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Sunday, June 14, 2015

The 26 Line Preamplifier


In the tube of the month post about the 26 I mentioned that I am working on a preamp with this triode. The preamp has been finished since a while and was playing in my system since then.

Shown above is the signal section with Cunningham CX-326 tubes. The layout is a bit different from my 10Y line stages. This time all chokes placed on the top under transformer covers. There are two filament chokes and two B+ chokes for decoupling of both channels. Since the 26 is perfect for filament bias, this approach is used here.

As usual, the power supply unit has a separate chassis, which contains two independent filament supplies and a common B+ supply for each channel. So another 4 chokes in the PSU and 3 power transformers.

The 26 is a very beautiful sounding tube compared to the 10Y it offers a slightly 'creamy' sound. A tad less resolution but therefore much more forgiving and to some tastes maybe more enjoyable and fun.

The globe tubes even further enhance those characteristics with the sound almost having a 'dark chocolate' flavour. Different ears might perceive this in another way. Although this description might suggest that the 26 has a coloured sound, this is not the case. The overall sound is very detailed and the above is just an attempt to describe the difference to the 10 line stage.

This was a fun project and I am glad that I used the 26 again which I have not used since quite a while. A great tube which has a lot of magic. I hope when he receives it, the owner of this preamp will enjoy it as much as I did during last week.

Best regards



  1. love to try that 'dark chocolate' sound.... :-)

  2. Hallo Thomas, Glückwunsch zum 26-Projekt!! Steht echt klasse da!
    Suche schon seit längerem was mit der "fast vergessenen 26-Triode".
    Mich würde der Schaltplan ( Preamp/ PSU) interessieren.
    Grüsse aus Ba-Wü

  3. Hallo Alex,
    Diese Vorstufe gibt es auch als Bausatz (ohne Gehäuse). Mit dem Bausatz gibt es dann auch den Schaltplan. Auch ein Teilbausatz ist möglich, z.B. nur die Übertrager, Netztrafos und Siebdrosseln. Bei Interesse weiteres genre per email.

    Viele Grüße