The 1484 OT is used in the 1485 also, as mentioned. The 1484 uses the 4 ohm tap, and the 1485 uses the 2.66 ohm tap. I did measure this btw just to confirm what my brain told me it should be. It is WAY undersized, so it limits the frequency response, but it a large part of the tonal character of these amps so if you change it, the tone will change....might be better...might be worse. Power will go up too with a bigger OT. You can also move power up by adding a seperate filter cap node for the screens and move the screen tap to the next lug up on the doubler so it is going to the CT of the OT, then to the screens through a filter node like in a Fender. Power increases in a otherwise stock 1484 to 30 watts RMS from the stock 25. With a bigger OT, if you did this mod, you could get more like Super Reverb territory most likely. Another useful mod is to add a doubler and adjustable bias pot to the bias supply. You can get the tubes running in a safer range and extend tube life even more than stock, and get better tone too.....not so loose on the bottom and easy to distort. Preamp changes can really help too.....going towards a blackface fender can liven things up as far as supply voltages and cathode components are concerned. The reverb sux on these...don't mess with it if it doesn't work...not really worth the time. You can get better regulation, lower hum, and a slightly tighter bass by using larger cap values in the two doublers in the power supply. With what they have now, you essentially have the equivilant of a 25uf cap there. The resistors were poor quality in these amps and often drift out of spec. Any resistor will be better, and of course metal films, carbon films, and metal oxide will be quieter. You might keep the carbon comps on the plates for tonal reasons, but use better quality modern ones. The trem is fantastic...leave it alone on these if it works. I wouldn't bother with the standby change.....guitars amps don't need it to save the tubes from cathode poisoning, so as long as you have a mute feature from a standby, that is all that is needed. The Silvertone setup doesn't cancel the frequencies completely when on standby so it gives a somewhat cool sound effect when in standby if you play hard, but it still works as a mostly effective standby in a mute respect.
You used to be able to get a reproduction can cap from Zack at Vibroworld, but he closed up shop. My brother's 1484 and my stock one have the last two of these can caps that he made. (He was across town from me) I've fixed a couple since then with varying methods. Due to space limitations a can is the best choice for these amps. I had Weber do a custom can, and had to mod the hole in the chassis to make it fit, but it worked just fine. I also did one with discrete caps inside on a new terminal strips. It worked, and was cheaper as far as parts cost, but space is an issue. If I did another, I'd go with a can again. I'm on record as not liking can caps too. :)
Greg
Topic: Silvertone 1484 OT secondary impedances?? (Read 8288 times)