Members bassman339 Posted October 3, 2007 Members Share Posted October 3, 2007 hello everyone...I am re-tubing my amp for the first time and according to the rear panel of the amp, the (tube complement) is (6) 6550's, (2) 12AU7's, and (1) 12AX7. The Ampeg site shows: (3) 12AX7's, (2) 12AU7's, and (6) 6550's. Im assuming that the other 2 12AX7's are pre-amp? But I cannot locate them on my amp. Anyone that has worked on one know where the other tubes are located other then what you can see from the rear panel? Its a 2000-01modelSVT Classic Head. Anything would be a great help! Thanks in advance for your responce. -Jack Link to comment Share on other sites More sharing options...
Members Rippin' Robin Posted October 3, 2007 Members Share Posted October 3, 2007 That's weird. I'd stick with whatever the rear panel says. If you're not comfortable working around tubes, I suggest you take it to a qualified tech for safety's sake. Link to comment Share on other sites More sharing options...
Members Wanderlusterer Posted October 3, 2007 Members Share Posted October 3, 2007 hello everyone...I am re-tubing my amp for the first time and according to the rear panel of the amp, the (tube complement) is (6) 6550's, (2) 12AU7's, and (1) 12AX7. The Ampeg site shows: (3) 12AX7's, (2) 12AU7's, and (6) 6550's. Im assuming that the other 2 12AX7's are pre-amp? But I cannot locate them on my amp. Anyone that has worked on one know where the other tubes are located other then what you can see from the rear panel? Its a 2000-01modelSVT Classic Head. Anything would be a great help! Thanks in advance for your responce. -Jack Your assumption is correct, the two other 12AX7's are for the pre-amp. Where those are, I have no idea since I recently bought one myself and haven't had the need to replace the tubes. Someone on here knows though and hopefully they'll respond soon. Link to comment Share on other sites More sharing options...
Members fretless Posted October 3, 2007 Members Share Posted October 3, 2007 on a V4Bh they are inside , however I don't really recommend trying to remove 85 lbs of chassis to find out , but that's my guess . Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted October 3, 2007 CMS Author Share Posted October 3, 2007 Yup, the rest of the tubey goodness is inside the chassis. Link to comment Share on other sites More sharing options...
Members hawkhuff Posted October 3, 2007 Members Share Posted October 3, 2007 They are easy to change out. Just don't touch anything else on the chassis. 12AX7 and 12AU7's are similar tubes and are associated with preamps. They look similar too. Link to comment Share on other sites More sharing options...
Members bikehorn Posted October 3, 2007 Members Share Posted October 3, 2007 Make sure your amp is unplugged! the SVT-CL allows you to set it up yourself, so that if you can follow the directions in the manual under the 'replacing the tubes' section, you can even bias the output tubes using the little provision on the back(LEDs and a pair of bias adjustment pots). If you aren't comfortable doing it, or removing the chassis to replace the two 'hidden' preamp tubes I would turn it over to someone qualified. Link to comment Share on other sites More sharing options...
Members bassman339 Posted October 3, 2007 Author Members Share Posted October 3, 2007 thank you guys (and gals) for your responces... i picked up some new issued Tung-sol 6550 and Electro Harmonix preamp tubes to replace the original ones that came with my amp (6550WE). im hoping that those will kick some serious a$$! im also hoping that the other (hidden) tubes dont need to be replaced anytime soon...hey, anyone know any good amp techs in the SoCal area??? thanks again! -Jack Link to comment Share on other sites More sharing options...
Members Thumper Posted October 3, 2007 Members Share Posted October 3, 2007 The hidden tubes might be inside metal jackets. Some preamp tubes on older Fender amps are in cans. Link to comment Share on other sites More sharing options...
Members bassman339 Posted October 4, 2007 Author Members Share Posted October 4, 2007 i didn't see any metal sleeves like what you were discribing... oh well... there goes the idea to do it myself... i wonder if i will still be ok with just replacing the 9 visible ones... Link to comment Share on other sites More sharing options...
