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- all tubes on the signal path
- no feedback
- min signal output voltage 250Vrms push-pull
- min signal output current 7mA
- max 2 stages
- only hi-end audio components on the signal path
- passive power supply
- vacuum diode on power supply
- no custom power supply transformer
- no regulator tubes or pentode with low linearity
- inductive power supply to prevent the generation of current peak on diodes
- no dc coupled of stage
- no dual power supply
- indirect heating tubes for zero noise
The requirements are not few items but the design is very easy.
All the audio transformers used in this project areLundahl products and the distributor list is available here
Lundahl is one of the world´s
leading manufacturer of audio transformers used in many professional studio
recording and radio stations so He have a very big experince and all these
products use a custom audio C-core.
I am using a The input stage is the very good Golden Dragon 6SL7.
I am using aDACT stepper attenuator instead of the normal ALPS or NOBLE solution, because the the sound is clearer. A good review of these components can be found on the article published in Hi-Fi World.
The input stage is the very good Golden Dragon 6SL7.
The vacuum diodes used are the 5Y3 Mullard.
About passive components types, I don't leave many choices:
Caddock resistances on cathode, ELNA Cerafine capacitors on cathode.
In all my previous projects I have used in the power supply the ELNA Cerafine capacitors with a very high sonic performances and compact size.
If we skip any economic aspect and no size problem the first components is a paper in oil capacitor.
In comparation test the paper in oil are best of the ELNA Cerafine or other electrolityc type.
Searching a paper in oil capacitor is very important buy new product as the Jensen and not an old stock.
About wire forget the teflon ! use only stranded tinned copper wire with pvc isulator and for loudspeakers the same.
A very good quality stranded tinned copper wire could be buy directly fromE-Z-HOOK that carries an extensive line of fine stranded and extra flexible wire.
This project give a first class sonic performance but this can be easily
compromised by a bad input signal so I suggest you to don't use preampl.
and use one of my DAC projects.
Using one of my top DAC projects all the DIYer's will reach the same sonic result.
The DAC normally included into commercial CDPlayer (even these of significant price) have a rather low performance because the common usage of high NFB operational amplifiers "destroy" the sound given compression effects and poor soundstage stability.
top performance !