I'm thinking 50% gain on the Aleph I source was just that. "Twice the bias current" sounds like 100% gain 
john-china, Are you taking all this in??? 
I went out with a ghost tonight, had a Martini, maybe a second, shakin-not stirred, a good app, some fine Italian food, Italian Chianti, Expresso, Baileys, and after,,, my favorite local entertainer, an old friend. It's been a while I live in Arizona, USA 
The former and the later are to warm here. But, we could be close to a 100 Watt ZV9!!!
I went out with a ghost tonight, had a Martini, maybe a second, shakin-not stirred, a good app, some fine Italian food, Italian Chianti, Expresso, Baileys, and after,,, my favorite local entertainer, an old friend. It's been a while I live in Arizona, USA The former and the later are to warm here. But, we could be close to a 100 Watt ZV9!!! 
flg said:john-china, Are you taking all this in???
yes ,thank you ,thank nelson.too
my english is so poor that i can not express well about big zv9.
but what you care about is what i want to ask? specially about -600mv/A this sweat pot . so you assist me to get a official answer , thanks.
i am glad to hear that sweet spot does not stay at only 2 A bias and 2.5 v D-S voltage with 0.6ohm source resistor .,
i can adjust lu1014d to any bias and any voltage i want . of course i will consider this sexy curve and power rate of the jfet
last, did i really understand what Papa said?
rmihai, I can't imagine why: "My speakers need as close as posible to 175W pc in 8 ohms." Is it possible you need new speakers? Is it possible you would be happier with a different Class of amp configuration? (AB or B) But then Nelson would probably say "a 175W ZV9 would be a simple matter of scaling the existing design with parallel Mosfets." Or maybe he would say "buy an X amp!" Or, maybe that dual JFET idea I posted a few pages ago might be useful
My concerns would actually be more like... That much power requires substaintial voltage drive or gain. That may become difficult, or at least more complex. It will also require gobs of current. At very least that will be more expensive. And, at an efficiency of 5-20% plus or minus, you may not be able to plug this beast into one typical 115VAC wall outlet
I just received some pretty good sized heat sinks for one of my projects. I'm only expecting to make 25W/ch
Is it possible you would be happier with a different Class of amp configuration? (AB or B) But then Nelson would probably say "a 175W ZV9 would be a simple matter of scaling the existing design with parallel Mosfets." Or maybe he would say "buy an X amp!" Or, maybe that dual JFET idea I posted a few pages ago might be useful My concerns would actually be more like... That much power requires substaintial voltage drive or gain. That may become difficult, or at least more complex. It will also require gobs of current. At very least that will be more expensive. And, at an efficiency of 5-20% plus or minus, you may not be able to plug this beast into one typical 115VAC wall outlet
I just received some pretty good sized heat sinks for one of my projects. I'm only expecting to make 25W/ch 
Yes, I'm also curious why you require 175 watts.
Is this what the speaker literature recommends? Or is it something you've tried and prefer? Have you tried smaller amps? I asking because the power required varies depending on a lot of things, including the size and furnishing and material of the room so the manufacturer's rating is a vary nebulous figure.
Also, half the power only makes the volume a small amount less loud and the average power is only a few watts usually - or even less!
Sorry if this is stuff you already know..
Is this what the speaker literature recommends? Or is it something you've tried and prefer? Have you tried smaller amps? I asking because the power required varies depending on a lot of things, including the size and furnishing and material of the room so the manufacturer's rating is a vary nebulous figure.
Also, half the power only makes the volume a small amount less loud and the average power is only a few watts usually - or even less!
Sorry if this is stuff you already know..
I think I need 175W because my speakers (a DIY project - Ellis Audio) are rated 83.5db/m.
I usually listen at low levels: SPL 68-70, but, when I really want to enjoy something I listen at 75db SPL.
To achieve an average of 75db SPL is not dificult. The problem are the peaks that can go as much as 30db!!! That is why I need an amplifier that will be able to deliver 175W - so that will have enough headroom to get the 30db peaks properly.
I usually listen at low levels: SPL 68-70, but, when I really want to enjoy something I listen at 75db SPL.
To achieve an average of 75db SPL is not dificult. The problem are the peaks that can go as much as 30db!!! That is why I need an amplifier that will be able to deliver 175W - so that will have enough headroom to get the 30db peaks properly.
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