Cascoded F5

[thor61]

Hello Everyone : I just purchased a set of the Cascoded F5 pcb's. Please advise me as to how to construct this amplifier ! Any help would be greatly appreciated !

[Russellc]

Originally Posted by thor61

Hello Everyone : I just purchased a set of the Cascoded F5 pcb's. Please advise me as to how to construct this amplifier ! Any help would be greatly appreciated !

Where did you get them from? That's where you should start. If from the DIY store, check Civler's blog explaining them.

Russellc

[Russellc]

http://www.diyaudio.com/forums/blogs...version-2.html

[Andersonix]

Start with selecting the heat sinks and work backward from there.

[tinitus]

no, first get hold of all transistors
and make sure they are genuine
too many frauds around

[AudioSan]

where to start depends on what is most important to you.
but in any way. you need the genuine J-fets. h_a and spencer on this forum can help with that.
next is price, power, size, heat.

[Andersonix]

I was trying to be too clever: All else falls into place once the HS are selected, because to choose a HS, one must first have decided power output, number of output devices, and bias point, which combined decide the PS size. Also, the HS sets most of the cost and influences the construction type (appearance).

[thor61]

Can a 400Va 2 x 18v transformer be used ? I understand the blog says 2 x 22v what can be expected from using a lower voltage ?

[Zen Mod]

yup

[flg]

Using 18VAC secondaries takes the "need" to cascode away. You can just use a few jumpers on the PCB and not use the cascode hardware. The original F5 was built with 18VAC secondaries without cacodes. However, for more output power you probably want higher voltage secondaries and a cascoded input.
There is also the possibility that cascoding could give better sound? There is no reason you can't use the cascode with your 18VAC secvondaries.