SUMO Power Amp - Page 12

djk · 26th June 2011, 01:00 PM

"does it have to be a fet-input opamp? "

Not at all, but remember that the input capacitor and resistance values are designed for a very high input impedance, and whatever you use must be able to work with the high voltage involved (the LF 353 was selected). You are in effect redesigning the amplifier and compensation and bias will also need to be examined.

I think changing out the ceramic caps will do more for the sound quality than changing the opamps. I chose the OPA 2604 on the basis that it has high input impedance, can run on the higher voltages without having to be selected, and I like the sound. JB suggested that he liked the AD 823 better, but that you need to select it for the higher than the spec sheet voltage used in the Sumo.

reteP2k · 29th December 2011, 12:46 PM

Does anyone know of any good books on Tube Amps & Building them?

Thanks

jpr_pt · 29th December 2011, 01:45 PM

Look at Morgan Jones books: Valve Amplifiers and Building Valve Amplifiers
You can also take a look at I.R.Menno Van Der Veen books: High End Valve Amplifiers.

26th June 2011, 01:00 PM	#111
djk diyAudio Member Join Date: Feb 2001 Location: USA	"does it have to be a fet-input opamp? " Not at all, but remember that the input capacitor and resistance values are designed for a very high input impedance, and whatever you use must be able to work with the high voltage involved (the LF 353 was selected). You are in effect redesigning the amplifier and compensation and bias will also need to be examined. I think changing out the ceramic caps will do more for the sound quality than changing the opamps. I chose the OPA 2604 on the basis that it has high input impedance, can run on the higher voltages without having to be selected, and I like the sound. JB suggested that he liked the AD 823 better, but that you need to select it for the higher than the spec sheet voltage used in the Sumo. __________________ Candidates for the Darwin Award should not read this author.

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29th December 2011, 12:46 PM	#112
reteP2k diyAudio Member Join Date: Dec 2011 Location: St. Lucia	Does anyone know of any good books on Tube Amps & Building them? Thanks

29th December 2011, 01:45 PM	#113
jpr_pt diyAudio Member Join Date: Dec 2008	Look at Morgan Jones books: Valve Amplifiers and Building Valve Amplifiers You can also take a look at I.R.Menno Van Der Veen books: High End Valve Amplifiers.

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