Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: fossilshark on May 15, 2017, 07:32:06 am

Title: This circuit for guitar amp
Post by: fossilshark on May 15, 2017, 07:32:06 am

Ive used this circuit as a headphone preamp, but would i be able to increase power output from the mosfet to get mabey 5 watts out of it? Or should i just replace the mosfet with a 5w audio amp chip?

Title: Re: This circuit for guitar amp
Post by: kagliostro on May 15, 2017, 09:47:07 am

Ciao Fossilshark

Your image results to be hard to read, seems that this is the same schem, only more readable

(http://i.imgur.com/8MZnq4Z.png)


http://www.instructables.com/id/Class-A-Hybrid-Headphone-Amp/ (http://www.instructables.com/id/Class-A-Hybrid-Headphone-Amp/)

Franco

Title: Re: This circuit for guitar amp
Post by: PRR on May 15, 2017, 04:16:37 pm

> Or should i just replace the mosfet with a 5w audio amp chip?

This.

Yes, a headphone amp "can be" a loudspeaker amp, except you want about 1,000 times more power. So simple-stuff which is also inefficient may be practical at phone level but excessive at loudspeaker level. This topology won't reach 25% efficient. That means to make your 5 Watts it must dissipate over 20 Watts. This is essentially the heatsinks from a 40 Watt push-pull AB transistor amp, 5 to 10 times the heatsinking you need for the 5W chip amp.