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Old 28th February 2011, 09:56 PM   #101
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by Melon Head View Post
7 pairs each biased at 286mA for a total of 2A using 24V rails or 7 pairs each biased at 186mA for a total of 1.3A with 40V rails.

What ever sounds best.
4 prs would work for me using 30V rails ....

Quote:
Originally Posted by flg View Post
Having said that, I did a little Pspice over the weekend and found the Low Z F5 version (19V rails and Dual Outputs) to be producing an OLG of about 233 vs. 333 for the std. F5. Source Rs of about 0R22 would raise the gain to about 255.
I'm going to procede with the build as in the schematic above.
Using Cvillier style boards ?
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Old 28th February 2011, 10:26 PM   #102
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OMG, just think, someone could build active line-arrays with like 20 F5 channels each side and trazillion Watts dissipation.

Stop, what am i saying ?
First that P guy lures me to this forum with his Monster routine.
And now i'm sucked into F5 transformer talk, on a thread of that guy who used to be at another thread.

Woosh, gone with the wind.
(well, out through the back door into the dumpster-array alley, actually)
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Old 1st March 2011, 12:01 AM   #103
flg is offline flg  United States
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Sure, CViller bds designed to be a std. circuit, and/or a cascoded circuit, and/or a dual output circuit. Whatever version that is? There is a picture on maybe your 3rd page.
Juma's suggested reading is good. But, did you notice it was centered around driving the capacitance of complimentary source followers? A Circuit like the F4?
The major consideration when driving the capacitance of a common source circuit involves the output cpacitance being multiplied by your voltage gain. For example: If the ouput stage gain is 10 multiply that * Coss for the C value you will really have to drive. Also consider how much the Coss changes with Vds.
And Jacco, I didn't say I was driving a 1000s or even 100s of watts, 25-50W is all i'll ever want with over 100db efficiency.
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Last edited by flg; 1st March 2011 at 12:05 AM.
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Old 1st March 2011, 12:25 AM   #104
flg is offline flg  United States
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Quote:
Originally Posted by EUVL View Post
The OLG is load impedance dependent.
Patrick
When I replied to you before Patrick, I may not have understood where you were coming from. Yes, as you say gain is dependant on output R. It is to easy to be thinking my version and comparing it to a std. F5 driving 8 ohms.
Truth is, in this regard, into 2 ohms is a big deal? The small mods I'm making may or may not change the sound to any great degree. But, a std F5 driving 8 ohms is well known, I stated OLG to be about 333 from my simming. I stated I found more like 233 in the version I'm workin on now, driving 2 ohms!
An F5 driving 2 ohms has an OLG of 83 @1kHz.
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Old 1st March 2011, 03:56 AM   #105
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I think the point Juma and Nelson are making is that the current requirement to drive 3 pairs compared to 1 pair is not necessarily 3 times as much. In fact it is less. This applies to both common source and common drain.
At least that is what simulations show. Thanks everyone for this discussion. I definitely had one of those forehead slapping moments here.
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Old 1st March 2011, 10:35 AM   #106
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Several years ago at this forum, someone was kind enough to thoroughly explain the charge/discharge routine to me.
As a bonus, i was informed that it also took Mr E. Borbely quite a while before he slapped his forehead.

(hey there, one could build an array of Mini F5's, not necessarily 20)

Duh, what's happening, i'm back at this thread again, starting to get that Groundhog sensation.
Woosh.
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Last edited by jacco vermeulen; 1st March 2011 at 10:42 AM.
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Old 1st March 2011, 10:46 AM   #107
Zen Mod is offline Zen Mod  Serbia
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if you mean on gate charge/discharge ( days when I couldn't get how Papa feeds 12 gates with one dreky little mosfet ,pumping 10mA ) - I was slapped by Mr. Insomnia itself (G. Rollins) .

but - hey - I'm still slapped on forehead , every second day .......
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Old 1st March 2011, 10:48 AM   #108
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Problem in your case, someone else does the slapping.
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Old 1st March 2011, 10:50 AM   #109
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No don't even suggest such things. I am sure Zen Mod will remember that one next time I say that I am dumber than him.

Seriously though this was actually an enlightening moment for me. I was actually close to discovering this several times in the past but kept ignoring the thoughts.

Too many bloody ideas kept getting in the way.
"Steve is also an ideas man. That's why Dad calls him the Ideas Man. He has lots of ideas." - The castle

You guys have to get this movie before I ruin it for everyone.
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Old 1st March 2011, 10:55 AM   #110
Zen Mod is offline Zen Mod  Serbia
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I dig it

great movie , indeed ;

just one proof more that I'm dumbest around
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