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Old 27th December 2011, 05:40 PM   #111
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May I ask why you are so determined to have a bypass capacitor? Is it for the extra gain?
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Old 27th December 2011, 05:48 PM   #112
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the extra gain yes and not to have feedbach or a 10uf series Cap at the input signal...
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Old 27th December 2011, 06:36 PM   #113
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I didn't listen to the amp with the bypass capacitor. In my case, the added distortion wasn't worth 3-4 dB of gain, so I didn't pursue it further.

You leave me a little perplexed. The source bypass cap does not make direct coupling the input any more or less possible. The input cap is there in Figure 11 in case your SIT has enough gate leakage current to drop some voltage across the input. If you measure the input, and it is at 0V, then perhaps you can go without.

May I suggest building the circuit as intended, getting it working, and then you can experiment and make sparks as much as you wish.

If you really want more gain and no degeneration, the circuit with the negative bias supply is the way to go.

Last edited by Michael Rothacher; 27th December 2011 at 06:42 PM.
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Old 27th December 2011, 06:45 PM   #114
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i mean i choose fig 11 instead of fig 10 because i can swap the input Cap and the negative bias circuit.. but if it must sound bad as it , i will change to fig10
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is there a problem just to have 10ohm resistor for the drain ? or is it must be 11/12ohm
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Last edited by juanitox; 27th December 2011 at 06:48 PM.
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Old 27th December 2011, 06:48 PM   #115
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10 Ohms will change the operating point, you can certainly try it though.

Are your speakers 8 Ohms?
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Last edited by Michael Rothacher; 27th December 2011 at 06:54 PM.
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Old 27th December 2011, 06:56 PM   #116
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yes , avant-garde nano are 8ohm nominal.
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Old 27th December 2011, 07:01 PM   #117
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Wow, those should sound terrific. Try the 10 Ohm. It's easy enough to add some resistance if needed.
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Old 27th December 2011, 07:13 PM   #118
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thanks michael , sorry to be the dumb and dumber of your post
do you think i still can use the 25k gate leak that i have already sold and mount on the 2SK82 with the LM337 schematic?
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Old 27th December 2011, 07:21 PM   #119
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No worries. We're all here to learn and have a little fun hopefully.

I'm sorry I don't understand your question.
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Old 27th December 2011, 07:26 PM   #120
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