Crack questions

[Viktor]

Thank you! Will definitely do that today. I listened for a very short time and the sound was wonderfull by the way but I didn't wan't to destroy anything so I shut it off.
And I guess the manual is correct
'Remember, we don't learn from doing something right, we learn from our mistakes.'

I'm learning loads from doing this! Is there any good read on the web for how the circuitry itself works? I'm a physics student so I am always interesting of finding out how things work!

Thanks a million

[InfernoSTi]

Congratulations on the build and being down to simple troubleshooting (my first DIY build had me chasing a bad power supply rectifier...you did much better than I did!).  I bet you will enjoy this amp more than you have any other amp: you KNOW how it works from power supply to signal input to signal output.  What a great feeling...enjoy!

John

[Viktor]

I did as jrebman suggested and just wiggled the tubes back and forth abit, took them out and put them back in and now the sound is gone. I really have a working crack! Sounds wonderfull but as I remember from my Fender guitar amp tubes do need some burn in to sound their best?

Also, thanks for all the helpfull advice, quick replies, and nice atmosphere! Wonderfull resource for help and information

[dstrimbu]

Sounds wonderfull but as I remember from my Fender guitar amp tubes do need some burn in to sound their best?

/quote]

Yeah, Viktor - they sure do need some burn-in time, as do the capacitors in any circuit.  Now you can spend your lunch money on new-old stock tubes to find the "right" combination for your musical tastes...

I settled on a NOS Amperex 12AU7 for the gain stage, and a vintage Sylvania 6AS7G to replace the stock 6080 in the current stage... the positives are a.) the 6AS7G looks like a real "bottle" <g> and b.) the Amperex sounds really sweet to me over my Senn HD-600s.

Congrats on your first Bottlehead kit!  As a physics student, you'll probably be able to visualize the space charge in those nicely glowing tubes... 

Enjoy!

-don

[Viktor]

Hi again! It is a bit weird with the cracking noise because I thought it was gone but now its back again. At least for a very short while when the amp is heating up, then it's gone....

I tried to poke around inside it but that didn't do anything.

[Jim R.]

Viktor,

Sounds again like a flakey tube socket connection and/or ttube, and that it's making a better connection as things heat up and expand abit..

Sounds like the rest of the amp is doing what it should though, so the tubes and sockets are where I'd be looking for an answer.

-- Jim

[Viktor]

Okay I've had a alot of other things to do so I haven't had time to look into the issue and actually it went away completely but now its back again. I've checked the solders and they looked fine and I also resoldered some of the connections but it doesn't seem to help. I also tried the chop-stick test but the cracking/popping noises are very irregular so it's hard to know if there's anything happening when I poke around...

I tried to 'clean' some of the pins on the large tube to get a better connection but that didn't help either...

edit:
Okay I found out that when I wiggle the big tube I can make the cracking noise appear/disappear but when I poke the connections there's I can't produce the noise...

[Grainger49]

Try inserting and removing the big tube 5 or 6 times.  This will clean the tube pins and the tube socket.

[dubiousmike]

Just thought I'd throw this out there as well - do you happen to have a cordless phone, cell phone, router, etc. sitting near your amp?  While I haven't had this issue with the amperex 12au7 in my crack, I have a pair of fairly pricey amperex e88cc PQ's (another 9pin variant that I used in my prior Woo headphone amp) that pop/crackle off and on if they are within several feet of any sort of radio.   Took me a week or so to puzzle out the cause of those crackles, and I just wanted to make sure your issue doesn't boil down to something so simple.