F4 power amplifier

[Zen Mod]

in Italy - look for Icar

that's enough - premium quality , even if Italian

joking of course .......

Forza Vale !

[jacco vermeulen]

Originally Posted by pjgregory

Do you have a manufacture

If you hand Goldmund $10K for Zeus' 1st wife, you receive one motor run cap for free.

[pjgregory]

The courier arrived today with two 5U 400mm cases from HiFi200. Great Italian craftsmanship. They are listed as "Pesante Dissipante" which literally translated means "Heavy Dissipater". Well they certainly are heavy - the courier left them on the front step rather than risk a hernia carrying them into the house.

As I suspected, each side heat-sink is in two parts. So now it's off to find some copper strip to thermally connect the six output JFETS.

(I am still worried about the small pile of screws leftover after assembly - never a good sign.)

PJG

[tinitus]

Originally Posted by pjgregory

(I am still worried about the small pile of screws leftover after assembly - never a good sign.)

PJG

not if it were an engine

but in this 'case', who is counting

[buzzforb]

Originally Posted by Zen Mod

well - there is a small tweak available for you :

omit output caps on , omit everything in front of two electrolyt caps on F4 input ( tossing out jfet buffer and everything related) , bypassing two elcos with 10-68nF polycarbonats ........ then tell me what's your impression






yeah ....... but only when I'm forgetting fact that I'm spitting image of Modesty Blaze

Modesty Blaise - Wikipedia, the free encyclopedia

Does a power buffer like the F4 benefit from SUSY affect created in Pumpkin FE. Having no V gain does it still benefit from cancellation. Also, any insight into why Nelson uses different buffer on BA amps. Is it just to be able to extend Class A bias further before going into AB?

[juma]

Originally Posted by buzzforb

Does a power buffer like the F4 benefit from SUSY affect created in Pumpkin FE. Having no V gain does it still benefit from cancellation. ...AB?

Yes it does, but only if F4 is included in SuSy feedback loop.

[buzzforb]

Thanks Juma. Do you happen to have Spice model for Toshiba fets.

[juma]

Only for small JFETs (k170/j74), but they are omnipresent anyway...
I suppose you are hunting for the big ones ?

[buzzforb]

Originally Posted by juma

Only for small JFETs (k170/j74), but they are omnipresent anyway...
I suppose you are hunting for the big ones ?

Yeah, looking for the 2sk2103/313. Not really experienced enough to just start building stuff. Would like to see if PSpice says it will not blow up. Oh well. I was going to try the OPA1632 with small F4 or F5 output. may use simpler Jfet FE and try SUSY.

[juma]

Originally Posted by buzzforb

... Not really experienced enough to just start building stuff...

There's nothing much to it: Vgs controls the Id which should be kept under 1A (2A peak if you keep the k2013/j313 reasonably cool). Basic stuff about MOSFETs and three ways to use them are described in Mr. Pass' F5 paper. That's all you need to get started.
Start with simple circuits, use the datasheets, analyze your results and understanding will come. You can't really depend on sims - they won't tell you the whole truth, but they can save you some time by calculating static parameters for you (after you learn how to do that manually).
Knowledge has never been so accessible, you just need to put some effort into it....