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Simple discrete unity gain buffer
Simple discrete unity gain buffer
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Old 7th June 2007, 10:33 AM   #111
nikwal is offline nikwal  Sweden
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Made a low voltage buffer with a depletion mode fet (bsp135 if I remeber correctly) just the fet and a resistor.. That worked nicely but it wasnt hifi-critical at that point.. If I'd do it now I'd try maybe irf610 and 9610 in some kind of diamond complementary design or whatever it's called.. (I made such a thing, but had no use for it so i dont know irl how it would sound, only through the function generator and scope, and spice of course it was nice..
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Old 7th June 2007, 06:55 PM   #112
lineup is offline lineup  Sweden
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Quote:
Originally posted by routhun

Thanks lineup for the JFET BOZ.

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Old 29th September 2018, 03:46 AM   #113
donovas is offline donovas  South Korea
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i p2p'd this and it sounds marvelous. probably the best i've heard for the parts count that it has. is 10uf the positive feedback? and can i increase it for more bass?
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Old 29th September 2018, 06:08 AM   #114
gannaji is offline gannaji  India
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Dear Donovas,
Can you kindly specify the actual circuit you used ?
gannaji
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Old 29th September 2018, 10:18 AM   #115
donovas is offline donovas  South Korea
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Its the one on post 81. Regards,
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Old 29th September 2018, 12:58 PM   #116
gannaji is offline gannaji  India
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Thank you !
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Old 29th September 2018, 04:50 PM   #117
donovas is offline donovas  South Korea
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so once again, its this circuit

Click the image to open in full size.

how can i bias this higher? do i change the bottom resistor 1.5k ohm and the top resistor 15k to lower values?

and is the input resistor necessary if you're not putting a pot before it?
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Old 29th September 2018, 06:34 PM   #118
donovas is offline donovas  South Korea
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p.s. this circuit has a nasty turn on thump... what would be the cause of this?
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Old 30th September 2018, 12:27 AM   #119
xrk971 is online now xrk971  United States
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Simple discrete unity gain buffer
Most SE Class A amps will have a turn on thump. There are a few ways to prevent it. 1) use a cap multiplier on the supply to slowly ramp up the voltage over 10seconds. Something like this (has a 4v dropout penalty though); 2) use a relay with time delay circuit either RC constant or microcontroller.
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Old 30th September 2018, 05:30 AM   #120
donovas is offline donovas  South Korea
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Xr971, i do use that cX, but mine the voltage comes up rather fast?

Ah so the buffers class a. No wonder i like the sound so much. Do u perhaps have any other 0gain circuits i can compare to?
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