bid $275  as it started creeping up there I thought for sure somebody else would get it but it ended exactly at $275.  So by my estimation I overpaid for it but I can't get the Sennheiser HD650's off my head since I got it.

Oddly enough I have some pretty epic 12AU7's and I think the best match for this tube is the cheap RCA clear top.  With other 6080's a Mullurd box plate CV 4003 was best.  For whatever reason I don't care for Telefunken tubes in the crack.  WE421A with orange label Clear Top = Best.

Bah. I went back and forth on the 421A and settled on my TS 1959 5998.  Then I went for a month on the WE41A, then back to the 5998 and the soundstage came back. The glare and noise in the treble went away. 

I bought my 421A for $150, sold for $190 is all I got on ebay. Buyer seems to be happy with it. I put around 100hrs on it only. Ebay had dried up that week. I was really happy when I got it, but after listening, I found the 'airy' treble to be false.