| Author |
Message |
< Music Gear ~ Re-Tubing a Hybrid Amp |
| Leather Mike |
 Posted: Wed Mar 28, 2012 11:00 pm |
 |
|
|
Joined: 18 Sep 2008
Posts: 2717
|
| Guys, my amp head is a Marshall AVT150x combo that i chopped to make a head. It's a valve pre-amp (1x12ax7) and solid powerstage. recently i've noticed a drop in output power and she's starting to fizz rather than grind, so i'm assuming the pre-amp tube has had its chips. is it simply a matter of buying a new 12ax7 and straight-swapping old for new? |
|
|
| Back to top |
  
|
| Mazzy Maz |
| Posted: Thu Mar 29, 2012 9:50 am |
|
|
Joined: 03 Sep 2008
Posts: 1655
Location: http://bit.ly/QahY0C
|
| if the pre-amp tube is indeed the problem (generally those 12AX7s last forever, usually only power amp tubes you've to worry about replacing) then it's just a straight swap, no biasing or anything like that required. |
|
|
| Back to top |
|
| deadmaker |
| Posted: Thu Mar 29, 2012 1:48 pm |
|
|
Joined: 17 Feb 2006
Posts: 356
Location: Derry/Belfast
|
yeah as above i have the combo of that amp and its a straight swap i heard mad things about tubes though so i didnt dare touch it with bare hands some sort of chemical reaction aparently can wreck the tube, i read it somewhere and never tried to disprove it  |
|
|
| Back to top |
|
| Mazzy Maz |
| Posted: Fri Mar 30, 2012 4:14 pm |
|
|
|
Joined: 03 Sep 2008
Posts: 1655
Location: http://bit.ly/QahY0C
|
| yeah, you're better off handling them with a clean cloth. apparently the residue from one's greasy mitts can effect the distribution of heat across the glass surface of a tube which can lead to problems. |
|
|
| Back to top |
|
| Leather Mike |
| Posted: Fri Mar 30, 2012 4:19 pm |
|
|
|
Joined: 18 Sep 2008
Posts: 2717
|
| but it is just a matter of getting a 12ax7 and doing an old-for-new? Thank jeebus. Tubes terrify me. |
|
|
| Back to top |
|
| fonniewhelan |
| Posted: Sun Apr 01, 2012 10:46 pm |
|
|
Joined: 02 Mar 2009
Posts: 153
|
| Yeah preamp tubes are just plug and play. Nothing to worry about. As said above handle them with a cloth. Probably a lint free cloth I'd say. |
|
|
| Back to top |
|
|
|
