Tube Rolling w/Crack

[Paul Birkeland]

If a 50s RCA black plate 12BH7 was extremely microphonic (even touching the headphone cable results in a tinging noise) in a Speedballed Crack amp, was that the fault of the tube or the amp?

The tube, especially if you have a bunch of 12AU7's that don't exhibit this behavior in your Crack.

The seller is kind of brushing it of as it being due to higher gain in a circuit that normally uses 12au7 or being due to a component in the circuit. After initially offering a replacement. (edit: we worked it out) still curious about microphonics with the SB installed though.

The difference in gain between the two is less than 2dB.  There are no components in the Speedball that are microphonic.  If anything, microphonics should be less apparent with a lower gain tube (the 12BH7).

I don't know enough about this to know if that warrants a refund or exchange, or not. Any advice?

This depends a fair amount on whether the seller ever mentioned that he had listened to the tube.  If the tube was new in a sealed box, and turned out to be microphonic, that's just bad luck.

[mSummers]

Is a Tung-Sol 6336B compatible with Crack?  I was told it was a 6as7g equivalent, but want to double check before I try it

[Doc B.]

Nope, it draws way more current. Whoever told you that does not know much about tubes.

[mSummers]

Thanks Doc!  I don't know that much myself. It didn't sound right, so I'm glad I asked

[12AU7-6SN7]

The tube, especially if you have a bunch of 12AU7's that don't exhibit this behavior in your Crack.The difference in gain between the two is less than 2dB.  There are no components in the Speedball that are microphonic.  If anything, microphonics should be less apparent with a lower gain tube (the 12BH7).This depends a fair amount on whether the seller ever mentioned that he had listened to the tube.  If the tube was new in a sealed box, and turned out to be microphonic, that's just bad luck.

Thanks, that's what I thought. It was NOS and tested very well. The seller and I came to a very fair agreement.

[mcandmar]

Here is an interesting tube for you collectors out there.   I have a few Gold Aero tubes in 6CG7 and 6DJ8 form and they all test with amazingly high emissions and perfectly matched sections. From what i was able to find out they cherry picked the best tubes they could find from a variety of manufacturers, then graded and branded them.  Granted they started life as lowly GE 5998A's but i could'nt resist picking one up to see how it performs..  http://www.ebay.co.uk/itm/172262170880

@Doc, would look mighty pretty in a limited edition walnut cased Crackatwoa

[adeep42]

Macandmar, Thanks for the info. Just ordered one. I'm new to tube rolling the Crack, but was moderately active with my old Rogue Cronus Magnum. In my few months with the Crack I've tried a TungSol 6520 and a new Svetlana 6AS7G. Still trying to figure out what I like best.

Have another tube issue that I would love some input for. Have also rolled in a Mullard NOS 12AU7. Always felt they were a guaranteed winner in any tube gear. I love the sound but would like a little less gain so that the volume was a tad easier to adjust. Any suggestions would be appreciated.

Thanks and happy holiday to all,

Alan

[ohshitgorillas]

I have been listening with the Raytheon VT-231 using a Garage1217 adapter for the last week or so and oh my god, the soundstage is spectacular. I now understand what people mean by 3d soundstage. (Listening with modded HD650)

[braijos16]

I managed to build the crack+speedball a year ago, but I know nothing about tubes/tube rolling. Anyways, a picture fell off of the wall and landed on my tubes completely shattering them today. Listening to music is a daily activity for me and I love my crack, so I was hoping I could get some recs for some good replacement tubes, and where in the world I would buy them. I'm down to upgrade as well. Thank you!

[galyons]

For the universe's compiled Crack tube compendium, read here:
[urlhttp://bottlehead.com/smf/index.php?topic=663.0;topicseen][/url]

Most tube vendors and eBay generally have wide selections.  If you post your location, a nearby Bottlehead may have spars to sell and/or loan to get you back to the music!

Cheers,
Geary

[Tom-s]

My budget recommendation for a power tube is the Russian 6H13C (Winged C). Four of those cost about 30$.
It is much better compared to the normal 6080's. More air, harder hitting tighter bass, and good details (I prefer it over my RCA 6as7g).
For the input tube i'd recommend buying locally. Here in The Netherlands i'm now using an NOS Amperex 12au7 bugle boy.
Found those for 3-5$ or something and they do sound great.

[attmci]

My budget recommendation for a power tube is the Russian 6H13C (Winged C). Four of those cost about 30$.
It is much better compared to the normal 6080's. More air, harder hitting tighter bass, and good details (I prefer it over my RCA 6as7g).
For the input tube i'd recommend buying locally. Here in The Netherlands i'm now using an NOS Amperex 12au7 bugle boy.
Found those for 3-5$ or something and they do sound great.

WOW, that's a great price for a 12au7 bugle boy. How about a 7316 (one of the best 12au7 tubes)?

[Tom-s]

Those can be found for +-100-150€/pair. So since i don't pay that sort of money for tubes i've got no idea how they sound.
If i'm correct it's just the "better" computer version of the normal 12au7 from Amperex.

[mSummers]

I bought a Telefunken 6080WA on eBay and was told that it tested 110/110 on a B&K with no gas and no shorts.  When I plugged it into my Crack, the heaters glowed brightly and there was a blue flash with a popping sound.  Upon seeing that I shut the amp down.  Does that sound like a bad tube?

The bad news is that after re-installing the old tubes, I had no sound in the left channel and intermittent crackling in the right, so I trued an old crappy set of headphones and they seem to work fine, so it looks like I blew out a set of 600ohm Beyerdynamic drivers.

[Paul Birkeland]

A blue flash and popping would tend to suggest gas.  Is the silver getter still silver, or is it turning white?