Balanced F5 in a Small Footprint

[Zen Mod]

the current design, then add more outputs with matching source and gate resistors, (for a total of 5 outputs per rail) or 10 total outputs

doubled input Jfets , cascoded also , increased rails

so , yes

read F5 Turbo article , see 100W version (you can ignore diodes across source resistors for now) , imagine it bridged/X-ed ......... and you have 300-300W amp in practice

 

[Club-SPL.com]

FQA28N15 amp schematic

The first PCB was built using FQA28N15/FQA36P15 MOSFETs, .25 ohm Caddock source resistors, and 50 ohm Caddock feedback resistors as shown in the first image. Because of the limited power dissipation requirements, I mounted the Caddocks vertical to the PCB. I later found that this is a bad idea because the leads on the Caddocks are fragile and break after a few flexes. I "repaired" the Caddocks and mounted them to the heatsink using clamps as shown in the 2nd and 3rd images.

is it possible to use 5X5 (5 FQA28N15s and 5 FQA36P15s ) in a stereo mode amp, using 100v rails with that design? I'm interested in doing such a build
and would appreciate a schematic. in other words I have 10 of the FQA28N15s and 10X FQA36P15s and would like to use all of them in a build.
my power supply is already built tested, working with 50/50 rails or R-R 100v dc

 

[Zen Mod]

50+50V rails ...... we are speaking about megagigawatt range here ...... remember it's bridged amp

go either for BA3 or any similar , non bridged amp

I doubt you either need or you are capable of trouble-free making of 350W/8R/ch amp ....

besides that - this amp is having forur output quadrants ..... with smallest possible number of outputs (in elevated voltage range ) of 3 per quadrant

so , just for one channel you need 6P + 6N mosfets

 

[lhquam]

And those rail voltages would require that the input jfets be cascoded, and you would need an extremely massive heatsink. The "Balanced F5 in a Small Footprint" isn't the design you want to consider scaling to higher rail voltages.

http://www.diyaudio.com/forums/pass-labs/213152-balanced-f5-small-footprint-17.html#post4330928

 

[Club-SPL.com]

sure is, but I'm adding the extra power to my existing setup and want to do a home build amp this time around, and want to exceed more than just amp repair, want to build my own 300+ watt amp with what parts I already have, and just need a good schematic to go off of to test run

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[Zen Mod]

doable , yes

read F5T article , and then just make it in balanced fashion

 

[AndrewT]

read the F5x Threads. It is a balanced design and designed to be balanced from the outset.