Nada Posted July 20, 2013 Posted July 20, 2013 (edited) Any opinions on the F4 design ethos? Anyone heard one? Edited July 20, 2013 by Nada
georgehifi Posted July 20, 2013 Posted July 20, 2013 (edited) This is a unique amp that has no voltage gain, it is a current amplifer, so what is needed is a source or preamp that can give the voltage to it as it has no voltage amplification itself. You need a preamp or source that can swing good voltage around 15v output, so if you use a source like cdp/dac that has 2v, you'll need a preamp that has around 7 x gain, passives need not apply, unless your cdp/ or dac gives out 15v Cheers George Edited July 20, 2013 by georgehifi 1
hochopeper Posted July 20, 2013 Posted July 20, 2013 As George says, its usefulness depends on the efficiency of your speakers and gain of your pre/dac and target max output. I think many people have far more gain in their electronics than is necessary. I am a fan of the F4 concept and would love to hear one! I would love to hear one driving an active Synergy horn or similar. 1
davewantsmoore Posted July 21, 2013 Posted July 21, 2013 You can also use a "power amplifier" as the input for this type of amp.
ehtcom Posted July 21, 2013 Posted July 21, 2013 You can also use a "power amplifier" as the input for this type of amp. Would be interesting to hear one hanging off the back of a SET amp. 2
Rob181 Posted July 21, 2013 Posted July 21, 2013 Would be interesting to hear one hanging off the back of a SET amp. Hmmm....yes it would be....Rob
Nada Posted July 21, 2013 Author Posted July 21, 2013 This is a unique amp that has no voltage gain, it is a current amplifer, so what is needed is a source or preamp that can give the voltage to it as it has no voltage amplification itself. You need a preamp or source that can swing good voltage around 15v output, so if you use a source like cdp/dac that has 2v, you'll need a preamp that has around 7 x gain, passives need not apply, unless your cdp/ or dac gives out 15v Cheers George I get very confused with gain. Does "swing good voltage around 15v output" mean about 15 volts (p-p) ( = 5.3 volts (RMS) = 14.5 dBV = 16.7 dBu) How do we work out how many Vp-p our speakers need for full volume?
hochopeper Posted July 21, 2013 Posted July 21, 2013 Nada you're asking the right questions, but since I'm away from home I won't be able to give a comprehensive response by typing on my phone! The F4 is good to about 20V p-p ~14.5V RMS. The calc for peak output depends if your speaker is rated in dB/2.83V or dB/W and how honest the speaker manufacturer has been with their rating. They often don't give any data about peak output either. You also need to account for the crest factor and dynamic range of the source material you're playing. We really need an article 'Gain for Audiophiles' because it is quite widely misunderstood and proper gain structure IMO has more impact on sound quality than many of the things that we worry about. 2
henry218 Posted July 21, 2013 Posted July 21, 2013 we should have 1 dedicated day for nelson pass day. that man went above and beyond to contribute to a proper audio world (didnt mean to disrespectful to anyone) henry
Nada Posted July 21, 2013 Author Posted July 21, 2013 (edited) we should have 1 dedicated day for nelson pass day. that man went above and beyond to contribute to a proper audio world (didnt mean to disrespectful to anyone) henry he's one cool dude and vey smart giving his designs away to the DIY guys Edited July 21, 2013 by Nada 2
Nada Posted July 21, 2013 Author Posted July 21, 2013 (edited) RMS voltage, peak voltage and peak-to-peak voltage VRMS = 14 VoltsVp = 20 VoltsVpp = 40 Volts Edited July 21, 2013 by Nada
hochopeper Posted July 21, 2013 Posted July 21, 2013 (edited) I'm going to ban myself from posting from my phone (after this one to correct my earlier mistake). +/- 23V rails ... 20Vp unclipped (my post earlier says 20Vp-p which is wrong). F4 manual is quite handy Edited July 21, 2013 by hochopeper
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