Members hawkhuff Posted October 4, 2007 Members Share Posted October 4, 2007 The only way they might be hidden, so to speak, is they would have aluminum sleeves around them. You would still be able to see them. I think 9 tubes is probablt the right number. I've never experienced a situation where there are hidden tubes as you describe them. At least not on an amp, TV or radio. Link to comment Share on other sites More sharing options...
Members misterhinkydink Posted October 4, 2007 Members Share Posted October 4, 2007 The two preamp 12AX7s are inside the preamp chassis. Link to comment Share on other sites More sharing options...
Members bassman339 Posted October 4, 2007 Author Members Share Posted October 4, 2007 I know this may sound stupid....but where on the amp is the "preamp chassis"? Are the tubes lying on their sides? i find this very strange since the whole idea of tubes are to disapate heat. Link to comment Share on other sites More sharing options...
Members jackcheez Posted October 4, 2007 Members Share Posted October 4, 2007 ...hey, anyone know any good amp techs in the SoCal area??? thanks again! -JackDo not go to Valley Sound in Hollywood !! :mad: Link to comment Share on other sites More sharing options...
Members jackcheez Posted October 4, 2007 Members Share Posted October 4, 2007 I think 9 tubes is probablt the right number. There are 11 all together. 3 12AX7s, 2 12AU7s, and 6 6550s. Link to comment Share on other sites More sharing options...
Members jackcheez Posted October 4, 2007 Members Share Posted October 4, 2007 The two preamp 12AX7s are inside the preamp chassis.Would that be in the upper part of the amp where the controls and all that are ? Link to comment Share on other sites More sharing options...
Members misterhinkydink Posted October 4, 2007 Members Share Posted October 4, 2007 I know this may sound stupid....but where on the amp is the "preamp chassis"? Are the tubes lying on their sides? i find this very strange since the whole idea of tubes are to disapate heat. The preamp chassis is what the knobs are attached to. 12AX7s don't get very hot. The whole idea about tubes is to control the movement of many electrons under the control of far fewer electrons. Heat helps that to happen. Link to comment Share on other sites More sharing options...
Members bassman339 Posted October 4, 2007 Author Members Share Posted October 4, 2007 thank you so much for your help...do you think i should change out those tubes as well?? i have been playing the amp off and on for about 7 years now and im replacing the 9 visible ones. Link to comment Share on other sites More sharing options...
Members misterhinkydink Posted October 4, 2007 Members Share Posted October 4, 2007 thank you so much for your help...do you think i should change out those tubes as well?? i have been playing the amp off and on for about 7 years now and im replacing the 9 visible ones. Only if it doesn't sound right so it's up to you. Those tubes will likely last forever, though. I don't replace things unless they're bad. Link to comment Share on other sites More sharing options...
Members bassman339 Posted October 4, 2007 Author Members Share Posted October 4, 2007 awesome...thanks....that saves me some time and money... Link to comment Share on other sites More sharing options...
Members poorboy Posted October 4, 2007 Members Share Posted October 4, 2007 Just remove the 4 screws on the top of the head and slide the preamp/knob section out the front just enought to gain access to the tubes.reassemble in reverse order.Takes all of 10 minutes. Link to comment Share on other sites More sharing options...
Members Decker Posted October 5, 2007 Members Share Posted October 5, 2007 Unplug the damn thing and let it sit for a couple hours before you start messing with it. The power supply filter capacitors can hold a charge for a long time even if the unit is unplugged. 500 volts can really put a crimp in your style. Link to comment Share on other sites More sharing options...
Members misterhinkydink Posted October 5, 2007 Members Share Posted October 5, 2007 Unplug the damn thing and let it sit for a couple hours before you start messing with it. The power supply filter capacitors can hold a charge for a long time even if the unit is unplugged. 500 volts can really put a crimp in your style. There's no more than 300 volts in there which when contacted makes your pecker huge. Trust me on this. Link to comment Share on other sites More sharing options...
Members bassman339 Posted October 5, 2007 Author Members Share Posted October 5, 2007 300 volts? wow that will give me enough to sport one hell of a interesting hair dew...mmmmm....dew.....damn it, now im thirsty.... Link to comment Share on other sites More sharing options...
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