New Crack + speedball owner, buzz during start/warmup

[krystalnx]

Hi,

I just acquired a Crack (240V) with the Speedball mod and assembled them. It's my first tube amp, and it's quite nice !

To help in case of problem, I do pass via the crack-only milestone, runned the amp 24 hour to be sure everything was ok, and then deconstructed/added the speedball to it.

After the speedball upgrade, I noticed 2 things :
 - I have a pike between 10-20V on jack at startup which was not here with the crack only. A little googling told me that it is not something to worry about and that I should just unplug my headphone before powering it (and eventually do the mod when I use the buildin switch in the jack)
 - I have a buzz (100-120hz I think) when volume is down to 0 for something like 2 minute after startup. If I turn  the volume up, it disappear (like without fade) at approx 5% of the volume. If I wait, it fade away (in approx 2 minutes). The buzz intensity is "medium" and is not affected by the volume button (up to 5% where it disappear). I've runned the amp hours without issue before noticing it (the first time I plugged my phone only after 5 minutes). There is absolutly no buzz when I turn the volume up to the max. The buzz is not present (not during the first 30 sec) if I do a warm start.

Is this an issue I should investigate or is it ok to live with (like a little tube default) ?

If I have to investigate, where should I start ?

Thanks !

[glwinthedrk]

Are you talking about your output jack?
Did you ground the two unsoldered terminals on your output jack?
If not you can try grounding it and see if that helps. (This wasn't in the Crack Manual, at least not in mine)
Check this thread out:

newbielink:http://www.bottlehead.com/smf/index.php/topic,2946.0.html [nonactive]

See if that helps.

[krystalnx]

I'm talking about the output jack, yep.

I know I can ground the other pin, but if I get it right it won't help when the phone are plugged in ...

I can live with this issue easily (I just have to turn up the volume a little bit), I'd like just to be sure it's not a symptome of a possible issue ...

[Paul Birkeland]

- I have a buzz (100-120hz I think) when volume is down to 0 for something like 2 minute after startup. If I turn  the volume up, it disappear (like without fade) at approx 5% of the volume. If I wait, it fade away (in approx 2 minutes). The buzz intensity is "medium" and is not affected by the volume button (up to 5% where it disappear). I've runned the amp hours without issue before noticing it (the first time I plugged my phone only after 5 minutes). There is absolutly no buzz when I turn the volume up to the max. The buzz is not present (not during the first 30 sec) if I do a warm start.

Some buzzing during warmup is normal, but am I correct in reading that the buzzing subsides after the amp warms up?

[krystalnx]

Yep, after 2 minutes, it fade away.

[Grainger49]

If so that isn't a major problem.  But it is likely a tube. 

Of course you will want to tube roll soon.  But until then just don't listen immediately to avoid the aggravation.