GrahamT Posted October 31, 2016 Share Posted October 31, 2016 HI All, My GB Stramliner 600 has developed a very pronounced hum. It is there from the moment that I connect it to my cab. Any suggestions as to what to do? Thanks, Quote Link to comment Share on other sites More sharing options...
DBerriff Posted October 31, 2016 Share Posted October 31, 2016 (edited) Check the simple options first. Does it hum with no instrument plugged in and the input gain turned down to zero? Have you tried another mains lead and a different supply socket to check for suspect earthing/grounding? Beyond that, take it to a competent repair shop for testing. The Streamliner has a few valves in the preamp, so it is possible a valve has failed. Edited October 31, 2016 by DBerriff Quote Link to comment Share on other sites More sharing options...
Twincam Posted November 1, 2016 Share Posted November 1, 2016 I would suspect a pre amp tube first. However also any dirty jacks can sometimes cause issues (on any amp) maybe a tiny bit of contact/electrical cleaner and playing in a jack in and out a few times in all the jack sockets (with amp off!) may help. Failing that as previously said look into the pre amp 12ax7s. Quote Link to comment Share on other sites More sharing options...
Japhet Posted November 1, 2016 Share Posted November 1, 2016 Try swapping out everything else first (i.e. power cable, bass, instrument lead, speaker lead, cabinet) to eliminate them as the source of the problem. Quote Link to comment Share on other sites More sharing options...
GrahamT Posted November 1, 2016 Author Share Posted November 1, 2016 Many thanks to all for replying. I will give the advice a try tonight. G Quote Link to comment Share on other sites More sharing options...
karlfer Posted November 2, 2016 Share Posted November 2, 2016 If it turns out to be pre amp tube, there's a very interesting thread regarding changing V1 to a Phillips. I keep thinking about doing it, but will wait until I give up trying to sell mine (ie when the PUMA that's up sells). Quote Link to comment Share on other sites More sharing options...
GrahamT Posted November 2, 2016 Author Share Posted November 2, 2016 Karlfer - I don't really understand what you mean. Please expand. Quote Link to comment Share on other sites More sharing options...
karlfer Posted November 2, 2016 Share Posted November 2, 2016 If it turns out to be a pre amp valve issue, you might simply want to replace the troublesome valve with exactly the same item. Or as some have done, you might like to try different pre amp valves to see if you like different sounds. This is the thread I referred to http://basschat.co.uk/topic/191375-new-valves-for-genz-streamliner-any-experience/page__st__30__p__2778083__hl__streamliner__fromsearch__1#entry2778083 Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted November 2, 2016 Share Posted November 2, 2016 (edited) There is an ex-Genz designer active over on Talkbass, and I'm sure he has mentioned at some point that they used a DC filament supply on these. If I've remembered that correctly, it would make hum less likely as a valve failure mode, since there should be no AC on them to leak into the signal. If you're a member over there it might be worth asking his advice - his name on TB is Agedhorse. Edited November 2, 2016 by Beer of the Bass Quote Link to comment Share on other sites More sharing options...
DBerriff Posted November 2, 2016 Share Posted November 2, 2016 The Streamliners are not designed for frequent valve swapping. I recall one TB member complaining about a broken valve base. He might have been heavy handed. I came to trust my GB gear in regular gigging use, and simply used them in stock configuration. Quote Link to comment Share on other sites More sharing options...
karlfer Posted November 2, 2016 Share Posted November 2, 2016 And yet here is a direct reply from Jeff Genz himself, referring to the Streamliner (personally I'm not advocating frequent changes but it would be kinda nice to try). [i]"Hello Greg,[/i] [i]Your experiment sounds like it is a true winner for your needs.[/i] [i]The ability to modify to tonal characteristics of the Streamliner by swapping tubes is part of the beauty of this design.[/i] [i]I think your choice of a 12AT7 in V1 makes perfect sense.[/i] [i]Thank you for commenting and we appreciate you continued to play GB.[/i] [i]Regards,[/i] [i]Jeff"[/i] Quote Link to comment Share on other sites More sharing options...
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