FritzS
Been here a while!
Sound of Blue Danube
Sound of Blue Danube
Posts: 1,364
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Post by FritzS on Jan 30, 2008 9:49:57 GMT
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Jan 30, 2008 22:15:28 GMT
Overcomplicating the simple is my thought WCF,SRPP,MU Stages,CCS tricks,all from the same "tolology gene pool" and may have some merit but my thought is most just can't STAND a simple topology so no matter what the amp sounds like set upon a path to "improve" on it through theoretical/measured specs then when it sounds like crap set out on the (usually) parallel path of boutique parts upgrades just to make the damn thing listenable yet when all is said and done ? This : will usually whip its ass if driven by a low source impedance and if powered properly.Single ended topology has a way of letting more information PASS ,and that in a musically accurate/relaxed manner rather than creating NEW inforation (details etc.) At least in my opinion anyway ;D
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Deleted
Deleted Member
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Post by Deleted on Jan 30, 2008 22:33:14 GMT
At last, a breath of sanity into these overengineered projects. SandyK
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leo
Been here a while!
Team wtf is it?
Posts: 3,638
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Post by leo on Jan 30, 2008 22:45:40 GMT
Come on Fritz, get the thing built and let us know how it sounds, you could easily build what Rick suggested point to point onto a heatsink, it couldn't be anymore simple
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Jan 30, 2008 23:35:27 GMT
At last, a breath of sanity into these overengineered projects. SandyK "..........if driven by a low source impedance and if powered properly." Simple as shit circuit with the devil being in the details : 1-The gate of the MOSFET MUST have a low impedance driving it or the gate capacitance in combination with the driving source impedance will make a dandy low pass filter that can in some cases destroy the top end 2-PSRR (power supply Rejection Range) is shite so any power supply contemplated better be up to the task or will be the limiting factor of the overall sonics (and is the most costly part of the build BTW ) 3-KISS-"KEEP IT SIMPLE STUPID"-and by "simple" i mean leave the fkn fancy CCS and boutique parts for R4 where they belong...as passing thoughts.Instead use a nice low inductance 5W resistor that using ohms law will get you in the 175-200mA range steady state draw for the MOSFET then close the fkn cover and listen. This last was the hardest lesson for me to learn with this amp with the second hardest being to go against my desire to make the amp a tube/mosfet hybrid,something DOOMED to fail unless you make the gain stage a Cathode follower,a single ended WOT stage (Se Class-a gain stage to 600 ohm out IT),a hybrid cascode CCS,a MU Stage or other SRPP type circuit ALL of which overcomplicate and over $$$$$$$ this "simple" amp without to be honest adding a single thing of sonic merit ;D
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Post by sometrolls2 on Jan 31, 2008 0:04:09 GMT
'low source impedance' what is okay for that? Is this just the output of an off the shelf CD player or does it need a buffer or preamp or something?
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Jan 31, 2008 0:53:10 GMT
pretty much any solid state gear will have a low enough impedance BUT you need to not only take into account the resistance of the interconnects but also their overall capacitance which WILL become part of the equation if the amp itself was ready to receive it properly which unfortunately it is not.
why ?
the volume pot is why !
The high value resistor is a major impediment to anything that goes before thus for best results needs to be isolated from the mosfets gate by adding another stage of active buffering so the amp goes
1-vol pot along with any RF filter or DC coupling caps 2-high-Zin/Low-Zout buffer (opamps are fine if you like 'em,Class-a discrete much better 3-Szekeres Stage
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Feb 2, 2008 18:54:31 GMT
BTW-Seldom,OK... NEVER do I see posted the actual "Szekeres" amp from the Greg's own page (Greg Szekeres that is ) so for posterity sake here is the bad boy live and in you face ;
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Feb 2, 2008 18:56:12 GMT
...note the absence of a volume pot (murders the highs 0 which is really really really not needed if the feeding source has its own rickaraptor
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Post by davygrvy on Mar 19, 2016 1:02:41 GMT
Found this thru Google, so I thought I'd post. This my version of a white cathode follower using depletion-mode MOSFETs. Have fun
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