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#971 |
diyAudio Member
Join Date: Jun 2014
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hi ive built this circuit following the layout that was posted by a member and the thing works, and offset is almost zero when the input is shorted. however when its not, the offset is 3.8v both at the output and the input. what could be the cause of this? oscillation?
it seems to play fine, and the sound is marvelously clear. however im missing a lot of drive i am used to and thinking its related to the misbehavior that is the offset. i should add i did not use bc560C but instead used B... whereas bc550 is C |
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#972 |
diyAudio Member
Join Date: Aug 2006
Location: Texas
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It sounds like your DC trimmer may be open or has a bad connection.
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The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer! Need something built, repaired or modded? PM me and ask what I can do! |
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#973 |
diyAudio Member
Join Date: Jun 2014
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Thank you, Keantoken. Yes, I fixed it by omitting the dc trimmer R9 altogether. I neglected to read the whole thread and chose a 5k pot based on the schematic alone.
As for the sound- this is by far the most delicate mid and high freq ive ever heard from a buffer. It seems to add that special something to the sound which makes yoh want to listen more and more, while being so much more transparent than most of my builds in the past that im hearing things ive never heard before. That being said, id like to try the push pull 8 transistor version you mentioned earlier. I believe it will help with the bass because the current transfer is bipolar. I can always tell the leaning of the bass with single ended circuits and the k buffer is sadly not an exception. If you could tell me how to go about doing the push pull version id muxh appreciate it. Do i just mirror the circuit and tie the input and output? |
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#974 |
diyAudio Member
Join Date: Aug 2006
Location: Texas
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Glad you like it!
One half probably wouldn't perform as well and one would always dominate over the other. In which case you would get better performance by just omitting the worse half. This is why I didn't go that route. The Kuartlotron is not like an EF stage where both halves need each other in order to approach linearity. You would not get a symmetrical output behavior, but rather something in between a good performing Kuartlotron and a worse performing one. One thing you could try is to use the BC337-40/327-40. These are slower but more robust transistors. I decided the BC550C/560C were best overall, but the others are also interesting.
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer! Need something built, repaired or modded? PM me and ask what I can do! |
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#975 |
diyAudio Member
Join Date: Jun 2014
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If i change the 10k ohm input to gnd to 100k ohm, will it affect the performance much, and what other values should be changed?
Also instead of 22pf of lpf, id like to use the 100pf wima caps i have. Once again what other values should be changed? |
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#976 |
diyAudio Member
Join Date: Aug 2006
Location: Texas
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Those will both be fine. 100k input resistance will be more sensitive to the input offset trim, but it is a common input resistance chosen for the Kuartlotron.
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer! Need something built, repaired or modded? PM me and ask what I can do! |
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#977 | |
diyAudio Member
Join Date: Sep 2018
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witout stupid people ! there wouldnt be clever ones |
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#978 |
diyAudio Member
Join Date: Aug 2006
Location: Texas
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1W 520 ohm.
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer! Need something built, repaired or modded? PM me and ask what I can do! |
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#979 | |
diyAudio Member
Join Date: Sep 2018
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witout stupid people ! there wouldnt be clever ones Last edited by rookiesparks; 18th February 2021 at 11:38 AM. Reason: add |
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#980 |
diyAudio Member
Join Date: Sep 2018
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oops ,,,,i seem to of worked it out myself, will have to get a 5m trimmer instead of a fixed 2.7m resistor,
__________________
witout stupid people ! there wouldnt be clever ones |
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