I give high marks to Orange for delivering a serviceable design of amp(s). As always, you made short work of this. Stuart. I look forward to the next spine-tingling episode. Stay safe, and warm mate. Cheers!
Hi, this is agreat video. Do you where I can find information or a video on changing the preamp valves? I understand the reverb and loop have one valve each so leaves 4 preamp valves. It would be good to know which these are and which have to be matched/paired together. Thanks
Hi Preamp valves don't need matching or paitring so just go ahead and change like for like. EG ECC83 for an ECC83 etc. Also, only change them if you really need to. Valves are expensive these days and preamp valves last ages.
Hello again Stuart I am trying to find a compatible Reverb Tank for the Orange RockerVerb MK 2 amp that I have just managed to repair with your help. May I ask if you know the input and output impedance of the spring unit? I cannot find any specific Orange replacements, as most retailers only give the input/output values, and most only refer to other amp manufactures. Thanks once again. Regards Keith
Hello Stuart Thank you for your response. I acquired the amp second hand, in nearly new condition and I just replaced the 2 output valves. It did not have the reverb tank installed. However, I have the serial number on the back of the Amp and the serial number on the main board. This may be useful to try and purchase the correct spring reverb module for it? I have searched the web with no luck so far. I am not sure whether or not, that Orange made identical reverb units for the Rockerverb MK2? Best regards Keith
Great For about £30.00 its probably worth the try? I am going to research a bit more, just in case I can get a bit more information. It is a personal project anyway and not about money. I am a retired electronics technician, mostly doing old fashioned electronics, component level replacement etc. I have found a new joy in valve technology - you can actually repair them instead of throwing the boards in the bin - as is most technology now? Thanks Stuart. Keith
STUART, if the bias is 35mA and the plate voltage is 350vdc or 400vdc the bias voltage on the grid of the power tubes should technically be HALF of the plate voltage? so around 150vdc on the grids of the power tubes?
Hi Wayne. Absolutely not! In general the grid is held NEGATIVE with respect to the cathode. Even 0V on the grid would cause the power tubes to burn out. I think I've done a video on this, try my 'How Guitar Amplifiers Work' mini series. All the best.
@@stuartukguitarampguy5830 When Biasing PNP transistors the Collectors output voltage is HALF the +Vcc Power Voltage. For Power Tubes its the same as biasing PNP transistors that the Plates should be HALF of the +Vcc power voltage. This is to get the correct symmetry of the positive cycle and negative cycles to have no clippage and the most headroom
@@waynegram8907Transistors are biased completely differently to valves. For a valve the grid is held negative wrt to the cathode. I'm talking DC of course, not AC.
@@stuartukguitarampguy5830 thanks for this, I was using the output transformer resistance method to bias coupled with a bias probe as outlined as the preferred method on Rob Robinette´s calculator website. Obviously that method is a bit more engaging not necessarily difficult, I was wondering if the method shown in your video will achieve the same results?
