• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Audio Note Kit 1 Upgrade

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Hello ! I've built a DIY Audio Note Kit 1:

Amplificador a triodos 300B Single Ended

I have no HUM (this is good) but I'm not fully satisfied with the results. The sound is clear and detailed but a little bright. I've change the JJ for the EML 300b (much better tubes) and i bought a RCA 6sn7, but the sound is still a little bright.

I have two options:

_ Re-build the amp with another schematic (I don't know which, if JELABS, etc...)

_ Follow the Audio Note kit1 modification of DIYPARADISO:

Upgrade Audionot kit 1

with two 5670 instead one 6sn7 and two 5687.

What do you think?
Someone has tried this schematic?

Thank you very much
 
Pre tubes in K1 are good choice. /In my SE 300B I use pre E180F Phillips and plate current 300B is 90 ma/. You can disconnect two caps 0.47uF from cathode 300B and cap 0.47 from pretube /paralleling caps with different media is bad choice/. Put electrol. caps Black gate, Elna Cerafine or Nichicon in both cathodes.
 
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Hi Henry, someone might be able to design a gNFB path for your amp but the SRPP driver stage makes that difficult and tricky to implement (at least for me) since the feedback must be introduced at the grid of the SRPP. If you have a problem with sibilance, feedback is not necessarily the answer. Have you tried different brands of tubes or coupling capacitors? Have any modifications been made? Has it always had the sibilance or was something changed?
 
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