Hi All, Slowly making headway on designing the 2xEL84 Class AB1 amp with twin cathode follower preamp. My only experience with picking power transformers is Class A single ended designs, so I’ve got questions. Here’s what I have so far as design estimates: B+1 voltage 400V @ idle B+1 current 55mA @ idle, 201mA peak @ power tube full drive 1st question, does the idle current vs. peak current at full drive look about right for P-P EL84’s howling at 400V plates and 320V screens? For the peak overdrive condition, I just added up the estimated plate and screen current for one tube (since the other tube is cutoff) and then added in estimates for current from the preamp tubes. Transformer: Hammond 373EX Rectifier: 5AR4/GZ34 I went through Merlin’s power supply design using the above conditions (idle and full overdrive). I estimated B+1 at 408VDC at idle, sagging to 384VDC at full overdrive. I estimated the maximum overdrive RMS ripple current in the input filter cap (reservoir) to be 362mA. Since this is a center-tapped HT winding and I’m using a two-phase rectifier, Merlin notes that actual RMS ripple current in one-half of the secondary is 0.707 times the full amount, so that brings the RMS ripple current seen by each half of the secondary winding down to 256mA. The Hammond 373EX secondary is rated at 325v-0-325v @345mA. So it appears this transformer can handle my demands. My second question is, is the power transformer too large for my needs? Is the current rating listed on the Hammond datasheet a hard limit that I should not exceed? Or can I exceed it and just expect more sag out of the transformer. Maybe a smaller PT would sag more and add a nice dynamic to the overall feel of the amp. If so, how small could I safely go on the current rating, assuming the HT winding still provided me with 400V B+1 at idle? I was surprised that I would need such a big power transformer for this amp with 2xEL84’s. But I’m new to this particular game, so maybe that’s just the way it is. Any tips or points about what I might be missing? I searched the web on this and was surprised to find a lot of people just met the current demands at idle and made no estimates of what the current would rise to when driving the amp hard. But I’m assuming in the P-P world, you have to look at worse case current and that would be when overdriving the power tubes. Correct?