Background hum

[Grainger49]

Another source of noise could be the source you feed into your Crack.  If it is too close it might inject noise/hum into the circuit downstream of the volume control.  Checking this costs nothing just move the source or any other electronic device away from the Crack.

 

[Viktor]

I have done that to no avail sadly. Right now I'm listening to some music and tapped the 6080-tube slightly and the sound went away completely in the right channel. I know about microphonics but didn't know it it should be this apparent. I will report back when I get the tubes, ordered a 6AS7GA (mostly based on looks...) and a TAD 12AU7WA. Also found a store in germany so I should get them fairly fast!

Cheers

 

[Laudanum]

It sounds promising that tapping the tube remedied the noise, atleast in the one channel.  Promising in that you just may simply have a bad tube.  I learned a good while ago that it's always a good idea to have a few spare tubes on hand.  Even if they are inexpensive newer production tubes or cheaper used or NOS tubes.  The spares may not be your tubes of choice but atleast they get you up and running if a tube goes south.  Reading through the forum threads regarding troubleshooting, seems like Doc nails it on the head most every time.  If he thinks it's a problem tube, it's probably a problem tube.

 

[Grainger49]

Let's second Laudanum's suggestion.  For trouble shooting purposes a pair of tubes you hate are a thousand times better than a questionable tube you love.

 

[Viktor]

Laudanum: The cracking noise didn't go away, the noise went away completely which further strenghtens my and also Doc's thoughts that it is a bad tube. Found a store located in germany so I'll probably have them next week or so!

 

[Viktor]

Okay the tubes arrived yesterday and now I've tested both of them, changing the 6080 the crackling noises went away but the background hum was still there though slightly lower. Chaning the 12AU7 tube the amp is now dead silent as far as I can tell!

The big 6080-tube looks alot more like the Bottlehead logo so that's nice! I also think the sound is a tad better but than could just as well be placebo...

 

[Grainger49]

Viktor,

Tubes should look cool too!  As I just posted in another thread, Elcraigo's about Paramour 76 driver conversion, one of the reasons I like the 76 as a driver on my Paramours is that they are a slightly shorter and similarly shaped tube as the 2A3. 

I'm glad the problems went away.  Now for some serious tube rolling.  There is a very long thread on tube rolling in Crack that has some good suggestions.

 

[Laudanum]

Okay the tubes arrived yesterday and now I've tested both of them, changing the 6080 the crackling noises went away but the background hum was still there though slightly lower. Chaning the 12AU7 tube the amp is now dead silent as far as I can tell!

The big 6080-tube looks alot more like the Bottlehead logo so that's nice! I also think the sound is a tad better but than could just as well be placebo...

FANTASTIC NEWS!!!  2 problem tubes, who woulda thunk it, but it happens.  The heaters are AC and I know there are some 12AX7's that tend to produce hum with ac heater supply (The Svetlana 12AX7 new production tubes back close to a decade ago come immediately to mind).  I wonder if there are any specific 12AU7's, old or new production that are particularly susceptible to it.
Anyway, Viktor, I would highly suggest looking for some deals on ebay, or elswehere, for some tubes, atleast as spares if money is tight.  Many NOS or good UOS 12AU7 and 6080 / 6AS7 types are inexpensive with very good deals to be had.  The telefunken, Amperex, Mullard etc. 12AU7 types can fetch a good deal more, but there are even deals to be had there (not as much for Telefunken) if you want to try some. 
For example, I recently picked up a Silvertone labeled Amperex (Herleen) that tested NOS range for 5 dollars (US).  There are quite a few European based tube sellers on ebay with the more "botique" tubes so shipping cost would be less for you.  But some very good steals and deals can be found from North American sellers that would offset the bit of additional shipping cost.  Those tubes you dont favor you can turn around and resell if you want to.

Anyway, glad your Crack amp is up and running now.

 

[Viktor]

Yeah I thought it was a bit weird to but seriously it does seem like that's the case since it's working now. Who knows, the box was a bit damage when it arrived to me, it could have taken a hit during transfer that damaged the tubes!?

After all I'm just glad it's finally working, it will take some time before doing some serious tube-rolling after this business but I will definitely check ebay for some good deals, thanks for the tip!

By the way, here's a hipstamatic pic of the amp where you can see the look of the tube! Sorry for all the OT

 

[Laudanum]

Viktor, I dont doubt that both tubes were bad.  Just bad luck, that's all.  Your problems sound like they are in the past and you can now just enjoy the music.