Hello All, Several years ago I completed a 5f1 build in part with the advice / help of some folks here. I really quite enjoyed it, and have been using it exclusively (other than a pignose I keep in my office at work) since it was completed. However, I have also been itching since that time for another project amp, but life has not generally been particularly friendly to that goal (live in an apartment, have a 2-year old, money tight, etc). In addition, I have also found myself occasionally wishing that the amp had a few more options for tone given that it is my only rig and I would rather not have a cumbersome pedal board. Had various mods in mind, but as is commonly noted the form factor of the 5f1 isn't very forgiving on space. So, I have decided to gut and rebuild the amp to address these problems and also clean up a lot of beginner sloppiness that has been bothering me from the beginning. My plan is to basically modify it to more of a 5f2a, but with an added tremolo circuit, attenuator (I`m exclusively a bedroom player, so getting some crunch without one is a no go), and switchable NFB. I am making a chassis that is copied from the ga-5 skylark, in part because I like the look of it but more so because it is accessible to me with the tools/resources I have available. I`ll also make the cab as I did with the original build. I know the 5f2a had a 10" speaker, but I am planning to stick with the 8" weber sig8 from my 5f1. The goal here is three-hold: 1) a new project to work on; 2) expand the tonal options of the amp, as I am a bit of a minimalist gear wise and this is my only rig; and 3) provide a platform that is amenable to later tinkering and modification. However, I wanted to ask a few specific questions before starting, and also solicit input from the community about what other changes might be good ideas. Circuit: My understanding is that the principal circuitry differences between the 5f1 and 5f2a are the tone pot and the addition of a second 16uf filter cap. My plan is to simply copy those verbatim, but someone please tell me if I have overlooked some detail. Tremolo: I am planning to copy the tremolo circuit from the aa764 vibrochamp and splice it into my 5f1/5f2a circuit. The aa764 overall schematic appears very similar, and I can see where the tremolo enters it on the cathode of v1b. However, the aa764 has an extra 47 ohm resistor after the "normal" 1500 ohm resistor heading into the ground. In addition, there appears to also be a cathode bypass cap on v1b, which is not present in the schematic of either the 5f1 or 5f2a. So, I`m curious what the origin of these differences is, and are they required to make the tremolo work with the 5f1/5f2a circuit? Also, if I use a pot with on/off functionality similar to the volume control of the 5f1 for the intensity control of the tremolo, will that effectively cut it out of the signal path when in the "off" position, or is some other mechanism required to isolate the circuit? Suggestions: I would happily take any other suggestions regarding what other modifications might provide the most "flexibility" in the amp. The chassis will have plenty of space for other things, although I of course want to strike a balance between flexibility and complexity.