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FDP Forum / Amp Mods, Repairs, and Projects / Frontman 15G Experiment



Jan 26th, 2018 02:28 PM   Edit   Profile  

Currently came across an old frontman 15G practice amp. It's a solid state 15w with an 8ohm speaker which actually sounds ok paired with a 12'' efficient speaker. I was thinking on experimenting to try to make the amp work with a 4ohm load, was wondering if possible at all what would i have to mod? power transistors would do the trick maybe?



Jan 27th, 2018 04:57 AM   Edit   Profile  

The Frontman 15G doesn't use discrete power transistors, it uses the TDA2050 power amplifier IC. This is rated at up to 35 Watts into 4 ohms, so the power section of the amplifier is capable of doing what you want.

The unknown factor is the power supply. You won't get 35W since it requires a ±25V supply, the Frontman has ±23V (as far as I can tell from the scanned schematic). The limiting factors will be the current the power supply can safely deliver and the heatsinking of the TDA2050. By running it at twice its design rating you could overheat the mains transformer if you use the extra power for any length of time. There's also the question of how much heatsinking Fender have supplied for the TDA2050. Will it cope with double the power? Will its maximum temperature be exceeded?

If you just want to use the 4 ohm because of how it sounds and don't keep the volume cranked for long(ish) periods you should be OK, just don't think of it as a 30W amp.

edited to add TDA2050 data sheet link


Frontman 15G schematic

(This message was last edited by SonicBlue at 07:06 AM, Jan 27th, 2018)



Jan 29th, 2018 01:14 PM   Edit   Profile  

Thanks, I will give it a try at 4ohm. What would be the first or most possible component(s) to fail?



Jan 29th, 2018 03:37 PM   Edit   Profile  

It could well be something in the power supply or the TDA2050.

FDP Forum / Amp Mods, Repairs, and Projects / Frontman 15G Experiment

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