one possibility is to use the floating ps output stage - allows low voltage op amps to control output transistors which give the full supply Vgain
http://www.diyaudio.com/forums/solid-state/101602-qsc-clones-backwards-amps.html#post1204834
QSC and others have used the topology with an op amp front end
you could have A/DSL driver op amps directly driving the output mosfet gates with this topology - the entire amp's active circuitry could be op amps except for the output Q
http://www.diyaudio.com/forums/solid-state/101602-qsc-clones-backwards-amps.html#post1204834
QSC and others have used the topology with an op amp front end
you could have A/DSL driver op amps directly driving the output mosfet gates with this topology - the entire amp's active circuitry could be op amps except for the output Q
Hi Djk,
i did some digging but couldn't find any hafler schematic with op amp.Do you have one?
Thanks.
i did some digging but couldn't find any hafler schematic with op amp.Do you have one?
Thanks.
hafler schematic?
Hi Djk,
i did some digging but couldn't find any hafler schematic with op amp.Do you have one?
Thanks.
Hi Djk,
i did some digging but couldn't find any hafler schematic with op amp.Do you have one?
Thanks.
lme49830 voltage amp & driver stage is designed specifically for a discrete MosFET output stage.
Makes for a pretty good hybrid of chip & discrete SS amplifier.
Makes for a pretty good hybrid of chip & discrete SS amplifier.
Hi Andrew,
that was my first option together with lm4702,but the drivers are not available here in Kenya.
I could easily replicate a pioneer car amp and add more mosfets though,but i couldn't find someone willing to have his dismantled.Does anyone have a pioneer car amp schematic?Pioneer parts are available.
In a country full of cheap china products,diy is the way to go,not even pioneer amps produce the power it claims! I need the power of several of them.
that was my first option together with lm4702,but the drivers are not available here in Kenya.
I could easily replicate a pioneer car amp and add more mosfets though,but i couldn't find someone willing to have his dismantled.Does anyone have a pioneer car amp schematic?Pioneer parts are available.
In a country full of cheap china products,diy is the way to go,not even pioneer amps produce the power it claims! I need the power of several of them.
Hallo Djk,
wow! Thanks man. That hafler schematic has such a neat output stage.
You mentioned pull-up/pull-down resistors,please explain that.
Sorry for all these questions,this is my first ss power amp.
Thanks again!
wow! Thanks man. That hafler schematic has such a neat output stage.
You mentioned pull-up/pull-down resistors,please explain that.
Sorry for all these questions,this is my first ss power amp.
Thanks again!
Hi Xeclipse
Have you considered importing? Connexelectronics offers the components, PCBs and complete kits. See Class AB amps.
Have you considered importing? Connexelectronics offers the components, PCBs and complete kits. See Class AB amps.
http://www.qsc.com/support/library/schems/Discontinued/Series One/1100.pdf
R11, R12 are the resistors in question, the values may need to be changes a bit for the Hafler bias circuit.You will probably need to change C8 in the Hafler schematic, probably larger. This amplifier is quite simple, but will probably require you to have a friend with an oscilloscope to lend a hand for C8. Without an oscilloscope I would overcompensate, something around 30pF. R11, R12 may be determined with nothing more than a voltmeter (and before you hook up the outputs), 1K5 may be a good place to start.
R11, R12 are the resistors in question, the values may need to be changes a bit for the Hafler bias circuit.You will probably need to change C8 in the Hafler schematic, probably larger. This amplifier is quite simple, but will probably require you to have a friend with an oscilloscope to lend a hand for C8. Without an oscilloscope I would overcompensate, something around 30pF. R11, R12 may be determined with nothing more than a voltmeter (and before you hook up the outputs), 1K5 may be a good place to start.
Hi Shaun,
i thaught of importing but i wanted to build my first ss amp from locally available materials just for the experience.
Thanks for the link.
i thaught of importing but i wanted to build my first ss amp from locally available materials just for the experience.
Thanks for the link.
Hi guys,
i have this idea,i don't know if its going to work:since a large voltage swing is what is needed at the output of the op amp,i figured out i can replace the whole input stage circuit with a small power amp and a step up transformer.
I have a 22 watt btl amp.I connected the output to the primary of the transformer.At 50% volume,the voltage swing at the output was about 70 volts.I did some calculations and got a current of roughly 10 mA.
Is this setup able to drive the output stage? If so,would there be any negative effect on the signal?
i have this idea,i don't know if its going to work:since a large voltage swing is what is needed at the output of the op amp,i figured out i can replace the whole input stage circuit with a small power amp and a step up transformer.
I have a 22 watt btl amp.I connected the output to the primary of the transformer.At 50% volume,the voltage swing at the output was about 70 volts.I did some calculations and got a current of roughly 10 mA.
Is this setup able to drive the output stage? If so,would there be any negative effect on the signal?
the point of my floating supply output post above is that you don't need full Vsupply swing to drive the gounded emitter/source output transistor inputs - you only need to swing the base or gate drive V - easy with standard op amps
floating supply "backwards amp" output requires a indiviual power supply for each output - no "extra" cost if you only want mono
currently active thread with commercial schematics (for BJT, MOSFET have been used too): http://www.diyaudio.com/forums/soli...o-floating-supply-amplifiers.html#post2202342
you really don't want to drive a high current unity gain buffer stage with a conventional audio power chip amp - the chip amp is slow and decompensated - even high output V monolithic op amps are slow
the better performance potential comes from mating low V but fast opamps driving a output stage with Voltage gain - the floating ps common source topology best uses the output device V gain as well as current gain
floating supply "backwards amp" output requires a indiviual power supply for each output - no "extra" cost if you only want mono
currently active thread with commercial schematics (for BJT, MOSFET have been used too): http://www.diyaudio.com/forums/soli...o-floating-supply-amplifiers.html#post2202342
you really don't want to drive a high current unity gain buffer stage with a conventional audio power chip amp - the chip amp is slow and decompensated - even high output V monolithic op amps are slow
the better performance potential comes from mating low V but fast opamps driving a output stage with Voltage gain - the floating ps common source topology best uses the output device V gain as well as current gain
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