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Old 19th March 2010, 04:57 PM   #291
Ipanema is offline Ipanema  Malaysia
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Default My "en"lite

No depletion, but IRFP240. Anyway, it sounds pretty good, even nicer to look at (other lights off). Transistor biasing ala F2 but resistors value are 10X larger since only these are available in my junk tray. Does larger value biasing resistor affect performance?

BTW, reason for choosing depletion transistor is just for ease of biasing or because of its special sonic attribute? Can anyone share their experience with both delite and enlite comparison.
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Old 19th March 2010, 04:59 PM   #292
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Originally Posted by revintage View Post
Hey Stefano,

That it not an option as the FET already sets the current. Two different wills trying to set the standard.

Hello ,
Does not happens also in Zen V9 the same thing , the jfet
are selfbiasing , and the current source current has somewhat to be trimmed
for best results ?

If the light bulbs set the Zout , why not the CCS at the same place plus a resistor output -ground as seen many times in the Zen series .

The resistor also helps a lot to equalize the response of the driver , an effect that I like a lot .
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Old 19th March 2010, 07:57 PM   #293
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They don't fight if you have some DC feedback to hold the
operating point. It doesn't take much, as in the circuit
shown above.

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Old 19th March 2010, 09:26 PM   #294
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Location: Montreal

I am listening to this thing and woaw!!!

I am using a Quickie from Bottlehead (active preamp on batteries) and I hooked a pair of back loaded horns based on the Fostex 206 es-r . Right now, I am listening to "You Look Good To Me" (Oscar Peterson trio) and this is really wonderful!!!!

I had some problems (slow blow fuse blowing once in awhile), and the bias pots are 99 cents a piece and it shows.... But I am very pleased with this.

I will demo this to the Montreal diy show of April 24, along with other brothers in arms of the local diy community. Some have created variances on the same theme...

I might get sponsored by a sun screen lotion or sunglass company (or both), the light being so intense!


Thank you for another fun opportunity Mr Pass!
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Old 20th March 2010, 02:34 AM   #295
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I haven't build this amp since I haven't bought parts for a long time, but I like the simplicity. What about trying a fixed bias SRPP type of setup. It seems like it would be simpler then the common ways of doing a current source but still use only a few more parts, like this setup:

The Tube CAD Journal,SRPP Decoded
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Old 20th March 2010, 05:09 AM   #296
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I have a couple of those for this same circuit, and they
work like glue. But you can't read by them.

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Old 20th March 2010, 05:22 AM   #297
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Hey Nelson,

Does work like glue mean slow and sticky or awesome?

I was wondering per chance if you have tried these depletion mode mosfets in any tube type circuits with an output transformer? I thought it would be cool to build a Champ or something like that using these mosfets.
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Old 20th March 2010, 08:18 PM   #298
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It means reliably.

And yes, I have a project using an output transformer
scheduled for publication this summer.

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Old 20th March 2010, 09:07 PM   #299
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Old 21st March 2010, 02:15 AM   #300
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Default Am I hallucinating?

OK, so I finally decide to build the De-lite. Got it going no problem. Spend a day listening in my workshop then a day listening in my sun room with no problems. I brought the amp in tonight and hooked it to my Bride of Zen and Hawthorne Duets. I have a pair of t-line subs using plate amps. I put the amps in the floor one near each sub - about 8" away. Most everything sounded great except for Patricia Barber's - Ode to Billy Joe. One channel of the amp started buzzing slightly when the bass hit certain notes. I kept working trying to track the buzzing down. I finally touched the amp to see if it was hot and the buzzing diminished. I moved the amp a foot away and the buzzing totally quit. Can those light bulbs suffer from microphonics or have I just lost my mind?



BTW - Hanging with NP is a love/hate relationship. I just kicked my McCormack DNA-1 to the sunroom and am having to start a F5, Aleph 30....something! hehe j/k At least it keeps me out of trouble. Oops, wife demanding attention. ttyl
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