Tweet
I've been hanging on to some giant potted output transformers for a few years, thinking they'd make a great bass amp. I was wrong.
I ordered up some Sovtek 6550's and Tung-Sol KT120's so I could build a small bass amp with the 6550's and a large one with the KT120's. I have some large power transformers that have been recycled from various old equipment so I thought I was all set.
I hooked up the 6550's with a transformer I know to be at least half decent- it's a New Sensor generic 50 watt output, roughly the size of a Fender Twin output transformer. With about 500 volts on the plates and 350 on the screens the setup made about 70 watts. Sounds great, all I need for an overgrown B15 or a 4x10 wired up with 4 8 ohm speakers in parallel (the TF has a 2 ohm tap).
I tried the KT120's and got about the same power- so I know that either the transformer or plate voltage is the limitation. No big deal, I expected that.
I hooked up the big potted outputs in hope of easily producing the same power since the impedances are the same. Boy was I wrong.
The potted transformers only got to about 40-45 watts before the waveform looked CRAZY. While the New Sensor transformer was only drawing 280 or so ma to make 65 watts, the potted transformers were closer to 400 for way less output. I wondered if I'd miscalculated the taps so I double checked and I was right the first time. I tried mismatching up and down and really wasn't able to get much more out of the things. The core in the potted TF is about the size of a twin reverb power transformer so I thought it would have easily done closer to 100 watts. No dice.
So anyway, I had to vent. I'm sad that I won't be building a giant and powerful bass amp with my KT120's any time soon. Time to look for another output transformer. Meanwhile I have battleship grey potted outputs that are probably only good for about 35-40 watts each. They have ultralinear taps that I didn't hook up. Maybe I should try them and see if it helps. I guess I can use a spare Fender PT and make a new shop stereo or something. At 13 pounds each I don't really want to put them into anything I intend to haul around a lot.
I wonder if they actually WERE for a battleship?
jamie
I ordered up some Sovtek 6550's and Tung-Sol KT120's so I could build a small bass amp with the 6550's and a large one with the KT120's. I have some large power transformers that have been recycled from various old equipment so I thought I was all set.
I hooked up the 6550's with a transformer I know to be at least half decent- it's a New Sensor generic 50 watt output, roughly the size of a Fender Twin output transformer. With about 500 volts on the plates and 350 on the screens the setup made about 70 watts. Sounds great, all I need for an overgrown B15 or a 4x10 wired up with 4 8 ohm speakers in parallel (the TF has a 2 ohm tap).
I tried the KT120's and got about the same power- so I know that either the transformer or plate voltage is the limitation. No big deal, I expected that.
I hooked up the big potted outputs in hope of easily producing the same power since the impedances are the same. Boy was I wrong.
The potted transformers only got to about 40-45 watts before the waveform looked CRAZY. While the New Sensor transformer was only drawing 280 or so ma to make 65 watts, the potted transformers were closer to 400 for way less output. I wondered if I'd miscalculated the taps so I double checked and I was right the first time. I tried mismatching up and down and really wasn't able to get much more out of the things. The core in the potted TF is about the size of a twin reverb power transformer so I thought it would have easily done closer to 100 watts. No dice.
So anyway, I had to vent. I'm sad that I won't be building a giant and powerful bass amp with my KT120's any time soon. Time to look for another output transformer. Meanwhile I have battleship grey potted outputs that are probably only good for about 35-40 watts each. They have ultralinear taps that I didn't hook up. Maybe I should try them and see if it helps. I guess I can use a spare Fender PT and make a new shop stereo or something. At 13 pounds each I don't really want to put them into anything I intend to haul around a lot.
I wonder if they actually WERE for a battleship?
jamie