Tube Rolling w/Crack

[cddc]

Quick question on tube rolling. I just finished my crack about 2 months ago. Thought I'd give tube rolling a try and purchased a RU-6H13C from "thetubestore.com". Got it in today, and "rolled" it in. Powered my crack up and the tube crackled and I could see some arcing going on inside for a second. I thought Oh, SH$T, I mean, SHOOT, there goes $25 bucks.

Fed it some audio, and, well, good to go. Sounds great.

So, is that normal for a new tube to do that? Any concerns about tube life or reliability?

I've got a 5998 on order too, so want to make sure if I see that again, it's normal.


Thx.

When you fire up a tube for the first time, make sure you don't have your expensive headphones plugged in. Arcing from a tube could blow/kill your headphones or eardrums.

If you see arcing, as Doc said, there could be something in between internal components, or there could be some gas residuals inside the tube. Leave the tube on for 24+ hours, the getter inside tube will absorb the remaining gas.

Then you power off your amp, let it cool, and sometime later carefully examine if there is still arcing happening.

 

[Crackling]

Hi all! Been lurking around here for a few weeks. I am a recent and very proud owner of a Bottlehead Crack. Been experimenting with some tubes; without a doubt the best power tube I currently own is the Tung-Sol JAN-CTL 5998. So far I have not noticed much difference when using various pre-amp tubes though, but more on that to follow in my future posts. For now, I just wanted to see what's the best recommended practice when it comes to actually swapping the tubes. Obviously, I need to turn the amp off first, but beyond that must I wait until the tubes have reached room temp first? I don't want to burn my hands but I was thinking I can use some cloth to remove the hot tubes, but I'm not too sure if that can damage the tube, the socket, or anything else. Do I need to unplug the power, headphone jack, RCA cables, etc.? As you can tell, I'm no electrical engineer--or any kind of engineer for that matter : ) I have read a lot of the posts in this thread and many on the Head-Fi forum threads, but clearly there's well over a decade worth of posts and I'm sure I missed the answer I'm looking for somewhere along the way. Any help will be greatly appreciated!

 

[Paul Birkeland]

Just turn the amp off first.  A silicone oven mitt would let you pull out hot tubes without burning your fingers.

 

[Crackling]

Thank you, Paul!

Now on to the main subject of this thread, been doing some reading on the 6SN7 tube and I'd like to try it on my Crack. I understand it's not compatible and I'd need an adapter. Any particular recommendation on the adapter? Does the 6SN7 tube to 12AU7 socket adapter Garage1217.com sell work? (according to their site, it is compatible with the Crack)

 

[Paul Birkeland]

I think the Garage 1217 one might be the only one that's not noisy.

 

[Crackling]

Thanks again! Any recommendation on a reliable tube supplier that's not eBay and also any decent 6SN7 variant that won't break the bank? I see a lot of 6SN7GT/B around. Will these work?

 

[Paul Birkeland]

I tend to use Vacuum Tubes Inc., but he isn't the kind of seller that will go pick through his stash to find the exact brand and construction that you're looking for.  Personally I just buy them on eBay.

Any of the suffixes of 6SN7 will work provided the adapter works.

 

[adeep42]

If you want to be assured that the tubes are good, try Brent Jesse. Just google him.

 

[Crackling]

Thank you, PB & @adeep42! For now I went ahead and ordered an adapter from garage and a very reasonably priced NOS 6SN7 from a vendor on reverb with lots of reviews.

On a somewhat related note, I saw this https://www.ebay.ca/itm/312213040699 and wondered if it's worth the investment to add even more adapters and tubes! Someone on head fi made a post about it but can't find it at the moment. A ton of 6J5 tubes on the cheap sides on eBay would be my only motivation for now but of course I prefer to hear others who have tried this and their thoughts on the sound change. I always prefer more warmth, brightness, bass, less treble, and wider sound stage. I have a variety of headphones such as DT 1990 Pro (my absolute favorite right now), HD 650, Modhouse Argon MK3, and a few other, less noteworthy, ones...

 

[Paul Birkeland]

A 6J5 and a 6SN7 are identical other than the 6J5 only having half of what's inside a 6SN7.  The tremendous downside of that adapter is that you need to find construction matched pairs of 6J5s.  This is already done for you with 6SN7s.

 

[adeep42]

The Garage 6SN7 adaptor worked for me. I really enjoy the Crack plus Speedball with the 6SN7.

 

[Crackling]

Glad to hear that. I'm already very satisfied with mine with speedball and Tung-Sol 5998 but if upgrading my input tube improves the sound even further, then why the heck not!

 

[kill_surf_city]

I've been tube rolling for a while and I finally find my perfect combo. Both RCA tubes. 6AS7G and 12BH7. Both are grey plates but they have a very incredible synergy. I'm running with Speedball and the 12BH7 has been my go to with or without Speedball when comparing to the RCA clear tops. I've tried black plates of the RCA 6AS7G and even the Tung Sol 5998 and both were incredibly microphonic. The combo I have is pure bliss with the Speedball. If I'm gonna be totally honest, black/grey plate doesn't really matter. The Crack w/Speedball sounds incredible no matter what tube you put in it. I've tried both and the difference is unnoticeable. The amp just sounds incredible. Maybe I just got lucky with my RCA tubes, but IMO don't waste your money on the 5998 Tung Sol tube if you're thinking about it.

 

[Crackling]

That's good info. Thank you! I got lucky when I bought my Crack, the gentleman I got it from had a Tung-Sol 5998 and he threw it in as part of the whole package, which was great. Re the 12BH7, did you have to make adjustments since it's on the "kinda drop-in" compatible list of tubes?

 

[kill_surf_city]

That's good info. Thank you! I got lucky when I bought my Crack, the gentleman I got it from had a Tung-Sol 5998 and he threw it in as part of the whole package, which was great. Re the 12BH7, did you have to make adjustments since it's on the "kinda drop-in" compatible list of tubes?

nope. Adding the Speedball was the only adjustment I've made.

 

[Doc B]

"Perfect combo" suggestions should also mention the source and the type of headphones used to be useful in the general scheme of things.

 

[Crackling]

Great point, Doc. Mine for now is the stock input tube plus the Tung-Sol 5998 fed from my pc to Khadas Tone Board and using this set up my most favorite pair of cans among all the ones I've tested (TH-X00, HD 6XX, HD 650, Fostex T60RP, Argon t50rp MK3, DT 1990 Pro, and more) has got go be the DT 1990 Pro. Nothing comes even close to them.

 

[Foscolo]

Hi everyone,

It's my first post on the forum, as a happy new owner of a Crack+Speedball! The gentleman I bought it from included the two tubes shown in the attached pictures. I'm having a hard time identifying them. Can anyone help?
I hope this is the right thread for this question.

Thank you!
Tommaso

 

[Tom-s]

General Electric 6080
Sylvania 12au7

 

[Foscolo]

General Electric 6080
Sylvania 12au7

Thank you!